«. 8, DEPT. OF iSfllCLilTUI«

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RICE IN THE UNITED STATES:

VARIETIES AND PRODUCTION

Agriculture Handbook No. 289

\

Agricultural Research Service

U.S. DEPARTMENT OF AGRICULTURE
RICE IN THE UNITED STATES:

VARIETIES AND PRODUCTION

l/4epé4á^í¿aled^aff¿^

POI-LOW THE LABEL

u s. eeritiMiNT OF A&IKULTUIE

Agriculture Handbook No. 289

Agricultural Research Service

U.S. DEPARTMENT OF AGRICULTURE

Washington, D.C. IsHued 196«

For sole by the Superintendent of Documents. U.S. Government Printing Office. Washington. D.C. 20402 Price .$1.
CONTRIBUTORS

C. ROY ADAIR, leader, Rice Investigations, Crops Research

Division, Agricultural Research Service, Beltsville,

Md.

J. G. ATKINS, plant pathologist. Crops Research Division,

Agricultural Research Service, Beaumont. Tex.

H. M. BEACHELL, formerly, researcli agronomist, (^rops

Research Division, Agricultural Research Service.

Beaumont, Tex. ; now, plant breeder. Varietal Improvement Department, International Rice Research

Institute, Los Banos, Philippines.

N. S. EvATT, associate agronomist, Rice-Pasture Research

and Extension Center, Texas Agricultural Experiment Station, Beaumont, Tex.

T. R. EVERETT, formerly, leader. Rice Insects Investigations, Entomolog^^ Researcli Division, Agricultural

Research Service, Baton Rouge, La. : now, associate

professor, Louisiana State Universitv. Baton Rouire

La.

V. E. GREEN. JR., associate agronomist, p]verglades Experiment Station, Florida Agricultural Experiment

Station, Belle Glade, Fla.

NELSON E. JODON, research agronomist. Crops Research

Division, Agricultural Research Service. Crowlev. La.

T. H. JOHNSTON, research agronomist, Crops Research

Division, Agricultural Research Service, Stuttgart

Ark.

D. S. IMiKKELSEN, associate agronomist. University of

California, Davis, ('alif.

M. D. MILLER, assistant state director, Agricultural Extension Service, University of California, Davis,

Calif.

W. C. SHAW, formerly, leader. Weed Investigations in

Agronomic Crops, Crops Research L)ivision, Agricultural Research Service, Beltsville, Md. ; now, interdepartmental pesticides coordinator, U.S. Department

of Agriculture, Washington, D.C.

R. J. SMITH, JR., research agronomist, Crops Research

Division, Agricultural Research Service, Stuttgart,

Ark.

J. R. THYSELL, formerly, research agronomist, Crops Research Division, Agricultural Research Service, Biggs,

<'alif. ; now, agronomist. Crops Research Division,

Agricultural Research Service, Brookings, S. Dak,

B. D. WEBB, research chemist. Crops Research Division,

Agricultural Research Service, Beaumont, Tex.

Trade names are used in this publication solely for the purpose of providing specific information.

Mention of a trade name does not constitute a guarantee or warranty of the product by the U.S.

Department of Agriculture or an endorsement by the Department over other products not mentioned.
CONTENTS

Introduction 1

History of rice in the United States 1

Distribution of rice in the United States 3

Acreage, yield, and production of rice in the

United States 3

Selected references 4

Distribution and origin of species, botany, and

genetics 5

Distribution of the species of Oryza and origin

of cultivated rice 5

Description and development of the rice plant

and classification of cultivated varieties 6

Description of plant 7

Development of plant 8

Classification of varieties 9

Genetics 9

Selected references 16

Rice breeding and testing methods in the United

States 19

History and objectives 19

Cultural methods and equipment for breeding

rice in the United States 20

Breeding methods 24

Introduction 24

Selection 25

Hybridization 25

Irradiation 28

Breeding for agronomic characters 28

Testing for milling, cooking, and processing

qualities 33

Milling quality 33

Cooking and processing qualities 35

Breeding for disease resistance 38

Blast 39

Brown leaf spot 39

Narrow brown leaf spot 40

Straighthead 40

White tip 40

Hoja blanca 40

Description of varieties 42

Short-grain varieties 42

Medium-.grain varieties 44

Long-grain varieties 45

Other kinds of rice 47

Performance of varieties 47

Choosing the variety 49

Varietal response to seeding date 51

Results of tests with older varieties 51

Results of tests with newer varieties and

selections 52

Production of seed rice 56

Origin of high-quality seed rice 50

Classes of seed in a certification program, 56

Cleaning, grading, and processing seed rice 59

Standards for seed certification 61

Selected references 62

Soils and fertilizers 65

Types of soils used for rice production 65

Arkansas 65

Louisiana 65

Texas 65

California 65

Chemistry of flooded soils 67

Fertilizers 69

Southern rice area 69

California 71

Selected references 72

Culture 74

Rotation or cropping systems 74

Arkansas 75

Louisiana 76

Mississippi 77

Missouri 78

Texas 78

California 79

Land leveling and seedbed preparation 79

Land grading and leveling 79

Seedbed preparation 81

Seedbed preparation as related to method

of seeding 82

Construction of levees 83

Seed and seeding 84

Seed quality 84

Source of seed 85

Seed treatment 85

Time of seeding 86

Rate of seeding 87

Method of seeding 88

Transplanting rice 91

Irrigating and draining 91

Amount of water required 92

Source of water 92

Quality of water 93

Water temperature and oxygen content 94

Water control methods 95

Water management 97

Draining for harvest 99

Harvesting, drying, and storing 99

Harvesting 99

Drying and storing 103

Selected references 106

Weeds and their control 111

Rice diseases 113

Major diseases 113

Blast 113

Brown leaf spot 114

Narrow brown leaf spot 114

Root rot 115

Seedling blight 116

Stem rot 116

Straighthead 117

White tip 117

Minor diseases 118

Bordered sheath spot 118

Hoja blanca 118

Kernel smut 119

Kernel spots 119

Leaf smut 119

Selected references 120

Insects and their control 121

Rice water weevil 121

Rice stink bug 121

Grape colaspis 122

Other pests of rice 122

Selected references 124

111
RICE IN THE UNITED STATES: VARIETIES AND PRODUCTION

INTRODUCTION

By C. ROY ADAIK

Eice, a leading cereal crop in many countries,

is grown on all continents. It often is considered

to be a tropical crop, although it is grown in both

the temperate and the tropical zones in Africa,

Asia, Xorth America, Oceania, and South America, and in the southern part of Europe. About

93 percent of the world rice crop was produced

in Asia during the 5-year period ending in 19(30

(table 1). Only slightly more than 1 percent was

produced in the United States during this period.

The United States is, howeyer, the leading riceproducing country in North America and is secTABLE 1.—Rice- acreage, production, and yield' per

averages for 5-year

ond i o Ri'azil in the AVestern Hemisphere. Other

leading rice-producing countries, outside of Asia

and adjacent islands, are United Arab Republic

(Egypt) and Malagasy Republic (Madagascar)

in Africa, and Italy and Spain in Europe.

Rice yields yary widely among the rice-producing countries (table 1). Yields generally are

nnich liigher in temperate than in tropical

zones, not only because of diiferences in climate

but also because of differences in cultural practices and in yarieties grown.

arre for each continent and selected' countries,

period. 1956-60

Continent and country Acreafre Production Yield

Asia

1,000 acres

258,000.4

81,353.2

8,050.2

8,091.6

0,615.0

166.4

7,808.0

400.0

095.4

2,825.0

315.0

1,501.8

860.6

325.6

157.0

117.2

50.2

277,702.8

Million pounds

427,330.2

99,106.7

32,845.4

12,496.2

9,539.7

574.4

9,686.0

392.C

2,832.4

6,985.3

582.0

4,946.2

3.434.8

1,440.3

841.7

330.9

240.7

460,263.4

Pounds per acre

1,656

1,218

4,081

India

Japan

South America

Brazil

1,544

1,442

P»^ru - - 3,452

Africa 1,240

Coníío 982

United Arab RepubUo (Etiypt)

North America

Mexico

TTnited States

4,073

2,473

1,844

3,294

Eurooe 3,991

Italy 4,423

Spain 5,341

Oceania 2,823

Australia

World total

4,795

1,657

Source: U.S. Department of Agriculture, Agricultural Statistics: 1958, p. 21; 1959, p. 1960. p. 1961, p. 22.

History of Rice in the United States

Rice has been grown in the United States since

the latter part of the 17th century {;3)} Trial

plantings of rice were made in Virginia as early

as 1609 (4). Apparently other plantings were

made in the colonies along the South Atlantic

coast from that time on, and ricegrowing was

firmly established in South Carolina about 1090.

Until about 1890, rice in the United States was

grown principally in the Southeastern States, although some was grown along riyers in the South

Central States. Experimental plantings were

1 Italic numbers in parentheses refer to Selected References, p. 4.

made in the prairie section of southwest Louisiana

from 1884 to 1886 (7), and rice culture became

established in that area about 1888. Production

then increased rapidly in that part of Louisiana,

and in the adjacent part of Texas. Some rice was

grown along riyers in Arkansas in early years,

but it did not become an important cash crop in

the State until after 1904 (P), when ricegrowing

was started in Grand Prairie. Experimental

plantings were made near Butte Creek in the Sacramento Valley in California in 1909 (5), and

rice became established as a commercial crop in

that area about 1912. Rice production has been

of considerable importance in the delta area of

Mississippi since about 1948 (2).
AGRlCLíLTURE HANDBOOK 2 89, tl.S. DEPT. OF A(iRI(!ULïURE

ARKANSAS

SECTION AND ACRES

COUNTY

NORTHEAST

Clay 7,770

Croigbeod 16,935

Crittenden 6,439

Cross 34,060

Faulkner 318

Greene 5,406

Independence 852

Jackson 20,200

Lawrence g 251

Mississippi 1,505

Poinsell 38,400

Randolph 2,100

St. froncis 17,840

While 1,140

Woodruff 19,760

CENTRAL

Arkansas 76,150

Clork 400

Con wo y 114

^la' Spring 4 70

Jefferson 17,04 6

L" 8,395

'""f^e 39,000

""airoc 14,000

''^"y 981

''''illips 5,068

'''"'"'le 39,570

Puloski 1,855

SOUTHEAST

Ashley 6,429

'^'''"' 9,603

?,= ^*'a 14,000

""''" 4,594

Lincoln 9,410

FluUKE 1.—:

ARKANSAS CONT. CALIFORNIA LOUISIANA

SOUTHWEST

Lo f a y e 11 e

Linie River

Miller

TOTAL ACRES...

ARKANSAS 1963

SECTION AND

COUNTY

ACRES

.... 2,000

430,061

TEXAS

SECTION AND

COUNTY

EAST

ACRES

Chambers "

Ho r d i n

Jasper

Jefferson ••

Liberty

Newton

Oronge

CENTRAL

Br az 0 r ia• "

Ft. Bend"--

GaI ves f 0 n "

Harris

Waller

WEST

Austin

Co 1 h ou n -'•'

Colorado •--

Jackson •••-

Lavaco

Ma t ag 0 r d 0 -

Victorio

Whar Ion-...

.... 559

•43,503

•- 1,004

86

62,294

37,540

731

-• 4,972

SACRAMENTO VALLEY

Butle 55,202

Coluso 74,125

Glenn 40,846

Placer 3,050

Sacramento 10,126

Suiter 57,789

Yolo 25,062

Yubo 12,549

SAN JOAQUÍN VALLEY

Fresno 20,818

-• 3,435

197

••2,745

•• 7,429

•• 7,453

•• 2,260

.... 544

Kern

Kings

Modero

Merced

Son Joaquin*

Stanislaus-..

Tulare

SECTION AND

PARISH

NORTH

Eost Corroll*

Grant

Madison

Morehouse.*..

West Carroll •

RIVER

Ascension-^'

Assumption -

Iberville

Lafourcfie -••

St. j om es •••

St. John •••-

Tensos

ACRES

-•5,267

••••185

•••896

5,949

• 1,185

•1,316

•••196

• 323

.... 54

•1,472

1,436

•• 126

-54,003

19,203

• 12,143

34,889

15,038

TOTAL ACRES

CALIFORNIA 1963

323,630

iSSISSIPPI

-.2,865

•••4,287

•35,599

• 27,153

•••6,194

•44,846

•• 5,083

-52,740

TOTAL ACRES

TEXAS 1963 '

•464,732

COUNTY

Bolivar

Coohoma

De Soto

Hancock

Humphreys

Leflore

Quitmon

S horkey

Sunflower

Tallohotche

Täte

Tunica

Washington

TOTAL ACRES

MISSISSIPPI 196'3'

ACRES

TECHE

Avoy elles.

Iberio

LafayetteR 0 p i d e s • • • •

St. MartinSt. Mory-^^

2,770

6,500

• 9,530

•••574

4,060

• 3,100

,400

664

639

184

935

874

408

,150

300

510

246

895

427

SOUTHWEST

Acodia

Allen

Beauregord •••*

Colcasieu

Cameron

Evan geline

Jeffe r son Da vi

' 93,500

•24,000

•• 4,943

•65,088

•13,337

• 39,640

-95,692

St. Londry 16,945

Vcrmillion 114,800

TOTAL ACRES 5,2,884

LOUISIANA 1963

50,632

Distribution of the United States rice acreage in the principal producing States.
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION

Distribution of Rice in the United States

Although rice is probably the leading food

crop of the world, it is a major crop in the United

States in certain areas only. Rice production in

the United States is centered in the Southern

States of Arkansas, Louisiana, Mississippi, and

Texas and in California. It is the principal cash

crop in many counties and parishes (fig. 1).

Small amounts of rice also are grown in Missouri,

Oklahoma, South Carolina, and Tennessee. Some

rice has been grown in each of the States in

Southeastern United States.

In the United States, satisfactory rice crops

require (1) high temperature, especially relatively high mean temperatures during the growing season; (2) a dependable supply of fresh

water for irrigation; (3) a terrain that is level

enough to permit flood irrigation but that slopes

enough so that surface water can be readily

drained; and (4) soil that will hold water well

because of its fine texture, or a subsoil through

which loss by seepage is small (6). These climatic and soil conditions prevail in the areas

where rice is grown in the United States.

Rainfall and humidity during the growing season are comparatively high in the Southern

States, so less irrigation water is required there

than in California (i). Irrigation water is supplied from streams, from reservoirs where water

is impounded in winter and early spring, and

from wells. To produce optimum yields, proper

cultural practices must be followed. These practices include preparing a suitable seedbed, maintaining a uniform depth of irrigation water,

providing sufficient soil nutrients for optimum

growth, and controlling insects and diseases and

weeds and grasses. Good-quality seed of adapted

varieties must be used to maintain quality and to

produce high economical yields. For safe storage, the rice must be harvested at the right stage

and dried to the proper moisture level.

Acreage, Yield, and Production of Rice

in the United States

In the 5-year period ending in 1963, Arkansas

produced 2Í.89 percent of the total United States

rice crop; Louisiana, 24.26 percent; California,

24.12 percent; Texas, 23.99 percent; Mississippi,

2.47 percent ; and Missouri, 0.26 percent (S). The

United States has been self-sufficient in rice production since 1917, and now is one of the leading

rice-exporting countries of the world.

Rice acreage in the United States (fig. 2) increased from a 5-year annual moving average of

301,000 acres in 1899 to 1,105,000 acres in 1922.

It then declined imtil 1936. The 5-year annual

2,250

2,000

250

,750

1,500 -

1,250

1,000

750

500

FIGURE 2.—Harvested acreage of rice in the United

States (5-year annual moving average), 1899-1963.

moving average acreage increased each year until

1955, when it was 2,106,000. The peak acreage of

2,550,000 was reached in 1954. The annual acreage then declined until 1957, when it was

1,340,000. Starting in 1958, acreage increased

slightly each year until 1963, when it was

1,765,000.

Yield per acre (fig. 3) in the United States increased from a 5-year annual moving average of

1,091 pounds per acre in 1899 to 3,563 pounds per

acre in 1963. This gradual increase in yield per

acre has been brought about by improved cultural

practices, such as better rotations, weed control,

and irrigation and fertilization practices; better

machinery, which led to improved and more timely field operations; better methods of controlling

diseases and insects; and improved varieties.

Average yields have fluctuated from year to year,

with a long-term upward trend. However, there

have been short periods when average yields declined. The 5-year annual moving average yield

per acre increased gradually from 1899 to 1940,

but six times during this period the 5-year average yield was lower than that of the previous

year. Yields declined from 1941 to 1945. Labor

and equipment were scarce during the war years,

and the acreage was expanded to include some
AGRICULTTTRE IIxVNDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE

3,500

3,000

5 2,500

2,000

5 1,500

1,000 -

1899 1929 1939

YEAR

969

FIGURE 3.—Yield per acre of rice in the United States

(5-year annual moving average), 1S£M;^1963.

fields with p(X)r soil. These factors may have

accounted for the lower yields in this periocl. The

5-year average yield per acre increased each year

from 1946 through 1963. Higher rates of fertilizer application and other improved cultural

practices increased yields during this period.

Production of rice (100-pound bags) in the

United States in I7l8 was estimated to be over

79,000 bags of rough rice (J). Production increased to nearly 3.5 million bai^s in 1849. It

then declined to about 637,000 bags by 1871. By

1899, production had increased to ^3.4 million

bags.

The 5-year annual production increased to 19.4

million bags in 1922. Production declined until

1926 and then increased slightly. However, it

remained within the range of Í4 to 20 million

bags until 1936. The annual production fluctuated from year to vear but with an upward trend

during the period from 1937 to 1954 when production reached a high of 64.2 million bags.

Annual production declined until 1958 and then

mcreased each year until 1963 when the annual

production was 69.3 million bags, and the 5-year

annual moving average was 59.3 million bapfs

(fig. 4).

Selected References

(1; ADAIK, C. R., and ENGLER, KYLE.

1955. THE IRRIGATION AND CULTURE OF RICE. lu

Water, U.S. Dept. Agr. Yearbook of Agr

pp. 380-394.

(2) MILLER, M. D., and BEACHELL, H. M.

1962. RICE IMPROVEMENT AND CULTURE IN THE

UNITED STATES. Adv. in A^roD. 14: 61-108.

(3) CHAMBLISS, C. E.

1912. A PRETJíMINARY REPORT ON RICE GROWING IN

THE SACRAMENTO VALLEY. U.S. Dept, Agr

Bur. Plant Indus. Cir. 97, 10 pp.

(4) GRAY, L. C, and THOMPSON, E. K.

1941. HISTORY OF AGRICULTURE IN THE SOUTHERN

U.S. TO 1860. Carnegie Inst. Wash. Pub.

430. [Reprinted in 2 v.] Peter Smith,

New York.

(5) HOLMES, G. K.

1912. RICE CROP OF THE UNITED STATES, 1712-1911.

U.S. Dept. Agr., Bur. Statis. Cir. 34, 11 pp.

(6) JONES, J. W., DOCKINS, J. O., WALKER, R. K., and

DAVIS, W. C.

1952. RICE PRODUCTION IN THE SOUTHERN STATES.

U.S. Dept. Agr. Farmers' Bui. 2043, 36 pp.

( 7) KNAPP, S. A.

1899. THE PRESENT STATUS OF RICE CULTURE IN

THE UNITED STATES. U.S. Dept. Agr., Bot.

Div. Bui. 22, 56 pp.

( 8 ) UNITED STATES DEPARTMENT OF AGRICULTURE.

1968. RICE. ANNUAL MARKET SUMMARY, Yô^J.

U.S. Agr. Market. Serv. AMS-277, 47 pp.

(9) ViNCENHELLER, W. G.

1906. RICE GROWING IN ARKANSAS. Ark. Agr.

Expt. Sta. Bui. 89, pp. 119-129.

KTGT RF 4.—Production of rice in the United States

(5-year annual moving average), 1899-1963.
DISTRIBUTION AND ORIGIN OF SPECIES, BOTANY, AND GENETICS

By C. ROY ADATR and NELSON E. JODON

Distribution of the Species of Oryza

and Origin of Cultivated Rice

Species of Ori/sa have been reported from all

continents except Europe and from many of the

hirger islands. Rosclievicz (53) ^ reported a comprehensive study of the genus, and he concluded

from his study that there were 20 species of

Orysa.^ Chevalier {lo) reported a similar study

in which he recognized 22 species. Chatterjee

i IS) later summarized the information on Ort/2a

and listed 28 species. Tateoka (64) summarized

the information on species of Oryza in 1968 and

recognized 22 valid species. The 18 species that

were recognized by both Chatterjee {13) and

Tateoka (6'4) are listed in table 2.

Five species were reco^iized by Chatterjee [13)

but not by Tateoka {6^ so they were not listed

in table 2. These are O. granulata Nees & Arn.

ex Hook, f.; 0. pereyinis Moench; 0. sativa L.

var. fatua Prain; O. stapfi Roschev. ; and 0.

sxihvJata Nees. Four species were recognized by

Tateoka (6'4) but not by Chatterjee {13) so they

were not listed in table 2. These are 0. angu^stJ'

folia Hubbard; 0. IjarthU A. Cheval.; 0. longigluwis Jansen; and 0. rufpogen Griff. The

cliromosome number of the species of Oryza as

reported by Kihara (35) and the distribution as

reported bv Chatterjee {14) also are shown in

table 2.

TABLE 2.—Species, chromosome rmmher. and elistriljiition of Orvza

Species

1. 0.

2. 0.

3. 0.

4. 0.

5. 0.

*3. 0.

T. 0.

S, 0.

9. 0.

10. 0.

11. 0.

¿k Roelir.

(fc Roehr.

alta Swallen

australiensis Domiii __

brachyantha A. Cheval.

bre vil if/ida ta A. Cheval.

coarctata Roxb.

eichinrjeri Peter

[jlabrrrlma Steiid.

rjrandirjlumis fDoeU ) Prorloehl

JatifoJia Desv.

meyeriana (Zoll. *fc Mor.) I>aill.

minuta Presl

12. 0. offlcinalis Wall, ex Watt __

13. 0. perrieri A. Camus

14. 0. punctata Kotschy ex Steiid.

15. 0. ridleyi Hook. f. I

16. 0. sativa L.

IT. 0. srlilechteri Pilger

IS. 0. tisseranti A. Cheval.

Chromo

some Xc

f2n)

Distribution

24

24

and 4S

24

24

24

48

48

24

and 48

48

24

48

24

48

24 and 48

South America and Central America.

Australia.

West Tropical Africa and Central Africa.

West Tr(»pical Africa.

India and Burma.

East Africa.

W>st Tropical Africa and Central America.^

South America.

Central America, South America, and West Indies.

.Java, Borneo, Philippines, and Siam.

Malay Peninsula, Philippines, Sumatra, Java, and

Borneo.

India and Burma,

^ladagascar.

Northeast Tropical Africa.

^lahiy PetiÍnsula, Siam, Borneo, and New Guinea.

India and Indo-China.

New Guinea.

Cnntral Africa.

1 P.I. 269630. Collected in El Salvador by H. M. Beaohell and identitied l)y Eugf-iip Critlith, Crops Research

1 Mvision, Agricultural Research Service, Beltsville, Md., and J. R. Swallen, Smithsonian Institution, Washington, D.C.

Rosclievicz (53) divided the species of Oryza

into four sections on the basis of morpholo<ric

characters and geographic distribution. Kihara

(35) modified this grouping to include species not

reported by Roschevicz.

In 1963, a committee ^ reviewed the classifica1 Italic numbers in parentheses refer to Selected References, p. 16.

2 This committee was appointed at the Rice Genetii^*

Symposium convened at the International Rice Research

Institute, Los Banos, the Philippines. The members w^ere

S. Sampath, India ; T. Tateoka, .lapan ; and M. T. Henderson, United States.

tion and nomenclature of Oryza and recommended

that standards be adopted and used uniformly.

This committee recognized 19 valid species of

Oryza. Seventeen of these species are listed in

table 2. The species not recognized by this committee tliat is listed in table 2 is O, graiidiefivmix.

The other two species recognized l3y this committee ai'e 0. angastifalia and O. longiglnrnis.

The committee also believed that certain aspects

of taxonomy in Oryza are uncertain. These are:

(1) The relation and nomenclature among i\\^

taxa commonly designated as Ö. saliva var. fatvba
AGMí ! i rUiœ HANDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE

(or /. spontanea RosclieA,:' uid 0. perenm's

(Asiatic, American, and Afriraii) subspecies and

varieties; (2) the relation of the form commonly

designated 0. stapfii to 0, glahemmu and 0. breviUgulata; (3) the relation between 0. gramdata

f. and 0. imyerkma; (4) the relation between 0.

alta and 0. grandiglumis; and (5) the status of

the taxa previously designated 0. ubœnghemi><

Chev. and 0, malampuzhaensls Krish. and Chand.

The committee also believed that the form commonly designated 0. subidata should be excluded

irom Oryza and should be recognized as Rhynchoryza subuhta (Nees) Baill.

Chatter]ee (li) reviewed the literature on the

origin and distribution of wild and cultivated

rice. He concluded that the eastern part of

India, Indo-China, and part of China could be

considered the area where cultivated rice {Oryza

sativa) originated. Chatterjee further concluded,

as did Roschevicz (55), that for the genus as a

whole or the section Sativa Roschev., the center

of origin is Africa. He was of the opinion that

0, altas 0. aii^tralieiisis^ 0, hixichyantha, 0,

eichingeri^ 0, grandiglumis^ 0. latífolia, 0. mmuta^ 0, pemeri, 0. schlechteH^ 0. subidata^ and

0. tisseranti had little part in the ancestry of cultivated rice. This view seems to be based either

on the fact that these species do not cross with

0, sativa or on the fact that they occur naturally

in areas far removed from the center where rice

cultivation orimnated.

Many investigators have studied and discussed

the origin of the genus Oryza and of cultivated

rice {13, U, 15, 35, 1^6, 1^8. 50, 53, 55, 56, 67, 70),

It is generally concluded that the original ancestral species may no longer exist and that present

varieties evolved through progressive stages from

known wild species {56).

Nandi {U) and Sakai (5^) proposed that a

species with a haploid number of five chromosomes was the ancestor of Oryza. This proposal

was rather widely accepted. Nandi (^4) observed

that in the somatic complement having 24 chromosomes there were two members of eight types

and four members of two types. The maximum

association in second metaphase was two groups

of three and three groups of two. It was concluded from this observation that the haploid

genome of the present 0. satina is composed of

two original five-paired species belonging to two

different ancestral genomes in which two chromosomes were duplicated.

Later, Shastry, Rao, and Misra {60) identified

12 pachytine bivalents in a strain of 0. sativa.

based on their length and arm ratios. This finding seems to cast considerable doubt on the validity of the supposition "that O. sativa is a secondarily balanced allo-tetraploid which originated through hybridization between two different

five-paired species in which two chromosomes

were duplicated, probably due to meiotic irreguhirities in the hybrid. This followed by a subse-

((uent doubling of the chromosomes attained the

secondary balance of n = 12, the present existing

number of 0. sativa'''^ (4-^).

Sampath and Rao {56) "inferred that Oryza

perennis is the ancestral form of cultivated rices,

having given rise to 0. sativa in Asia and 0. glaherrima in Africa by human selection." These

authors were of the opinion that 0, hreviligulata

and 0. sativa var. fatua are of collateral descent

from O. perennis. The present types that are

classified as O. sativa var. fatua or spoiitanea

show morphologic differences that may be due to

genetic transfer from cultivated rice. From this

it is inferred that these wild forms are derived

from hybrids with cultivated rices and are not

the progenitors of cultivated rice. Instead it has

been strongly suggested {55, 56. 70) that an intermediate type may be the immediate ancestor of

O. sativa-.

Description and Development of the

Rice Plant and Classification

of Cultivated Varieties

Cultivated varieties of (9. sativa are divided

into groups on the basis of several characters.

The principal division is on the basis of sterility

of the hybrid. Kato and others {33, 31^) observed

that in crosses of certain varieties from the temperate zone and certain varieties from tropical

areas, the hybrids had a high percentage of sterile

florets. The hybrids between varieties within

these two groups were as fertile as self-pollinated

parent varieties.

They proposed that the temperate zone varieties

be named japónica and the tropical zone varieties

indica. Kato and others {31^) observed no difference between japónica and indica varieties in

chromosome number and behavior or in pollen

formation. However, in the hybrid, pollen formation Avas abnormal. Serological investigations

showed differences between japónica and indica

varieties.

Later, Terao and Midusima {66) noted that

another group of varieties, principally from tropical islands of Southeast Asia, were intermediate.

This last group is referred to as bulu.

It appeared from the earlier studies that the

varieties could be divided into three distinct

groups based on sexual affinity. Mizushima {39),

however, determined that this was not true and

that sexual affinities among varieties from these

groups varied gradually from one extreme to the

other.

Oka (^5) compared 147 varieties from widely

different geographic areas on the basis of a number of morphologic and physiologic characters
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION

and by observing sexual affinity in hybrids. From

these studies, he placed the 147 varieties tested

into indica (continental) and japónica (insular).

He subdivided the japónica gi^oup into ''tropicalinsular" and ''temperate-insuhir/'

In a review on reports of sterility in hybrids

between indica and japónica varieties, Sliastry,

Rao, and Misra (60) explained sterility on the

TABLE 3.—Characters of japanwa.

basis of chromosome structural differences, lethal

o-enes, inversions, paracentric inversions, genie

nuitations, and cryptic structural hybridity.

There are many morphologic differences between typical japónica, indica, and bulu varieties

(table 3). Varieties that are known to be progenies of hybrids are intermediate in many

respects.

indica, and hiiiu ri^e varieties

Character Japónica Indica Bulu

Grain shape Short

Short

Long .

Long

La rire

Large.

Long.

Small.

Light green.

Stiff

Second foliar leaf :

Length

Angle -_ _ Small

Foliage color _ _ Dark green Lisrht srreen

Culm :

Stiffness _ - Stiff Not stiff

Erectness Upright Sureadins" Upright.

Long.

Medium

Length Short Long

Upright

Flag leaf :

Angle Medium

Shape Narrow and short

Medium

Narrow and long

Well emerged

Many

Broad and long.

Not emerged.

Few

Degree of emergence

of upper node.

Number of tillers Many

Pubescence Pubescent Variable

None

Víí riablp

Awns None

Many

Heavy

Many

Panicles : Number Many

Light

Long

Few

Weight Heavy

Length Short Medium

Density- Dense Medium Medium

Branching of rachis Few Medium Many.

Source: Nagai HO).

Description of plant

The principal parts of the rice plant are a

fibrous root system, cuhns, leaves, and panicles.

The fibrous root system extends outward and

downward from the base of the plant. Adventitious roots that arise from the lower nodes of the

culms are finely branched. The extent of the root

system and the size of the roots vary with variety

and type of culture.

The culm and leaves develop from ih.^ plumule.

The culm consists of the nodes, which have solid

centers (septum), and the intemodes, which are

hollow. The culms of most varieties of Oryza

sativa are erect or ascending, although there are

procumbent types. Varieties range in height

from less than 15 to more than 96 inches (37 to

240 centimeters) although varieties grown in the

United States range from 36 to 54 inches. The

culms vary in diameter at the base from 5 to 15

millimeters. The number of nodes in the culm

ranges from 13 to 16 (5^), and the number is

significantly correlated with length of growing

season. Usually, four internodes elongate; the

upper internode (peduncle) is usually the longest, and it bears the panicle.

The leaves of the rice plant are flat and range

from 7 to 20 milimeters wide. The coleoptile

usually is considered to be the first leaf. It has

stomata but few chloroplasts. The mature foliage

leaf consists of the sheath at the base, which surrounds the culm for some distance; the blade,

which is set at an angle with the sheath; the

ligule; and the auricles. The junction of the

sheath and blade often is called \h^ collar or

junctura. The swollen zone at the base of the

sheath where it joins the culm is the pulvinus.

The panicle of most varieties is fairly dense

and drooping. There is, however, much intervarietal variation, since the panicle ranges from

open to very compact and from erect to drooping.

From one to three or sometimes more branches

arise alternately or somewhat in whorls at each

node of the peduncle. The rachilla bears the

spikelet, and each rachilla arises on the same side

of the rachis. Each rachilla usually has a single

spikelet, although some varieties may have two or

more spikelets on a rachilla. The spikelet is

laterally compressed, is one flowered, and articulates below the outer glume.

The two outer glumes usually are short, that is,

less than one-third the length of the lemma, al-
AGRICUl/l LHCE HANDBOOK 289, U.S. DEPT. OF AGRICULTURE

thoiio;h tliere are types that ]i;i\e uluines as lono;

as the lemma or long-er. I1i<' lemma (inferior or

k-)wer ñoweriiig ghime) is rigid, keeled, and three

nerved, and has' two additional thin, marginal

nerves that can be seen only in section. The

apiculus or ti]) of the lennna is sometimes i)rolonged to form the awn. The palea (snperior or

upper riowering glume) is similar to the lemma,

Init narrower. It lias two nerves near the margin

and a thin midnerve that can be seen only in section. The ñower is composed of a one-carpellate

pistil with a bifurcated, plumose slender style;

and six stamens with yelhnvish, four-lol)ed, twocelled anthers. The principal parts of the caryopsis (brown rice) are the embryo and endosperm and the covering tissues.

Development of plant

Rice seed germinates rapidly when moisture,

temperature, and oxygen are optimum. The embryo, which consists of the organs that develop to

produce the rice plant, lies in a slanting position

at the base of the grain on one side of the endosperm. The endosperm contains the stored food

that nourishes the developing seedling until the

roots have developed sufficiently to obtain nutrients from the soil.

At germination, the coleorhiza pushes through

the pericarp, leaving a cavity. The primary root

soon elongates, fills the cavity, and then pushes

through the coleorhiza. The root extends upward

for a short distance and then turns down. About

this same time, the coleoptile emerges and rapidly

elongates. The epicotyl below the coleoptile also

elongates. Elongation varies with the depth the

seed is planted. It elongates enough to l)ring the

base of the coleoptile to the surface of the soil.

When the coleoptile emerges from the soil, it

splits on the side opposite the scutellum, and the

foliage leaves soon appear. Usually in about 2

days, two adventitious roots start t<) develop in

the meristematic zone on the side opposite the

scutellum. A third adventitious root may appear

later at the coleoptile divergence opposite the two

older ones. Lateral roots soon develop from the

primary and adventitious roots {71),

The main axis of the plant, often called the

primary tiller, is differentiated rapidlv. The

meristematic region is at the base of the internodes; this is typical of all grasses. With three

early (130-day) United States varieties, tillering

started within 3 weeks after germination, and all

tdlers that produced panicles were formed within

a 3-week period (4). Japónica varieties started

to tiller about 14 days after transplanting and

tillering was completed in 23 to 25 days (5í2).

Indica varieties started to tiller about ^14 days

after transplanting, and all tillers were initiated

m 3 to 5 weeks from this time, depending on the

length of growing period of the variety {Jß).

Tillers develop from buds in the axil of the node

and the arrangement is alternate {32^ Jf9). Japónica varieties {32) develop secondary tillers from

the buds at nodes 3 or 4 to 10. Tillers from node

10 often do not produce panicles. Tertiary tillers

may develop from buds at nodes of the secondary

tillers.

Panicle formation starts when all nodes have

been formed. The length of the period from

seeding or transplanting to the starting of panicle

formation varies with the length of growing

period of the variety. The period up to formation of the panicle primordium constitutes the

^'vegetative'' stage. It is this period that accounts

for the variation in length of growing period

among varieties. Formation of the panicle primordium starts about 50 days after seeding for

very early United States varieties and about 100

days for later United States varieties. The period from formation of the i^anicle primordium to

emergence of the panicle from the sheath ranges

from 24 to 31 days for indica varieties {1^9) and

from 28 to 36 days for japónica varieties (5).

For indica varieties, the panicle primordium

can be noted when it is 0.125 to 0.25 millimeters

long. By the time it is 0.5 millimeters long,

''hemispherical excrescences are observed at the

base" (45^). The hemispherical excrescences represent the branches of the panicle. Rudiments of

the spikelet on either side of the basal a^is are

perceptible when the panicle primordium is 5.0

millimeters long. The panicle primordium then

elongates, and the spikelets are differentiated

progressively from the tip down to the base of the

panicle. Spikelets in the tip and middle of the

panicle have reached maximum length by the

time the panicle has completed its elongation,

which is 15 to 20 days after formation of panicle

primordium. The spikelets at the base of the

panicle complete their elongation by the time the

panicle emerges from the sheath {Jf9),

Similar results were reported for a variety from

the Philippines {30), Anthesis starts the first

day of emergence of the panicle. It begins with

the ñowers at the tip of the panicle and continues

progressively at the tip of each branch of the

panicle. The greatest number of flowers open

the second or third day after the panicle emerges.

Anthesis occurs over \\ period of 6 to 10 days,

vaiwing with weather and variety. It usually

occurs from midmorning to shortly after noon.

The time differs with variety, location, and

weather (5, 52), Pollen is shed just before or at

the time the flower opens.

The formation and development of the embryo

of a japónica variety {65) and of a variety from

tlie Philippines {30) has been described! The

process is similar in both varieties. Juliano and

Aldama {30) reported that "development of the
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 9

megasporange, megaspore mother cell, and embryo is normal and folloAvs very closely those

reported by other investigators. The embrvo sac

is of the normal octonncleate type/' These nivestigators also observed that ''clevelopment of the

microsporange is normal and follows those reported in many angiosperms" ; that '\livision of

the microsi:)ore mother cell is successive''; and

that ''long before anthesis the young microspore

contains two coats, a thin peripheral cytoplasm,

wherein a single nucleus is embedded, and a single

germ pore." Double fertilization occurs about 12

hours after anthesis (65). In a japónica variety,

the caryopses reach maximum length in about Í2

days after flowering, maximum width or breadth

(dorsoventral diameter) in about 22 days, maximum thickness (lateral diameter) in about 2S

days, and maximum dry weight in about 35 days

(o7). Similar results were obtained for United

States varieties; air-dry kernel weight and percentage of germination were maximum about 35

davs after the first panicles emero^ed from the

sheath (61).

Classification of varieties

Cultivated varieties of rice belong to the gemis

Oryza L., tribe Oryzeae, and family Gramineae.

Most cultivated varieties are in the species Oryza

sativa L., although varieties of the species 0.

gJahemma are cultivated in Africa. 0. sativa, is

an annual ; but when moisture and temperature

are optimum and in the absence of disease, jilants

have survived and produced grain for 20 years

or more.

All varieties of rice groAvn in the United States

are in the species 0. sativa L. The commercial

varieties are classified on the basis of (1) length

of growing season, (2) size and shape of the

grain, and (3) chemical character of the endosperm. Ito and Akihama {22) further classified

varieties on the basis of plant height, straw

strength, disease resistance, and color of various

plant parts.

On the basis of length of growing season,

United States varieties grown in the Southern

States are divided into four groups: (1) Very

early (100-115 days); (2) early (116-130 days)^

(3) midseason (131-155 days) ; and (-1) late (150

days or more). The length of growing season is

somewhat longer in California than in the South.

The difference in length of growing season between these two areas is caused by day lengtli

and temperature.

The LTnited States varieties are divided into

three grain size and shape classes: short (Pearl),

medium, and long. The more slender long-grain

varieties sometimes are considered a fourth class.

Examples of the respective groups are Caloro,

Nato, Bluebonnet 50, and Kexoro. (See ^'Eice

Breediiig and Testing Methods in Ú\^ United

States,'' p. 31.)

On the basis of chemical characters, rice types

are divided into waxy (glutinous; endosperm

contains no amylose) arul conunon (ordinary

starchy; endosperm contains amylose as well as

amylopectin). Only a very small acreage of

waxy rice is grown in the United States. The

})ercentage of amylose in the starch in the endosperm of varieties groAvn in the United States

varies rather widely. (''See Eice Breeding and

Testing .Methods in the United States,'^ ]>. 38.)

A more detailed system is needed to classify the

many varieties and lines used in breeding studies.

Much work has been done to devise objective

methods of classifying rice varieties. Previous

work was summarized and a proposal for classifying rice varieties was formulated by a special

committee in India {21), The committee proposed that rice varieties be classified on the basis

of qualitative and quantitative characters. Nagai

{IfO) reviewed systems used to classify rice varieties. These systems were followed rather closely

in the Food and Agriculture Organization,

^'World Catalogue of Genetic Stocks—Eice,^' (i)

and subsequent supplements. The classification

system used in the laiited States includes the

items in these systems with certain modification

and additions.

Genetics

Varieties of ordinary cultivated rice, being

largely self-pollinated, remain uniform and constant if care is taken to preserve pure seed. Mutations, chromosome changes, and natural crossing, however, have brought into existence a wide

diversity of types and varieties that aiïect every

part and function of the plant. Plants may be

short or tall enough to grow in deep water; may

have colored pigments of various shades distributed in different ^^atterns over the plant; may

tiller little or profusely; may have long and

slender or short and round grains, with or without awns; and may have translucent or opacjue

kernels that differ in chemical composition. Also,

the life cycle of one plant may be three times as

long as that of another.

Differences that can be sorted into distinct contrasting classes make possible the study of segregation and recombination as well as linkage relationships of genes, which are the units of heredity.

For convenience in publishing genetic studies,

differences that have individual efforts great

enough to be recognized are assigned gene sjmibols. To promote uniform usage among rice

geneticists, the International Eice Commission of

the Food and Agriculture Organization of the

United Nations has adopted and recommended

the gene symbols listed below {2),
10 AURK L LIUIU: nANI)P>()OK 2 8 9, U.S. DEPT. OF AGRIC'ULIXTRE

Inherited differences, sucli as plaiii height, tluit

are not clear cut but tliat grade from one extreme

to another involve the interaction of several genes

that have similar effects, but the actual number

and the individual contribution of the genes involved remain uncertain.

Gene symbols adopted and recommended

for rice ^

A

D

A, A^ a

al

An

ail

be

Bd

Bf

I-Bf

bg

Bh

bl

bn

QBt pBr

C alone

CA

CAP

En-C

Ce

chl

Cl

els

clw

da

Dn

Dno

Dn¡

Dp

dw

^ allelic anthoeyanin activator Kcnes

(compleiuentary action with C genes

prodiiees red or purple in apieulus)

-^ albino -

.= Awned -

= laidinientary aui'iele

--= ))i'ittle eulni

= Beaked hull (tip of lemma i-eeurved

over palea )

= Brown furrow (dark brown eolor in

furrows of lemma and palea). See

=^ Inhibitor of dark brown furro^^'

= eoarse (l)ig) culms

= BlaekhuU (complementary genes)-

= physiologir diseases showing dark

brown or blaekish mottled discoloration of leaf

— bent node—culm forms angle at node

— allelic basic genes for anthoeyanin

«•olor; highei" alíeles have pleiotropie

expression in internode

^^ tawny colored apieulus

== red or purple colored apieulus

= completely and fully purple colored

apieulus

= Enhancer of C

= Cercos por(I resistance

=^ chlorina (chlorophyll deticiency)

= Clustered spikelets, also super cluster

.= eleistoganious spikelets

= claw-shaped spikelets. See tri and

Bd

.- dwarfs,^ al:M)Ut % to i/o height or

normal ; discrete classes in segregating populations

-^ double awn

= Dense or '^compact" ; very close ari-angement of spikelets (vs. normal

panicle) ; epistatie to Ur. See Lx

also Cl

= Dense vs. lax

= Normal vs. lax

= Depressed palea and underdeveloped

palea

= deep water paddy, so-called floating

rico

/Reemnmended by the Eighth (1059) PAO International Rice Commission Working Party on Rice Productioii and Protection; the list includes present revisions

^More than one gene involved; subscripts to be supplied by workers as needed. Letter subscripts are suggested for complementary genes, numeral subscripts for

genes having phenotypically similar effects and also f<upolymerie genes.

H

:\i

N

()

FA

KneiEx

Egifs

vr

gh

gl

Crm

H , H',

He

hsp

I

Tla

Ld

Lf

Ig

Lh

Ik

Imx

hi

Lx

Lxo

me

mp

nal

nl

nk or I-Nk

o

Pau

Pg

Ph

Pi

^- Early flowering (low photosensitivity ).- See Lf

= Enhaneei' (intensifier). Precedes

symbol of character affected

-- erect growth habit, recessive to

spreading or procumbent. See dw, la

= Exerted vs. enclosed panicle

= Eragrant flower

= fine stripe

= long glume 2 exceeding % length of

the spikelet

^ goldhull (golden yellowhuU, recessive to straw eolor. ) See Wh

= glabrous (nonhairy) leaf. See Lh

= semi-dominant long glume. More extreme and less regular in expression

than g. Epistatie to g

green and white stripe ; see fs, v.

(H or h is suggested to denote hull, i.e.,

lemma and palea )

= allelic genes for nonanthocyanin colors of lemma and palea appearing

only in the presence of Gh ; goldhull

colors appear with gh

-^ Hf'lmintliosporium resistance

= huUspot

= positive vs. negative staining with

iodine-potassium iodide solution

^ inhibitor (precedes symbol of character inhibited )

( K or k is suggested to denote kernel,

i.e., caryopsis)

(1 (as second letter of a symbol) is

suggested to denote leaf.)

= lethal (precedes symbol of character

having lethal effect )

=^ lazy. See er

~= Lodging

= Late flowering ( highly photosensitive).- See Ef

= liguleless (auricle and collar also

al)sent) ^

= very hairy (long hair) dominant to

ordinary pubescence. See gl

.= grain length (long grain) 2

--= extra lemma

= lutescent

= Lax vs. normal panicle. See Dn

= Lax vs. compact

= multiple embryos (polyembryonie)

= multiple pistils (polyearyoptic)

mottled leaf ; see bl

= narrow leaf

= neckleaf

^ notched kernel

= open hull (parted lemma and palea)

(P (as first letter of a symbol) is suggested to denote anthoeyanin color.)

Exceptions : Ph, Pi

= (V)mpletely purple apieulus (complementary action with C and A)

= Purple auricle, basic to Pig

= Purple outer glumes

= Phenol staining of hull and bran

= Piricularia resistance
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 11

R

U

V

W

Pin

Pl

Pia

Plg

I-Pl

Pn

Pr

Prp

Ps

Psh

Pu

Pw

Px

Kc

Rd

Rk

rl

Sc

Se

Sh

Sk

spr

I-T

tb

Tf

th

tl

tri

Ur

wb

TABLE 4.

= Purple internode. See C

= Purple leaf. See Pw

= Purpleleaf apex (complementary action with C and A )

= Purple ligule. See Pau

= colorless leaf except margin

= Purplenode

= PurplehuU (lenuna and palea)

(complementary action with CAP)

= Purple pericarp

= Purple stigma (complementary action with CAP)

= Purple sheath

= Purple pulvinus

= I*urplewash. See PI

^ I'urple axil

= Brown pericarp (basic to Rd )

= Red pericarp (complementary action

with Re)

= verticillate (whorled) arrangement

of racliis ("rinshi" character)

= Round spikelet (kernel)

= rolled leaf

= sterility -

= ScJriotiiDn onjzdc resistance

= Photosensitivity. See Ef, also Lf

= Dominant shattering as in drop-seed

or wild types vs. diftirult or intermediate threshing. See th

= Scented kernel

= sinuous neck. See Ur

= spreading panicle branches

spreading growth habit ; see er, also la

superclustered spikelets ; see Cl

(T is suggested to denote plant height

( "Tallness" ) except where controlled

Ity dwarfing genes. ) See d

= short nondwarf plant vs. tall

--= tipburn yellow

= Tough ilehulling

= shattering or easy threshing recessive to difficult separation. See Sh

^ twisted leaves

= triangular hull (spikelet). See clw

^^ Undulate racliis vs. normal. See sn

virescent, also green

stripe. See fs

white belly (endosperm)

white

who

Wh

wx

y

= white core (endosperm)

= Whitehull, epistatic to gh

= waxy (glutinous) endosperm

= yellow leaf

= lethal yellow, also xantha ^

z = zebra stripe

Plant colors have been studied more extensively

than other characters in rice because they are

readily classified, and it is possible to analyze precisely the genie action and interaction. From the

economic standpoint, colors are of limited importance. Red bran color usually is objectionable as

a mixture in ordinary white rice; purple bran

varieties are used locally for rice wine or special

preparations; purple leaf varieties have been distributed for growing in red-rice infested areas,

so that the weedy type may be identified in the

seedling stage and pulled out.

The segregation and interaction of color genes

in Japanese varieties have been analyzed thoroughly {62). Purple (anthocyanin) colors, if

present, ordinarily are manifest at least in the

apiculus. The gradations from dark purple to

pink and colorless were found to be controlled by

five allelic chromogen genes, C^, C^^, C^*, C^%

and c. HoAvever, C genes alone produce no color

in the flowering stage but are responsible for

brown colors in decreasing intensity, which appear as the spikelet matures.

Activator gene A also must be present to convert the basic color pigment to purple anthocyanin. There are three allels at the A locus. A

third gene P, present in all but a few varieties,

brings out distinct coloration. The numerous

colors produced in the apiculus by the interactions of the C and A allels in the presence of P

are shown in table 4.

The C^ allel in the presence of A and A^ also

has pleiotropic effect, producing color in the internode. C allels with A and also less distinctly

with A^ result in colored outer glumes.

Apiculus colors resulting from- interactiori of C and A allels in the presence of the

P gene in Japanese rice

Activator

allels C^ QBp QBt (JBr c

Color at time

indicated

(PuiTJle

(Purple

jDeep red

[Brown

j Colorless

[Dark brown

Red purple

Red purple

Red

Red Pink Colorless

do

do

do

do

do

Flowering.

A Red Colorless

Orange tinge __

Colorless

Colorless

Yellow tinge

Maturity.

Orange tinge __

Yellow tinge __

Colorless

Light brown

Flowering,

A^

a

Light brown __

Colorless

Brown

Maturity.

Flowering.

Maturity.

Source: Takahashi {62).

Combinations of C and A are basic to the

appearance of color in other parts of the plant as

well as in the apiculus. Purple color of inner

glumes (lemma and palea), leaves, and nodes was

shown to result from the complementary action

of C and A with Pr, PI, and Pn, respectively.
12 V(iRl( I LIURE HANDBOOK 289, U.S. DEPT. OF AGRICULTURE

The expected segTegatioii ratio ii» tlie Fo of a

cross between a line witli purple apicuhis and

inner glumes and a completely colorless line is

given below to illustrate the many color patterns

That appear as the result of recombinations of

color genes.

Ratio of

ye tie eomhinations Color patterns

27 C A Pr Purple apieiilus and glumes.

9 C A pr Purple apiculus, colorless glumes.

9 C a Pr Brown (tawny) apiciUus and

glumes.

8 C a pr Brown (tawny) apiculus, colorless

glumes.

1(3 (j All combinations with c are colorless.

Many of the seg:regation ratios previously reported in publications in Japan and other countries can noAv be reinterpreted with fewer assumptions in accordance with the above analysis.

Other workers had recognized two basic complementary color genes, but the pleiotropic action

and the existence of multiple allels had not been

fully realized.

Indian workers {50) have established an allelic

series for another set of glume colors : H"^',

mottled; W, piebald; H^, green changing to straw

at maturity; and H^ dark furrow color. These

colors appear only in the presence of the gene for

strawhull color, Gh; and witli gh, only goldhull

colors appear.

Purple bran appears in varieties apparently

lacking pigmentation in all other parts and segregates in 8:1 ratios in crosses witli colorless bran.

A cross between a purple bran line that carried a

gene for red bran and a colorless line gave 9

purple-red :8 purple :3 red:l colorless (9)'. The

red underlaid the purple m such a way that it

was possible to separate the first two classes. A

cross between a purple bran line having colorless

vegetative parts and a line having ordinary bran

and partly purple leaves segregated in the F.

generation in a ratio of 18 colorless or partlv

purple leaves to 8 fully purple leaves. The

results show that an inhibitor gene restricts expression of full purple leaf color. Purple leaf

appeared only in the presence of purple bran.

Red rice varieties are grown in southern India,

in Ceylon, and in other areas: but red-rice mixtures hi white milled rice detract from the

appearance. Work reported from Japan (47)

showed that red bran color required tAvo genes

for expression. A gene Re for brown bran is

basic, and with Rd the bran is bright red. Rd

and A are closely linked; this makes it appear

that the apiculus color gene is basic for red. In

a cross between a red line of the genetic constitution C A Rd Re and colorless C a rd re, the segregation is 9 red bran, colored apiculus :8 coloi^ess

bran, colored apiculus :8 brown bran, colorless

apiculus:! both bran and apiculus colorless. In

this cross, red bran is found only with colored

apiculus and brown bran only with colorless. In

the cross C A Rd Re X c a rd Re, on the other

hand, red bran occurs with and without colored

apiculus; but brown bran never occurs with colored apiculus. The F2 ratio is 9 red bran, colored

apiculus :8 brown bran, colorless apiculus :3 red

bran, colorless apiculus:! both bran and apiculus

colorless.

The existence of varieties with life cycles that

range from as short a period as 3 months to about

10 months contributes greatly to the wide adaptability of rice to different areas and conditions.

Varieties are classified for time of flowering as

photosensitive or as insensitive. The photosensitive class includes late-maturing varieties, which

remain in a vegetative stage while the days are

long but probably enter the flowering stage when

the night period reaches a critical length. In

Ceylon, differences in varietal response to variations of less than an hour in day length were

found and were controlled by one dominant gene

for sensitivity (11). Early varieties tend to enter

the flowering stage after the completion of a

fairly constant vegetative stage.

In Japan, a series of six maturity genes dominant for lateness and having accumulative effects

have been postulated (40). The action of these

genes is conditioned by temperature. Sampath

and Seshu (57) reported an Indian study that

dealt witli crosses of two varieties from Japan

with photosensitive Indian varieties. One Japanese variet}^ was insensitive and the other

photosensitive in Japan; but under the temperature and day length conditions at Cuttack, India,

both flowered early (48 and 68 days from seeding,

respectively).^ The Fi plants of crosses of the

Indian varieties with the insensitive Japanese

variety flowered early, and segregation in the Fo

generation was 3 early:! late^or !5 early:! late.

However, in crosses iDetween the photosensitive

Japanese variety and Indian varieties the Fi

plants flowered late and segregation in the Fo

generation was ! early :8 late or ! early :!5 late.

It was assumed that in the crosses with the photosensitive parent, genes involved in temperature

responses and modifying the photoperiodic response were segregating. These authors cite a

Japanese study in which a gene for late flowering

was found to be epistatic to one for early

flowering.

In Louisiana, a cross between varieties that

headed in 90 and !25 days was studied (8). The

Fo segregation was bimodal and indicated the

action of one major gene for earliness.

Disease resistance can be analyzed genetically

if distinctly resistant and susceptible classes

occur. Specialized races of fungus diseases must

be taken into account ; usually segregation is best
RICE IN THE UNITED STxVlES : VARIETIES AND PRODUCTION 13

determined follo^Ying inoculation with cultured

spores of individual races. Single and duplicate

genes for resistance to four racles of Ccrcosporn

orijzae I. Miyake, the fungus that causes narrow

brown leaf spot, have been determined {ß'7). Xo

linkage was found between genes for Cercospora

resistance and the chromosome marker genes C

apiculus color, W furrow color, gh goldhull, and

wx waxy {26).

Several types of genetic segregation have been

reported for inheritance of resistance to Piricidaria oryzae Cav., the fungus that causes blast.

As early as 1922, resistance was reported to be

controlled by a single dominant gene {W) - However, no work has been reported on segregation of

resistance to established races. In 196Û, a laboratory study of three crosses was reported from

India (7). Survival was controlled by one or

two dominant genes, but the surviving plants and

the parents showed rather high degrees of

susceptibility.

AAVUS are a conspicuous morphologic character.

Although little is known of their physiologic

value to the plant, they are supposed to be associated with general hardiness [ßO] and to offer

some protection against pests. Awns are objectionable in threshing and handling the grain.

The development of awns varies considerably

with environmental conditions. Varieties that

show mere tip awns at moderate levels of fertility

may develop much more prominent awns at

higher levels. In Louisiana, the Caloro variety

develops awns when seeded very early but ma}^ be

practically aAvnless wlien seeded late. In the F.

generation, ratios of aAvned to awnless phiiits of

3:1, 15:1, and 9:7 have Ijeen reported from India.

Japan, and the United States. These ratios show,

respectively, tliat single, duplicate, and complementary genes act to produce aAvns. A study in

California (28) shoAved that fully aAvned plants

differed from awnle-s 'jy tAvo genes, fully aAvned

from partly aAAmed Ijy one gene, and partly aAvned

from awnless l3y one gene.

Most rice A^arieties have pubescent leaves and

hulls, although a few are essentially glabrous.

Pubescence has Ijeen eliminated from tlie varieties groAvii in the Southern United States. In

most varieties, a single gene pair Gl :gl controls

the development of plaiit hairs on all outer surfaces of the plant. However, some varieties have

some pubescence on the leaf surface, although the

lemma and palea are smooth. Xagao, Takahashi,

and Kinoshita {1^3) reported the segregation in

crosses of the latter type with ordinary pubescent

Japanese types. Three classes of pubescence plus

glabrous appeared in the F2 generation in ratios

of 9 :3 :3 :1 and 27:9 :21:3. It was concluded that

tAvo genes Hla and Hlb together but not singly

bring about the deA^elopment of hairs on the leaf

surfaces even in the presence of gl.

The strength of attachment of spikelets to their

I)edicles is of practical importance to the groAver.

Sliattering (shedding) of grain in the Avind,

which occurs in red rice, Avould make it impossible to harvest the crop; whereas at the other

extreme, Avhich occurs in some of tlie Japanese

varieties, the attachment is so tight that in combining much grain Avould remain on the straw.

Types tliat thresh free of the straAv yet do not

shatter easily are needed for mechanized harvest.

Easy threshing Sh is dominant to intermediate

or tough threshing sh; but, on the other hand,

tough threshing is dominant to intermediate

threshing.

^lultiple gene inheritance of grain length was

reported in a study in the United States {29). In

crosses of short X medium, short X long, and

medium X long types, variation in length in the

Fo generation Avas continuous. Similar results,

also sliOAvino- trans<>:ressÍA^e seírreo;ation, Avere obtamed for breadth of grain.

Tillering ability is of gi^eat importance Avhere

rice is transplanted, but much less so Avhere direct

seeding at relatively high rates is practiced.

Ramiali and Eao ('5()) reported from India that

the Fi plants of three crosses were intermediate

for num))er of tillers per plant, and the F2 progenies showed traiisgressive segregation. In one

cross higli correlation ))etAveen the number of

tillers 111 F2 plants and their respective F3 progenies indicated that the controlling genes are

limited in mimljer—proliably no more than three

or four. In another cross the occurrence of numerous F3 progenies, each comparatiA^ely uniform

in number of tillers, led to the same conclusion.

Standing ability or lodging resistance is a complex cliaracter that is difficult to measure in inheritance studies. In a study reported from

India {ÖO), the F2 progenies of a cross segregated

o lodging :1 nonlodging, Ijut the latter were low

tillering and late maturing.

In Louisiana, a cross betAveen an early-maturing, medium-grain selection and the late-maturing

A'ariety Eexoro indicated transgressive segregation for yield (5). F4 lines Avere recoA^ered that

had yields significantly higher than those of the

high-yielding parent, but none had yields significantly loAver than those of the loAv-yielding

parent. Higher yield Avas strongly associated

Avith earlier maturity. No correlation Avas found

betAveen yield and spikelet length and breadth, or

betAveen yield and grain weight.

In correlation studies from other countries

Ramiah and Rao (5(9) indicate association of

higher yield Avith number of tillers, number of

grains per ear, and plant height.

Genetic information on the quality character of

rice is A^ery limited, although the single gene segregation between common and Avaxy types Avas

one of the first characters studied. The inherit-
14

WAXY

.\(iK:ri I,TL UE IIAXDI'.OOK 2S9, U.S. DEPT. OF AGRIGULITJRE

PURPLELEAF

25

38

_A_

52

_A_

47

35 31

PI

49

28

7, 24

Ig Ph Pr

ACTIVATOR

LONG GLUME

0.3

A Rd

14

30

_A_

27

30

Pn

29

Re

LAZY

NECKLEAF

la

39

34

th

INHIBITOR

DWARF

FINE STRIPE

Ur

42

-Bf

40

Ps

/

A„ \

L-^l. 1 28 1

V di gh

46

_/^

28 I

BLACKLEAF

BRITTLE

GLABROUS

fs Dn

FiGiKE T).—Rice linkage .i;r(tiips

bl

gl

25

ds

48

-A—

44

41

doAni

An

aiice of aiiivlose rontent as iiidicated

value was studied u\ a ei-oss of Toro

value) ' Texas Pbv the iodine

hiixli iodine

^atiui (low iodine \'alue) {68).

The value in tlie Fi generation was low, indicating })ai'tial (h)nnnanr'e. A hiniodal distri])ution

was obtained in tlie FM, indicating- dominance of

one major ^-ene for low iodine value. An association was shown between low iodine \'alue and

colored ai)iculus; the latter is also a cliaracttu' of

the low iodine parent. RecoAcred lines with high

iodine value Avere much more numerous in the

early-uiaturino- than in the late-maturmg group.

Tinkage refers to the closeness of association in

inheritance of genes located on the same chromosomes, (xenes controlling characters that segregate into clear-cut classes and that are viable

are useful for determining linkage relationships.

Several of the genes for color are suitable marker

genes. Easily classified morphologic characters

dependent on single genes are also useful, includ-
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION

ing some of the more conspicuous characters such

as awns, h)ng outer ghunes (of which recessive

and semidominant types are known), pubescence,

neckleaf, liguleless,^ hizy (ageotropic), brittle

cuhn, numerous dwarfs, waxy endosperm, and

viable types of chlorophyll deficiencies.

In a report from Japan^ Nagao and Takahashi

(Jf2) presented data that established V2 linkage

groups, representing, as expected, the number of

chromosomes found in rice. Takahashi {63) has

since amplified the information on the linkage

groups. The linkage diagrams (maps) shown in

TABLE 5.

figure 5 are based on the Japanese results. Data

from other studies and reviews (¿, 23, 2^. 25, 38\

()3)^ are provisionally included with the groups to

wliich they aj^pear to l)elong. Linkages between

genes that ha^T been reported but not definitely

h:>cated on the respective chromosomes are listed

in table 5. Linkages between genes that have

been reported but have not been assigned to a

linkage group are also shown in table 5. Linkage maps of rice are much less complete than

tliose of barle}^ and maize.

LJnl'dges not defnitely located on the respective cfnowosomes

Link;i.2:es tentatively

assiirned to groups

WAXY CiKoUP

\vx vs. Pia

C vs. H'

C vs. Se

C vs. Lf

C vs. dp

C vs. n_

1 vs. do.

wx ^1- vs. X|

wx vs. Vi

PUKPLE LEAF GROUP

PI VS. An

PI vs. lop

1^ vs. Wh

Iff vs. Xa

Pr vs. P

P vs. (blackspot)-

Pr vs. Ig

Pr vs. Px

Px vs. Psh

Pr vs. gh

Pr vs. h

gh. vs. Wh

Ps vs. Pr

d vs. PI

Pi vs. Ig

ACTIVATOR GROUP

A VS. bn

bn vs. doo

^22 '^^''- l^t

Igt VS. bn

A vs. doo

Rd vs. Pin

LONG GLUME GROUP

dfi vs. dT

g vs. Rk___

Apic vs. g_

Percentage

recomt)ination 1

45

29

16

32

Unknown

do___..

217?

Unknown

do

29?

Unknown

S

Unknown

32?

33?

30

9

C

32

36

Unknown

____do

_do_

_do_

23

28

16

30

37

21

39

17

Authoritv

Nagao and Takahashi iJß).

Ramiah and Rao

(50).

Chandraratna ( 10 )

Yamagnchi {68).

Xagamatsu and

Ohrnura.i

Do.i

.Jodon (unpul)-

lished).

Oka (1953).!

Do.i

Jodon (unpublished ).

Na2:amatsu and

ohnnira, 1961.^

Jodon {2Ji, 25).

Nishimura.^

Jodon Í unpublished ).

Do.

Richharia and

others (51).

Do.

Do.

Jodon (24, 25).

Do.

Do.

Hsieh {20).

Do.

Do.

Hsieh {19).

Do.

Do.

Do.

Do.

Ramiah and Rao

{50).

Nagao and Takahashi {1^2).

Kadam and D'Cruz

{SD.

Do.

Linkages tentatively

assigned to groups

LONG GLUME GROL^P—

Con.

Rk vs. I-An

Pin vs. Re

Re vs. Lf,?

IXHIBrroK GROUP

Ps vs. Psh

Ps vs. Apic

Ai)ic vs. Psh

Ps vs. Pr

DWAHF GROUP

gh VS. AUß

gh VS. p or Pr_

FINE STRIPE GROUP

None

LAZY GROUP

La vs. d

NECKLEAF GROUP

nl vs. An

GLABRO L^S GROUP

g] VS. H^

LINKAGES NOT

ASSIGNED TO

LINKAGE GROUP

Rk VS. An

Bh vs. An

Bh vs. Pin?

An vs. d

Pr? vs. Pig?

Pr? vs. Pin

Purple collar vs. Prp

Psh vs. Prp

bl vs. Prp

d2i vs. Prp_

sk vs. Prp__

Percentage

recombination 1

31?

Unknown

10

9

12

43

30

Unkn(nvn

32?

39

14 and 24

21

17

11

13

10

13

16

Unknown

.-__do

_do__

Authority

Jodon (unpublished).

Ramiah and Rao

[50).

Yamaguchi {69).

rhao {12).

Shafi and Aziz {59).

Do.

D'Cruz (17).

Nagao and Takahashi (^2).

Jodon and Chilton

{26).

Nagamatsu and

Ohmura.^

Jodon (unpublished) .

Nagao and Takahashi {1^2).

Anandan (6').

Kuang {S6).

Parnell, Rangaswami Ayyangar,

and Ramiah {1^1)

Kuang {S6).

Hebert {18).

Do.

Breaux {9).

Comeaux {16).

Jodon (unpublished ).

Do.

Ramiah and Rao

{50).

1 As reported by Takahashi ( 6S ),

2 Entries followed by question

available.

marks have not been verified and may be changed as more information becomes
16 ¡Kiri I;í IRE JIANDBOOK 289, U.S. DEPT. OF AGRICULTURE

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CHARACTERS. PUBESCENCE OF LEAVES AND

FLORAL GLUMES, AND DEFORMATION OF

EMPTY GLUMES. Hokkaido Imp. Univ.,

Faculty Agr. Jour. 51: 299-314. [In English.!

(44) NANDL H. K.

1936. THE CHROMOSOME MORPHOLOGY, SECONDARY^

ASSOCIATION AND ORIGIN OF CI^LTIVATED RICE.

Jour. Genet. 33(2) : 315-336.

(45) OKA, H. I.

1958. INTERVARIETAL VARIATION AND CLASSIFICATION OF CULTIVATED RICE. Indian Jour.

Genet, and Plant Breeding 18(2) : 79-89.

(46) and CHANG, W. T.

1962. RICE VARIETIES INTERMEDIATE BETWEEN WILD

AND CUTITIVATED FORMS AND THE ORIGIN OF

THE JAPÓNICA TY^PE. Acad. Slulca Bot.

Bul., 3(1) : 109-131.

(47) PAENELL, F. R., RANGASWAMI AYY'ANGAR, G. N.,

and RAMIAH, K.

1917. THE INHERITANCE OF CHARACTERS IN RICE.

L India Dept. Agr. Mem., Bot. Ser. 9:

75-105.

(48) RAMIAH, K., and GHOSE, R. L. M.

1951. ORIGIN AND DISTRIBUTION OF CULTIVATED

PLANTS OF SOUTH ASIA—RICE. Indian Jour.

Genet, and Plant Breeding 11(1): 7-13.

(49) and NARASIMHAN, M.

1936. DEVELOPMENTAL STUDIES IN RICE. I. Madras

Agr. Jour. 24(2j : 50-66.

(50) and RAO, M. B. Y. N.

1953. RICE BREEDING AND GENETICS. Indian Council Agr. Res. Sei. Monog. 19, 360 pp.

(51) RICHHARIA, R. H., MISRO, B., BUTANY, W. T., and

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Euphytica 9: 122-126.

A.

POLTJ NATION AND THE b'LOWER ol RICE.

Philippine Agr. 14(3) : 155-171.

RoSCHEVlCZ, R. J.

TlON TO THE KNOWLEDGE OF RICE.

Bot., Genet., and Plant Breed1-133. [English summary, pp.

(64)

UODKTGO,

li)2,

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119-133.]

SAKAI, K. I.

1935. CHROMOSOME STUDIES IN ORYZA SATIVA L.

I. THE SECONDARY ASSOi IATIOXN OF THE

MEioTic CHROMOSOMES. Jap. JouT. Gouet.

11(3) : 145-156. [English summary, p.

154.]

SAMPATH, S., and GOVINDASWAMI, S.

1958. WILD RICES OF ORISSA—THEIR RELATIONSHIP

TO CI^LTIVATED VARIETéS. Rice News Teller,

July.

and RAO, M. B. V. N.

1951. INTERRELATIONSHIPS BETWEEN SPECIES IN

THE GENUS ORYZA. Indian Jour. Genet, and

Plant Breeding 11: 14-17.

and SESHU, D. V.

1961. GENETICS OF PHOTOPERIOD RESPONSE IN RICE.

Indian Jour. Genet, and Plant Breeding

21: 38-42.

SEETHARAMAN, RAMASWAMY.

1959. THE INHERITANCE OF

AND ITS ASSOCIATION

IODINE VALUE IN RICE

WITH OTHER CHARACTERS. Ph.D. Diss., La. state Univ., 65 pp.

SHAFI, M., and Aziz. M. A.

1959. THE INHERITANCE OF ANTHOCYANTN PIGMENT IN THE OUTERGLUME AND APICULUS

OF RICE. Agr. Pakistan 10: 217-232.

SHASTRY, S. V. S., RAO, D. R. R., and MISRA, R. N.

1960. PACHYTENE ANALYSIS IN ORYZA. I. CHROMOSOME MORPHOLOGY^ IN ORYZA SATIVA. Indian Jour. Genet, and Plant Breeding

20(1) : 15-21.

SMITH, W. D., DEFFES, J. J., BENNETT, C. H., and

others.

1938. EFFECT OF DATE OF HARVEST ON

MILLING QUALITY OF RICE. U.S.

Cir. 484, 20 pp.

TAKAHASHI, M.

1957. ANALYSIS ON APICULU;

TIAL TO ANTHOCYANIN

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COLOR GENES ESSENCOLORATION IN RICE.

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LINKAGE GROUPS AND GENE SCHEMES OF SOME

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Inst., Los Banos, Philippines, pp. 215-236.

Elsevier Pub. Co., Amsterdam, London, and

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TAXONOMIC STUDIES OF ORYZA. III. KEY^ TO

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Hokkaido Imp. Univ., Col. Agr. Jour.

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Jap. Jour. Bot. 10(3) : 213-258.
18 A(iRIOl^í/r' Jí ilAXDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE

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YA^fAGUCHI, Y^.

1921. ETUDES D'HéRéDITé SUR l^\ COUUEUß DES

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1929. FURTHER CONTRIBUTIONS TO THE KNOWLEDGE OK THE SECOND (S.M.) LINKAGE GROUP

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(70) YEH, B., and HENDERSON, M. T.

1961. CYTOGENETIC RELATIONSHIPS BETWEEN CULTIVATED RICE, ORYZA SATIVA L., AND FIVE

WILD SPECIES OF ORYZA. Crop Sci. 1: 445-

450.

(71) YUNG, G. T.

1938. DEVELOPMENTAL ANATOMY OF THE SEEDLING

OF THE RICE PLANT. Bot. Gaz. 99(4) •

786-802.
RICE BREEDING AND TESTING METHODS IN THE UNITED STATES

By C. ROY ADAIR, H. M. BEACHELL, NELSON E. JODON, T. H. JOHNSTON, J. R. THYSELI^

y. E. GREEN, JR., B. D. WEBB, and J. G. ATKINS

History and Objectives

Rice improvement in the United States has been

discussed by Jones (55),^ and the descriptions and

performance of varieties developed have been

reported by several authors {1,2, 25, ^í2, ^5, ^8.

52, 57, 55, 59, 67). Although some work to improve United States rice varieties was done before

1909, it was not until about then that comprehensive, cooperative rice-breeding studies were

started in the United States. Objectives of the

rice-breeding program and methods used have

been described (7, 18, 55, 69), According to a

report by the Rice Millers Association,^ all rice

varieties grown in the United States in 1963

evolved from these cooperative rice-breecling

experiments.

Although introductions were made by individuals after the original introductions into South

Carolina in the I7th century, little effort was

made by Federal or State agencies to improve

rice varieties until work was started by the U.S.

Department of Agriculture in 1899. At that time

Seaman A. Knapp, an explorer in the Division of

Botany, introclucecl from Japan 10 tons of Kiushu

rice that Avas distributed in southwestern Louisiana and probably in eastern Texas, where he arranged farm demonstrations of rice varieties and

cultural methods. Many varieties were introduced and tested by Department workers on

demonstration farms in Louisiana and Texas, and

later in Arkansas and California, before the establishment of rice experiment stations in these

States.

The Rice Experimental Station at Crowley,

La., was established in 1909. The Biggs Rice

Field Station at Biggs, Calif., (now the Rice

Experiment Station) and the Rice Experiment

Station at Beaumont, Tex., (now the Rice-Pasture Research and Extension Center) were established in 1912. The Rice Branch Experiment

Station at Stuttgart, Ark., was established in

1926. Rice investigations were started at the

Delta Branch Experiment Station, Stoneville,

Miss., about 1951. Rice-breecling investigations

are conducted cooperatively by the U.S. Department of Apiculture and the State a2:ricultural

^ Italic numbers in parentheses refer to Selected References, p. 62.

2 Shown printed in Rice Jour. 66(12) : 14-15. 1963.

experiment station at each of these locations. The

rice-breeding studies were started in Louisiana in

1909, in California in 1912, and in Arkansas in

1931. Although a comprehensive rice-breeding

program was not started in Texas until 1931 and

in Mississippi until 1958, some breeding work had

been done in these States before these dates.

Most of the early work consisted of testing

selections from foreign introductions and commercial fields. Many varieties, such as Caloro,

Colusa, Fortuna, Nira, and Rexoro, were developed and released from 1909 to about 1937.

S. L. Wright, r. farmer in Louisiana, developed

sevei-al rice varieties by selection. These varieties

probably were progenies of natural hybrids between varieties, such as the long-grain Honduras

and the short-grain Shinriki. The most widely

grown varieties developed by Wright were Blue

Rose and Early Prolific, which are mediumgrain types, and Edith and Lady Wright, which

are long-grain types. None of these varieties

were grown in 1963, but they were the leading

varieties in the southern rice area from about

1915 to 1940.

During the early years, no attempt was made

to improve varieties by hybridization. Although

a few hybrids had been made at experiment stations in the southern rice area at an earlier elate,

it was not until after 1922 that this method of

breeding was used.

The primary objective in rice breeding in the

United States is to develop varieties that will

assure a maximum and stable production of the

types of rice required by producers and consumers. Emphasis is given to developing shortseason varieties. Short-, medium-, and long-grain

types—with a wide maturity range within each

grain type class—should be developed. The objectives of that program are to develop varieties

that (1) germinate quickly and grow rapidly in

the seedling stage; (2) tolerate low temperature

in the germinating, seedling, and flowering stages

and tolerate low irrigation water temperatures

during the entire growing season; (3) are resistant to alkaline and saline soils and to salt in

the irrigation water; (4) are resistant to diseases

and insects; (5) have short, stiff straw and resist

lodging; (6) respond to and make efficient use of

maximum rates of fertilizer; (7) mature uni19
20 A(íiaCUI/rUKE IIAXDIÎUOK 1289, U.S. DEPT. OF AGRICULTURE

formly ami produce seed that has a period of

dormancy so that the o-raiii will not (jerminate

when ]Kir\est is dehiyed by i-ain; (S) produce

maximum held and milling yields when grown

under a wide range of environmental conditions:

and (9) have the desired cooking and processing

([ualities required by domestic and foreign trade.

Each of tliese objectives is important in earli

rice-producing area in the T'nited States, altliough

some of the olijectives are more important in one

area than in another. For example, cold tolerance, esjiecially tolerance to cold irrigation water,

is more important in California than in the southern rice area. Disease resistance, on the other

hand, is more important in the southern rice area

than in California.

Cultural Methods and Equipment

for Breeding Rice in the United States

Land for rice-breeding experiments should be

of uniform soil type and topography. A gradual

and uniform slope is desirable to afford reasonal)ly rapid drainage when necessary. Howe\-er

the slope should l)e sucli that blocks of tlireetenth aci'e or larger can be uniformly irrigated

without contour levees.

In the Taiited States it is customarj- to locate

roadways at 200- to 300-foot intervals running in

the directiim of the fall of the land and wide

enough to acconnnodate held equipment and other

vehicles. The road ditches are used for drainage

and are paralleled by border levees. The entire

area should be graded to a uniform slo])e before

roadways and irrigation laterals are constructed.

Cross levees at designated points divide the field

into areas of approximately one-tenth acre that

can be irrigated or drained independently (fig. 6).

Larger blocks can be formed by eliminating one

or more cross levees. Irrigation laterals parallel

roadways and are located midwa}' between the

roadwaj'S or directly adjacent to one side of the

roadways.

Ricefield machinery is used to build levees. In

heavy clay soils, a steel-bladed levee builder (fig..

tvim^MtKi»«ai-'-«ÊÊinim .1

FiGUKE 6.—Seeded nursery plots. Some of the plots are irrigated.
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 21

FIGURE -Constructiug levees in the nursery with

steel-bhided levee builder.

7) is used; in the nioi-e loamy soils, a disk-type

levee builder (fig. 8) is used. Usually the cross

levees have an S- to Id-foot base. A concrete

levee packer is useful in packing newly constructed levees. A concrete tile, -Í to G inches in

diameter, is placed at the lower end of each block

to drain the water into the road ditch so that it

will hold the irrigation water. The tile is closed

with a metal plate. Sometimes plastic tube

siphons are usecl to irrigate from the lateral or

to drain the water into the road ditch.

In the southern rice area, it is customary to

plow down the cross levees after each rice crop

and to cultivate the fields with ricefield equipment. The irrigation laterals and border levees

may or may not be torn dowji. After cross levees

have been i^lowed down, the areas are disked or

plowed ancl are leveled with a land plane. A 3-

year rotation system is practiced in Arkansas and

Louisiana. In Arkansas, the land may be cropped

to soybeans the first year. The soybeans may be

harvested or turned under or disked into the

ground as green manure, after which a winter

grain crop may be sown. The grain crop may be

overplanted with lespedeza the following spring.

The grain crop is harvested in early sunmier, and

the lespedeza is harvested for hay or seed in the

summer or fall. The field is plowed or disked,

and land is leveled during the winter and early

spring preparatory to seeding rice the following

year. In Louisiana, the land is fallowed when

not in rice.

A 3-year rotation system is also practiced inTexas. It consists of 1 year of rice followed by 2

years of summer fallow. The first summer after

rice is grown and harvested, the field is fallowed

and then clover or ryegrass is sown in the fall.

The crop is harvested for hay or seed in the

spring, and the field is sunnner-fallowed throughout the second summer. Land is leveled during

the second summer as time and weather permit.

On clay soils the cross levees are reconstructed

in the late fall or winter before the fields are

seeded again with rice. After cross levees are

construi'ted, the land is prepared by using lifttype implements attached to a lightweight farm

tractor. On silt loam soils the cross levees may

be made inunediately after seeding.

In California, a 2-year rotation generallj' is

usecl in rice-breeding nurseries. The land is

plowed in the winter or early spring after the

rice crop has been grown and harvested. The

fields usually are irrigated one or more times during the summer when they are not cropped to rice

to germinate weed, grass, and rice seeds. The

field is cultivated after each irrigation to destroy

the plants that emerge.

Permanent levees are maintained in some of

the areas used for rice nurseries. In other areas,

plastic levees are used, or earthen levees are constructed with a bulldozer or front-end loading

tractor each year before seeding.

Weeds and grass are controlled on lateral and

drainage ditch banks, levees, and alleyways in rice

by spraying with a contact herbicide.

Various types of seeding equipment are used.

FIGURE 8.—Constructing levees in the nur.sery with a

disk-type levee builder.
22 AGRICULTURE HANDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE

In field plot varietal experiments, seeds are sown

with small grain drills or specially equipped

drills. In yield trials on nursery plots or in

experiments where multiple seed sources are involved, belt-type seeders (fig. 9) or other readily

cleaned drills are used for seeding. Breeding

nurseries involving numerous panicle-row selections are sown by dribbling seed into a singlerow manually operated drill (fig. 10) or a multiple-row power-operated drill.

On experimental plots uniform application of

known amounts of fertilizer materials is difficult.

A basal application of phosphorus and potassium

may be applied with a conventional fertilizer distributor before seeding rice or to one of the other

crops groAvn in rotation with rice. Although the

fertilizer usually is distributed by a tractordrawn implement, it may be distributed by airplane. In the southern rice area, the nitrogen

fertilizer for breeding trials usually is applied as

a topdressing, although sometimes part or all is

applied at seeding time.

Various methods and devices have been used

to apply fertilizer to rice grown in breeding

nurseries. Weighed amounts of fertilizer are

applied by hand as a topdressing. Mechanized

fertilizer distributors have been tried with only

limited success. Most devices are slower than

hand application, do not apply or distribute uniform amounts of fertilizer, and can be used only

on relatively dry soil.

At Stuttgart, Ark., a manually operated

"planter" is used to apply nitrogen fertilizer be-

;i*í¿5íyi^^':--íí«í

FrouBE 10.—Manually operated seeder used to seed

selections.

r^:^.r

FIGURE 9.—Belt seedt-r, mounted on a small tractor, used

for seeding nursery yield experiments.

tween alternate rows when the soil is dry (fig. 11).

At Crowley, La., a single-row seeder that has an

agitator-type fertilizer attachment with a separate shoe places fertilizer just below the seed.

For a number of years a fertilizer distributor

attached to a 3-row seeder was used at Beaumont,

Tex. This drill used regular grain drill fertilizer

distributor parts. Top-feed and other hoppertype distributors have been used with limited success to topdress plots. A force-feed type distributor that drops the fertilizer on the soil surface is fairly successful (fig. 12). Cross-plot fertilizing with this type distributor appears to be

desirable in overcoming irregularities of distribution.

Because rice nurseries are likely to be muddy at

harvesttime, mechanical han^esting equipment is

not used. Hand sickles are used to harvest small

plots; combine harvesters may be used to harvest

large plots.

Bundles from small plots are air dried by hanging in a drying shed or by using heated-air driers.

When dried by heated air, the bundles are placed

in drying trays as harvested and dried over a tunnel or rack-type drying unit with forced heated
RICE IN TUE UNITED STATES : VARIETIES AND PRODUCTION 23

<»•• ï-<*i,*.i«.. : ;«*•«*««(

FiGUKE 12.—A force-feed fertilizer used to distribute

nitrogen as a topdressing.

FIGURE 11.—A distributor used to apply nitrogen fertilizer between the rows as a topdressing.

air (fig. 13). Bundles are left in the trays until

the grain is ready to be threshed.

Bundles from large plots are threshed in a

Vogel thresher (fig. 14) or a modified Kansastype nursery thresher (fig. 15). Sometimes the

concave teeth are removed to reduce breakage.

Threshing rice is primarily a stripping action,

and breakage is avoided when concave teeth are

not used and cylinder speed is reduced. Breakage caused by improper adjustment of the

thresher should be avoided because it causes a

bias of grain yield and milling quality.

In some instances, bundles are placed on the

cross levees for a few hours after cutting and are

threshed the same day. The threshed grain is

placed in cloth bags and artifically dried with

forced air heated to between 90° and 100° F.

Threshed samples usually are cleaned before

weighing for yield determinations. It may also

be necessary to break off awns and attached fragments of rachises. This is accomplished by placing the sample in a section of automobile innertube and pounding several times. An easily

cleaned aspirator, dockage machine, or small fanning machine can be used to remove foreign material. If the threshed samples are relatively free

from foreign material, the grain weight can be

obtained before cleaning.

Maintenance of viable seed of varieties and

breeding lines is important in a rice-breeding

program. The main causes of rapid deterioi-ation of seed viability are moisture content of the

seed and storage temperature. A method of drying the seed and storage facilities with low humidity and low temperatures are needed.

The moisture content of the grain is probably

more important than temperature in retaining

viability. Bice with a moisture content of 10

percent or below (wet basis) retained viability

for several years at Beaumont, Tex. The temperature in the storage room ranged from 70° to

90° F., and the relative humidity was below 50

percent most of the time.

The moisture content of rough rice can be reduced to 4.7 percent (wet basis) when stored 42

days over a saturated solution of lithium chloride

{60). The moisture content of rice can be reduced to about 6 percent with a silica gel drying

unit (fig. 16). Rice reduced to this moisture

content probably will retain viability for 5 years

or longer when stored at room temperatures.

At Beaumont, Tex., seed of rice varieties, breeding lines, and genetic stocks is dried in a silica

gel drier to about 6-percent moisture and stored

with silica gel in sealed 1.2-cubic foot metal containers at about 34° F. About 2 pounds of silica

gel is put in each container. An indicator, such

as cobalt chloride crystals or paper, that changes
24

AGRICULTURE HANDBOOK 289, U.S. DEPT. OF AGRICULTURE

FiGL-KK 13.—ln-yiug bundles of rice in trays with forced

¡leated aii'.

color with increase in moisture is used, so that an

increase in moisture is easily detected. The silica

gel is usually chang-ed every 2 years. Seed can be

stored in polyethylene bags with silica gel. However, since these bags do not exclude all the

moisture, the silica gel must be changed more

frequenth.

At Crowley. La., and Beltsville. Md.. seed is

stored at a temj)erature of about 0"' F. Seed

stored in this manner has retained its viability

for more tiian -20 years.

Breeding Methods

The three major breeding methods commonly

used foi' small grain have been used in rire

breeding ( 'i''). These are (1) introduction of

varieties from foreign countries, (-2) selection (if

pure lines from ciunmercial and introduced varieties, and (3) creation of new varieties by hybridization followed liy selection. Irradiation breeding also has been used in the United States.

The varieties now grown in the United States

were developed liy using progressively the thi'ee

major methods. For e.xample. the (iulfrose variety was selected from the i)rogeiiy of a cross

between a selection from an introduced variety

and a pure line selection from a commercial

variety.

Introduction

The introduction of varieties from other counti-ies has been and still is an important source of

germ plasm for rice breeders in the United States.

Some of the introduced varieties have been developed by Ijreeders in the country of origin, and

others have been indigenous varieties grown for

manv years by farmers in the country of origin.

FiGURK 14.—Thresliing breeder seed with a Vogel thresher.

According to Jones (öß), few varieties were

introduced from about 1G85 to 188'.). It became

evident then that the varieties being grown m

the United States were not as productive as

varieties grown in other countries. Starting

about 1800 and continuing to the present, many

varieties have been introduced. Jones (on) listed

and described nine varieties that were introduced from other countries and grown in the

Ignited States. These were Carolina Gold, Carolina White. Early Wataribune. Hcmduras, Kmshu. Omachi, Onsen, Shinriki. and Wataribune.

About 193,5, Asalii was introduced from Japan by

T. M. Sabora, a Texas rice farmer. He increased

this \-ariety for commercial production al)out

mill {'>7).' Tlius, there have been at least 10

introduced \arieties that have been grown rather

extensively. None of these varieties are now of

commercial importance.

Varieties now introduced into the United States

are grown the ñrst year in a greenhouse away

from rice production centers to avoid the introduction of diseases and insects. The seed produced in the greenhouse then is sown in a singlerow plot at one of the rice experiment stations.

Notes are taken on such characters as seedling

\igor, straw strength, plant height, length of

growing season, grain type, kernel characters,

and reaction to diseases and insects. Whether

the variety is a pure line or consists of mechanical

or hybrid mixtures is also noted. Varieties that

appear to have no desirable characters are discarded. Varieties that have some but not all

desirable characters are held in reserve for possible future use in the breeding program. Varieties that look promising in all respects in the
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 25

FIGURE 15.—Threshing bundles of rice from nursery yield

experiment with a modified Kansas nursery thresher.

preliminary trials are tested for at least 3 years

in replicated yield trials and are evaluated ior

disease reaction and cooking quality. AVlien a

variety is proved to be superior to commercial

varieties, the seed is purified and increased and

seed of the new variety is distributed to farmers.

Selection

Selections from introduced or commercial varieties have been an important source of rice varieties in this country. Practically all of the

varieties grown in the United States from 1920

to about 1945 were developed by this method.

Jones {ôô} named the breeders who participated in this work from about 19U0 to about 1930.

Most of these breeders were employees of the U.S.

Department of Agriculture. Chambliss and

Jenkins (25) listed and described six varieties

that were developed by selection. These are

Acadia, Delitus, Evangelhie, Salvo, Tokalon, and

Vintula. These six varieties were not grown extensively but probably were important for a few

years in local areas in Louisiana. Ten other varieties developed by selection and listed and briefly

described by Jones (-'T-5) are Blue Rose, Caloro,

Colusa, Early Prolific, Edith, Fortuna, Lady

Wright, Xira, Rexoro, and Shoemed. Other

varieties developed by pure line selection are Conway (29), Sunbonnet (4^), Bluebonnet 50 (-57),

and lola. Latex, Mortgage Lifter, Storm Proof,

and Zenith (58). Other selections have been

made by farmers and grown locally for a few

years.

Selection is a relatively easy method for breeding rice, but it takes many years to develop a

variety by this method. The procedure is to

select a large number of plants or panicles from

a variety that consists of diverse types. These

selections are sown in single-row plots and careFiGURE 16.—Silica gel drying apparatus for drying small

samples of rice.

fully observed for the principal characters. If a

selection from the progeny of a hybrid is segregating, desirable plants or panicles are selected

and sown in single-row plots the second year.

AVhen promising lines are breeding true to type,

they are tested in replicated yield trials in the

same manner as introductions. When a selection

is proved to be outstanding, it is named, the seed

supply is purified and increased, and it is released

for commeivial production.

]Most of the varieties developed by the selection

method have been replaced by newer varieties,

although there are a few notable exceptions. Li

19().3. Bluebonnet ."lU was the leading variety in

the South, and Rexoro was grown rather widely

in Louisiana and Texas. Caloro was the leading

variety in California, and Colusa also was widely

grown in that State.

Hybridization

Varieties developed by the selection method

were a A'ast improvement over the varieties they

replaced, but varieties developed by this method

did not have all the desired characters. Since

about 1922 rice breeders in the LTnited States

have used the hybridization method of rice breeding, and hundreds of crosses have been made.

Three S3'stems are followed in the hybridization

method of breeding rice. These are: (1) Two

varieties are crossed and the progeny grown in

pedigreed rows or bulk plots until pure lines are

selected; (2) the backcrossing system in which

two varieties are crossed and the Fi plants crossed

to one of these varieties and repeated for four

or five times; and (3) the multiple cro.ssing system in which four or eight varieties are crossed

in pairs, followed by crossing the Fi plants from

the different combinations so that after two or

three rounds of crossing, Fi plants are obtained

that contain some genes from each of the parent
26 A'liKlJ HANDBOOK 289, U.S. DEPT. OF AGPaCULTLlKE

varieties, These systems iiiny O be modiñed in

A'^arious ways.

CROSSING TECHNIQUES.—Tlie two basic techniques used for making rice crosses are the clipping- and the liot Avater method. There are several modifications of the clipping method but in

each case a part of the lemma and palea is removed. In the hot water method the panicle is

emersed in hot water.

An example of the clipping technique that has

been widely used was described by Jones {55) and

may be summarized as follows : In the morning

before the rice begins to bloom, or in the afternoon after the daily blooming period has passed,

all except 10 to 20 spikelets are removed from the

female panicle. The upper part of the lemma and

palea of the remaining spikelets are clipped off at

about a 45° angle. This removes about half of

the lemma but only the tip or none of the palea

so the anthers can be easily removed with finepointed forceps. The emasculated panicle then

is tagged and covered with a glassine bag. The

same day or the next day between 9 :00 a.m. and

2:00 p.m., depending somewhat upon the weather,

the emasculated panicles are pollinated. Phmts

of the variety to be used as the male parent are

examined, and a panicle that has spikelets about

to bloom is taken. A spikelet that has the

anthers pushing up toward the tip of the floret

is opened, and an anther or two are placed in the

emasculated flower. Usually the anthers are

broken open and the pollen is dusted on the

stigma. This process is repeated until all flowers

have been pollinated. After pollination, the panicle is again enclosed in the bag and the designation of the parents and the date of pollination

are written on the tag.

A modification of the clipping method has been

used at the Eice-Pasture Research and Extension

Center, Beaumont, Tex. In this method, the tips

of the lemma and palea are clipped off at right

angles to the longitudinal axis of the spikelet.

The anthers then are removed by vaccum, Ijy

means of a fine glass nozzle connected to a vacuum jnunp that is driven by an eleotric motor

operating from a storage battery. Emasculating

is done in the early morning or in the late afternoon; and pollinating, bagging, and tagging are

completed in the same mainier as in the clipping

method described by Jones {55).

Another techniciue that has been used for crossing rice is a modification of a method developed

for wheat and barley {85). In this method, the

lemma and palea are^clipped at right angles to the

longitudinal axis of the spikelet at a point just

above the tip of the stigma. This cuts the anthers, and it is not necessary to remove them.

The florets are clipped early in the morning or in

the afternoon, and then the emasculated panicle

is covered with a fairly large glassine bag. Later

that day or the next day, pollen from a male

panicle that has many florets just starting to

bloom is dusted on the stigmas of the emasculated

panicle. Before pollination the bottom of the

inverted bag on the emasculated panicle is slit so

that it can be spread open and can serve more or

less as a funnel while the pollen is being applied.

The bag then can be closed, folded over, and

fastened with a paper clip. The pollinated panicle is then tagged to show the designation of the

parents and the date of pollination.

As a result of the elevated temperature within

the bag, seed set may be poor in crosses made by

clipping the floret. In an effort to devise a technique for making a cross that would not require

bagging the female panicles, Jodon {39\ developed the hot-water method for emasculating rice

flowers. In this method, the female panicle is

immersed in water at a temperature of 40° to

44° C. for 10 minutes in the morning before any

of the florets have opened. This critical temperature renders the pollen grains ineffective but

does not prevent the normal functioning of the

female portion of the rice florets. Within a few

minutes after the panicle is removed from the

warm Avater, the florets that w^ould have bloomed

later that day open. These florets can be pollinated in the same manner as in the clipping

method. Spikelets that already have been pollinated and spikelets that do not open are clipped

off. Spikelets at the base of the panicle usually

are immature and can be left to produce mother

seed. It may not be necessary to bag the panicle,

because the lemma and palea usually close in

about 45 minutes. Thus, they usually are closed

before other plants start to shed pollen. The pollinated panicle then is tagged to show the designation of the parents and the date of pollination.

SINGLE CROSSES.—The crossed seeds are planted

in a greenhouse in the fall after the cross is made

or in the field the next spring. AVlien the Fi

plants are grown in the greenhouse during the

winter, a year is saved because the F2 population

can be grown in the field the year after the cross

is made.

Usually several Fi plants are grown to assure

that typical parental strains were used in making

the crosses. The cross should be made so that the

Fi plant can be distinguished from the female

parent variety. For example, when pubescent X

nonpubescent varieties are crossed, the nonpubescent variety should be used as the female parent.

Fi plants should be propagated vegetatively until

it is known that they are not needed for additional seed production or other purposes. Vegetative propagation of Fi plants is also helpñil in

obtaining increased quantities of F2 seeds.

Seeds from the Fi plants are spaced thinly or

space sown in rows 12 inches or farther apart.

When space sowai, seeds are placed 3 to 6 inches
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 27

apart in the row, so the F2 plants can be examined

mdividually for plant characters and disease

reaction. A further advantage of space seeding

F2 populations is that all the seed produced by a

selected F2 plant can be harvested and used for

(1) preliminary quality tests on milled samples

(5 to 10 grams), (2) growing at different locations or dates of seeding to obtain information

on reaction to diseases and to photoperiod and

other environmental influences, and (3) seedling

tests in greenhouse or growth chamber for blast

reaction and seedling hardiness. In important

crosses where known genetic variables can be

identified, early-generation testing has proved

very effective.

The rice-breeding procedures used in the F3

and subsequent generations usually are governed

by particular circumstances such as available personnel, physical facilities, financial considerations, urgency of a particular development,

number of characters involved, and mode of

inheritance.

The pedigree system has been more widely used

than other systems of handling hybrid progenies,

although modifications of the pedigree and bulk

systems are frequently followed.

In the pedigree system, the F2 plants are carefully examined in the field and laboratory. The

selections that appear to be satisfactory for all

characters studied are sown in individual rows

(8 to 16 feet long and 12 inches apart) the

next spring. Seeds are spaced thinly in rows.

Space seeding is seldom used for F3 and later

generations.

"ÍYlien facilities and circumstances permit, a

system of multiple screening of selections may be

used. Desirable plants are saved from the Fo

progenies in the field, and each i)lant is threshed

individually. A small portion of the grain of

each is milled, and plants having chalky kernels

are discarded. Milled samples from the remaining plants are tested in the laboratory to determine cooking quality. Undesirable plants are

eliminated, and the seeds of each of those remaining after the double screening are divided into

three parts. One part (about 25 seeds) of each

is tested for reaction to hoja blanca under controlled conditions. Another part is seeded late in

the field under conditions believed to be favorable

for the development of blast. The third part is

seeded in the breeding nursery to observe agronomic characters and to proAdde seed for further

testing of lines surviving the multiple screening.

This screening method eliminates many undesirable lines in the F3 generation.

The F3 lines are carefully examined throughout the growing season and usually from 6 to 15

panicles are selected from lines that have the

desired plant and grain type and that appear to

be resistant to diseases. The quantity of seed

from each panicle is seldom sufficient for seeding

at more than one or two locations. Small samples

for quality tests and a few seeds for disease

nurseries may be obtained by bulking part of the

seed from each of the 6 to 15 panicles harvested

from a given F3 line. The remaining panicles in

a line may be harvested in bulk to provide additional seed for testing the line for resistance to

straighthead, hoja blanca, and blast; and for

seedling hardiness, grain quality, or other characters. The F4 lines are handled in much the

same manner as the F3 lines. Usually from 3 to

6 selected panicles of each line are sown in

panicle-row plots the following year.

Early-generation testing is continued until it

is reasonably certain that the lines are no longer

segregating for the characters under study.

From 10 to 15 panicles are selected from nonsegregating rows, and then the rows are harvested

and threshed in bulk. Part of the seed from the

harvested rows is used for more extensive laboratory grain quality tests.

Lines that have suitable grain type are then

tested in a preliminary yield trial. Some lines

may be discarded because of lack of vigor, weak

straw, disease susceptibility, undesirable cooking

quality, or other undesirable characters. Lines

that are heterozygous for one or more characters

but otherwise appear to be desirable are replaced

by pedigree sublines selected from later generation panicle rows. True breeding lines usually

can be isolated in six to eight generations. The

true breeding lines then are tested for at least 3

years to determine yielding ability, disease resistance, time of maturity, plant height, stiffness of

straw, and cold tolerance, and to check thoroughly

milling, processing, cooking, and other characters.

Lines that prove to be superior to existing varieties in one or more characters are then named, the

seed is purified and increased, and the seed of the

new variety is distributed to growers.

The bulk sj^stem has been used to a limited

extent, particularly where time and space were

limiting factors. True breeding lines usually

can be obtained in fewer generations when the

pedigree method is used.

In the bulk system of breeding, the Fi plants

are grown and the F2 populations are sown in the

same manner as in the pedigree method. The F2

population is harvested and threshed in bulk.

Progenies from each cross may be kept separate

or the progenies from several crosses with similar

parentage may be combined. From 10 to 25 rod

roAvs are grown in F3. They are harvested and

threshed in bulk and sown on a similar size plot

the next year. This procedure is followed for

each succeeding generation until Fe or F7. In

bulk-hybrid populations, special care should be

taken to be sure that desirable plant types are not

teing eliminated through natural selection. For
28 K LV' :i: HANDBOOK 289, U.S. DEPT. OF AGRK ULTURE

example, tall and profiise-i illeiiiia' tv})es tend to

eliminate shoi*t types (6").

The bulk system often is modiñed in various

ways. For example, if there is a diíí'erential

plant reaction to a natural or artifically induced

infection of a serious disease, a bulk is made up

by selecting the resistant plants. Plants that

make up the bulk are sometimes tested for processing and cooking quality. Where the parents

differ in grain type, panicles having the desired

grain types are selected in bulk or the Indked

seed is graded on the basis of length and width,

and the desired grain type is saved. This operation might be repeated foi* seA'eral generations.

AAHien unfaAV)ra))le v\'eather or a shortage of helj)

makes selections in the field impossible, a composite may be harvested and panicles selected in

the laboratory. In tliis case, the grain from

selected plants is combined for seeding the bulk

plot the next year.

In California, progenies from each cross are

sometimes grown in small, water-seeded plots

where the material is seeded under conditions

similar to those of tlie commercial ricefields.

This method aids the l)reeder in selecting plants

that emerge readily through deep water. Also,

when rice is water seeded, some varieties do not

develop sufficient roots, and plants may tend to

lean as the grain matures. Thus, when rice is

water seeded in l)reeding studies, plants may be

evaluated for resistance to this type of lodging.

Each year the material may be subjected to

natural selection pressures in an attempt to eliminate undesirable types. Examples of luitural

selection pressures are: Harvesting I)efore late

plants are mature if short-season types are desired; seeding uiider conditions where straighthead is likely to occur; or inoculating with

Aphelerichohles hessey¡ Christie (sometimes called

A. orijzae Yokoo) to eliminate plants susceptible

to white tip. After six or seven crenerations, a

large number of plants or panicles' are selected,

preferably from a space-planted population. The

plants are carefully examined and only those that

appear to have strong straw, disease resistance,

and good grain type are selected. Seeds of the

selections are then examiiied in the laboratory

much the same as seeds from Fo plants are exammed, and those that appear to liave the desired

kernel characters are sown in single-row plots the

next year. The selections are then handled in the

same manner as advanced-generation selections

obtained by the pedigree method.

Many rice varieties have been developed in the

I lilted States by the livl)ridizatio]i method. Varieties rhat were named and rele;ised are as folh)ws: Arkrose, Belle Patna, Bluebonnet, Caladv

Century Patna 2:]1, Cody, Delrex, Gulfrose, Improved P>]uebonnet, Kami'ose, Lacrosse, Ma^niolia

Missouri R-500, Nato, Xortlirose, Nova, Prelude^

I{-I), Rexark, R-N, Saturn, Texas Patna, Toro,

TP 4Í), and Vegold. Many of these varieties were

not in commercial production in 1963, although

\'arieties developed from crosses comprised about

S5 ¡percent of the United States acreage that year.

BACKCKOSS.—The Ijackcross system or a modification of the typical backcross system is successfully used to some extent in rice breeding in the

United States. As w^th other small grains, this

system LS used when it is desired to transfer one

^^^w^ or a small number of genes to a fairly welladapted variety. This system has not been used

as widely with rice as with other small grains.

Commercial rice production methods in the

United States have undergone periodic changes

(combine harvesting, increased fertilizer use, new

herbicides) that have resulted in rather drastic

changes in plant-type requirements. Because rice

breeders have had to search for divergent types,

the use of standard varieties as recurrent parents

in a formal backcross ¡program has been prevented. As production methods become more

stable and satisfactory plant types are developed,

and as rice breeding progresses in the United

States, the backcross method may be used more

generally. Adair, Miller, and Beachell (7) described briefly the development of hoja blanca

resistant, long-grain types by backcrossing.

Calrose {ñ7), a medium-grain variety, was de-

\'eloped by this method of breeding.

MULTIPLE CROSS.—IMultiple crossing has been

used very^ little by rice breeders in the United

States. Several varieties have been developed

from rather complex crosses, but none of these

were selected from a population obtained from

systematically crossing four or more varieties.

Irradiation

Irradiation breeding has been employed in the

United States. Several mutants that niay be useful m breeding programs have been obtained in

this manner, but no varieties have been developed.

Breeding for Agronomic Characters

Rice often is seeded early in the spring when

the soil temperature is low,^r it may be sown in

water that is below the optimum temperature.

Ihus, seedling vigor is an important character

of rice varieties, and it is desirable to studv seedling vigor and cold tolerance concurrently \and to

cond)ine the two characters in a rice variety.

At optimum temperatures, indica varieties generally grov^ faster in the seedling stage than do

japónica varieties. However, some of the japónica varieties are more tolerant to low temperatures, and seedlings of these cold-tolerant janonica

varieties may grow and develop faster than seedlings of mdica varieties when the temperature of

the soil or water is low.
RICE IN THE UNITED STATES : VAPvIETIES AND PRODUCTION 29

Vigor and cold tolerance of seedlings are

studied under controlled conditions {68) and in

the ñeld. In the controlled studies, the seeds are

sown in water and the temperature is maintained

at 60° F. The length of longest leaf at about 'M)

days is the criterion used to judge tolerance and

vigor. The varieties aiid lines that are vigorous

and cold tolerant under controlled conditions are

tested in the fieUl. P^ield experiments are conducted by water seeding in ñelds where the irrigation water is cold, or by drill seeding early in the

spring. Because variability is high under field

conditions, results for a particular experiment are

not always dependable. But over a period of

years, useful information can be obtained on the

performance of varieties under these adverse

conditions.

Varieties also diifer in their response to low

temperatures during the flowering stage. This

character of rice varieties and breeding lines is

studied by seeding late, so that pollen development and flowering occur when the temperatures

are low. In Texas, when temperatures are below

the optimum in October when rice is flowering,

hardy varieties, such as Caloro, continue to develop; whereas cold-sensitive varieties, such as

Bluebonnet 50 and Century Patna 231, may not

produce seed.

Eice varieties also vary in response to high

concentration of salts in the irrigation water and

in the soil. Varietal response to salt was studied

at Stuttgart, Ark., and Beaumont, Tex. At

Stuttgart, on soils with a high salt content. Arkrose produced 4,180 pounds per acre and Bluebonnet 50 produced 3,172 pounds. On soils with

lower concentration of salts, Arkrose produced

4,531 pounds per acre and Bluebonnet 50 produced 3,838 pounds. At Beaumont, with a concentration of sodium chloride of about 2,500

parts per million in the irrigation water. Caloro

produced 1,789 pounds of grain per acre, whereas

Toro produced only 842 pounds. "N^Hien no salt

was added to the irrigation water, Caloro produced 4,820 pounds per acre ancl Toro 3,716

pounds.

The Beaumont studies were conducted in 1/10-

acre blocks of Beaumont clay soil. Approximately 2,500 parts per million of salt was maintained in the irrigation water by adding sodium

chloride. Frequent additions of salt were needed

because of dilution from rains and soil moisture

exchange. As much as 15,000 pounds of salt per

acre was used during the 70- to 80-day test. Salt

was first added to the irrigation water when the

rice plants were about 45 days old.

Under these conditions an attempt w^as made to

grow breeding lines in single-panicle rows as well

as to conduct yield tests in replicated nursery

plots. Widely different responses occurred because of weather conditions during blooming and

inmiediately thereafter. When blooming occurred

during periods of cloudy weather and moderate

temperatures, practically all lines showed good

seed sets. When temperatures were higli and

humidity was low, practically all lines showed

poor seed sets. After several years, the test was

abandoned because it required a great amount of

time and efl'ort and provided little information.

Varieties that produce maximum yields must

have relatively short and sturdy straw, so that the

rice does not lodge before harvest (fig. 17).

Japónica varieties have smaller and shorter culms

and shorter, narrower, and darker green leaves

than do most indica varieties. Although there

are exceptions, japónica varieties generally produce higher yields than do indica varieties; this

indicates that morphologic characters might be

associated with grain yield. The japónica varieties have tough but willowy stems. The less

willowy straw character of the indica varieties is

preferred since this type is less likely to lodge.

For several years, rice breeders have been

searching for plants with short, slender stems;

with erect, relatively narrow, dark-green leaves

of intermediate length; and with low percentages

of sterility at high rates of nitrogen fertilization.

Strains approaching this description have been

selected from crosses between a Taiwan variety,

Tainan-iku Xo. 487 (P.I. 215,936),^ and United

States varieties. Ten short-stature selections from

these crosses were grown in a variety-fertilizer

test in 1961. They averaged 4,224 pounds of

rough rice per acre at the 160-pouncl nitrogen

rate and 3,367 pounds at the 80-pound rate. The

highest yielding strain yielded 5,658 pounds at

the 160-pound rate and 4,022 pounds at the 80-

pound rate, compared with Bluebonnet 50, an

indica type variety, which yielded 3,448 and

•*->*/'

FIGURE 17.—A field of Caloro rice showing serious lodging.

3 P.I. refers to the accession number assigned to foreign

introductions by the Crops Research Division, Agricultural

Research Service, U.S. Department of Agriculture.
30 AGRICULTURE HANDBOOK 2 8 9, U.S. DEFT. OF AGRICUijTURE

2,916 pounds, respecti\'ely, at tlie two rates of

nitrogen fertilization.

In an eti'ort to find short-stature types possessing superior yielding capacity, varieties that combine extremely narrow and erect leaves and small

stems have been crossed.

Short-strawed plants have been found in hybrid

and irradiated populations, as mutations from

varieties, and in introductions from foreign countries. In Arkansas, naturally occurring dwarf

types were saved from C.I. 9187,'' a high-yielding,

lodging-resistant, early long-grain experimental

variety that has short straw and narrow leaves.

Crosses were made with Eluebonnet types to improve milling quality, and dwarf and semidwarf

types were saved for testing.

The short-stature types showed considerable

variation in plant height because of the degree of

internode elongation. Club and grassy dwarfs

seldom grow more than 12 to 18 inches tall. Since

grains are shortened and fretjuently are otherwise

distorted, they are of no economic value. Some

intermediate-height, dwarf-type lines exhibit

varying degrees of grain distortion. Other intermediate-height, dwarf-type lines appear to produce grains of normal size and shape.

All of the dwarf-type plants examined appeared to have the normal number of nodes. The

reduced height was governed by the extent of

internode elongation, including the peduncle (internode just below panicle). In all but one

dwarf-type selections examined, all internodes of

the stem, including the peduncle, showed reduced

elongation when compared with normal height

plants. An exception to this elongation pattern

was observed in a dwarf plant selected at Beaumont, Tex., iii 1955, from an irradiated population of Century Patna 231. The panicles of this

selection were normal in length and floret number, and the peduncles were of about normal

length. The lower internodes showed only minor

elongation; this resulted in an extremely short

and sturdy plant.

The grains of the dwarf were of normal length

but appeared to be slightly tapered. This dwarf

was crossed with normal Bluebonnet 50, Century

Patna 231, Rexoro, and Texas Patna. Dwarftype selections resembling the original strain were

recovered in about a 3 normal :1 dwarf-type ratio

m all crosses. The original and the dwarf-type

selections from the crosses were tested in yield

expermients and invariably showed about 15- to

20-percent lower yields thkn did normal strains.

All the dwarf-type strains showed considerably

more sterility than did the normal strains, which

was probably responsible for the reduced yields.

^ C.I refers to the accession number used in the Cereal

Cops Research Branch, Crops Research Division Agrieumn-al Research Service. U.S. Department of AgHcûiThe cause of the increased sterility was not determined. This promising dwarf type will be

studied further.

üenerally a high rate of nitrogen fertilizer is

applied to rice-breeding nurseries to select tyjDes

that respond to fertilizer and that resist lodging.

When pure lines are isolated, they are then tested

at two rates of nitrogen fertilization. Usually a

I'andomized, split-plot design is used with varieties as the main plots and with nitrogen rates as

subplots (fig. 18).

At Stuttgart, Ark., a continuing experiment

designed cooperatively by the agronomist, the

plant breeder, and the plant pathologist has been

established to compare outstanding experimental

varieties with commercial varieties they might be

expected to replace. Varieties are tested in maturity groups and receive nitrogen fertilizer at a

number of rates and times. The varieties are

checked closely for grain yields and disease reaction, lodging, and other characters in the field.

Milling yields and chalkiness of the grain and

kernels resulting from the various treatments are

also checked. To deA'elop a satisfactory nitrogen

fertilization program for each variety'^so that it

will give consistently high grain yields with a

minimum of lodging and disease," possible new

varieties are tested 2 or 3 years as part of a final

evaluation before their release.

In fertilizer-variety tests at Stuttgart, Ark.,

C.I. 9434, a very short-season, experimental long-

.V"-,

,.-. mm^

ViGXTRK 18.—C.I. 9446 fertilized at two rates: Left, 200

pounds of nitrogen per acre produced a yield of 5,707

pounds of rice per acre; right, 40 pounds of nitrogen

per acre produced 3,942 pounds of rice per acre.
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 31

grain variety, produced 5,992 pounds of grain per

acre compared with 5,839 pounds produced by

Bluebonnet 50. In both tests the treatment inchided 200 pounds of nitrogen per acre, but C.l.

9434 produced this relatively high grain yield in

45 days less time than did Bluebonnet 50; and

the straw of C.I. 9434 was 14 inches shorter.

The resvdts from these experiments indicate

that it will be possible to develop short-strawed,

nonlodging varieties that respond to high rates of

fertilizer. Notes on breeding lines and strains in

yield tests recorded about 30 and 60 days after

seeding and at maturity provide valuable information on plant type. By using symbols, brief

notes are obtained on (1) habit of growth of

leaves (erect to spreading) ; (2) color of leaves

(light to dark green) ; (3) leaf width (narrow to

wide) ; (4) plant or seedling height (short to

tall) ; and (5) degree of tillering (low to high).

Calculating sterility percentage by counting the

number of sterile and fertile florets on selected

panicles of breeding lines appears to have merit.

The grain yield of breeding lines and experimental varieties is determined by using replicated

nursery plots. For comparison, standard varieties are included in each trial. The experimental

design is a complete randomized block, usually

with four replications. The plots are about 1 rod

(5 meters) long and three or four rows wide,

usually the rows are spaced 9 inches apart in the

4-row plot or 12 inches apart in the 3-row plot.

The plots are trimmed to a uniform length before

harvesting. For yield determination, the center

row is harvested in the 3-row plot, and the two

interior rows are harvested in the 4-row plot.

One or both of the border rows may be harvested

in order to have a larger sample for milling and

cooking tests.

An alternate method is the use of 4-row plots

usually 15 or 16 feet long with a 12-incli spacing

between rows. An 8-foot segment from the two

center rows is harvested. By careful harvesting,

the remainder of the plot is left standing for later

observations and for collection of panicle samples.

In California, where the rice on all farm fields

is sown broadcast in the water, the method used

for testing varieties is somewhat different. The

rice is sown in the water by hand.

The design used for preliminary trials is a complete randomized block with three or four replications. The individual plots are a single row,

12 to 16 feet long, with the rows spaced about 24

inches apart. The preliminary trial gives information on the ability of the variety to emerge

through the water, straw strength, and other

characters. The best varieties then are tested in

randomized, quadruplicated plots large enough to

be harvested with a small combine.

Time of maturity (length of growing season)

is an important consideration in the breeding program. Although early and very early types have

gained favor in recent years, a complete range of

maturity types is maintained.

Partial dormancy in rice is desirable, so that

rice does not germinate if rain and humid weather

occurs at harvesttime or if plants are badly

lodged. -Seed of nondormant varieties will germinate before cutting if there is a prolonged period

of rain after the grain is ripe. It sometimes is

desirable to break dormancy of seeds soon after

harvest. This is necessary in the case of crossed

seeds to be planted in the greenhouse in the winter

or otlier breeding material to be grown during the

off season in another region. This can be done

by treating in a 0.10- to 0.05-percent solution of

sodium hypochlorite for 24 hours or by heating

in shallow, open containers for 3 to 5 days at 47°

to 50° C. ^ Rice varieties in the United States are divided

by grain size and shape into three types. These

are short- (Pearl), medium-, and long-grain

types. The more slender, long-grain varieties are

sometimes considered as a fourth type. Examples

of each type are Caloro, Nato, Bluebonnet 50, and

Rexoro, respectively. The grain type can be

visually classified; but for more critical comparisons of varieties and for classification, more exact

measurements are needed. At the Cooperative

Rice Quality Laboratory at Beaumont, Tex., the

various grain types are characterized objectively

according to length, width, length/width ratio,

thickness, and grain weight« Dimensions of

rough (paddy), brown, and milled (head) rice

grains are measured and reported in accordance

with tlie following definitions:

(1) Length of awnless rough rice is the

straight-line distance (millimeter) from the point

of disarticulation of the grain, which is below the

outer glumes, to the tip of the apiculus (fig. 19,

B). For awned rough rice the tip of the lemma

is the reference point. Length for brown and

milled rice is the distance between the most distant tips of the kernel, including the embryo of

the brown rice kernel (fig. 19, A).

(2) Width (dorsiventral diameter) for rough

rice is the distance (millimeter) across the lemma

and palea at the widest point (fig. 19^ B). Width

for brown and milled rice is the distance across

the kernel at the widest point (fig. 19, x4).

(3) Thickness (lateral diameter) for rough

rice is the distance (millimeter) from one outside surface of the lemma to its opposite at the

thickest point (fig. 19, />). Thickness for brown

and milled rice is the distance from one side of

the kernel to its opposite side at the thickest

point (fig. 19,6^).

By modifying a photographic enlarger, a device

was built for measuring the length and width of

rice (fig. 20). The enlarger was mounted on a

box with three sides that were painted black on
32 AGKICUI/rUIUÍ HANDBOOK 289, U.S. DEFT. OF AGRICULTURE

FIGURE ]».—Points from which rice grain and kernel

lueasiirenient .should be inarle.

the inside. A black cloth was placed over tlie

open side of the box to exclude most of the li<;ht,

so that a distinct image of the rice grain would

appear on the white grid. Minute adjustments

were made to obtain a magnification of exactly

10 times.

FIGURE 20.—Device for mea.suring rice grains and kernels.

The light source was a 6- or 12-volt cold, sealedbeam, automobile spotlight. The spotlight had a

smooth surface, so that light or shaded areas

would not be projected on the grid. Any cold

light source of similar intensity should be

satisfactory.

A 50-mm.F/4.5 liminized lens was used. This

lens made it possible for the enlarged image

(lOX) to be projected on a grid that was less

than 24 inches from the lens.

A glass slide that held 10 grains was placed in

the light field just above the bellows and the 50-

millimeter lens. A millimeter scale was placed

on the glass slide. The image of the millimeter

scale was magnified 10 times and made possible

accurate focusing before use. The adjustable

bellows to which the 50-millimeter lens was attached made it possible to obtain a clear-cut

image. The enlarged images of the rice grain

were measured to obtain the length and width.

The thickness of the rice grain was determined

by using a micrometer caliper graduated in millimeters. The micrometer was placed in a small

vice attached to a table. A sheet-metal tray at

the base of the micrometer, to catch grains

dropped during the operation, is useful.

If similar equipment is not available, a random

sample of 10 grains or kernels can be placed

adjacent on transparent tape in the desired position for the particular measurement, and the total

length, width, or thickness can be measured with

a fair degree of accuracy by using a transparent

ruler.
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 33

The length, width, and thickness of milled

kernels are determined by measuring 15 whole

kernels selected at random from a representative

sample. The coefficient of variation for each

dimension is calculated for each of 15 kernels to

determine the uniformity, of size and shape. Size

and shape classes for brown kernels are as

follows :

Leïigth

Size classiricatio)i {MiUunetejs)

Extra long (EL) Over 7.5

Long (L) 6.61 to 7.5

Medium (M) 5.51 to 6.6

Short (S) Up to 5.5

Lengthy

Shape classiticatio)i icidth ratio

Slender Over 3

Medium 2.1 to 3

Bold Up to 2.1

The average length, length/width ratio, thickness, and 100-grain weight of rough, brown, and

milled (head) rice for each of 18 varieties are

tabulated in table 6.

Testing for Milling, Cooking,

and Processing Qualities

The determination of milling, cooking, and

processing qualities of hybrid progenies, breeding

lines, and new varieties is an essential part of the

rice-breeding program. New varieties that are

released for commercial production must meet

established standards for these qualities. Certain

cooking and processing qualities are historically

associated with specific grain types. For examiole, most of the long-grain varieties grown in

the United States cook dry and flaky, and some

are used for specific processed products. The

short- and medium-grain A^arieties grown in the

United States are more moist Avhen cooked than

are the long-grain varieties and are used for specific processed products such as dry cereals. Thus,

it is desirable that a new variety have the same

cooking and processing qualities as the variety it

replaces.

Milling Quality

The objective of rice milling is the removal of

hulls, bran, and germ with a minimum breakage

of the endosperm. The milling process generally

consists of four fundamental operations: (1)

Cleanino' the field-run rouirh rice to remove sucli

thnigs as mud lumps, rice stems and leaves,

weed seeds and stems, and other foreign matter;

(2) shelling the cleaned rice to remove the hulls;

(3) scouring the brown rice to remove the coarse

outer layers of bran, white inner-bran, aleurone

layers, and germ; and (4) gi^ading the mixture

of Avhole and broken milled kernels according to

size classes known as head rice (whole-grain

milled kernels), second head (larger pieces of

broken milled kernels), screenings (smaller pieces

of broken milled kernels), and brewers rice (very

small pieces of broken milled kernels) (7, 16).

In modern rice mills, all operations in the ricemilling process are performed mechanically with

a minimum amount of manual labor, including

the transfer of rice from one machine to another

for the next series of operations. Fraps (-5Ö),

Geddes {31, pp, 2043-2051)^ Kik and Williams

(62), Wayne (5-^), and, more recently, Kester

{61) have described the commercial milling of

rice as practiced in the United States. Additional

information describing rice milling and processing equipment has been published by the Food

and Agriculture Organization of the United Nations (9. ¿4).

The milling quality of rice is based on the yield

of head rice obtained, since it is usually the milled

product of the greatest monetary value. Yields

of head rice vary widel}^, depending on variety,

grain type, cultural methods and other environmental factors, and the drying, storing, and milling conditions. The yield of total milled kernels

(head rice and all sizes of broken kernels) is important, too, and this yield is influenced by the

proportion of hulls and the amount of fine particles of broken kernels unavoidably included in

the bran fraction during the milling process.

In rice-breeding programs, rigid laboratory

milling tests are required to insure that any new

variety released will consistently produce high

vields of head rice and total milled rice. At the
34 71)1'.<>ÔK 28 y, U.S. DEPT. OF AííRIOUÍ/rURE

TABLE 6.^—(rníin .'luc; . / ,s for IS rice ra riet¡es grown in Unifomi Yield Nurseries

in Arkansas and Texa^iy 1959-61

[Values are averages and are for first cutting only]

Grain type and variety Grain form ^

Grain characters

Length Ratio

L/W Thickness 100-grain

weight

Short-grain :

Caloro --

Cody

Colusa

Medium grain :

Arkrose

Calrose _

Gulfrose

Magnolia .

Nato

Northrose

Zenith

Long-grain :

Belle Patna

Bluebonnet 50

Century Patna

Rexoro

Sunbonnet

Texas Patna _

Toro

TP 49

231

Millimeters

Í Rough

I P>ro\vn_^

I MilledÍRoughBrown.

[Milled.

ÍRough

Brown.

Ulilled.

ÍRough.

Brown.

|Milled_

fRough_

¡Bi-own.

(Milled.

Ruugh.

•Brown

(Milled.

ÍRough.

Brown

(Milled._

ÍRougli

Brown _

I Milled.

ÍRough..

(Brown.

I Milled-.

fRough.

¡ Brown.

I MilledRough..

Brown..

MilledRough

Thrown

Milled.^

ÍRough--

•Brown-.

I Milled-.

ÍRough-,

Brown-_

iMilled.

ÍRough..

Brown.-

(MilledI Rough..

Brown..

IMilled—

ÍRough..

¡Brown.

[Milled.

ÍRoughj Brown,.

IMilled- .

7.3

5.4

4.9

7.1

5.4

5.0

7.2

5.4

5.0

2.0:1

1.7:1

1.8:1

1.9:1

1.7:1

1.7:1

1.9:1

1.7:1

1.8:1

1 Rough = unhulled grain: brown =

bran, and germ removed.

8.4 2.6:1

6.3 2.3:1

5.8 2.2:1

7.8 2.4:1

5.9 2.2:1

5.6 2.3:1

8.0 2.5:1

6.3 2.3:1

5.8 2.3:1

8.3 2.5:1

6.3 2.3:1

5.9 2.3:1

7.3 2.4:1

5.8 2 2*1

5.3 2 2 '1

7.7 2.4:1

5.8 2.1:1

5.4 2.2 :1

7.8 2.4:1

6.0 2.3:1

5.7 2.3:1

8.7 3.7:1

6.8 3.4:1

6.5 3.4:1

9.6 3.8:1

7.2 3.4:1

6.8 3.4:1

9.1 3.9:1

7.0 3.4:1

6.5 3.4:1

8.8 3.9:1

7.1 3.6:1

6.5 3.5:1

8.9 3.6:1

7.2 3.3:1

6.7 3.3 :1

9.1 4.0:1

7.1 3.6:1

6.6 3.6:1

9.0 3.8:1

7.1 3.4:1

6.5 3.3:1

9.4 4.0:1

7.3 3.7:1

6.7 3.6:1

MilUnieters

2,3

2.1

2.0

2.5

2.1

2.0

2.3

2.0

1.9

2.2

1.9

1.8

2.1

1.8

1.8

2.0

1.8

1.7

2.1

1.8

1.7

2.0

1.7

1.6

2.1

1.9

1.7

2.0

1.7

1.6

1.8

1.7

1.6

1.9

1.7

1.6

1.8

1.6

1.6

1.7

1.6

1.5

2.0

1.8

1.6

1.7

1.5

1.5

1.9

1.7

1.5

1.8

1.6

1.6

Grams

2.8

2.3

2.2

2.8

2.3

2.2

2.8

2.3

2.2

3.1

2.4

2.2

2.5

2.0

1.9

2.5

2.0

1.9

2.6

2.1

2.0

2.1

1.7

1.6

2.4

1.9

1.8

2.3

1.8

1.7

2.1

1.7

1.6

2.5

2.0

1.8

2.1

1.6

1.5

2.1

1.7

1.5

2.4

1.9

1.8

2.0

1.6

1.5

2.2

1.7

1.6

2.2

1.8

1.7

irain with hull removed; milled = whole grain milled kernels with hull,
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 35

Cooperative Rice Quality Laboratory at Beaumont, Tex., three methocls are available for estimating the milling quality of rice varieties and

selections. The method used depends on the

amount of rice available for testing. The official

grading method for determining the milling quality of rough rice bv United States standards,

described by Smith {78, 79, 80. 81) and adapted

to laboratory conditions, gives the breeder comparative information regarding milling quality of

the more advanced selections grown in larger

plots. The method requires 1,000 grams of rough

rice for each determination.

A modification of the official method requires

only a 125-grani sample {19) to estimate the

milling quality of rice and enables the breeder to

check milling cpuility at very early stages of selection. The samples of rough rice are sealed in

glass jars and kept at room temperature for at

least 24: hours to bring the moisture content to

equilibrium before the rice is milled. The moisture content is determined, a 125-gram sample of

the rice is hulled in a ÄIcGill sheller, and the

brown rice is weighed. The weight of the hulls

is determined by subtracting the weight of the

brown rice from the weight of the rough rice.

The brown rice sample is milled in a small

McGill miller for 30 seconds, using a 14-pound

weight over a steel j)late that covers the rice. The

sample is immediately milled a second time for

30 seconds, using a 4-pound weight. This second

milling gives a high polish to the rice kernels but

causes little additional breakage. The milled kernels are sealed in a glass jar to prevent unnecessary breaking due to rapid or uneven cooling.

The bran is screened through a 20 X 20 mesh wire

screen to recover the small, broken kernels that

passed through the miller screen. The finely

broken kernels thus recovered are aspirated and

added to the milled kernels. The milled kernels

are weighed when the rice has cooled to room

temperature. The weight of the bran and polish

is the difference between the weight of brown

rice and the weight of total milled rice.

The whole kernels are separated from the total

milled portion with a sizing device developed by

the Grain Division, Consumer and Marketing

Service, U.S. Department of Agriculture. This

device makes use of two indented plates, with flatbottom holes, tilted at a slight angle and shaken

by an eccentric mechanism. During the shaking

motion, the rice travels the length of the top

sloping plate and drops onto the bottom sloping

plate. A^Hiole kernels drop off the end into a

container; broken kernels fall into the indents in

the plates. Plates with specific size indents are

used for each grain type. Results usually are

reported as percentage of hulls, bran, head rice,

and total milled kernels.

A method also is available for milling very

small samples of rice (76). This method can be

used to mill the rice from one panicle. The rough

rice sample is thoroughly cleaned and hulled in a

McGill sheller, and a ö-gram sample is weighed

for milling. The weighed sample is put into a

test tulje witli 3 grams of abrasive (40- to 60-mesh

fused white aluminum oxide or clean, sharp,

white quartz sand). The stoppered test tube is

mounted in the test-tube miller, which holds 80

test tubes, and is shaken for 45 minutes at a speed

of approximately 390 strokes per minute. The

samples then are remo^Td and polished in a small

sample polishing machine (77). This method of

milling small samples not only gives information

on the milling quality of individual plant selections but also provides a milled sample to use for

preliminary tests of the physical and chemical

properties of the kernel.

The average milling yields of hull, bran, total,

and head milled kernels for each of 18 varieties

grown in the Uniform Yield Nurseries in Arkansas, Louisiana, and Texas from 1958 through

1961 are tabulated in table 7. Estimated yields

were determined according to the modified procedure of Beachell and Halick (19).

Cooking and Processing Qualities

Rice varieties differ gi^atly in cooking and

processing qualities. Among the domestic varieties the quality of home-cooked rice has been

described as varying from very sticky to flaky

(46)' Fully cooked grains of typical United

States short- and medium-grain varieties are

usually somewhat sticky, relatively firm, and tend

to stick together. Typical long-grain varieties

usually cook to a flaky state with a minimum of

splitting and do not tend to stick together. Other

terms used to subjectively describe cooking quality are moist or clry, soft or firm, and mealy or

che^v;\^ Since different cultural groups prefer

different textures, there is a rather widespread demand for all types for use as home-cooked table

rice.

There is also a demand for all types of rice for

use in the widely different prepared products.

Processors of rice prefer different textures for

their various products and also specific qualities

adapted to the processes themselves. According

to Kester (61)^ a substantial amount of the domestic rice crop is processed into various kinds of

prepared foods such as parboiled rice, quick-cooking rice, breakfast cereals, canned rice, canned

soups, canned rice and vegetable mixtures, dry

soup mixes, enriched baby foods, and frozen

dishes. Rice flour is used in various processes,

and broken rice is often used in brewing. Typical

long-grain varieties are preferred for many parboiled and quick-cooking products, and specific
'M'> .X1)F,( )OK 2 8*J, I .8. DEPT. OF AíílíICULTUKE

TABLE 7.—MilliiKj ///./rZ/v fo)' 18 riee vro-ietics (frown in Uniform Yield Nurseries^

/n A/'/]'((nrsa.s^ Loui^^ianiu (ind Te.rru^^ 1958-61

I Values are avei-a^res and are for first cutting only]

Grain type and variety

Short-grain :

Caloro

Cody

Colusa

Medium-grain :

Arkrose

Calrose

Gulfrose

Magnolia

Nato

Northrose

Zenith

Long-grain :

Belle Patna

Bluebonnet 50

Century Patna 281

Rexoro^

Sunbonnet

Texas PatnaToro

TP 492

Milling yields ^

Milled rice

Hulls

average

Pereent

18

19

18

20

19

20

20

19

20

20

19

19

21

19

19

19

19

19

Bran

average

Pereent

10

10

9

9

12

10

11

11

12

13

10

13

10

11

Total

average

Percent

73

71

71

70

71

72

68

70

70

70

67

68

71

68

71

70

Head rice

Average

Percent

68

67

65

63

69

65

m

68

64

64

Range

Percent

58-72

58-71

42-75

33-70

63-72

58-70

63-72

63-73

59-69

53-71

60 50-69

63 52-68

62 50-67

52 36-61

62 50-71

58 48^65

67 60-70

58 52-62

1 Total milled rice is the head rice and all sizes of broken kernels. Head rice is the whole grain milled kernels

2 Grown only in Louisiana and Texas.

long-ofrain varieties are preferred for certain

canned soup products. Medium- and slu)rt-o;rain

varieties are more suitable for dry breakfast

cereals and for use in baby foods and'in brewin^r.

The short-grain types exclusively are used for

makinfi puffed rice.

Ahhouirh in the Uiuted States each o-rain type

is generally associated with specihc crmking and

processing qualities, notable varietal exceptions

withm each grain type have been reported; and

the nontypical cooking and processing quality of

these grain-type exceptions in relation to nieasured differences in some chemical and physical

qualities of the rice grain has been discussed {2(K

Tn rice-breeding pi'ograms, cooking and i)rocessmg quality is considered to be an important

measure of the suitability of a variety or selection

tov specihc purposes. At the Cooperative Rice

Quality Laboratory at Beaumont, Tex., results of

specihc chemical and physical tests collectively

serve as indices of cooking and processing qualities Ihe results guide the rice breeder in selecting lines that combine the desired cookino- and

processing qualities and agronomic features^ The

merit of this type of evaluation has been clearly

demonstrated. *

Some of the chemical and physical tests are the

determination of amylose content (57), starchiodine-blue value {3%)^ gelatinization temperature {S3), type and extent of disintegration of

whole milled kernels in contact with dilute alkali

{65), and amylograph pasting qualities {33).

The amylose content of rice, particularly of

long-grain types, has recently been associated

with cooking quality (77,57). The investigations

of Williams and others {87) showed that the

long-gi^am domestic varieties known to cook dryñaky usually had the highest amylose content;

whereas the^ amylose cont^ents of tlie short- and

medium-grain varieties investigated were somewhat lower. The glutinous (w^axy) varieties contain virtually no amylose. The simple, rapid, and

somewhat empirical starch-iodine-blue test {31^)

IS particularly useful in breeding programs for

estimating the relative amvlose content of earlygeneration breeding material.

The gelatinization temperature of rice is believed to be closely related to cooking quality.

Ihe amylograph studies {33) showed that most

short- and medium-grain varieties gelatinized at

lower temperatures than did most of the longgram varieties investigated. These results were

conhrmed by granule swelling and birefringence
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 37

end-point temperature (BEPT) determinations

The reaction of milled rice kernels in contact

with dilute alkali has been used to classify the

cooking quality of rice {66^ 83). The type and

extent of disintegration of whole milled rice kernels in contact with dilute alkali were reported

more recently {65). Two distinct reactions w^ere

noted: (1) Spreading where the kernels disintegrated into small granules and spreading to several times the origmal kernel size; and (2) clearing where the starch is solubilized with a loss of

opacity. Spreading and clearing were evaluated

on a numerical scale from 1 (minimum) to 7

(maximum). A slight-to-moderate reaction was

characteristic of most domestic long-grain varieties and a more pronounced reaction w^as characteristic of most short- and medium-grain varieties.

A very high correlation between tlie alkali reaction and gelatinization temperatures has been

observed {SS).

The pasting quality of several domestic varieties as determined w^ith the amylograph have been

described {33). In general, amylograph curves

of rice varieties were typical of those of other

cereal starches, but they showed appreciable differences among the varieties studied. Long-grain

varieties with the highest amylose content usuallj^

showed the greatest increases in viscositj^ when

cooled to 50° C. Amylograms of most short- and

medium-grain varieties generally exhibited relatively shorter gelatinization times.

Notable varietal exceptions within each grain

type were observed by Halick and Kelly {33).

For example, the long-grain varieties Rexark and

Toro had amylose contents, gelatinization temperatures, and alkali spreading and clearing reactions similar to those of typical short- and

medium-grain varieties. These long-grain varieties are also thought to resemble the typical shortand medium-grain varieties more in cooking quality than thej^ do other long-grain varieties. Of

all the varieties tested, Century Patna 231, a longgrain variety, and Early Prolific, a medium-grain

variety, had the highest gelatinization temperature and were the most resistant to the action of

dilute alkali. Tti general, these varieties have not

been widely accepted for certain types of cooked

rice and processed products.

Average values for some of the physical and

chemical characters of 18 rice varieties grown in

the Uniform Yield Nurseries in Arkansas, Louisiana, and Texas, from 1958 through 1961, are

tabulated in table 8. Environmental and other

factors influence these qualities to some extent;

however, within a limited range, the values are

representative of each variety. In the rice-breeding program, characters of new selections are always compared with comparably grown commercial varieties. Some of the physical and chemical

characters of the short- and medium-grain varieties listed in table 8 are a relatively low amylose

content, a relatively low gelatinization temperature, a very pronounced alkali reaction, and M

relatively low viscosity of the cooked paste wdier

cooled to 50° C. The typical long-grain varieties

are qualified by a relatively high amylose content, an intermediate gelatinization temperature,

a slight-to-moderate alkali reaction, and a maximum increase in viscosity of the cooked paste

when cooled to 50° C. Of the typical long-grain

types, the late-maturing varieties Rexoro, Texas

Patna, and TP 49 consistently had the highest

amylose content, the lowest peak viscosity, and a

maximum viscosity of the cooked paste W'hen

cooled to 50° C. These varieties are preferred

for certain canned souj) products. The nontypical cooking and processing quality of Century

Patna 231 and Toro, both long-grain varieties, has

been discussed previously.

Physical and chemical grain quality evaluation

tests are invaluable to the plant breeder in developing varieties with specific processing and

cooking quality. The specific tests used depend

on the quality variables of the particular hybrid

population in question and the purpose for which

the end product is to be used.

The results of the starch-iodine-blue and the

alkali digestion tests enable the plant breeder to

classify early-generation hybrid lines as to gelatinization temperature of starch and relative

amount of amylose. Promising advanced-generation lines are evaluated from data obtained in

analytical tests for amylose and protein content,

pasting qualities using an amylograph, and cooking, parboiling, and canning tests. In certain

crosses where it is essential to retain a specific

pasting quality or parboiling and canning character, it may be necessary to obtain amylograph

data on early-generation lines to make certain

that the desired qualities are recovered. Such

tests are usually conducted on a relatively small

number of samples because of the quantities of

grain required and the time used in performing

the tests. Parboiling and canning tests using 5

to 10 grams of rough rice can be conducted on

rather large numbers of samples if necessary, but

the cost is relatively high.

The cross Gulfrose X Bluebonnet 50 is an example of how quality tests aid in the rice-breeding

program. In this cross, the objective was to

develop a long-grain Bluebonnet 50 type possessing the hoja blanca resistance of Gulfrose. Gulfrose ordinarily shows a low gelatinization temperature and relatively low amylose content,

whereas Bluebonnet 50 ordinarily shows intermediate gelatinization temperature and relatively

high amylose content.

A large number of long-grain types resembling Bluebonnet 50 were saved from the F2 plant
38 .SJDBOOK 2 8 9, I.S. DEFr. OF AíjKICULTURE

TABLE S.—Physical cuui rnnnicaJ characters of ¡nilled kernels for 18 rice varieties grovni

in Uniform Yichi Xurscries in Ar/i'an^as, Loiii^siana. and Texas^ 1958-61

[Values are for fírst cuttin.s: only]

Physical character

(paste viscosity ) ^

Chemical characters

Grain type and variety

Amy lose

content -

Gela tin ization

temperature 2

Alkali reaction 3

Peak Cooled to

50° C. Spreading Clearing

Short-grain :

Caloro

(^ody

Colusa ---

Medium-grain :

Arkrose __ _ -

('airóse

(iulfrose

^la^^nolia

Bidboider

Units

850

950

840

820

900

750

920

900

820

800

820

790

î)50

000

810

03O

870

090

Brtihrndcr

Units

690

090

090

000

080

000

700

040

030

710

770

730

730

750

740

7(]0

740

770

Perçoit

19

17

18

21

19

19

14

10

15

19

20

24

10

28

20

28

17

28

° C.

00

07

07

04

05

66

07

67

07

00

70

73

77

09

73

71

05

09

7

6

6

7

7

6

6

6

6

6

4

4

o

4

4

4

7

4

6

6

5

6

6

5

5

5

0

5

2

2

1

3

2

3

6

3

Nato --

Northrose

Zenith

Long-grain :

Belle Patna

P>luelj()nnet 50 _^

Century Patna 231

Rexoro

Sunbormet

Texas Patna

Toro

TP 49

1 Average LTniform Yield Nursery in Texas, 1958-61.

2 uniform Yield Nurseries grown only in Arkansas and Texas.

3 Reaction in 2.0 percent potassium hydroxide S( dution.

population. A portion of the grain from each

plant saved was milled in a test-tube miller. The

milled samples were visually examined for grain

texture, size, and shape; and alkali digestion and

iodine-blue values were determined. Samples

showing grains of intermediate gelatinization

temperature and relatively high amylose (an

iodine-blue value of 25 or below) were saved for

hoja blanca testing. In the F3 plant generation,

a bulk made up of 15 or more panicles was again

milled, and the quality tests were repeated. The

strains that appeared satisfactory agronomically

after F5 or F^ plant generations were increased

for yield testing; and at this stage other quality

tests for characters, such as analytical amylose

and protein content and pasting viscosity, were

made.

Breeding for Disease Resistance

The easiest, most i)ra('tiral, and least expensive

way to control rice diseases is to use resistant

varieties. Considerable research has been done in

the United States on the reaction of rice varieties

to the various rice diseases and on developing

resistant varieties. Much of this work has been

reviewed (Í5, 14). The symptoms, control measures, and importance of the rice diseases occurring in the United States are given in the section

'^Rice Diseases,'' ]). 118. Methods used to breed

resistant varieties are presented in this section.

Certain basic principles apply to breeding for

disease-resistant varieties of a crop. Techniques

to create an epiphytotic of the disease and to

evaluate and record the response of the plant to

the causal organism must be developed. Then the

available varieties and breeding lines must be

tested to determine sources of resistance to the

causal org-anism. ^ Resistant varieties can then be

crossed with varieties possessing other desirable

characters, the progenies can be tested, and the

resistant lines can be isolated. A^Hiere a resistant

variety has few attributes other than resistance to

the disease under study, it may be used as the

donor variety in a backcross program. In order

to develop efficient breeding techniques, the mode

of inheritance of reaction to causal organisms

must be determined.
RICE IN THE UNITED STATES I VARIETIES AND PRODUCTION 39

Blast

Blast, caused by the fungus Pirwiilaria oryzae

Cav., is an important disease of rice. Much research has been done on it in the United States

and in other rice-producing countries. Physiological races of P, oryzae that occur in the United

States (6'4) make the breeding of resistant varieties more complex than if races did not occur.

(renes for resistance to eacli race that is known to

occur in the United States are available, but not

all are present in any one variety.

A satisfactory method for inoculating plants

(5) and a system of rating reaction have been

developed (64). Many varieties in the World

Collection and breeding lines have been tested

under controlled conditions for reaction to specific

races of F. oryzae. Uniform trials have been conducted in the field under a wide range of environmental conditions {13), Some studies on

the genetics of reaction to P. oryzae have been

made (IS. 66)^ but information is not available on

the genetics of reaction to all races.

An accelerated program of testing and breeding

rice for resistance to blast in the United States

was started in 1959. The initial tests consisted

largely of screening in the greenhouse the more

promising varieties and selections for reaction to

races 1 and 6. Later, many other breeding lines

from Arkansas, Louisiana, and Texas rice experiment stations were screened. Material grown in

the field and harvested in the late summer or

early fall is available for greenhouse testing from

Xovember through March.

The method used for developing blast-resistant

varieties in the LTnited States {13) is as follows:

(1) Seeds from F3 or F4 progenies of crosses

between varieties possessing the desired resistance

genes are saved.

(2) Seedlings from these progenies are inoculated in the greenhouse to determine reaction to

race 6. Susceptible selections are not tested

further.

(3) Seedlings that are resistant to race 6 are

then inoculated, in the greenhouse with race 1.

(4) Selections that carry resistance to races 1

and 6 are sown in the field for further evaluation

of field and gi^ain characters. Many of the less

desirable lines are eliminated at this stage.

(5) Seedlings of the selected lines are inoculated in the greenhouse with races 1 and 6 to confirm results of previous tests.

(6) Selections that are resistant to races 1 and

6 then are inoculated with races 2 or 4, 7, 8, 16,

and 19, as time and facilities permit.

(7) Selections that are resistant to all races are

then grown in the field in observation rows or in

yield tests for further evaluation as potential

new rice varieties.

Selections that are resistant to the desired races

of blast but do not appear promising for developing an improved commercial variety are crossed

with a suitable variety or strains. Testing for

reaction to blast is then repeated. This operation

may be repeated several times, or until suitable

plant types occur.

Many breeding lines have been tested, and

promising strains of all grain types have been developed to combine resistance to several of the

more connnon races of blast found in the United

States. In Arkansas, in greenhouse tests. Nova

was resistant or moderately resistant to most of

the races of blast. In field tests, it was considerably more resistant than was Nato. Nova

was released in 1963 jointly by the Crops Research Division, Agricultural Research Service,

U.S. Department of Agriculture, and the Arkansas Agricultural Experiment Station (4^).

Brown Leaf Spot

Brown leaf spot, caused by the fungus Helminthosjyorhim- oryzae B. de Haan, is a common

disease of rice in humid areas. In 1941 a report

was published (4) concerning the mode of inheritance of resistance to Hehninthospormm in a cross

of a moderately resistant and a susceptible variety. Inoculation with conidia was used to induce

infection. All gradation from moderately resistant to susceptible occurred in the segregating populations. This indicated that the reaction was

controlled bv several o-enes lackino- dominance.

The reaction of seedlings grown in the greenhouse showed a fairly close relationship with that

of mature plants grown in the field and suggested

the possibility of early elimination of a large proportion of susceptible segregates in breeding for

resistance (J^.).

According to Nagai [66)^ he and Hara studied

an especially susceptible mutant, and susceptibility proved to be due to a single recessive gene in

crosses of a very susceptible and a normal plant.

A breeding program to develop varieties resistant to brown leaf spot was begun at Beaumont,

Tex., about 1938. C.I. 9515, a resistant but

agronomically undesirable strain selected from a

cross made at Beaumont in 1938, was crossed with

popular long-grain commercial varieties in 1945.

Resistant selections from the 1945 crosses were

crossed to commercial long-grain varieties in

1959. Selecting for resistance was started in the

F3 population by saving the more resistant plants

in rows showing the best resistance, along with

other desirable quality. A highly susceptible

spreader variety was sown adjacent to each selection. Differences in disease reaction were relative

and were more apparent between panicle rows

than among individual plants. Resistance was

based on the number and size of spots. The

studies indicated that inheritance is not simple
40 HA NDBOOK 2 8'J, U.S. DEPT. OF AGRICULTURE

and probably involves seveinl o-eiies. Selecting

for resistance was continued tlirough several generations or until apparent true breeding lines

Avere established. Resistant lines possessing good

agronomic characters were selected from the 1959

crosses.

Narrow Brown Leaf Spot

Narrow broAvn leaf spot, caused by the fungus

CercospoTd oryzae I. Miyake, is a common disease

of rice in the Southern States. There are physiological races of the causal fungus (^6\ 73, 7If.

75), but genes for resistance for each race are

available. The mode of inheritance of reaction to

O, oryzae has been studied (4, Jiß, Ifï), No linkage between genes for reaction to Cercospora and

those for expression of five qualitative characters

was found (.f5). Most of the work on the development of Cercos¡)om-Y^ú^{^\\t varieties has been

done in the field under conditions of natural infection. Selection is based on type of lesion and

relative severity of infection. In Louisiana, a

number of resistant selections were obtained when

Blue Rose was crossed or backcrossed to Rexoro,

although both parental varieties were susceptible

to one or more races.

Straighthead

Straighthead is a physiological disease that

occurs under certain environmental conditions in

the United States. A breeding program to develop straighthead-resistant varieties was begun

in the united States in 1958, at Eagle Lake, Tex.

The method of testing consists simpl}'- of drill

seeding the test entries in an area with a soil type,

such as Hockley fine sandy loam, conducive to

straighthead development and keeping the nursery test area continuously submerged after the

initial irrigation (82). The reactions of the

American rice varieties (11, 12) served as a basis

for selecting parental varieties for resistance in a

breeding program. Straighthead resistance is

relative, and none of the varieties tested are

immune or highly resistant. The resistance of

Bluebonnet, Bluebonnet 50, Lacrosse, Prelude,

and Toro is derived directly or indirectly from

Fortuna, selected from the Pa Chiam variety

obtained from Taiwan. C.L 5094, selected from

the Sinanpagh variety from the Philippines,

served as the source of resistance in Texas Patna

and the original Century Patna.

Testing selections from several crosses was

begim in 1954. For example, straightheadresistant selections were recovered from a cross of

Bluebonnet (resistant) X Century Patna 231

(susceptible) and from backcrosses to Century

Patna 231. Although a number of the straighthead-resistant selections from Ú\^ Century Patna

231 crosses were promising and were seriously

considered as new varieties, none were released.

Belle Patna, from a diflFerent cross, was released as a new variety in 1961 {23), This

variety has Bluebonnet as its source of straighthead resistance.

In the breeding program, straighthead-resistant

selections have been obtained readily by selecting

panicles from resistant or segregating lines for

retesting in panicle rows. The number of genes

involved in straighthead reaction was not established, but inheritance appeared to be relatively

simple in crosses within the long-grain groups of

varieties. Resistance seems to be dominant (12),

White Tip

White tip, first observed in Louisiana before

1930, was considered to be a physiological disease

until 1949, when it was found to be caused by a

seedborne, foliar nematode, ApheJenchoides hesseyi Christie {27), However, by that time considerable progress had been made in selecting for

resistance in nurseries in which the disease occurred rather consistently each year.

After white tip was found to be caused by a

seedborne nematode, various methods were used

to insure infection in order to determine the

reaction of varieties and selections to white tip.

These methods consisted of including heavily

infested seed of susceptible varieties as spreader

rows, using rice hulls containing large numbers

of nematodes, or introducing nematodes from

laboratory cultures into the irrigation water.

Atkins and Todd {15) determined reaction of

many rice varieties in the United States to white

tip. No studies have been made on the genetics

of inheritance.

Hoja Blanca

Hoja blanca is a virus disease of rice that occurs in the Western Hemisphere. In 1957, a

large number of United States varieties and selections, as well as introduced varieties, were tested

for hoja blanca reaction under conditions of

natural infection in Cuba and Venezuela {10).

On the basis of marked differences in disease

reaction in the nursery tests, Arkrose, Asahi,

Colusa, Lacrosse, Mo. R-500, and several experimental varieties were designated as sources of

hoja blanca resistance for use in breeding.

Since both resistant and susceptible entries

^vere found among a number of advanced-generation selections from two crosses having Lacrosse

as one parent, it was concluded that the genes for

resistance could be readily transferred in crosses.

Other studies showed that resistance was genetically controlled and could be transferred to varieties of all grain types {22) and that resistance

was dominant {21). Since 1957, other lines resistant to hoja blanca have been recovered from
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 41

several crosses between susceptible and resistant

parents. Thus far, none have been released as

varieties.

Gulfrose, released in 1960 as a hoja blancaresistant variety (i, 28)^ was an increase of a

selection rated as resistant in the 1957 and subsequent tests. Xova, released in 1963, also a hoja

blanca-resistant variety (4^), was an increase

from a selection rated as resistant in early tests.

Testing and breeding for resistance to hoja

blanca are being continued in cooperation with

Government and private agencies m several Central and South American countries. Much of the

testing of varieties and breeding lines for reaction to hoja blanca has been done under conditions

of natural infection in the field. This work has

been done in foreign countries where epiphytotics

of the disease usually occur. Hybrid and backcross plants and progeny lines also are tested in

the greenhouse where plants are inoculated with

viruliferous vectors. Since resistance to hoja

blanca is dominant, backcross plants that carry

resistance can be identified in greenhouse tests.

Backcross seeds are planted in the greenhouse or

field. As soon as the plants tiller, they are divided and part of the plant is tested for reaction

to hoja blanca. The reaction can be determined

by the time the plant flowers, so that plants carrying resistance can be identified and used as parents in the backcross program.

The pedigree method, the backcross method,

and a modification of these two methods were

used in Texas to develop long-grain varieties

resistant to hoja blanca. The material used in

the pedigree method was obtained by crossing the

long-grain variety Bluebonnet 50 and several

promising long-grain hybrid selections with

the hoja blanca-resistant varieties Gulfrose and

Taman-iku Xo. 487 (P.I. 215,936). The Fi

plants were grown in the greenhouse during the

winter of 1957-58, and the Yo populations were

grown in the field during the summer of 1958.

In the fall of 1958, the seeds from 353 carefully

selected Fo i^lants were saved. A few grams of

grain from each selection were milled in a testtube miller, and alkali digestion and iodine-blue

tests were performed. In 1959, progenies from

each F2 plant were grown in Colombia, Cuba,

and Venezuela to test their reaction to hoja

blanca ; at Eagle Lake, Tex., to test their reaction

to straighthead; and in the nursery at Beaumont,

Tex., to advance each selection on a pedigree basis

and to select on the basis of plant type and vigor.

In 1960, scientists at Beaumont selected 507

panicles from the better F3 lines grown in 1959.

Seed from each of these selections was sent to

Colombia for further hoja blanca testing and

progeny of each was grown in the breeding nursery at Beaumont. About 20 panicles were har-

^^ested from each row, and this grain was used to

determine the cooking and processing quality of

the F4 lines.

Excellent hoja blanca readings from Colombia

were obtained on the F4 lines tested in 1960, as

well as the F5 and Fe lines tested in 1961 and

1962. Hoja blanca-resistant selections were tested

further for reaction to straighthead at Eagle

Lake, for reaction to blast of seedlings at Beaumont, and for quality behavior in the cooperative

Rice Quality Laboratory at Beaumont.

In 1962, a number of the more promising strains

carrying hoja blanca resistance were grown in

advanced yield trials at Beaumont. From the

crosses made in 1957, hybrid selections of early

and midseason maturity and short-, medium-, and

long-grain types that are promising for resistance

to hoja blanca are now available for extensive

testing.

In the modification of the backcross method

used in the hoja blanca breeding program, the

Fi plant of the cross Bluebonnet 50 X Gulfrose

was backcrossed to Bluebonnet 50 in 1958. A

total of 31 backcrossed seeds produced plants.

Tlie seeds from each plant were sent to the hoja

blanca testing laboratory, then located at Camaguey, Cuba, and backcross populations carrying

hoja blanca resistance were identified. Spaceplanted populations of each backcross line also

were grown in the breeding nursery at Beaumont

in 1959, and plants were selected from the lines

that were promising for hoja blanca resistance.

In 1960, F3 lines were tested for hoja blanca reaction in Colombia, and for straighthead reaction

at Eagle Lake. F2 lines were also sown at Campo

Cotaxtla, near Veracruz, Mexico, in the fall of

1959; and two crops per year were obtained

through 1961. Selections from the Mexico nursery were sent to Colombia for testing for hoja

blanca reaction and to Beaumont for grain quality testing. By the end of 1961, many long-grain

selections promising for hoja blanca resistance

were available for extensive testing at Beaumont.

Long-grain selections of early and midseason

maturity that are resistant to hoja blanca and

straighthead and that possess Bluebonnet milling,

processing, and cooking qualities were tested for

yield and other field characters at Beaumont in

1963.

Since hoja blanca resistance is dominant, Bluebonnet 50 was used as the recurrent parent in the

modified backcross method. The ho]a blanca reaction of Fi backcross plants was obtained at the

hoja blanca testing laboratory at Baton Rouge,

La. In 1963, Fi plants with four backcrosses to

Bluebonnet 50 were tested for hoja blanca reaction. Some of these plants are similar to Bluebonnet 50 in plant and grain type and they are

resistant to hoja blanca.
42 AORICULÏUKE HANDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE

Description of Varieties

The names and accession numbers of the 18

varieties reported in this section of the handbook are listed in table 9. These include the^principal commercial varieties in the United States.

Short-Grain Varieties

In 1963, about 12.3 percent of the total rice

acreage in the United States was sown with shortgrain (Pearl) varieties.^ In Arkansas, Louisiana,

Mississippi, and Texas only 0.08 percent of the

crop produced was the short-grain type, whereas

in California, 67.7 percent was this type.

The commercial short-grain varieties grown in

yield tests were Caloro, Cody, and Colusa. Rough

i-ice and milled kernels of each of these three varieties are shown in figure 21. These and other

short-grain varieties have rather slender culms,

narrow (about 3/g-inch) leaf blades, and yellow

or straw-colored rough hulls enclosing the kernels.

A plant of Caloro is shown in figure 22. When

milled, short-grain varieties usually yield as high

a percentage of head rice (whole grain milled) as

do the medium-grain varieties and higher than

do the long-grain varieties. Short-grain varieties

are not grown in the Southern States because the

varieties available are not well adapted for this

area and there is little demand in this area for

rice of this type.

CALORO.—Caloro was selected from Early

Wataribune in 1913 at the Biggs Rice Field Station, Biggs, Calif., and was distributed in the

5 See footnote 2, p. 19.

spring of 1921. It is an early to midseason,

partly awned variety that heads and matures uniformly in California and produces relatively high

yields with reasonably good milling quality on

either virgin soil or old ricelands. It is the leading variety grown in California, yields well in

Arkansas {50, 51, 67) and Missouri {63), and

yields reasonably well in Louisiana and Texas.

Although it appears to be adapted for growing

under a wide range of conditions, it is grown

principally in California. Caloro is the most

important short-grain variety grown in the

United States,

CODY.—Cody (57) was selected from the cross

Colusa X Lady Wright at the Biggs Rice Field

Station, Biggs, Calif. Seed of Cody was tested

in Missouri and then increased and distributed to

growers in Arkansas in the spring of 1944. Cody

is an early-maturing, awnless variety that can be

grown in all rice-producing States. It yields and

mills well in the absence of diseases. It has been

grown on a small acreage in Arkansas but has

not been grown in California.

COLUSA.—Colusa {25) was selected in 1911 at

the Rice Experiment Station, Crowley, La., from

Chinese, a variety introduced from Italy in 1909

by Haven Metcalf. It was tested at the Biggs

Rice Field Station, Biggs, Calif., and distributed

in 1917 and 1918. Colusa is an early-maturing,

awnless variety of reasonably good milling quality that heads and matures rather uniformly and

that produces relatively high yields on fertile

land. In California it is much less productive

than Caloro on old riceland of average fertility.

However, when nitrogen fertilizer is applied at

FIGURE 21.—Rough rice and milled kernels of (A) Caloro, (B) Cody, and (C) Colusa.
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 43

Ut h ^

m

FIGURE 22.—Plants of (A) Caloro, (B) Nato, and (C) Rexoro.

TABLE 9.—Name, C.I. number., FAO number, and registration num-ber for reported rice varieties

Grain type and variety C.I.

number i

FAO

number -

Registration

number ^

uniform

group *

Short-grain :

Caloro 1561-1

8642

1600

8310

8988

9416

8318

8998

9407

7787

9433

8990

8993

1779

8989

8321

9013

8991

211

212

213

207

1013

1339

216

1133

1364

206

1334

1012

1014

214

1019

221

1134

1020

5

20

8

1

6

_-_

13

IV

Cody I

Colusa I

Medium-grain :

Arkrose ^

Calrose

IV

IV

Gulfrose I

Magnolia I

Xato I

I

Zenith 19 I

Long-grain :

Belle Patna VI

Bluebonnet 50 3

7

14

15

16

18

17

III

Century Patna 231 II

Rexoro V

Sunbonnet III

Texas Patna V

Toro III

TP 49 V

1 Accession number, Cereal Crops Research Branch, Crops Research Division, Agricultural Research Service.

2 Accession number, World Catalogue of Genetic Stock.s—Rice, Food and Agriculture Organization of the United

Nations.

3 Registration number, American Society of Agronomy—U.S. Department of Agriculture (48).

* Uniform Yield Nursery Group number.

fairly high rates, it produces as much as Caloro.

Colusa yields well in Missouri and fairly well on

fertile land in Arkansas, but it frequently lodges

when the crop is heavy. Colusa has been for

many years, and still is the most popular earlymaturing variety grown in California.
44 AGIUCULÏUKE HANDBOOK 289, U.S. DEPT. UF A(ÏKI<ULTURE

Medium-Grain Varieties

In 1963, 47.5 percent of the rice acreage in the

TTnited States was sown to medium-grain varieties.« In California, 32.3 percent of the rice acreage was sown to this type. Of the total rice production in the United States, Nato made up 38.6

percent, Zenith 0.1 percent, and the Roses (principally Arkrose, Calrose, Gulfrose, and Northrose) 8.7 percent.

The principal medium-grain varieties grown in

the yield tests were Arkrose, Calrose, Gulfrose,

Magnolia, Nato, Northrose, and Zenith. Rough

rice and milled kernels of each of these seven varieties are shown in figure 23. These varieties,

with the exception of Calrose, have rather stout

culms and relatively wide (about %-inch) leaf

blades. A plant of Nato is shown in figure 22.

When milled, medium-grain varieties usually

yield more head rice (whole kernels) than the

long-grain varieties yield.

ARKROSE.—Arkrose (57) was selected at the

Rice Branch Experiment Station, Stuttgart, Ark.,

8 See footnote 2, p. 19.

from the cross Caloro X Blue Rose. Arkrose was

distributed in 1942. Arkrose matures about a

week earlier than Supreme Blue Rose, and in

some sections of Arkansas it is meeting the demand for a Blue Rose type. Arkrose yields well

and is relatively easy to thresh. It is similar to

Blue Rose in milling and table quality. It is

more difficult to dry artificially than are most

long-grain varieties. Arkrose has been grown in

Arkansas and, rarely, in Texas.

CALROSE.—Calrose (57) was selected at the

Biggs Rice Field Station, Biggs, Calif., from the

cross Caloro X Calady backcrossed to Caloro. It

is a partly awned variety very similar in growth

habit and maturity to Caloro. In California,

Calrose appears to be equal to Caloro in yielding

capacity and in milling quality. It stands up

well, matures evenly, and is as easy to combine as

Caloro. Calrose was grown on a small acreage

for the first time in 1948, and in 1963 it was

grown on 32.3 percent of the California rice

acreage.

GULFROSE.—Gulfrose was selected from the

cross Bruinmissie selection X Zenith at the RiceFIGURE 23.—Rough rice and

milled kernels of [A)

Arkrose, (B) Calrose,

(O Gulfrose, {D) Magnolia, (E) Nato, {F)

Northrose, and (Ö) Zenith,
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 45

Pasture Eesearch and Extension Center, Beaumont, Tex., in 1953, and released in 1960 (i).

It is similar to Zenith in plant and grain type

but matures a few days earlier. Gulfrose is resistant to hoja blanca. This was the principal

reason for releasing it since none of the leading

United States varieties grown at that time were

resistant. Gulfrose was grown on a limited acreage in the southern rice area in 1963.

MAGNOLIA.—Magnolia (67) was selected at the

Eice Experiment Station, Crowley, La., from the

cross Improved Blue Rose X Fortuna. It was

released in 1945. It is an early-maturing variety

that matures about the same time as Zenith.

Magnolia usually heads and matures evenly and

it combines more readily than Zenith. Under

favorable conditions it produces relatively high

yields, with good milling quality. The grain can

Î3e dried satisfactorily. Magnolia appears to be

adapted for growing throughout the southern

rice area.

î^ATO.—Xato was selected from the cross

(Eexoro X Purple-leaf) X Magnolia at the Rice

Experiment Station, Crowlej', La. It was released in 1956. It is an early-maturing variety

with comparatively short, strong straw; it produces good field and mill yields; and it is suitable for making dry cereals and for other uses for

which varieties of similar type are adapted (43).

Xato was the leading rice varietv in the United

States in 1963.

XoRTHROSE.—Xorthrose was selected in 1955

from the cross Lacrosse X Arkrose and released

from the Rice Branch Experiment Station, Stuttgart, Ark., in 1962. It is an early-maturing variety, and its outstanding characters are its short,

stiff straw and high grain yields. Because of its

tendency to be slightly chalkier than Xato and

because of its occasional low yields of head rice,

Xorthrose was not designated for general production. Instead it was designated a special-purpose

variety for relatively late seeding in northeast

Arkansas where its earlmess and high degree of

lodging resistance are urgently needed (52^ 53).

ZENITH.—Zenith {57) was selected from Blue

Rose in 1930 by Glen K. Alter, near DeWitt, Ark.

In 1931, several selections were tested in the cooperative breeding program at the Rice Branch

Experiment Station, Stuttgart, Ark. Of these

selections, Arkansas 141-8 proved to be the best ;

it was named Zenith and distributed in 1936.

Zenith is an early-maturing, awnless variety, and

it is uniform in heading and in maturing. In

1954, Zenith was grown on over 50 percent of the

rice acreage in the Southern States. It has since

been replaced by the shorter strawed, smoothhulled Nato variety. Strains similar to Zenith

have been isolated from Early Prolific.

Long-Grain Varieties

In 1963, 19.1 percent of the rice ijroduced in

Arkansas, Louisiana, Mississippi, and Texas was

the long-grain type.'^ The leading long-grain

varieties were Bluebonnet 50 and Sunbonnet,

comprising 33.5 percent of ih^ southern acreage ;

Belle Patna, 10.6 percent; Rexoro, 2.9 percent;

and Century Patna 231 and Toro, each 1.1

percent.

The principal long-grain varieties grown in the

field tests were Belle Patna, Bluebonnet 50, Century Patna 231, Rexoro, Sunbonnet, Texas Patna,

Toro, and TP 49. Rough rice and milled kernels

of each of these eight varieties are shown in figure

24. Most of these varieties have rather large

culms and relatively wide (about %-inch) leaf

blades. A Rexoro plant is shown in figure 22.

Because of the long growing season required,

Rexoro, Texas Patna, and TP 49 are grown only

in Louisiana and Texas.

BELLE PATXA.—Belle Patna was selected from

the cross Rexoro X (Hill selection X Bluebonnet)

at the Rice-Pasture Research and Extension Center and was released in 1961 (2). It is a very

early-maturing, slender-grain variety with cooking quality similar to Rexoro.

BLUEBOXNET 50.—Bluebonnet 50 was selected

from Bluebonnet in 1950 at the Rice-Pasture

Research and Extension Center. Bluebonnet

was a progeny of the cross Rexoro X Fortuna

Seed of Bluebonnet 50 was distributed in 1951.

Bluebonnet 50 is a midseason variety. It has

relatively short, stiff straw, and the grains are

partly awned. It yields and mills well and has

good cooking quality, being comparable to Rexoro

and Texas Patna in those characters. The grain

of Bluebonnet 50 is thicker than that of Rexoro

but is more slender than that of Nira. Bluebonnet 50 is well suited for harvesting by the

combine-drier method.

CEXTUET PATXA 231.—Century Patna 231 {57)

was selected in 1946 from a cross between Texas

Patna and a selection from the cross Rexoro X

Supreme Blue Rose at the Rice-Pasture Research

and Extension Center. It was released to

farmers in the spring of 1951. It is an earlymaturing, slender-grain variety. Century Patna

231 usually matures about 3 days later than

Zenith. It has rather short straw and narrow,

semidrooping leaves, and tillers exceptionally

well. Century Patna 231 is moderately resistant

to the common races of the fungus causing the

narrow brown leaf spot disease, so the leaves and

stems remain alive for some time following maturity. In cooking quality. Century Patna 231

is inferior to Bluebonnet 50, Rexoro, and Texas

Patna.

'^ See footnote 2, p. 19.
46 AÜKICULTURE HANDBOOK 2 89, U.S. DEFT. OF AGRICULTURE

FIGURE 24.—rough rice and milled kernels of {A) Belle Patna, (B) Bluebonnet .50, (C) Century Patna 231, (D)

Rexoro, (£) Sunbonnet, (F) Texas Patna, (Ö) Toro, and (H) TP 49.

EEXORO.—Rexoro (25) was selected in 1926 at

the Eice Experiment Station, Crowlej', La., from

the Maron^-Paroc variety introduced from the

Philippine Islands in 19Í1 by the U.S. Department of Agriculture. Rexoro was distributed by

the Department in cooperation with the Louisiana

Agricultural Experiment Station in 1928. Rexoro is a stilf-strawed, late-maturing, slendergrain rice that yields and mills well for a variety

of this type. The cooking quality is very good.

SuNBONNET.—Suiibonuet was selected from

Bluebonnet at the Rice Experiment Station,

Crowley, La., and released in 1953 (43). Sunbonnet is similar to Bluebonnet in plant characters, although somewhat taller than Bluebonnet

50. Sunbonnet is similar to Bluebonnet in cooking quality but is usually slightly superior in

milling quality.

TEXAS PATXA.—Texas Patna (57) was selected

m 1935 at the Rice-Pasture Research and Extension Center from the cross Rexoro X C.I.

5094. Seed of Texas Patna was distributed to

growers m 1942. Texas Patna is similar to Rexoro but grows slightly taller, matures about 10

days earlier, and has a more translucent grain.

It yields and mills well. Because Texas Patna is

slightly taller than Rexoro, it is more inclined to

lodge when grown on rich land. It is well suited

for combining and the ^rain is easy to dry. Texas

Patna is grown principally in the Eagle Lake

section of Texas and to a limited extent in

Louisiana.

ToRO.—Toro was selected from a cross in which

the varieties Bluebonnet, Blue Rose, and Rexoro

were the parents. It was developed at the Rice

Experiment Station, Crowley, La., and released

in 1955 {4ß). It is similar to Bluebonnet 50 in

plant height and straw strength. It yields and

mills well, but it is about as hard to thresh as

Zenith. The grain type is similar to that of Bluebonnet, but the cooking quality of these two varieties is different. Toro, when cooked, is firmer

than Bluebonnet but not as dry and flaky.

TP 49.—TP 49 (48) was selected from the

cross Texas Patna X (Rexoro X C.I. 7689) at the

Rice-Pasture Research and Extension Center
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 47

and released in 1951. It is a late-maturing,

slender-grain A^ariety, similar to Texas Patna

except that it has shorter and stronger straw and

somewhat thicker grain.

Other Kinds of Rice

Most of the rice varieties grown in the United

States are generally called common varieties ; that

is, they have no distinctive flavor or odor when

cooked, and the starch in the endosperm contains

both amylose and amylopectin. There are, however, minor acreages of two other kinds of rice—

aromatic or scented, and glutinous or waxy.

AROMATIC OR SCENTED.—Varieties having a distinctive odor and flavor somewhat like popcorn

when cooked are known as aromatic or scented

varieties ; they are cultivated widely in India and

other southeast Asian countries. Scented rices are

said to be low yielding; but because they are

greatly esteemed, they may sell at twice the price

of other rices of fine quality. The odor and

flavor are assumed to be due to an aromatic substance. Since aroma is sometimes noted in the

growing crop, it is not limited to the endosperm.

The aroma occurs in waxy as well as in ordinary

types of rice.

Two varieties, Delitus and Salvo, were selected

from introductions released m the United States.

Delitus has been grown commercially, and attempts have been made to place it on the market.

A cross between Eexoro and Delitus produced Delrex and R-D, which fully retain the flavor. R-D

is a productive, medium-late variety that should

make possible profitable marketing of scented rice

as a food specialty. C.I. 9483, an early-maturing

selection from R-D X Rexoro-Zenith, has improved milling quality and a more translucent

endosperm.

GLUTINOUS OR WAXY.—Waxy varieties, commonly called glutinous, differ from common varieties in that they contain only amylopectin starch

in the endosperm. Glutinous rice is grown on

about 1,000 acres in California each year. It is

grown as a specialty crop, and the acreage needed

to meet market demands has been small. Historically, the principal use of glutinous rice has

been for preparing oriental ceremonial foods and

confections. In some countries, glutinous rice is

harvested slightly green, is lightly parched before

milling, and is used as a breakfast food. Recent

research has shown that glutinous rice flour may

find a special use in the frozen food industry.

The flour, when made into foods for freezing,

such as white sauce and desserts, resists syneresis

(separation or weeping) when thawed after

freezing.

Mochi Gomi is the variety of this type grown

in California. It is a short-grain, midseason

variety. Compared to Caloro, it has about the

same straw strength and is about 6 inches shorter.

The glumes are less pubescent, and the grain

matures 5 to 10 days later. The waxy-white kernels are opaque.

Performance of Varieties

The performance of rice varieties is studied at

several rice experiment stations in the southern

rice area and in California. The grain yields and

milling quality data reported for the southern

rice area in this bulletin were obtained from the

Uniform Yield Nurseries from 1951 through 1961.

In these nurseries, varieties are grown in 3- or

4-row, randomized, quadruplicated, drill-seeded

plots. These nurseries were grown each year in

Arkansas, Louisiana, and Texas, and in some

years in Florida and Mississippi. Yields reported for California were obtained from drillseeded, quadruplicated nursery plots except in

1960 and 1961, when the rice was seeded in the

water.

Entries in the Uniform Yield Nurseries grown

in the southern rice area are grouped according

to grain type and length of growing season. The

six groups are: I, short- and medium-grain

early varieties; II, long-grain early varieties;

III, long-grain midseason varieties; IV, shortand medium-grain midseason varieties; V, longgrain late varieties; and VI, medium- and longgrain very early varieties. There usually were

14 entries in each group, many of them experimental varieties, (xroup numbers of the 18 varieties reported in this section of the handbook

are in table 9, p. ^li

The varietal experiments at each location were

on soil that was typical of large areas in the respective States. In Florida the tests were made

on Everglades peaty muck soil. Crop rotation,

seedbed preparation, time and rate of seeding,

fertilization, and weed control used for these experiments were practices that were thought to

l3e optinmm for each area.

Average grain yields in table 10 were obtained

from 1951 through 1961 at the following locations: Rice Branch Experiment Station, Stuttgart, Ark.; Everglades Experiment Station,

Belle Glade, Fla.; Rice Experiment Station,

Crowley, La.; Delta Branch Experiment Station,

Stoneville, Miss. ; Rice-Pasture Research and

Extension Center, Beaumont, Tex. ; and Rice

Experiment Station, Biggs, Calif. The actual

number of years each variety was tested is

shown. The yield of each variety is compared

with the yield of one or two standard varieties

that were grown throughout the entire period.

In Arkansas, the short-grain varieties all produced the highest average yields except those of

the medium-grain varieties Arkrose and Northrose. All medium-grain varieties except Magnolia produced higher average yields than did
TABLE 10.—Grain yield for 18 rice varieties grcnon at 6 locations during the 11-year period, 1951-61

Grain type and

variety

Arkansas Florida r .ouisiana IVl[ississippi Texas California

Years

grown

Yield 1

Y^ears

grown

Y ifddi Years

grown

Yie Id i

Years

grown

Yield 1

Years

grown Yield 1

Years

grown

Yield 2

Short-grain :

Caloro

Cody

Number

11

10

11

11

11

4

11

10

4

11

4

n

11

Pounds

4201

4149

4242

4^38

4174

4715

4008

4510

4933

415(;

3834

3556

4128

Percent

lOi)

111

110

112

108

107

104

109

112

108

87

92

107

Number

5

5

5

5

5

Pounds

2023

2559

2862

3344

2073

Percent

61

78

87

101

63

Number

10

10

11

10

10

4

11

10

4

11

4

11

11

11

11

11

10

11

Pounds

2852

3423

2743

3080

2721

2804

3114

3250

3802

3231

3245

3012

3674

2128

2922

2404

3237

2417

Percent

91

113

88

98

87

80

100

107

109

104

93

96

118

68

94

77

106

77

Number

6

5

6

6

6

3

6

6

3

6

3

6

6

Pounds

5836

4034

4036

6064

5514

4715

4273

4477

5337

4227

4543

4791

5083

Percent

129

89

90

134

122

103

95

99

117

94

99

106

113

Number

9

10

11

9

9

4

11

10

4

11

4

11

11

11

11

11

10

11

Pounds

3314

3642

3754

3575

3134

3559

3454

3786

4158

3593

3476

3703

3540

2676

3827

3009

3738

3269

Percent

94

100

103

101

89

90

95

103

105

98

87

102

97

73

105

82

102

90

Number

11

Pounds

3375

Percent

100

Colusa

Medium-grain :

Arkrose

11 3555 105

Calrose

Giilfrose _

11 3544 105

Magnolia 5

5

2806

3640

85

Nato 110

Northrose

Zenith

Long-grain :

Belle Patna

5 3232 98

Bluebonnet 50 _ 5

5

3365

3350

102

102

Century Patna

231

Rexoro

Sunbonnet 11 3592 93 5 3758 114 6 4863 108

Texas Patna

Toro 10 4113 100 5 3594 109 6 4869 108

TP 49

1 Percent of the yield is based on the mean of Zenith and Bluebonnet 50 for the years grown ; quantity

2 Percent of yield is based on the yield of Caloro.

given in pounds per acre.
RICE IN THE UNITED STATES I VARIETIES AND PRODUCTION 49

most of the long-grain varieties. Century Patna

231 produced nearly the same average yield as

the medium-grain varieties, but the other longgrain varieties produced lower average yields.

In Florida, none of the short-grain varieties

produced an average yield that was as high as

that of the higher yielding medium- or longgrain varieties. Of the medium-grain varieties,

Nato produced the highest average yield. The

long-grain variety Sunbonnet produced the highest average yield of any variety.

In Louisiana, Cody was the only short-grain

variety that pi*oduced an average grain jâeld

comparable to the jàelds of the higher yielding

medium- and long-grain varieties. The highest

yielding medium-grain varieties were Nato and

Zenith, except for Northrose, which was grown

only 4 years. Of the long-grain varieties, Century Patna 231 and Toro produced high average

yields. The late-maturing, long-grain varieties

feexoro, Texas Patna, and TP 49 produced quite

low yields.

In Mississippi, Caloro produced the highest

average yield of the short-grain varieties tested,

but the other two short-grain varieties produced

quite low yields. Arkrose, Calrose, and Northrose produced highest average yields of the medium-grain varieties tested. The average yield of

these three varieties was somewhat higher than

that of the long-grain varieties. Of the longgram varieties, Century Patna 231 produced the

highest yield. All long-grain varieties except

Belle Patna produced higher average yields than

did many of the commonly grown medium-grain

varieties.

In Texas, the short-grain varieties Cody and

Colusa produced average yields comparable to

the higher yielding medium- and long-grain varieties. Of the medium-grain varieties, Nato and

Arkrose produced highest average yields except

for Northrose, which was grown only 4 years.

Sunbonnet, Bluebonnet 50, and Toro produced

highest average yields of the long-grain varieties.

In California, Colusa and Calrose produced

slightly higher average yields than did Caloro.

The average number of days from seeding to

maturity, average plant height, estimated straw

strength, and pubescence and color of hull for the

18 varieties included in this handbook are given

in table 11.

Milling quality was determined each year for

the varieties grown in the Uniform Yield Nurseries. Included in table 7, p. 36, are the average

milling yields of hulls, bran, total, and head rice

for each of 18 varieties grown in the Uniform

Yield Nurseries in Arkansas, Louisiana, and

Texas for the years 1958-61. Milling yields were

determined according to the modified procedure

of Beachell and Halick (19), Treatment and

preparation of Uniform Yield Nursery samples

before milling was described in the section ''Testing for Milling, Cooking, and Processing Qualities,'' p. 33. The average milling yields of hulls

ranged from 18 percent for the short-grain varieties Caloro and Colusa to 21 percent for the

long-grain variety Century Patna 231. Average

bran yields ranged from 9 percent to 13 percent.

In general, bran jâelds were lower for short- and

medium-grain varieties than for long-grain varieties. Northrose, a newly released, special-purpose, medium-grain variety yielding an average

of 12 percent bran, was an exception. The latematuring, long-grain varieties Eexoro and Texas

Patna grown only in Louisiana and Texas produced the highest bran yields (13 percent) of any

of the varieties tested.

The average yield of total milled rice varied

from 67 percent for Century Patna 231 to 73

percent for Caloro and Colusa. Short-grain varieties, as a group, produced slightly higher

yields of total milled rice than did medium- and

long-grain varieties. The medium-grain variety

Northrose and the long-grain varieties Century

Patna 231, Rexoro, and Texas Patna gave the

lowest total milled rice yields.

Head rice yields for the varieties listed in table 7 are reported as average values and as individual minimum and maximum (range) values.

Average yields of head rice varied widely among

the varieties, from 52 percent for Rexoro to 69

percent for Calrose. In general, the average

yield of head rice was highest for the short- and

medium-grain varieties and lowest for the long-

^rain varieties. Toro, a long-grain variety yieldmg 67 percent of head rice, was an exception.

The milling qualitj^ of this variety has been noted

in earlier publications (iP, 41)- Individual

minimum and maximum values of head rice

yields also varied widely. This variability was

evident, not only among varieties but also within

the varieties. Individual minimum head rice

yields ranged from 33 percent for Arkrose to 63

percent for Calrose, Magnolia, and Nato; whereas individual maximum values ranged from 61

percent for Rexoro to 75 percent for Colusa.

Choosing the Variety

Several factors affect the choice of a variety.

These are listed by Johnston, Cralley, and Henry

(51) as market demand, satisfactory yielding

ability, location, proposed seeding date, soil fertility or anticipated fertilizer practices, relative

maturity, susceptibility to diseases that may occur, and seed supply. Growers of large acreages

may wish to sow two or three varieties that differ

in date of maturity and grain type in order to

extend the harvesting period and to provide rice

of different types for the market.

A grower should carefully consider market re-
TABLE 11.—Plœnt characters for 18 rice varieties grown, at 6 locations during the 11-year period, 1951-61

Grain type and variety

Short-grain :

Caloro

Cody

Colusa

Mediiim-^ain :

Arkrose

Calrose

Gulfrose

Magnolia

Nato

Northrose

Zenith

Long-grain :

Belle Patna

Bluebonnet 50

Century Patna 231

Rexoro

Siinbonnet

Texas Patna

Toro

TP 49

Average time from seeding to maturity -

Arkansas

Days

141

129

130

150

141

126

134

132

134

133

115

149

136

Florida

148

148

Days

149

127

128

153

148

127

127

Louisiana

Mississippi

129

145

133

143

144

)ays Days

145 133

122 5 124

123 124

150 144

143 129

121 123

127 131

126 130

130 128

126 134

108 118

140 147

131 137

174

140 147

166

140 148

172

Texas

Days

138

119

118

142

137

116

121

122

123

122

109

137

126

172

137

149

137

165

California

Days

153

134

153

Average plant height

Arkansas

Inches

46

44

46

52

46

48

51

47

46

50

43

47

47

52

'49'

Florida

Inches

31

36

37

44

32

45

41

44

44

37

47

44

Louisiana

Inches

44

42

43

50

43

43

46

42

42

46

42

45

43

50

48

50

45

48

Mississippi

Inches

39

39

36

47

37

37

42

41

37

44

36

49

44

51

Is'

Texas

Inches

46

46

47

52

46

47

50

47

43

50

45

50

48

52

54

55

49

52

California

Inches

35

34

33

Estimated

straw

strength 3

Weak

Midstrong_

Very weak.

Very weak

Weak

Weak

Weak

Midstrong.

Strong

Midstrong.

Weak

Strong

Strong

Strong

Strong

Very weak

Strong

Weak

Hull

pubescence 4

R

R

R

R

R

S

R

S

S

R

S

S

s

s

s

s

s

s

Hull

color

Straw.

Straw.

Straw.

Straw.

Straw.

Straw.

Straw.

Straw.

Straw.

Straw.

Straw.

Straw.

Gold.

Gold.

Straw.

Gold.

Straw.

Gold.

1 Years of test : Arkansas, 1951-61 ; Florida, 1953-56 ; Louisiana, 1951-61 ; Mississippi, 1959-61 ; Texas, 1951-61 ; and California, 1951-61.

2 Average seeding date: Arkansas, May 7; Florida, March 31; Louisiana, April 17; Mississippi, May 18; Texas, April 24; and California, May 6.

3 Based on results for Arkansas and Texas.

^ R = pubescent ; S = glabrous.

6 2-year average.
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 51

quirements in selecting varieties to grow. He or

his marketing agent may have difficulty in selling

his rice if it is of poor quality, even though

locally the variety may produce high yields.

Also, growing a short- or medium-grain variety

on a limited basis in an established long-grain

district, for example, can pose real problems to

the grower, driers, warehousemen, and millers

to prevent mixtures of the different types.

Seeding rice on highly fertile soil, such as

newly cleared woodland, ''new ground,'' or a field

used as a reservoir just before being seeded to

rice, would necessitate the choice of a stiff'-

strawed variety that would be less likely to lodge.

Even on old riceland low in natural fertility, if

a grower anticipates using heavy rates of nitrogen fertilization, with part of it applied relatively late, such a practice nvàj make it desirable

to choose a relatively early-maturing variety.

Growers in the northern part of ricegrowing

areas in the United States are limited to earlymaturing varieties because of the somewhat

shorter growing season and cooler night temperatures than those prevailing farther south. It

may be desirable to avoid a given variety because

of its susceptibility to a certain disease when rice

is to be grown under conditions known to be

favorable for development of that disease.

Varietal Response to Seeding Date

By NELSON E. JODON

Results of Tests With Older Varieties

Growers need to know how rice varieties will

respond when sown at various dates. They should

be able to tell the probable effect on yield, days

to full maturity, plant height, milling quality,

and other characters. Date-of-seeding tests have

been conducted at Arkansas, Louisiana, Texas,

and California rice experiment stations.

At Stuttgart, Ark., an experiment was carried

on for 5 years with 10 varieties seeded at three

dates (5)^ The average seeding dates were April

20, May 11, and June 5. Bluebonnet and Blue

Rose yielded well from the first two seedings but

usually matured too late when seeded in June.

Arkrose yielded about the same from each of the

seeding elates. The highest average yields from

the latest seeding were made by Cody and Zenith,

which have shorter growing seasons.

Most varieties sown in June in Arkansas risk

injury by possible October frosts, although Arkrose and Zenith seeded in mid-June and Caloro

and Cody seeded late in June have produced

satisfactory yields (51). Xato should be seeded

before the first of June and Bluebonnet by May

25. In the northern part of the State, seeding

should be 7 to 10 days earlier.

In an Arkansas experiment, Arkrose and Blue

Rose matured in shorter periods of time when

sown late than did Bluebonnet (5). Varieties

that responded to the sliortened days of late summer by [leading at nearly the same date whether

seeded early or late were termed photosensitive.

They also headed out quickly and uniformly.

Length of time required for the photosensitive

varieties to reach the heading stage decreased

with each delay in the seeding date; plant height

also decreased. Varieties that did not continue

to shorten their growing period in response to

late seeding were termed indiiferent.

In Louisiana, the maximum number of days

to flowering resulted from seedings on March 1

or March 15, except for the variety Caloro (37)^

in an experiment reported in 1936. The minimum for all varieties Avas from June 15 seedings.

The difference between maximum and minimum

days to flowering was a varietal characteristic.

Some varieties tended to have a comparatively

fixed growing period; others tended to head at

a certain date late in the season, and if sown

late, their growing periods were shortened materially. The maximum number of days from first

heading to full maturity was 45; this number

added to the number of days to flowering for

each variety gave the total length of the growing

period.

Another field plot experiment with six varieties

was conducted over a 5-year period in Louisiana

and reported in 1944 (38), The seeding dates

were approximately the 15th and the 1st of each

month from March 15 to June 15. Best yields

were obtained from April 1 and May 1 seedings.

Lower yields Avere obtained from June seedings

than from April and May seedings.

The rice varieties Bluebonnet, Magnolia, Rexoro, and Zenith were grown in a date-of-seeding

test in Louisiana and reported in 1958. In all,

27 seedings were made on dates as early as February 20 and as late as June 20 in the years 1941

to 1952 (40). Usually, four seedings were made

each season. A tabular guide (40) for use in

planning seeding schedules gave, for alternate

days during the planting period, the growing

season midpohit date (latest date to topdress),

date of first heading, date when mature for combining, and total length of the growing period.

Xine varieties were seeded monthly from midMarch to mid-July in a 3-year experiment conducted at Beaumont, Tex., (72) and reported in

1954. Yields of early varieties showed no definite relation to seeding date, but midseason varieties gave markedly lower yields from May

and later seedings. Late varieties gave the best

yields from the earliest seedings and failed to

mature from June and July seedings.

Effects of 10-hour daylight periods on length

of growing period were studied in Texas (Ï7).

The day length was reduced by covering the
52 AUKiCMlJIí ~iE HANDBOOK 2895 U.S. DEPT, OF AGRICULTURE

plants part of each da>. SimiJar results were

obtained from the 10-, 20-, and 30-day periods

of short-day treatment. Two groups of varieties,

termed sen'sitive and less sensitive, were compared. Varieties in the sensitive group showed

a marked reduction in the number of days from

seeding to headhig when the treatments began

about 50 days after seeding. The less sensitive

varieties in general responded only slightly

from the 50-day treatment but responded more

when the treatments were started 60 to 80 days

after seeding. The response depended on the

variety. Reduction in length of growing period

was accompanied by reduction in number of

tillers and panicles, plant height, and straw and

grain weight.

At Biggs, Calif., a date-of-seeding test was

conducted for 9 years {54), Three seedings of

the Wataribune variety were made each year,

beginning as early as possible m the spring. The

seedings were made at 2-week intervals. In all

but 1 year's test, the highest yields were obtained

from the earliest seeding.

Results of Tests With Newer Varieties

and Selections

Tests similar to those reported in 1953 (40)

were continued in Louisiana in the 9 vears from

1953 through 1961 (44, pp. 8-25). In these experiments, seedings were made each year in

March, April, May, and June, Each year the

seedings were made to coincide with peaks of

planting operations on farms in the area. Entries included varieties from four maturity

groups. These included Nato (early), Sunbonnet

and Toro (midseason), Blue Rose and R-D

(medium late), and Rexoro (late). They mature

in about 120, 135, 150, and 165 days, respectively.

Extra early types (100-day group) were first

included in 1957. One or two standard varieties

representative of each maturity group were tested

throughout the 9-year period. Each year additional entries of current interest were included.

Data for individual varieties are used in the

following discussion of length of life cycle. Data

for yield, height, and milling quality were averages of a standard variety and two other varieties

or selections belonging to each of the four maturity groups, except in the late group. In the

late group, data for only Rexoro and one selection were used for 2 of the years. The early

group included Nato and two other varieties ; the

midseason group, Sunbonnet, Toro, and one other

variety; the medium-late group, Blue Rose, R-D,

and one other variety; and the late group, Rexoro

and one other variety. Thus, the three varieties

mcluded in maturity-group averages for each

month of the seeding period were the same in

any 1 year; but, aside from the standard variety,

they were not necessarily the same from year

to year.

LENGTH OF LIFE CTCLE IN RELATION TO SEEDING DATE.—Average number of days from seeding to first heading by monthly seeding date for

six varieties representing four maturity groups

are summarized in table 12. Date of first heading was used as the criterion of the length of

growing season of varieties, since it can be determined more precisely than date of maturity.

The length of the period from first heading to

maturity ranged from 35 to 40 days for the varieties listed. During warm w^eather, however, varieties that head very evenly may ripen in 30

days after the tips of panicles first emerge from

the boot; whereas late in the growing season, the

period from panicle emergence to full maturity

may be 45 to 50 days.

Relative heading dates of five of the six varieties were fairly constant when sown at successively later dates, although the number of days

from seeding to heading was progressively fewer.

Nato headed 14 to 18 days earlier than Sunbonnet

or Toro. Sunbonnet and Toro headed 12 to 19

days earlier than R-D. Rexoro was 9 to 17 days

later than R-D. The number of days from seeding to heading for Blue Rose decreased more

than some varieties as seeding was delayed. Blue

Rose headed 1 day later than R-D when sown

in March; but when sown in June, it headed 19

days earlier than R-D and 7 days earlier than

Sunbonnet.

The reduction of length of life cycle of Blue

Rose from successive seedings is an example of

photoperiodic response. This response is governed by the length of the dark period during

the 24-hour day. Blue Rose may be termed photosensitive and the other varieties may be said

to have relatively inflexible growing seasons because their life cycles tend to remain constant in

length once a certain minimum has been reached.

For example. Nato seeded in June reached maturity in only 4 days less time than when it was

seeded in May.

Low^ temperatures in the early spring retard

germination and seedling development, thus extending the length of the life cycle. Average

lengths of life cycles from April seedings were

17 days less than from March seedings. Those

from May seedings were only 8 days less than

from April seedings, and those from June seedings were only 9 days less than from May seedings.

The greater reduction in number of days from

seeding to maturity in April as compared with

March seeding was caused by greater temperature

differences that occur between April and later

seeding dates. The further reduction obtained

from May and June seedings probably was

largely the result of photoperiodic response. Be-
RICE IN THE UNITED STATES I VARIETIES AND PRODUCTION 53

TABLE 12.-—Average days fro7n seeding to first heading of 6 rice varieties representing ^ maturity

groups^ when sown in each of the 4 months of the planting period in the years from Í95S to 1961

Maturity group and variety

Time of seeding

Average

March April May June

Early : Nato

Days

103

118

118

137

136

153

Days

88

103

102

115

121

137

Days

80

98

96

102

115

127

Days

76

93

90

86

105

114

Days

87

Midseason :

Sunbounet 103

Toro

Medium-late :

Blue Rose

R-D

Late:

Rexoro

102

110

119

133

Average 128 111 103 94

cause of slow ripening late in the gTowing season,

very late seeclings tend to lengthen the life cycle

rather than reduce it.

Seven varieties that mature in from 100 to 165

days were sown at four successive dates each year

from 1953 to 1961. The response of these varieties is shown in ñgure 25. The upper part of the

curve for each variety, representing the earlier

part of the planting period, tended to be steep,

because when the weather warmed in the spring,

the length of the period from seeding to heading

was rapidly reduced. Further reduction in time

until heading for five of the seven varieties proceeded at a slower but comparatively uniform

3-20

Belle Patna

Nato

Sunbonnet

Blue Rose

R-D

Rexoro

C.I. 6001

DATE OF HEADING

FiGUEE 25.—Heading date in relation to seeding date of 7 adapted varieties grown at Crowley, La., from 1953 to 1961.
54 AGB! Oí UKE HANDBOOK 2 8 9, U.S. DEPT, OF AGRICULTURE

rate through the remainder of tîie season. Consequently, the curves indicating the response of

those five varieties are roughly parallel.

Blue Rose and C.I. 6001 had steeper curves

than did the other five varieties. This reflected

greater sensitivity to photoperiod. C.I. 6001 Avas

later than R-D Vnd Rexoro when seeded early

but became earlier from subsequent seeding. Blue

Rose Avas later than Sunbonnet when seeded early

but became earlier from subsequent seeding.

Early-maturing varieties do not shoAv the characteristics of photoperiodic response, otherwise

they Avould not head during the long days of

June and July. Or possibly the critical length

of the dark period is much shorter for them than

for the more sensitive later varieties.

All varieties have a vegetative stage of development during which they are not photosensitive. The less sensitive midseason and later

varieties may have a longer vegetative stage than

do the early A^arieties.

Sensitive and short-season (early) varieties

may be seeded later than less sensitive midseason

or ïate A^arieties. HoAvever, Arkrose and Caloro

are the only sensitive varieties noAv in production.

Any of the less sensitive A^arieties can be used for

successiA^e seedings because the plants mature in

the order seeded, and the fields can be liarA^ested

Avithout conflict.

Data obtained from date-of-seeding experiments may be used to predict time of maturity

of rice A-arieties. This information makes it possible to schedule seedings so that different fields

and varieties may be harvested consecutively.

The approximate dates of maturity of eight A^arieties Avhen soAvn at 10-day intervals, March 1

to June 30, in southwest Louisiana are shown in

table 13.

YIELDS IK RELATION TO SEEDING DATE.—Average yields of variety groups by monthly seeding

dates are summarized in table 14. Production

of the early varieties varied but little because of

date of seeding. Midseason and medium-late

varieties Avere less productiAœ from June seedings

than from earlier seedings. Yields from May

seedings of Rexoro and other late varieties were

reduced. Yields from June seedings were unprofitably IOAV or were complete failures.

Probably Rexoro should not be seeded after

about May 20 at the latest (^0), and April seeding is preferred. Currently, no medium-late varieties, such as Blue Rose, are in production.

These have been replaced by early-maturing,

medium-grain A^arieties. The midseason varieties

Bluebonnet 50 and Sunbonnet may be seeded in

Louisiana as late as the first week of June with

satisfactory results. Nato and other early varieties may be seeded in Louisiana at any time from

early March to the end of June with expectation

of profitable yields. In some years blast may be

serious during the warm humid weather in the

summer months. During years when this disease

is prevalent, there may be a reduction in stand

of late-sown susceptible varieties. There may at

the same time be a reduced yield from earlysoAvn, short-season A^arieties caused by the rottenneck phase of blast.

PLANT HEIGHT IN RELATION TO SEEDING DATE.

—AAverage plant heights of four groups of varieties by monthly seeding ranges are summarized

in table 15. Midseason and late A^arieties were

taller than were early A^arieties. Midseason varieties seeded in June and late A^arieties seeded

in May and June were shorter than when seeded

earlier. Adair (3) reported that in Arkansas

later seedings produced shorter straw, and Beachell (17) found a marked reduction in plant

TABLE 13.—Approximate dates of vimturity of 8 rice varieties when sown at 10-day intervah

in sauthwest Louisiana

Seeding date

Mar. 1.

10

20

30

Apr. 10

20

30

May 10

20.

30

June 10.

20

30.

BeUe Patna

7-13

7-17

7-22

7-26

8-2

8-9

8-14

8-21

8-29

9-5

9-13

9-26

10-8

Gulfrose

7-25

7-27

8-2

8-4

8-13

8-21

8-27

8-31

9-4

9-12

9-23

10-4

10-16

Nato

7-28

7-30

8-4

8-9

8-16

8-22

8-30

9-5

9-15

9-24

9-30

10-9

10-17

Bluebonnet,

Sunbonnet,

or Toro

8-13

8-15

8-22

8-27

8-31

9-5

9-15

9-21

10-1

10-11

10-18

10-25

11-4

Texas Patna Rexoro

9-8 9-18

9-11 9-20

9-15 9-25

9-21 10-2

9-27 10-6

10-3 10-13

10-7 10-19

10-13 10-25

10-18 10-30

10-25 11-^

11-3 11-15

11-12 (^)

(1) (1)

1 Failed to mature.
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 55

TABLE 14.—Average yields of 3 rice varieties in each of If maturity groups, from seediiigs raade in each

of the Jp months of the planting period in the years from 1953 to 1961

Time of seeding Maturity groups

Early Midseason Mediuni.-late Late

Average

March

April

May

June

Pounds per acre

2,771

2,674

2,604

2,623

Pounds per aere

2,740

2,744

2,632

2,395

Pounds per acre

2,634

2,852

2,826

2,452

Pounds per acre

2,521

2,324

2,172

1 1,197

Pounds per acre

2,667

2,649

2,568

2 2,167

Average 2,668 2,628 2,691 3 2,054

1 Late varieties failed in 1954 and 1957.

- Average of June seedings, late group excluded, 2,490.

3 Average of late varieties, June seeding excluded, 2,339.

TABLE 15.—Average plant heights of 3 rice varieties in each of 4 maturity grcjups, from seedings made

in each of the 4 months of the pJanting period in the years from 1953 to 1961

Maturity groups

Average Time of seeding

Early Midseason ]\Iedium-late Late

March

April

Inches

43

44

44

45

Inches

47

47

47

46

Inches

49

50

49

45

Inehes

49

49

48

45

Inches

47

48

May

June

47

45

Average 44 47 48 48

height of varieties that headed in response to a

10-hoiir photoperiod.

The reductions in average heights from later

seedings, as shown in table 15, correspond to reduced yields in the respective months, as shown

in table 14.

A correlation of 0.25 between height and yield

within individual varieties from seedings in the

earlier months indicates that higher yields tend

to be associated with greater plant heights from

early, medium, or late seeding dates. This does

not mean that short-strawed varieties necessarily

tend to be low yielding. However, among fields

of the same variety, plants with taller straw are

likely to be higher yielding than those with

shorter straw. Exceptions to this generalization

may occcur when nitrogen fertilizer is applied at

different times.

MILLING QUALITY IN RELATION TO SEEDING

DATE.—Average percentages of head rice from

varieties representative of four groups are summarized according to monthly seeding date in

table 16. No comparison can be made of the

average milling quality of these groups because

of the lack of correspondence in grain type of

the varieties within groups.

March seeding resulted in low percentages of

head rice, probably because of higher temperatures during the maturation period. Ripening

is hastened in hot weather, and more chalky

grains are produced. Also, rapid changes in

temperature and moisture tend to cause checking of the gi^ain. Compared to March seedings,

April and May seedings gave improved milling

quality. The average percentage of head rice

was 3 percent higher from May than from April

seedings.

The average percentages of head rice from

May and June seedings were equal. However,

the midseason and especially the late varieties

were lower in milling quality from June seedings, probably because of effects of low temperatures late in the season.

The early and medium-late, medium-grain varieties tended to give increasingly higher percentages of head rice from each successive seeding. Thus, apparently improved milling quality

is a major advantage of late seeding.
56 ÍRLiJUL/rulíJS HzVKDBOOK 2 8 9, U.S. DEFT. OF AGRICULTUKE

TvBLE IQ,—Average perrent.ï./e^; of head rice from samples of S rice rarieties m each of Í maturity

groups, from seedings vutde ¡n each of the if months of the planting period in the years from 1953

to 1961 '

Maturity groups

Time Average of seeding

Early Midseason Medium-late Late

March

Percent

57

60

60

65

Percent

53

56

61

59

Percent

49

54

57

58

Percent

47

49

52

48

Percent

52

April

May

June

55

58

58

Production of Seed Rice

By T. H. JOHNSTON

Origin of High-Quality Seed Rice

According to Wise (88), new and superior

varieties of crops make their intended contributions to agriculture only ''when the seed stocks

of such crops reach the farmer varietally pure,

in a viable condition, free of noxious weeds, in

adequate quantities and at a reasonable price."

To produce this high-quality seed, a grower

must have a source of superior seed of a welladapted variety. Promising new strains are

compared to standard varieties continually at the

rice experiment stations to determine their adaptation. When an experimental strain proves to

be superior to standard varieties, it is increased

for release to growers.

Formerly each farmer could obtain a small

amount of seed of a new or standard variety and

thereafter produce his own seed. However, modern harvesting and processing methods, including

bulk drying and storage, have increased the

possibility of mixing. These methods and the

use of more specific types of varieties that differ in maturity, grain type, and processing and

cooking quality have emphasized the need for

sources of pure seed. As a result, the seed certification program now in effect in each major

rice-producing State is an important part of the

rice industry.

"Minimum Seed Certification Standards'' (36)

states :

The purpose of Seed Certification is to maintain and

make available to the public sources of high quality

seeds and propagating materials of superior varieties

so grown and distributed as to insure genetic identity.

Only those varieties that contain superior germ phasm

are eligible for certification. Certifie<:l seed is high in

varietal purity and of good seeding value.

Varieties eligible for certification have resulted either

from natural selection or through systematic plant

breeding In either case without a planned method of

maintaining genetic purity, there is grave danger of

losing varietal identity.

Varietal purity is tlie first consideration in seed certification but other factors, such as weeds, diseases,

viability, mechanical purity and grading are also important. One of the most effective methods of preventing the wider distribution of weeds is to plant weedfree seed. Adverse effects of plant diseases can be reduced by planting clean seed from disease-free fields.

Properly cleaned and graded seed is easier to plant and

gives more uniform stands.

Seed certification is designed, therefore, to maintain

not only the genetic purity of superior crop varieties,

but also reasonable standards of seed condition and

quality.

It also is stated in this publication :

Only those varieties that are approved by a State or

Goverumental agricultural experiment station and accepted by the certifying agency shall be eligible for

certification.

In general, before a variety is approved by an

experiment station, it must be tested thoroughly

(usually for a minimum of 3 years), and it must

show merit as a new variety in production, disease resistance, or some other outstanding

character.

Classes of Seed in a Certification Program

The classes of seed usually included in a certification program are breecler, foundation, registered, and certified. These are described by the

International Crop Improvement Association

[36) as follows:

(1) Breeder seed is seed directly controlled by

the originating, or, in certain cases, the sponsoring plant breeder or institution, and which provides the source for the initial and recurring

increase of foundation seed.

(2) Foundation seed- shall be seed stocks that

are so handled as to most nearly maintain specific genetic identity and purity and that may

be designated or distributed by an agricultural

experiment station. Production must be carefully supervised or approved by representatives

of an agricultural experiment station. Foundation seed shall be the source of all other certified

seed classes, either directly or through registered

seed. Wliite tags are used to designate this class

of seed.

(3) Registered seed shall be the progeny of
RICE IN THE UNITED STATES I VARIETIES AND PRODUCTION 57

foundation or registered seed that is so handled

as to maintain satisfactory genetic identity and

purity and that has been approved and certified

by the certifying agency. Purple tags are used

to designate this class of seed.

(4) Certißed seed shall be the progenies of

foundation, registered; and, in some cases, previously certified blue tag seed that is so handled

as to maintain satisfactory genetic identity and

purity and that has been approved and certified

by the certifying agency. Blue tags are used to

designate this class of seed.

For the production of the various classes of

certified seed, it is necessary to have clean land

and to prevent mixtures in seeding, harvesting,

and processing. Although careful roguing of all

fields to remove undesirable weeds, other crops,

or offtype plants increases the production costs,

it is necessary.

The production of breeder and foundation seed

is an integral i^art of the cooperative rice-breedhig projects of the U.S. Department of Agriculture and the Agricultural Experiment Stations.

The production and ceitification of registered

and certified seed are not a part of the breeding

program.

BREEDER SEED PRODUCTION.—After an experimental variety of rice has been developed in the

coordinated breeding program and has been

proved sufficiently outstanding, procedures are

begun to purify it and to provide a seed supp)ly

for possible release to growers for commercial

production.

Procedures differ at the various experiment

stations but the steps included usually are somewhat as follows: (1) From 100 to 500 panicles

are selected from the interior rows of nursery or

field plots of the experimental varietj^; (2) these

panicles are Aveighed and the weight is added to

the plot weight so as not to cause inaccurate plot

yield reports; (3) each panicle is inspected and

any having offtype seeds is discarded; (4) each

panicle typical of the variety is tlireshed individually; and (5) the seeds are placed in a small

envelope.

The following year the seed from each panicle

that passed the screening test is sown in a single

row from 4 to 20 feet long and 12 to 24 inches

apart. In some cases there are 3-foot alleys between ranges of rows to facilitate careful inspection and roguing. The block of panicle rows of

each variety is isolated from those of varieties

similar in maturity so as to eliminate natural

crossing and subsequent segregation for oft'typjes.

After the seedlings emerge, they are carefully

inspected at intervals to identify any off'type

plants or rows. Rows that show offtype plants

or any apparent dift'erences at any stage are removed immediately or tagged for removal before

harvest. In the early seedling stage, special empliasis is given to noting albino seedlings or variable plant types. Later in the season special

attention is paid to uniformity of vegetative

growth and heading within and among rows.

During tlie ripening period, careful observations

are made to detect differences in plant type, plant

height, panicle type, f)ubescence, color of apex or

apiculus, and grain type. If the entire group of

panicle rows appears uniform, the rows are harvested in bulk.

However, if considerable variability attributed

to genetic segregation is evident or if numerous

offtype plants are found, then it may be necessaiy to make further selection of rows for purification. This ma}^ be done by selecting from

within a block of rows individual rows that appear to be uniform in appearance and that typify

the variety being increased.

The grain from 30 to 50 or more such rows

(families) may be harvested separately after 25

to 100 panicles are selected from each row. A

number is assigned to each family for maintaining its identity. The following year, from 10 to

20 or more rows may be sown from the bulk seed

of each family, or a similar number of panicle

rows from panicles saved from each familj^ row

may be used instead of the bulk.

An alternate method would be to select a few

panicles from all rows that appear to be typical

of the variety and grow three to six panicle rows

of each row.

The panicles saved from each family row are

examined individually for off'tj^pes and are grown

by seeding each family in a group or block of

3 to 25 or more panicle rows. As before, the

rows are observed for offtype or undesirable type

plants in the seedling and later stages. If several

off'types are found within a family or if the rows

within a family tend to be variable or are not

typical of the variety, tlie entire family may be

eliminated. If tliere still appears to be too much

variation in the material, it ma^^ be necessary to

again select individual rows from families most

similar in plant type. Several rows may be selected from each of several families, again identifying the families and subfamilies, and the subfamilies grown in panicle-row blocks the following

year. Usually at tliis stage the material is sufficiently uniform, so tliat there are only a few offtypes to discard or eliminate.

If a variety needs to be released as soon as

possible because of a disease emergency, for example, one procedure would be to increase and

release seed at an earlier stage and at a designation lower than foundation seed. Purification of

the variety could be continued and foundation

seed could be released as soon as it becomes

available.

It may be desirable to check the processing

and cooking quality of the bulk seed from each
58 AGRICULTURE HANDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE

family row used in the puriHcation increase.

Useful quality tests are the alkali digestion {65)

and iodine-blue tests {34.). The final bulk representing all the family lines should be grown

in varioty trials to determine the overall performance of the mass-selected strain.

One method used to produce breeder seed of

established varieties is to select panicles from the

best available source of seed of that variety, such

as a field being grown for production of foundation seed. Depending on the facilities available and the amount of seed desired, individual

panicles may be selected in quantities varying

from 500 to possibly 5,000. These panicles are

carefully inspected and those that are typical for

the variety are threshed individually and head

rows are grown (fig. 26).

One procedure that has helped to eliminate

immm

FiGUKE 26.—Breeder seed head-row block.

natural crosses with other varieties has been to

seed the block of breeder panicle rows within the

area of a foundation field of the same variety.

Each I'ow must be examined carefully throughout the growing season and atypical rows eliminated. Failure to eliminate a row with a few

ofitype plants will adulterate the seed produced,

and It must be discarded. Typical rows are

bulked. The family method described for selecting new varieties may be necessaiy if a commercial variety becomes badly mixed. But this

method should be used as a last resort, since

severe mass selection may result in genetic alteration of the original variety.

An alternate method used for the production

of breeder seed of established varieties is to start

with the best source available and, depending on

the amount of breeder seed desired, to carefully

handpick a given quantity of seed to eliminate

grains that appear to be offtype or to have other

unclesirable characteristics. This handpicked

seed can be drilled thinly, possibly at one-fourth
RICE TN THE UNITED STATES ! VARIETIES AND PRODUCTION 59

the normal rate, in rows 50 to 150 feet long,

spaced 12 or more inches apart. This increase

block then is observed very carefully at intervals

throughout the growing season, and otft5^pe plants

are eliminated. This method is much less time

consuming than the panicle-row method and appears to be quite satisfactory for well-established

varieties that have been purified several times

previously. This method may be preferred to the

panicle-row method, since there is less chance of

genetic alteration.

A system that was inaugurated at Beaumont,

Tex., in 1962 may eliminate growing breeder

seed panicle rows of a variet}^ after a pure source

of breeder seed is established. Under this system the phint breeder produces a fairly large

quantity of seed from panicle rows or family

blocks that is true to type for the variety. This

seed is cleaned and put into 50- to 100-pound

containers and is placed in storage under conditions suitable for maintaining the viability for

at least 10 years. One or more units from storage can be sown each succeeding year to produce

foundation seed.

The advantage of this method is that once a

variety is purified, a continuing source of seed

of known purity is available. To carry this system one additional step, a portion of the seed

used to produce the seed for storage is saved and

stored micler conditions suitable for retaining the

viability for more than 25 years. Elach 5 to 10

years, or as needed, a portion of this remnant

seed may be sown to produce another supply of

breeder seed identical to that originally stored.

FOUNDATiox SEED PRODUCTION.—Foundation

seed usually is the first year increase from breeder

seed. Foundation seed is produced on fields that

have not grown another variety or a lower class

of the same variety during the 2 previous years.

Preventing mixtures throughout the various

phases of seed production requires very close

attention when several varieties are handled with

the same equipment. To facilitate roguing of

foundation seed fields, a space is left every few

feet by stopping up one or more of the holes in

the farm-type grain drill used for seeding. Such

fields should be roguecl several times during the

last part of the growing season. Insofar as possible, foundation seed fields are managed to produce satisfactory grain jàelds without excessive

vegetative growth and to minimize lodging. It

is impossible to satisfactorily rogue a field in

which an appreciable amount of lodging has

occurred.

The release of foundation seed to growers

usually is handled through a committee or seed

council or similar organization that allots tlie

seed to carefully selected growers, often on the

basis of rice acreage within a county or parish.

Sometimes the seed is turned over to a seed growers' organization or crop improvement association. Sometimes foundation seed is distributed

directly to growers from the State agricultural

experiment station. P\H' new varieties or for old

\arieties in short supply, requested amounts of

seed may be reduced in proportion to the amount

that is requested.

Cleaning, Grading, and Processing Seed Rice

Cleaning and processing seed rice is an exacting operation that requires specialized equipment.

Where conditions and facilities permit, it is desirable to delay harvesting seed rice until the

moisture content is below 20 percent. If the combine harvester is carefully adjusted, the rough

rice coming from ''clean" fields may be relatively

free of stems, weed seeds, and trash so that it can

be unloaded and safely elevated directlj^ into

aerated bins without prior aspirating or scalping.

In such case the seed rice is placed in hopperbottom bins and aerated with an excess of air to

dry the grain or at least keep it from heating.

Where necessary, the air may be heated to facilitate drj^ing of the seed rice to a moisture level

sufficiently low for safe storage. If rice coming

from the field contains considerable foreign material, it may be advisable to partly clean it with

a scalper-aspirator machine before putting it in

the bin for aeration. In some locations, facilities

and conditions require that the rough rice be

dried before it can be safely stored. This drying may require that the rice be passed through

the drier several times. Frequently the rice is

aspirated between passes to remove foreign matter and light-weight, immature grains. Extreme

care must be exercised to prevent mechanical

mixing if the drying and cleaning facilities are

used for more than one variety of rice.

The first step in the cleaning and grading

process is to put the rice through a fanning mill,

which has tlie following parts: (1) a wind aspirator that removes light grain, hulls, and other

light-weight foreign material; (2) a screen with

large perforations that removes any remaining

sticks, stems, mud lumps, or large weed seeds;

and (?)) a finely perforated screen that removes

the finer broken rice grains, small weed seeds,

and other small particles of foreign material.

It may be necessarj^ to put the rice through the

cleaner a second time to remove less easily separated material such as shelled rice grains and

weed seeds or an excess of light-weight, underdeveloped grains.

The next step is a grain-length separation that

may be accomplished either by a disk or an indented cylinder-type machine. Small pockets or

indents in revolving disks or cylinders retain the

shorter length grains (including broken grains

and hulled grains) slightly longer while the grain

is lifted by the revolving disk or cylinder, A
60 AGRICULTURE HANDBOOK 2 8 9, U.S. DEFT. OF AGRICULTtIRE

special compartment collects and eliminates the

rejected material from the grain.

The third step in the cleaning and grading

process is a diameter or width separation that

removes any large diameter rice grains, weed

seeds, or foreign materials. For this operation

either a vertical screen or a perforated cylinder

grader is used. The grains of normal diameter

pass through the screen perforations while the

grains of larger diameter, the weed seeds, or foreign materials are retained and thus removed

from the sample. For successful length and

width separations, the sample should be free from

sticks, stems, and other foreign materials because

such materials will interfere with the proper

functioning of the machine.

The length and diameter grading of seed rice

has been extremely useful in removnig the larger

diameter red rice grains from seed of long-grain

varieties. The use of these graders has been

important in the control of red rice. In mediumand short-grain varieties, the only means of red

rice control is the use of red rice free seed and

land, since no economical method of separation

has as yet been devised. In some instances longgrain red rice types have occurred in the longgrain varieties. Wlienever a lot of long-grain

seed rice has a mixture of long-grain red rice, it

should be discarded immediately and not used

for seed. The propagation of seed containing

long-grain red rice will soon result in a wide infestation of the soil with long-grain red rice

strains and will further complicate the maintenance of pure seed production.

Following the diameter-grading operation, the

seed rice usually is treated with a fungicide and

often with an insecticide and placed in wellmarked 100-pound bags. The seed is then ready

for distribution to selected growers.

Each of the rice experiment stations has a

plant for processing seed rice. These plants are

designed to make the installations as nearly selfcleaning as possible. They are being constantly

improved as new and improved equipment and

methods are developed. Gravity movement of

bulk seed is used whenever possible. Steel or

metal-lined bins with smooth walls and gravity

flow metal hopper bottoms simplify cleaning

the facilities. Belt conveyors are preferred to

other types because of ease of cleaning.

The seed rice processing plant at Stuttgart,

Ark., was described by Williams (86). It includes a concrete dump pit, a truck hoist, a 6Dhundredweight-per-hour drier, two bucket-type

elevators, ten 450-hundredweight bins, two halfsize working bins, cleaning equipment, a seed

treater, and 3,500 square feet of sack storage

space (fig. 27). In addition, seven 35-hundredFiGUKE 27.—Rice seed processing plant at Stuttgart, Ark.
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 61

weight bins are available for small lots of breeder

seed. All bins are of steel construction and are

equipped with aeration.

Small portable cleaning units without elevators or conveyors frequentlj^ are used for cleaning small lots of breeder seed. These small lots

usually are dried on sack driers or small laboratory driers to further reduce hazards of mixing.

Various sizes and types of seed-cleaning and handling equipment are described in detail by Harmond, Klein, and Brandenburg (35),

Standards for Seed Certification

The standards for field inspection and laboratory analysis of seed samples for seed certification are summarized in tables 17 and 18. These

reflect the ranges m the standards for the seed

certification agencies in the Southern States of

Arkansas (Arkansas State Plant Board), Louisiana (Louisiana Department of Agriculture and

Immigration), Mississippi (The Mississippi Seed

Improvement Association), and Texas (The State

Seed and Plant Board, Texas Department of

Agriculture), and in California (California Crop

Improvement Association).

In some States lots of seed that contain seedtransmissible diseases will not be certified, and in

other States lots of seed of this type must be

reported.

In order for the rice to be eligible for certification, the seed rice field must not have had another rice variety or the same variety of lower

class growing on it the previous 2 years. The

field also must be isolated from other ricefields.

When the seed rice field is drill seeded, the minimum isolation distances range from 10 to 29 feet

with a ditch, fence, roadway, or other definite

boundary. When the field is sown broadcast

with ground equipment, the minimum isolation

distance is 50 feet. When the adjoining field is

seeded by airplane parallel to the seed rice field,

the minimum isolation distance is 100 feet. When

adjoining fields are seeded by airplane at right

angles to the seed rice field, the minimum isolation distance is one-fourth mile. In California,

all ricefields that are to produce certified seed

must be marked before April 15 at the corners

and at one-fourth-mile intervals by red or other

vivid colored flags that are 3 feet square.

Specific requirements and standards are established for each State and a list of these is available from each of the ofiicial certifying agencies.

In general, they are concerned with application

procedures, field and harvest inspection, postharvest seed movement, seed processing, and ofiicial sampling.

TABLE 17.—Banges a77iang inajor ricegroiDing States in standards for field inspection of rice for 1962

Factor

Standards for each class

Foundation Registered Certified

Other varieties - definite

Per acre

0

0

0

0

Per acre

0 to IGO plants

Up to 160 heads

0

0 to 8 plants

Per acre

10 to 200 plants.

Up to 480 heads.

0.

0 to 18 plants.

Other varieties — similar grain tvp^

Curly indigo and other highly objectionable v^eeds

Red rice

TABLE 18.—Ranges among ina'jor ricegroiving States in standards for cleaned seed of rice for 1962

Factor

Standards for each class

Foundation Registered Certified

Pure seed (minimum)

Other varieties - definite (maximum)

Other varieties - doubtful (maximum)

Other crop seed (maximum)

Curly indigo, coffeebean, field bindweed

Other noxious weeds (maximum)

Red rice (maximum)

Total weed seed (maximum)

Inert matter (maximum)

Germination (minimum)

Moisture (maximum)

98 to 99 percent

0

0 to 7 per pound

0 to 1 per pound

0

0

0

0 to 0.05 per cent

1 to 2 percent

80 to 85 percent

14 percent

98 to 99 percent

0 to 1 per 5 pounds

0 to 10 per pound

1 to 2 per pound

0

0

0 to 1 per 2 pounds

0 to 0.1 percent

1 to 2 percent

80 to 85 percent

14 percent

98 to 99 percent.

3 per 5 pounds to

5 per pound.

0 to 20 per pound.

2 to 5 per pound.

0.

1 in pounds.

0 to 1 per pound.

5 per pound to 0.1

percent.

1 to 2 percent.

80 to 85 percent.

14 percent.
62 raOiiJLTTjRE HANDBOOK 2 8 9, U.S. DEPT, OF AGRICULTURE

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Selected Refe

ANONYMOUS.

1960. GTJLFROSE ... A NEW KICE VARIETY RESISTANT TO HOJA BLANCA DISEASE. TeX. Agl\

Expt. Sta. Leaflet 484, 4 pp.

1961. BELLE PATNA ... A NEW SHORT-SEASON,

LONG-GRAIN RICE VARIETY. TeX. AgY. Expt.

Sta. Leaflet L-512, 4 pp.

ADAIR, C. R.

1940. EFFECT OF TIME OF SEEDING ON YIELD, MILLING QUALITY, AND OTHER CHARACTERS IN

RICE. Amer. Soc. Agron. Jour. 32: 697-

706.

1941. INHERITANCE IN RICE OF REACTION TO HELMINTHOSPORIUM ORYZAE AND CERCOSPORA

ORYZAE. U.S. Dept. Agr. Tech. Bui. 772, 19

19 pp.

and CRALLEY, E. M.

1950. 1949 RICE YIELD AND DISEASE CONTROL TESTS.

Ark. Agr. Expt. Sta. Rpt. Ser. 15, 20 pp.

and JONES, J. W.

1946. EFFECT OF ENVIRONMENT ON THE CHARACTERISTICS OF PLANTS SURVIVING IN BULK HYBRID

POPULATIONS OF RICE. Amer. Soc. Agron.

Jour. 38: 708-716.

MILLER, M. D., and BEACHELL, H. M.

1962. RICE IMPROVEMENT AND CULTURE IN THE

UNITED STATES. Adv. in Agron. 14: 61-

108.

ANDERSON, A. L., HENRY, B. W., and TULLíS, E. C.

1947. FACTORS AFFECTING INFECTIVITY, SPREAD, AND

PERSISTENCE OF PIRICULARIA ORYZAE CAV.

Phytopathology^ 37: 94-110.

ATEN, A., and FAUNCE, A. D.

1953. EQUIPMENT FOR THE PROCESSING OF RICE.

FAO Devlpmt. Paper 27, 55 pp.

ATKINS, J. G., and ADAIR, C. R.

1957. RECENT DISCOVERY OF HOJA BLANCA, A NEW

RICE DISEASE IN FLORIDA, AND VARIETAL RESISTANCE TESTS IN CUBA AND VENEZUELA.

Plant Dis. Rptr. 41: 911-915.

— BEACHELL, H. M., and CRANE, L. E.

1956. REACTION OF RICE VARIETIES TO STRAIGHTHEAD. Tex. Agr. Expt. Sta. Prog. Rpt.

1865, 2 pp.

BEACHELL, H. M., and CRANE, L. E.

1957. TESTING AND BREEDING AMERICAN RICE VARIETIES FOR RESISTANCE TO STRAIGHTHEAD.

Internatl. Rice Comn. Newsletter 6(2) :

12-15.

BoLLiCH, C. N., JOHNSTON, T. H., and others.

1963. BREEDING FOR BLAST RESISTANCE IN THE

UNITED STATES. Blast Symp. Proc, Internatl. Rice Res. Inst., Los Banos, Philippines. July.

and JoDON, N. E.

1963. ASPECTS OF BREEDING RICE FOR RESISTANCE

TO DISEASES, PARTICULARLY BLAST (PIRICULARIA ORYZAE). Internatl. Rice Comn.

Newsletter, Spec, issue, 10th Pacific Sei.

Cong. Symp., pp. 41-52.

and TODD, E. H.

1959. WHITE TIP DISEASE OF RICE. IH. YIELD

TESTS AND VARIETAL RESISTANCE. Phytopathology 49 : 189-19L

AuTREY, H. S., GRIGORIEFF, W. W., ALTSCHUL, A M

and HoGAN, J. T.

1955. RICE MILLING EFFECTS OF MILLING CONDITIONS ON BREAKAGE OF RICE GRAINS. Jour.

Agr. and Food Chem. 3 : 593-599.

(IT)

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(24)

(25)

(26)

(27)

(28)

(29)

(30)

(31)

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(33)

(34)

(35)

BEACHELL, H. M.

1943. EFFECT OF PHOTOPERIOD ON BICE VARIETIES

GROWN IN THE FIELD. Jour. Agr. Res. 66:

325-340.

1959.

1961.

1959. RICE. In Matz, S. A., ed., The Chemistry

and Technology of Cereals as Food and

Feed, pp. 137-176. Avi Pub. Co., Inc.,

Westport, Conn.

and HALICK, J. V.

1957. BREEDING FOB IMPROVED MILLING, PROCESSING

AND COOKING CHARACTERISTICS OF RICE. Internatl. Rice Comn. Newsletter 6(2) : 1-7.

and HALICK, J. V.

1957. PROCESSING AND COOKING QUALITIES OF RICE

AND METHODS FOR THEIR DETERMINATION.

Presented Sixth meeting, Working Party

on Rice Breeding, IRC, FAO, Vercelli,

Italy, 9 pp.

and JENNINGS, P. R.

1961. MODE OF INHERITANCE OF HOJA BLANCA RESISTANCE IN RICE. Rice Tech. Working

Group Proc, pp. 11-12.

JoDON, N. E., JOHNSTON, T. H., and others.

BREEDING RICE VARIETIES FOR RESISTANCE TO

THE VIRUS DISEASE HOJA BLANCA. Internatl. Rice Comn. Newsletter 8(3) : 6-9.

SCOTT, J. E., EVATT, N. S., and others.

BELLE PATNA. Rice Jour. 64(6) : 6-8, 24-

26.

BoRAsio, L., and GARIBOLDI, F.

1957. ILLUSTRATED GLOSSARY OF RICE PROCESSING

EQUIPMENT. FAO, Rome.

CHAMBLISS, C. E., and JENKINS, J. M.

1923. SOME NEW VARIETIES OF RICE. U.S. Dept.

Agr. Dept. Bui. 1127, 17 pp.

CHILTON, S. J. P., and TULLíS, E. C.

1946. A NEW RACE OF CERCOSPORA ORYZAE IN RICE.

Phytopathology 36: 950-952.

CRALLEY, E. M.

1949. WHITE TIP OF RICE. (Abstract) Phytopathology 39: 5.

CRANE, L. E.

1959. NEW RICE VARIETY, "GULFROSE," INTRODUCED.

Rice Jour. 62(13) : 2-3, 17.

DAVIS, L. L.

1950. CALIFORNIA RICE PRODUCTION. Calif. Agr.

Ext. Ser. Cir. 163, 55 pp.

FRAPS, G. S.

1916. THE COMPOSITION OF RICE AND ITS BY-PRODUCTS. Tex. Agr. Expt. Sta. Bui. 191, 41 pp.

GEDDES, W. F.

1951. RICE. MILLING. In Jacobs, M. B., ed.. The

Chemistry and Technology of Food and

Feed Products. 3 v. Interscience Pub.,

Inc., New York.

HALICK, J. V., BEACHELL, H. M., STANSEL, J. W.,

and KRAMER, H. H.

1960. A NOTE ON THE DETERMINATION OF GELATINIZATION TEMPERATURES OF RICE VARIETIES.

Cereal Chem. 37 : 670-672.

and KELLY, V. J.

1959. GELATINIZATION AND PASTING CHARACTERISTICS OF RICE VARIETIES AS RELATED TO COOKING BEHAVIOR. Cereal Chem. 36: 91-97.

and KENEASTER, K. K.

1956. THE USE OF A STARCH-IODINE-BLUE TEST AS A

QUALITY INDICATOR OF WHITE MILLED RICE.

Cereal Chem. 33 : 315-319.

HARMOND, J. E., KXEIN, L. M., and BRANDENBURG,

N. R.

1961. SEED CLEANING AND HANDLING. U.S. Dept.

Agr., Agr. Handb. 179, 38 pp.
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 63

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(54)

INTERNATIONAL CKOP IMPROVEMENT ASSOCIATION.

1959. MINIMUM SEED CERTIFICATION STANDARDS.

Pub. 19, 111 pp. Chambers Printing Co.,

Clemson, S.C.

JENKINS, J. M.

1936. EFFECT OF DATE OF SEEDING ON THE LENCITH

OF THE GROWING PERIOD OF KICE. La Agi"

Expt Sta. Bui. 277, 7 pp.

and JONES, J. W.

1944. RESULTS OF EXPERIMENTS WITH RICE IN

LOUISIANA. La. Agr. Expt. Sta. Bui. 384,

39 pp.

JODON, N. E.

1938. EXPERIMENTS ON ARTIFICIAL HYBRIDIZATION

OF RICE. Ajuer. Soc. Agron. Jour. 30: 294-

305.

1953. GROWING PERIOD OF LEADING RICE VARIETIES

WHEN SOWN ON DIFFERENT DATES. La. Agr.

Expt. Sta. Bui. 476, S pp.

1955. IMPROVING VARIETIES OF RICE AND SORGHUM.

47th Ann. Prog. Rpt., La. Rice Expt. Sta.,

pp. 83-87.

1955. SUNBONNET AND TORO. 2 NEW MIDSEASON

LONG-GRAIN RICE VARIETIES. La. Agr. Expt.

Sta. Bui. 499, 12 pp.

1957. NATO. AN EARLY MEDIUM-GRAIN RICE.

Agr. Expt. sta. Cir. 47, 14 pp.

La.

1961. PERFORMANCE OF RICE VARIETIES IN 1961.

53rd Ajin. Prog. Rpt., La. Rice Expt. Sta.,

162 pp. [Processed.]

and CHILTON, S. J. P.

1946. SOME CHARACTERS INHERITED INDEPENDENTLY OF REACTION TO PHYSIOLOGIC RACES

OF CERCOSPORA ORY^ZAE IN RICE. Amer. SoC.

Agron. Jour. 38 : 864-872.

and DE LA HOUSSAYE, D. A.

1949. RICE VARIETIES FOR LOUISIANA. La. AgV.

Expt Sta. Bui. 436, 15 pp.

RYKER, T. C, and CHLLTON, S. J. P.

1944. INHERITANCE OF REACTION TO PHYSIOLOGIC

RACES OF CERCOSPORA ORYZAE IN RICE. Amer.

Soc. Agron. Jour. 36 : 497-507.

JOHNSTON, T. H.

1958. REGISTRATION OF RICE VARIETIES. AgroD.

Jour. 50: 694-700.

ADAIR, C. R., TEMPLETON, G. E., and others.

1963. NOVA AND VECIOLD . . . NEW RICE VARIETIES.

Ark. Agr. Expt. Sta. Bui. 675, 23 pp.

and CRALLEY, E. M.

1955. RICE VARIETIES AND THEIR YIELDS IN ARKANSAS, 1948-1954. Ark. Agr. Expt. Sta. Rpt.

Ser. 49, 20 pp.

CRALLEY, E. M., and HENRY, S. E.

1959. PERFORMANCE OF RICE VARIETIES IN ARKANSAS, 1953-1958. Ark. Agr. Expt. Sta. Rpt.

Ser. 85, 31 pp.

TEMPLETON, G. E., WELLS, J. P., and HENRY,

S. E.

1962. NORTHROSE, A NEW SPECIAL-PURPOSE RICE

VARIETY FOR ARKANSAS. Rice Jour. 65(8) :

10, 12-14, 18^19.

TEMPLETON, G. E., WELLS, J. P., and HENRY,

S. E.

1962. NORTHROSE RICE—A SPECIAL-PURPOSE, STIFFSTRAWED EARLY VARIETY FOR ARKANSAS.

Ark. Farm Res. 11(2) : 2.

JONES, J. W.

1923. RICE EXPERIMENTS AT THE BIGGS RICE FIELD

STATION IN CALIFORNIA. U.S. Dept. Agr.

Dept. Bui. 1155, 60 pp.

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1936. IMPROVEMENT IN RICE.

Yearbook 1936: 415-Í54.

U.S. Dept. Agr.

1938. THE ''ALKALI TEST" AS A QUALITY INDICATOR

OF MILLED RICE. Amer. Soc. Agron. Jour.

30: 960-967.

ADAIR, C. R., BEACHELL, H. M., and others.

1953. RICE VARIETIES AND THEIR YIELDS IN THE

UNITED STATES 1939-50. U.S. Dept. Agr.

Cir. 915, 29 pp.

JENKINS, J. M., NELSON, M., and others.

1941. KICE VARIETIES AND THEIR COMPARATIVE

Y^IELDS IN THE UNITED STATES. U.S. Dept.

Agr. Cir. 612, 34 pp.

JENKINS, J. M., WYCHE, R. H., and NELSON,

M.

1938. RICE CULTURE IN THE SOUTHERN STATES.

U.S. Dept. Agr. Farmers' Bui. 1808, 29 pp.

KARON, M. L., and ADAMS, MABELLE E.

1949. HYGROSCOPIC EQUILIBRIUM OF RICE AND RICE

FRACTIONS. Cereal Chem. 26: 1-12.

KESTER, E. B.

1959. RICE PROCESSING. In Matz, S. A., ed., The

Chemistry and Technology of Cereals as

Food and Feed, pp. 427-461. Avi Pub.

Co., Inc., Westport, Conn.

KiK, M. C, and WILLIAMS, R. R.

1945. THE NUTRITIONAL IMPROVEMENT OF WHITE

RICE. Nati, Res. Council Bui. 112, 76 pp.

KING, B. M.

1937. THE UTILIZATION OF WABASH CLAY ( GUMBO )

SOILS IN CROP PRODUCTION. Mo. Agr. Expt.

Sta. Res. Bui. 254, 42 pp.

LATTERELL, FRANCES M., TULLíS, E. C, and COLLIER,

J. W.

1960. PHYSIOLOGICAL RACES OF PIRICULARIA ORYZAE CAv. Plant Dis. Rptr. 44: 679-683.

LITTLE, RUBY R., HLLDER, GRACE B., and DAWSON,

ELSIE H.

1958. DIFFERENTIAL EFFECT OF DILUTE ALKALI ON

25 VARIETIES OF MILLED WHITE RICE. Cereal

Chem. 35: 111-126.

NAGAI, I.

1959. JAPÓNICA RICE. ITS BREEDING AND CULTURE.

843 pp. Yokendo Ltd., Tokyo.

NELSON, M., and ADALR, C. R.

1940. RICE VARIETY EXPERIMENTS IN ARKANSAS.

Ark. Agr. Expt. Sta. Bui. 403, 28 pp.

ORMROD, D. P., and BUNTER, W. A., JR.

1961. THE EVALUATION OF RICE VARIETIES FOR COLD

WATER TOLERANCE. AgroD. Jour. 53: 133-

134.

POEHLMAN, J. M.

1959. BREEDING BICE. VARIETAL HISTORY OF RICE

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RAMIAH, K.

1933. INHERITANCE OF FLOWERING DURATION IN

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RAO, B. S., VASUDEVA MURTHY, A. R., and SUBBAHMANYA, R. S.

1952. THE AMYTLOSE AND THE AMYXOPECTIN CONTENTS OF RICE AND THEIR INFLUENCE ON

THE COOKING QUALITY OF THE CEREAL. Indian Acad. Sei. Proc. 36B : 70-80.

REYNOLDS, E. B.

1954. RESEARCH ON RICE PRODUCTION IN TEXAS.

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RYKER, T. C.

1943. PHYSIOLOGIC SPECIALIZATION IN CERCOSPORA

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64 \j;la f í/iüKE JIANDBOOK L*89, U.S. DEP1\ OF AGRICULTURE

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1948.

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1955.

, T. ( \

NEW PATHOGENIC RACES i)V CEKCOSTOKA ORYZAE AEFECTING RICE. (AltStmCtl IMlVtopatholo^ry 37 : 1S)~'1().

and CowART, L. E.

DEVELOPMENT OF CERCOSPOR A-RESIST A NT

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RICE TEST-TUBE MILLER. CrOp Sci. "Brief

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WEBB, B. D., and BEAGHELL, II. M.

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W. D.

THE USE OF THE CARTER DOCKAGE TESTER TO

REMO\^ WEED SEEDS AND OTHER FOREIGN

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58(9) : 26-27.

1955. THE USE OF THE M CG ILL SHELLER FOR REMOVING HC^LS FROM ROT^GH RICE. Kico

Jour. 58 ( KJ ) : 20.

1955. THE USE OF THE MCGILL MILLER FOR MILLING SAMPLES OF RICE. Rice Jour. 58(11) :

20.

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USE OF THE SIZING DEVICE. Rice Jour

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ToDD, E. IT., and IîEACHELL, H. M.

1954. STRAIGHTHEAD OF RICE AS INFLUENCED BY

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WARTH, F. J., and DARABSETT, D. B.

1914. THE FRACTIONAL LIQUEFACTION OF RICE

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WAYNE, T. B.

1930. MODERN RICE MILLING AS PRACTICED IN THE

WORLD'S LARGEST COMPLETE MILL. FoOlJ

Indus. 2 : 492-495.

WELLS, D. G., and CAFFEY, H. R.

1956. SCISSOR EMASCULATION OF W^HEAT AND BARLEY. Agron. Jour. 48 : 496-499.

WILLIAMS, F. J.

1957. AT THE RICE BRANCH EXPERIMENT STATION

... A NEW^ SEED PROCESSING PLANT. Ark

Farm Res. 6(5) : 2.

WILLIAMS, V. R., Wu, W. T., TSAI, H. Y., and

BATES, H. G.

1955. THE DETERMINATION OF THE ESTIMATE OF

HEAD RICE AND OF TOTAL YIELD WITH THE

1958.

WISE, L

1954.

VARIETAL DIFFERENCES IN AM Y LOSE CONTENT

OF RICE STARCH. Agr. Food Chem. 6(1) :

47-48.

N.

RESEARCH IN SEED PROCESSING.

Agron. 1954 Annual Meetings

p. 91.

Amer. Soc.

Agron. Abs.,
SOILS AND FERTILIZERS

By D. S. MiKKELsKN and N. S. EVATT

Types of Soils Used for Rice Production

Rice, a semiaquatic plant, must be maintained

under flooded conditions during part or all of

the growing season to minimize weed competition

and to provide high jnelds. Because of these

water recpiirements, the ideal soil types for rice

production are those that conserve water. Usually clay and clay loams, silty clay loams, or silt

loams are considered most desirable. Soils with

a high clay and silt content provide conditions

for sloAv water percolation. Other soils, including organic soils, can be used if they possess a

hardpan or claj^pan capable of maintaining up to

8 inches of floodwater. Eice soils sliould be capable of easy surface drainage also, since many

aspects of mechanization require removal of the

surface water.

Apart from the aspects of water conservation,

light-textured clay and silt soils are generally

preferred because of their generally favorable

fertility and chemical and physical properties

conducive to the satisfactory growth of rice.

These soils, when drained, adequately supjHjrt the

mechanical equipment used in rice production.

Soil requirements for rice are not demandnig,

but the soil should be fertile and capable of satisfactory management.

Eice does not have a critical soil pH requirement, although the best pn'oducing soils have values between 5.5 and 6.5. In this range of pH

values, nutrient availability is generally good;

and toxicities from such things as aluminum,

iron, Sulfides, and sodium do not generall)^ occur.

The soil pH in the rice root zone normally increases from 0.5 to 1.5 pH units when placed

under flooded conditions, and it decreases when

the excess water is removed. This increase of

pH influences the uptake of nutrients and plant

development. Use of some fertilizers, particularly prolonged use of ammonium nitrogen

sources, increases soil acidity. It is not uncommon for soil pH to decrease as mucli as 2 pH

units where ammonium nitrogen sources have

been used in rice production for 15 to 20 years.

Salinity problems are sometimes encountered

in areas where soluble salts have accumulated or

where a poor quality of irrigation water is used.

Sea water that is intruded into rivers and waterways or that is brought in by storms of hurricane force may be a source of excess salinity.

Because rice can grow in flooded soils, it is occasiomilly used as a reclamation crop. Varieties difl'er in tolerance to salinity, but all are

aftected by the salt concentration of the soil solution in the root zone. The effects of salinitj^

on rice depend somewhat on its stage of development when it is exposed to saline conditions.

Studies of salinity effects indicate that rice is

most tolerant during germination and is most

sensitive during the 1- to 2-leaf stage. Salt tolerance apparentl}^ increases during the tillering

and elongation stages Ijut decreases during the

flowering stage. Results of field experiments

have indicated that high soil salinity occurring

at planting time may seriously impair yield by

reducing germination and stand establishment.

Most rice soils, often referred to as heavy soils

because of their high clay and silt content, present special management problems. These include tillage and seedbed prepjaration, maintenance of organic matter and soil structure,

adequate drainage for essential mechanized rice

operations and for other crops planted in rotation, green manure crops, fertilizer application,

and weed control. Management of rice soils is

discussed in the section ''Culture," p. T-I-.

The soils most widely used in rice production

in tlie United States are of alluvial origin (33)}

Brief descriptions of the soils used for rice in

the principal rice-growing States are given below.

Arkansas

Crowlej" silt loam, Callioun silt loam, and

Sharkey clay are the principal soils used for rice

production in Arkansas {31}. Other soils are

sometimes used.

CROWLEY SILT LOAM.^TIIC surface of Crowley

silt loam is gray to brown. It is underlain with

a gray or yellowish-gray silt loam that changes

with depth into a gray silty clay and finally into

a heavy clay usually mottled with yellow and

red. CroAvle)^ silt loam in its virgin state has a

fairlv liiirh or^'anic nnatter content, but it is low

in phosphorus and is strongly acid.

CALHOUX SILT LOAM.—Calhoun silt loam is a

1 ItaUc iiumbei-8 in parentheses refer to Selected RefereiH'es, p. Tu.

65
66 í'liUH IIANDIKHJK 289, IJ.8. DEPT. OF A(ÍRICULTURE

light gray to almost white sriallow soil iinderWm with a compact dral) or Yelh)wisri-(lrab clay.

This soil is common in lowlands in easterii Arkansas. Calhonn silt loam is low in total nitrogen and phosphorns, and it is acid to strongly

acid. Eice is commonly grown on Calhoun silt

loam in the ''North-end" of the Arkansas rice

area.

SííARKEY CLAY.—The snrface soil of Sharkey

clay is a dark, drab, or grayish-brown silty clay

usually mottled with l)rown. Tliis is underlain

at varying depths with a drab, steel-gray or blue,

sticky' clay. Sand is frequently found in the

surface layer. Sharkey clay occurs commonly in

the Mississippi River'bottoms. It is known as

"buckshot land" because it granulates and forms

a crumb structure. It can be plowed when w^et;

and as it dries out, it breaks down into granules

or into clods that are easily slaked by rain.

Under mitural conditions this soil is poorly

drained, and the natural A^egetation is hardwood

and cypress. In the virgin state it is well supplied with nitrogen and phosphorus, and it is

slightly acid to neutral in reaction. In recent

years, Sharkey clay has been widely used for rice

in the Mississippi Valley.

OTHER SOILS.—Other soils sometimes used for

rice production in Arkansas are AVaverly silt

loam, and Waverly, Miller, and Portland clay

soils. Because these soils usually have poor natural drainage, they have come into use for rice

production only in recent years.

Louisiana

According to Walker and Miears (55), the

principal soils used for rice production in Louisiana are the Crowley, Midland, and Beaumont

soils.

CROW^LEY SOILS.^—Soils of this type found in

Louisiana are the same as soils of this type in

Arkansas.

MIDLAND SOILS.—The Midland soils, which generally are alluvium deposited by the Red and the

Mississippi Rivers, are deep and poorly drained

(5). The surface soil is gray to dark gray and

strongly acid. The subsoil is strong-brown to

light olive-browm, heavy, silty clay mottled with

gray. It is very strongly acid to mildly alkaline.

MIDLAND-CROWLEY ^IIXED SOILS.—Soils that

are a mixture of Midland silt loam. Midland

silty clay loam, and Crowdey silt loam are used

for rice in Louisiana. Fertility and organic matter content of the soils are moderate, and surface

runoff, infiltration, and permeability are slow (5).

BEAUMONT CLAY\—Beaumont clay soil is acid,

poorly drained, and very slowly permeable (38).

It occurs mainly in southw^est Louisiana and in

Texas, east of the Trinity River.

Texas

In addition to Beaumont clay soil wdiich comprises about one-fourth of the riceland in Texas,

rice is growai on Lake Qiarles clay, Bernard

clay loam, Edna fine sandy loam, Hockley fine

sandy loam, and Katy fine sandy loam (38).

LAKE CHARLES CLAY.—Lake Charles clay is

the principal heavy soil in the rice belt west of

the Trinity River 'in Texas. It comprises probably one-third to one-half of the rice acreage

around Houston, Angleton, Bay City, and El

Campo. Lake Charles clay is darker and more

granular than Beaumont clay. It is slightly acid

to mildly alkaline in reaction, with a pH of

6 to 8.

BERNARD CLAY^ LOAM.—Bernard clay loam is

similar to Lake Charles clay but is more loamy

and slightly less dark, and it occurs on slightly

higher elevations. It is found both east and west

of the Trinity River in Texas. This soil is

slightly acid to neutral in reaction, w^ith a pH

of 6 to 7.

EDNA FINE SANDY^ LOAM.—Edna fine sandy

loam has a grayish, sandy surface and is underlain at a depth of 6 to 12 inches by a heavy, gray

claypan. It is found principally in the western

and southwestern parts of the Texas rice belt.

IIocKLEY FINE SANDY LOAM.—The Hockley

soils form a narrow belt along the northern part

of the rice area from Cleveland, in Liberty

County, westward through Hockley, Sealy, and

Eagle Lake to western Victoria County, Texas.

These sandy loam soils are underlain by friable,

sandy clay subsoils. They are slightly more

sloping and better drained than are the Katy

soils, and they require more irrigation water

than do the Katy soils.

KATY- FINE SANDY LOAM.—Katy fine sandy

loam occurs in large level areas adjacent to Lake

Charles soils and in the flatter portion between

the slightly more sloping and better drained

Hockley soils.

California

Stockton and Sacramento clay (27) and Willows (14) are the principal soils used for rice

production in California. However, several other

soils are also used.

STOCKTON SOILS.—Stockton adobe clay is one

of the principal soils used for rice culture in

California. The surface soil is dark-gray or

black clay, 5 to 16 inches deep. When w^et, it is

dense and plastic, but it shrinks in drying and

develops large blocks separated by wide cracks.

The upper part of the dark, grayish-browai, heavy

clay subsoil is similar in structure and consistency to the surface soil but is calcareous. The

subsoil has slightly more colloidal clay and less

organic matter than the surface soil.
RICE IN THE UNITED STATES : VxVKlETIES AND PRODUCTION 67

SACRAMENTO SOLLS.—Sacramento clay soil occupies low-lying flood plains and is derived from

transported material of mixed geological origin.

It was developed under poorly drained, marshy

conditions. The dark-gray or dark, brownishgray surface soil, 14 to 24 inches deep, is coarse

and lumpy. It is heavy textured, and contains

varying quantities of completely or partly decayed organic matter. The transition to a variable subsoil, made up of stratified layers of mineral and organic soil material, is rather abrupt.

WILLOWS SOLLS.—Willow soils consist of stream

sediment, usually reddish or j^ellowish brown or

dark brown, deposited along the courses of minor

creeks or in the waters of temporary lakes, and

underlain by brown to light-brown, compact and

relatively impervious subsoils.

OTHER SOILS.—Other California soils frequently used for rice production include Genevera, Meyers, and Yolo of sedimentary alluvial

origin; Marvin, Merced, and Sycamore of mixed

alluvial origin; and San Joaquin of granitic alluvial origin.

Chemistry of Flooded Soils

In the production of rice, the benefits of flooding the soil are recognized wherever the crop is

grown. Senewiratne and Mikkelsen (29) reviewed the literature and provided evidence that

flooding enhances foliar development, tillering,

and earlier flowering and increases yield of rice

when compared with nonflooding irrigated culture. The superior growth of rice under flooded

conditions can be attributed in part to the eftects

of the acjuatic environment ; but the chemical

characteristics of flooded soils are of major importance in the development of the crop.

The most distinguishing characteristic of a

flooded soil is the presence of standing water

during part or all of the growing season. The

layer of flooclwater, creating waterlogged conditions, exerts profound changes in the physical,

chemical, and biological status of the soil. The

immediate effect of flooding is a drastic curtailment of gaseous exchange between the atmosphere

and the soil. Water fills the soil pores, reducing

oxygen entry and often allowing accumulation of

gaseous products of anaerobic decomposition.

Carbon dioxide concentrations build up in the

flooded soils, together with methane, hydrogen,

nitrogen, and various oxides of nitrogen.

Entry of oxygen is not completely restricted

but is confined largely to a thin layer of soil at

the soil-water interface (23). Oxygen arises

from gaseous exchange with the atmosphere and

as a product of photosynthesis of phytoplankton

and hydrophytes.

Pearsall (24) and Pearsall and Mortimer (^5),

working with naturally flooded soils and lake

muds, determined that there were significant differences l)etween the soil at the soil-water interface and the soil inmiediately beneath. Ploodwater containing some dissolved oxygen maintained a thin surface layer of soil in an oxidative

condition with soil color characteristics and

pliysico-chemical and biological properties different from those of the soil beneath. Oxidationreduction potentials in the oxidative layer exceeded 3i>0 to 350 millivolts at a pTI of 5.0 and

contained such oxidized chemical radicals as

nitrates, sulfates, ferric, and manganic ions. The

underlying soil was conspicuous by the absence

of oxygen and the concomitant presence of the

reduced forms of chemical radicals such as ammonium, ferrous iron, and manganous manganese; nitrogen gas and its oxides; and various

Sulfides, including hydrogen sulfide. The oxidation potentials were generally below 350 millivolts at a pH of 5.0 in the reclucing layer. Mikkelsen and Finfrock (17) showed that reducing

conditions in Stockton clay develop about 3 days

after a soil is flooded. Patrick and Sturgis (23)

showed that when soils are flooded, the soil oxygen disappears within a few hours and may be

nearly absent at depths exceeding about one-half

inch.

The oxidation-reduction status of the soil under flooded conditions is governed by several

factors, including the rate of oxygen exchange,

microbial activity, the soil content of decomposable organic matter, and the base saturation

status.

Flooding has been shown to increase the soil

pH. The increase depends partly on the initial

pH value and organic matter content of the soil,

and on the period of submergence. The pH increase varies usually between 0.5 and 1.5 pH

units. Reed and Sturgis (26) showed that the

pH increase in flooded soils they studied varied

from 0.82 to 1.55 pH units, depending on soil

conditions and initial pH values. Generally, soils

with a low pH and with high soil organic matter

composition undergo the greatest pH changes

when flooded. The cause of the pH increase is

not completely understood but has been attributed variously to increased ammonium composition, soluble ferrous, and manganous hydroxides, which neutralize the exchangeable hydrogen

ions in the soil.

Another generally observed result of flooding

is the increased specific conductance of the soil

solution. The phenomenon is well established,

but detailed information is lacking on the specific nature of the increased composition of dissolved solids in the soil. The increase in the

concentration of ammonium, iron, and manganese ions, and in the bases displaced by these

ions from the soil exchange complex may in part
68 AiUuCULTURE HANDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE

account for the increased specific conductance.

The increased composition of carbon dioxide,

especially at high pH values, would increase the

bicarbonate ion concentration.

Several mechanical properties of soils, including permeability, plasticity, cohesion, and consistency, are changed by flooding. Ordinarily, these

changes do not adversely influence the growth of

rice. Allison [£) showed that the permeability

of a flooded soil is influenced by the amount of

air entrapped during submergence. He noted

that permeability decreased after flooding but

increased again as air trapped in the soil was

released. At a later period after flooding, permeability may again decrease if bacteria-produced material blocks the pores and restricts water movement.

Sturgis {31) called attention to possible deleterious effects of flooding on soil structure. He

cited evidence that low productivity of some

Louisiana soils was caused by deflocculation during flooding. The specific factors associated with

the deflocculation were not reported.

In addition to other effects, flooding has an

important influence on soil temperature and consequently affects the growth of rice both directly

and indirectly. The high specific heat and high

heat of vaporization of water prevent its temperature from dropping as fast or as low as does

air temperature. Under some circumstances, this

modification of the plant environment may enhance the growth of rice.

Upland soils with good aeration usually maintain diverse populations of microflora and microfauna. These organisms decompose organic matter from which they derive energ)^ and liberate

carbon dioxide. They exert a heavy demand for

nutrients, especially nitrogen, as they produce

cellular material. Under flooded conditions, the

normal soil complement of actinomycetes, fungi,

bacteria, algae, and protozoa is modified to produce a microflora consisting principally of anaerobic bacteria, some facultative anaerobes, and a

modified population of algae. The anaerobic

forms have a much lower energy requirement

than do the aerobic forms and consequently decompose organic matter at a slower rate. The

slower decomposition of organic matter under

flooded conditions is partly responsible for the

development of peat in bogs and marshes. The

modification in the soil microflora and microfauna is only temporary, and normal populations

develop when drainage and aeration are maintained.

The decomposition of organic matter proceeds

at a slower rate in flooded soils than in upland

soils, and the end products are different. Tenney

and Waksman (33) showed that the decomposition of cornstalks under flooded conditions proceeds at about half the usual rate; and with more

resistant materials, high in lignin, decomposition

under flooded conditions is delayed to a much

greater extent. In well-drained soils, the end

products of organic matter decomposition are

principally carbon dioxide, nitrates, and sulphates. Under flooded conditions, the end products include methane, hydrogen, various organic

acids, ammonium ions, nitrogen and its various

oxides, amines, mercaptans, and hydrogen sulfides.

The rate of organic matter decomposition in

soils depends on the kind of organic constituents

and their nitrogen content and the carbon-nitrogen ratio. Ordinarily, if nitrogen is adequate

for microbial function, nitrogen is mineralized,

and if carbonaceous materials are in excess, nitrogen is immobilized. Data from various sources

indicate that organic matter decomposition under

anaerobic conditions proceeds at lower total nitrogen values than the 1.2- to 1.5-percent nitrogen

values established under aerobic conditions and

that immobilization of nitrogen does not occur

except at higher carbon-nitrogen values than the

approximate 15:1 established for well-drained

soils. In well-aerated soils, the mineralization of

organic matter gradually increases nitrate production. In flooded soils, the mineralization process produces ammonium ions. The number of

ammonium ions reaches a plateau value rather

rapidly and then declines rather sharply.

The occurrence of two distinct layers—an oxidative layer at the soil-water interface and a reduction layer immediately beneath—exerts a significant influence on agronomic factors associated

with rice production. These layers should be

taken into account in seedbed preparation, crop

residue management, fertilization, cultivation, and

water management.

Two types of nitrogen transformations occur in

flooded soils, depending on whether oxidizing or

reducing conditions prevail. In the thin oxidizing layer at the surface, the nitrogen transformations are similar to those that occur in welldrained soils. Organic matter in this layer is

mineralized to ammonium ions and ultimately to

nitrate ions by the action of highly specialized

autotropic micro-organisms. The nitrate ions are

used by either plants or micro-organisms. They

may be immobilized, depending on the carbonnitrogen ratio of the organic matter; or they may

be moved into the underlying reducing zone by

leaching. The nitrogen status of the reducing

zone is characterized by the denitrification of

nitrates and the accumulation of ammonium ions.

The ammonium ions that are produced by the

more sluggish bacterial microflora are not reduced and provide the reservoir of nitrogen for

use by the rice crop. Nitrates that move into or

originate in this layer are reduced to nitrites and

fhially to nitrogen gas or its oxides. These gases

ultimately escape into the air. This reduction of
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 69

nitrates is favored by low oxygen tensions and the

presence of oxidizable organic matter. Janssen

and Metzger {10) have amply demonstrated that

nitrate nitrogen accumulates in well-drained soils,

in contrast with flooded soils wliere ammonium

ions accumulate.

The practical significance of the dilïerentiation

of distinct oxidation and reduction layers is apparent in results demonstrating the poor efRciency

of nitrate-nitrogen fertilizer sources in continuously flooded soil and the desirability of fertilizer

placement of ammonium nitrogen sources {20).

Nitrate nitrogen that is applied as a basal fertiHzer application or that develops in the oxidation

layer is largely lost through leaching and subsequent denitrification. Where reducing conditions

develop after flooding, drilling ammonium nitrogen several inches into the soil before flooding

provides good retention and availability of the

nitrogen for the rice crop [17).

Flooding a soil often provides conditions for

the increased availability of both the native phosphonis and that applied as fertilizer. Evidence

of this is obtained in both the uptake of phosphorus by rice and the increased solubility of

phosphorus, as shown by soil-test extraction methods (i-i. 20, 30). Factors that appear to be associated with increased phosphoras availability

include pH modification, reduction of insoluble

ferric phosphate to the more soluble ferrous form,

hydration and subsequently increased hydrolysis

of ferric and aluminum phosphates, and increased

displacement of soluble phosphorus by formation

of complex ion and substitution of organic anion.

Sulfur in organic forms or as the sulfate ion is

ultimately reduced, at least in part, to sulfides in

flooded soils. Sulfate reduction is accomplished

by anaerobic bacteria that are active over a wide

range of soil pH and operate under low oxidationreduction potentials. Hydrogen sulfide, the end

product of bacterial reduction, may occur free in

gases produced in flooded soils and may accumulate in amounts toxic to rice. This occasionally

occurs in light-textured soils under extreme reducing conditions and in the presence of large

amounts of readily decomposable organic matter.

Normally, soils contain sufficient active iron to

completely precipitate the sulfide ion as ferrous

sulfide.

Iron, a prominent constituent of the soil, occurs

in primary minerals, hydrated oxides, silicate

clays, and various organic complexes. "\'\nien a

soil is flooded, the iron undergoes considerable

changes in solubility, which is greatly influenced

by anaerobic bacteria. The extent of the change

is also a function of the organic matter content,

the low oxidation-reduction potential, and the

soil reaction. Ferric iron, which predominates in

well-drained soils, is reduced to the ferrous form,

especially as hydroxides and carbonates. Decomposable organic matter in the soil enhances the

reduction process. With sustained flooding, equilibriuni develops between the soil and the soil

solution, with a significant increase in soluble

and exchangeable iron. Both mineral and organic

salts of iron appear in the soil solution. Ordinarily, the abundance of soluble iron does not adversely aftect the growth of rice; but situations

may exist where toxicities or nutrient antagonism

may impair growth.

Manganese chemistry of the soil is not well

understood. Its forms are dynamic in equilibrium, depending on such factors as pH, oxidationreduction status, the presence of organic matter,

and microbial activity. Manganese occurs in

three valence forms, with some compounds containing manganese in two valence forms. In some

respects, the behavior of manganese in the soil is

similar to that of iron. In flooded soils, the higher oxides of manganese are reduced to soluble and

exchangeable ions. Biological reduction occurs

independent of soil pH if low oxidation-reduction

potentials exist. Decomposing organic matter reduces manganese, especially in the lower soil pH

range. It is unusual for soil manganese in flooded

soils to afl'ect growth of rice adversely. High

levels of soluble and exchangeable manganese in

the soil may be toxic to sensitive crops grown in

rotation after rice.

Fertilizers

Southern Rice Area

The proper use of fertilizers on rice increases

yield from 30 to 50 percent in the southern rice

area. Practically the entire rice area in Louisiana

and Texas requires additions of commercial fertilizers for economical yields. This is also tiaie

with most of the rice soils in Arkansas, particularly in the traditional ricegrowing area of the

Grand Prairie region; however, the newer rice

bottomland soils in the delta areas of Arkansas

and Mississippi may not require fertilizer during

the first year or two of rice cropping.

Commercial fertilizers were not used extensively in the southern rice area before World War

II. In fact, results from many of the soil fertility tests conducted in the early thirties showed

negative yield responses from fertilizer applications {12). This was usually true when various

rates and ratios of nitrogen and phosphorus had

been applied at seeding. This method of application greatly stimulated weed and grass growth

before the rice plants became established, and this

competition often severely reduced rice yield.

However, the real worth of commercial fertilizers

became apparent with the gradual improvement

of irrigation and drainage facilities, improved

land preparation, mechanized harvesting equipment, the development of varieties suitable for
70 Aonícu: .TURE HANDBOOK 2 8 9, U.S. DEFT. OF AGRICULTURE

mechanization, and the greatly increased use of

the airplane for applying fertilizers. Fertilizers

were also greatly improved. Pelleted or prilled,

granular, and large crystalline, high-analysis fertilizers are available and are ideally suited for

application with the airplane or with improved

ground equipment {l-^S),

Knowledge of previous cropping history and a

soil test are useful in determining the amount and

kind of fertilizer to use on rice in some Southern

States (^, 28). Specific fertilizer recommendations vary considerably between States and from

area to area within States, or even from farm to

farm within the same area. The rice variety,

water management, methods of weed control, and

other managerial variables affect use of fertilizers

{15). Various rapid, chemical, soil-testing methods are used effectively to determine the fertilizer

and lime requirements of rice soils (^). Chemical

determination can be made on soil reaction (pH),

percentage of organic matter, and the available

phosphorus, potassium, and calcium; and the

salinity hazard can be noted. The nitrogen level

is usually estimated from the organic matter content. Results of these tests obtained from airdried soil samples can be interpreted with reasonable accuracy, provided basic information is available on the complex chemical changes known to

occur under submergence. All this information is

of value in determining fertilizer requirements

for rice in southern rice areas.

Nitrogen is used at somewhat higher rates in

Arkansas than in the other States. Rates above

100 pounds per acre of actual nitrogen are rather

common, particularly on the soils of the Grand

Prairie {Slf). Some differences in the fertilizer

requirements of rice varieties are recognized, with

the stiffer strawed varieties being capable of using

and withstanding higher rates of nitrogen without lodging. Phosphorus and potash are usually

applied on the basis of a soil test. The nitrogen

requirements for rice grown in the delta areas of

Arkansas and Mississippi seldom exceed 60 to 80

pounds per acre. These newer soils frequently

require no fertilizer during the first year or two

of rice production.

The timing of fertilizer application on rice is

very important. Most rice farmers in Louisiana

and Texas prefer a somewhat earlier application

of the total amount of fertilizer than do farmers

in Arkansas and Mississippi (5^). For all States,

however, it is generally conceded that all of the

phosphorus and potassium and part of the nitrogen should be applied as near to seeding time as

possible. In Louisiana and Texas, the remaining

nitrogen should be applied before the rice has

completed half of its growth period. In Arkansas, a nitrogen application about 60 to 70 days

before harvesting has produced good results.

Thus, the timing depends to a large extent on the

total growth period of the particular rice variety.

The rice soils in Louisiana and Texas are generally deficient in phosphorus and in organic matter (35). Thus additions of from 20 to 40 pounds

of phosphoric acid per acre and from 40 to 80

pounds of nitrogen per acre are usually necessary

for the economical production of rice. In most instances, no potash is required. The small areas of

sandy soils in both States, however, sometimes

respond to a 20- to 40-pound per acre application

of potash.

When applying fertilizer as a topdressing on

rice growing in heavy soils, placing it on dry soils

is usually preferred to placing it on wet or flooded

soils. Soon after the fertilizer is applied, the

fields are flooded; thus the water is an effective

carrier to move the fertilizer into the root area.

If scarcity of irrigation w^ater, weed infestations,

rains, or timing difficulties prevent flooding, the

rate of application, particularly of nitrogen, is

increased slightly to compensate for reduced efficiency. The rate for nitrogen should be increased

about 5 to 10 percent on wet soils and perhaps

10 to 15 percent on flooded soils {28).

Applying a large amount of fertilizer directly

with the seed is hazardous, since germination may

be reduced or emergence may be delayed. The

time of seedling emergence directly influences

the flooding date and thus becomes important in

controlling grass weeds. These problems do not

ordinarily occur if the fertilizer is placed 2 to 3

inches below the seeds.

Limited research on the mineral deficiency

symptoms of rice has been conducted in the

United States. Olsen {22) reported typical foliar

symptoms due to deficiencies of nitrogen, phosphorus, potassium, calcium, magnesium, and iron

in three greenhouse experiments. A deficiency of

each of these elements, except calcium, reduced

tillering. Reduced tillering caused by nitrogen

deficiency was particularly pronounced. All elements reduced root and top development; potassium and nitrogen deficiencies caused the most

severe reductions.

The sources of nitrogen, phosphorus, and potassium used in southern rice areas vary widely

and to a large extent depend on the cost of application and physical condition of the fertilizer.

Ammoniacal forms of nitrogen are generally

preferred to the nitrate forms; however, compounds containing both sources, such as ammonium nitrate or mixtures of ammonium nitrate

and urea in liquid form, are considered equal on

an equivalent nitrogen basis to such materials as

ammonium sulfate, ammonium phosphate, urea,

and ammonium chloride. Because of the lower

cost of application, there is a definite trend toward the use of high-analysis fertilizers. Anhydrous ammonia is a good source of nitrogen for

rice, although it is difficult to apply wâth ground
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 71

equipment during wet periods. Application in

water is satisfactory only when precise watering

metliods are used, since uniform distribution of

the material depends on having a uniform distribution and depth of water.

Phosphorus is usuall}^ supplied in the form of

superphosphate (either 20 or 46 percent) ammonium phosphate, or diammonium phosphate.

Rock phosphate is sometimes used and is satisfactory.

Muriate of potash (KCl) is the connnon source

of potassium. Only limited quantities of potassium sulfate are used, although it is considered

equal to muriate of potash.

In areas where crops preceding rice have been

fertilized with phosphorus and potash, residual

amounts of these elements ma}^ be sufficient for

one or perhaps two consecutive rice crops.

Research has been conducted with minor elements; however, no positive effects on jdelds or

milling quality have been reported.

Addition of limestone has not been necessary

for rice grown on moderately to slightly acid

(pH 5.0 to 6.5) soils. Of equal importance is

the fact that no detrimental effects on rice yields

have been noted from adding lime, which is

usually added at the rate of 1 to 2 tons per acre

on crops rotated with rice.

The long growing seasons in southwestern Louisiana and southeastern Texas permit the production of a ratoon or stubble crop, particularly by

the earliest maturing rice varieties seeded around

the middle of AiDril. Research in Texas (8) has

shown that for best results, additional nitrogen,

usually about three-fourths of the amount applied to the first crop, should be applied immediately after first harvest. This practice consistently gave rice yields that were one-third to

one-half as much as the original crop. Ordinarily, fertilizers containing phosphorus and potassium need not be applied, since residual quantities

of these elements applied to the first crop fulfill

the ratoon requirements.

California

Fertilizers, particularly nitrogen, increased

rice yields in the earliest experiments conducted

in California, in 1914-16 (11). Dunshee (7)

continued rice fertilizer research, and it was

greatly expanded by Davis and Jones (6) from

1925 through 1937. They showed that nitrogen

fertilizers improved yields significantly on Stockton clay adobe. Applications at the time of seeding were more effective than were later applications. They also reported that phosphate and

potassium fertilizers did not increase yields on

Stockton clay adobe.

More recent fertilizer research has demonstrated the need for nitrogen on all soils except

those on which a good leguminous green manure

crop IS grown {18), Phosphorus fertilizers have

increased yields on the brownisli-red terrace soils

bordering the Sacramento and the San Joaquin

Valleys. Some basin soils after years of cropping i)roduce better rice yields when j^hosphoi'us

is included with nitrogen. In some areas, usually parts of large fields, where alkali salts have

accumulated and where the soil reaction exceeds

pH 8.5 in a 1:10 soil-water paste, dramatic responses have been obtained from various iron

sources (9).

Rice was fertilized in California before 1958

by broadcasting either on the dry seedbed before

flooding and planting or, more commonly,

on the water by airplane after seeding. Fertilizer placement work of Mikkelsen and Finfrock

(17) demonstrated that nitrogen broadcast on the

soil surface or ap])lied to the flooded fields was

not used efficiently by rice. Broadcast nitrogen

was lost through nitrification and subsequent

denitrification. However, annnonium nitrogen

drilled 2 to 4 inches into the soil, where reducing

conditions developed 3 to 5 days after flooding,

remained in the soil and was continuously available to the rice plants.

The time of applying fertilizer before flooding

is important, since nitrification is known to be

undesirable both before and during flooding.

Mikkelsen (16) established that nitrification occurs if annnonium nitrogen is drilled into a warm,

moist, aerated seedbed before flooding. As much

as 60 percent of the ammonium nitrogen can be

converted to nitrate in 7 days of typical spring

soil temperatures.

Split application of nitrogen, with part placed

in the soil before flooding and the rest used as a

topdressing during the ]3eriod of panicle formation, has proved effective in some regions of the

world. To])dressing experiments in California

rice production have shown no superiority over

preplant soil application (19). Where the seediDed application of nitrogen was not sufficient to

maintain normal color and growth of rice, supplemental applications have been profitable. For

effective use of topdressed nitrogen on California

rice varieties, the application should be made no

later than 50 to 60 days after planting.

Phosphate fertilizer should be applied before

flooding, usually simultaneously with nitrogen.

Phosphorus does not move appreciably from

where it is applied ; this makes placement in the

root zone of great importance.

The quantity of nitrogen fertilizer used in rice

production varies from 30 to 120 pounds of actual

nitrogen per acre. This is supplied as one of the

commercially available ammoniacal sources such

as ammonium sulfate, urea, anhydrous ammonia,

or ammonium phosphate sulfate mixtures. On

soil low in nitrogen, as much as 80 to 120 pounds

of nitrogen per acre (400 to 600 pounds of ammo-
72 AGîatMLTLTUKE HANDBOOK 289, U.S. DEFT. OF AGRICULTURE

nmin sulfate) is often used. Soils of iivera^^e

fertility, producing about 50 hundredweight of

paddy Vice, usually receive applications of 60 to

80 pounds of actual nitrogen.

On most California rice soils, a])])lications of

40 to 60 pounds of actual P2O5 per acre will supply the phosphorus needs of rice. Some residual

eifects have been observed on subsequent crops,

but the carryover from a single application may

not be sufficient for best yields during a second

year. In areas where phosphorus is needed, the

added growth and yield often require that additional nitrogen be supplied. Where rice produces

better growth with phos])horus, it is generally

advisable that nitrogen rates be increased 25 to

50 percent.

Experiments to determine the best nitrogen

sources for rice have been conducted over a longperiod. Davis and Jones (6) compared ammonium sulfate, Ammo-Phos, Leunasal]:)eter, urea.

Ammo Phos Ko, Leunaphos, Calurea, and cyanamide during 1932-36. They concluded that

ammonium sulfate was the most profitable. Experiments in which nitrogen from different

sources was drilled into the soil l)efore fiooding

are reported by ^Mikkelsen and Miller {19). In

yield comparisons with ammonium sulfate rated

as 100, ammonium chloride ranked 97, cyanamide

92, urea 90, aqua ammonia 85, anhydrous ammonia S3, and ammonium nitrate 57. A(iua ammonia and anlnalrous ammonia are good nitrogen

sources but in h)ose diy seedl)eds tliey sometimes

do not i)erform as well as do dry materials because of volatilization losses.

Ingebretsen and others (9) reported that in

alkali spots where rice ordinarily died soon after

emergence, l)roadcast applications of ferric sulfate corrected iron deficiency and ])roduced excellent yields. Su))sequent tests with other materials indicated that iron oxide, modified and

natural iron sulfides, and ferrous sulfate likewise

corrected the deficiency. Usually 125 to 250

pounds of actual iron from these sources corrects

the iron deficiency.

Selected References

( 1 ) ADAIR, C. K., and ENGLER, KYLE.

195Ó. THE IRRIGATION AND CULTIRE OF RICE. lU

Water, U.S. Dept. Agr. Yearbook of Agr ,

r)l). 389-304.

(2 ) ALLISON, L. E.

1947. EFFECT OF MICROORGANISMS ON PERMEABILITY

OF SOIL UNDER PROLONGED SUBMERGENCE.

Soil Sei. G3 : 439-450.

(3) HEACHELL, H. M.

1959. RICE. In Matz, S. A., eel.. The Chemistry

and Technoh)iJ:y of Cereals as Food and

Feed, pp. 137-176. Avi Pub. Co., Inc., Westport, (\nm.

(4) BEACHER, R. L.

1955. SAMPLING AND ANALYSLS OF PADDY SOILS.

Internatl. Rice Comn. Meeting Proc, FAO,

Penang, Malaya.

CLARK, H. L., HALEY, G. J., HEBERT, E. J., and others.

1962. SOIL SURVEY OF ACADIA FARISII, LOUISIANA.

U.S. Soil Conserv, Serv. in coop. La. Agr.

Expt. Sta. Ser. 1959 No. 15, 57 pp.

DAVIS, L. L., and .JONES, J. W.

1940 FERTILIZER EXPERIMENTS WITH RICE IN CALIF(JRNIA. U.S. Dept. Agr. Tech. Bui. 718,

21 pp.

DUNSHEE, C. F.

li)2S RICE EXPERI:MENTS IN THE SACRAMENTO VALLEY, 1922-1927. Calif. Agr. Expt. Sta. Biil.

454, 14 pp., i 11 us.

EvATT, N. S., and BEACH ELL, FT. INI.

19(;2 SECOND-CROP RICE PRODUCTION IN TEXAS.

Tex. Aíír. Prog. 8(6) : 25-28.

INGEBRETSEN, K., MARTIN, W. E., VLAMIS, JAMES,

and .lETEH, ROY.

1959. IRON DEFICIENCY OF RICE. Calif. Agr. 13:

6-7, 8, and 14.

.TANSSEN, GEORGE, and METZGER, W. H.

1928. TRANSFORMATION OF NITROGEN IN RICE SOIL.

Amer. Soc. Agron. .Jour. 20: 4.59-476.

JONES, J. W.

1928. RICE EXPERIMENTS AT THE BIGGS RICE FIELD

STATION IN CALIFORNIA. U.S. Dept. Agr.

Dept. Bui. 1155, 60 pp., illus.

— DocKiNs, J. O., WALKER, R. K., and DAVIS,

W. C.

1952. RICE PRODl'CTION IN THE SOUTHERN STATES.

U.S. Dept. Agr. Farmers' Bui. 2043, 36 pp.,

illus.

^MCGREGOR, A. J.

1953. PHOSPHATE MOVEMENT AND NATL^RAL DRAINAGE. Jour. Soil Sei. 4: 86-97.

MANN, C. W., WARNER, J. F., WESTOVER, H. L., and

FERGUSON, J. E.

1911. SOIL SI^RVEY OF THE WOODLAND AREA, CALIFORNIA. U.S. Dept. Agr., Bur. Soils, Soil

Survey Adv. Sheet 1909, 57 pp.

MiEARS, R. .T.

1958. FERTILIZER AND CULTURE PROBLEMS. Rice

Tech. Working Group Proc. 8 : 17-19.

^IlKKELSEN, D. S.

1962. NITROGEN FERTILIZATION OF JAPÓNICA RICE

IN CALIFORNIA. Rice JouF. 65(3) : 8-13.

and FiNFRocK, D. C.

1957. AVAILABILITY OF A^I^IONIACAL NITROGEN TO

LOWLAND RICE AS INFLI^ENCED BY FERTILIZER

PLACEMENT. AgTou. Jour. 49 : 296-300.

FiNFRocK, D. C, and MILLER, M. D.

1958. RKE FERTILIZATION. Calif. Agr. Expt. Sta.

Ext. Serv. Leañet 96, 12 pp., illus.

— and MILLER, M. D.

1963. NITROGEN FERTILIZATION OF RICE IN CALIFOBNiA. Calif. Agr. 17 : 9-11.

MiTSLU, SHINGO.

1954. INORGANIC NUTRITION, FERTILIZATION AND

SOIL AMELIORATION FOR LOWLAND RICE. 107

pp. Yokeiido Ltd., Tokyo.

NELSON, MARTIN, SACHS, W. H., and AUSTIN, R. H.

1923. THE SOILS OF ARKANSAS. Ark. Agr. Expt.

Sta. Bui. 187, 83 pp., illus.

(22) OLSEN, K. L.

1958. .MINERAL DEFICIENCY SYMPTOMS IN RICE.

Ark. Agr. Expt. Sta. Bui. 605, 11 pp.

(23) PATRICK, W. H., JR., and STURGIS, M. B.

1955. CONCENTRATION AND MOVEISIENT OF OXYGEN

AS RELATED TO ABSORPTION OF A^[MONIUM

AND NITRATE NITROGEN BY' RICE. Soil Sci.

Soc. Amer. Proc. 19: 59-62.

(24) PEARSALL, W. H.

1938. THE SOIL COMPLEX IN RELATION TO PLANT

COMMUNITIES. I. OXIDATION-REDUCTION POTENTIALS IN SOILS. Jour. Ecol. 26 : 180-193.

(5>

(6)

(7)

(8)

( 9 )

(10)

(11)

(12)

(13)

(14)

(15)

(16)

(17)

(18)

( 19 )

(20)

(21)
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION

(25)

(20)

(27)

(28)

(29)

(30)

PEARSALL, W. H., and MOKTIMER, C. H.

1939. OXIDATION-REDUCTION POTENTIALS IN WATEKLOGCJED SOILS, NATURAL WATERS AND MUDS.

Jour. Ecol. 27 : 483-501.

REED, J. F., and STURGIS, M. B.

1939. CHEMICAL CHARACTERISTICS OF I'HE RICE AREA

OF LOUISIANA. La. Agi'. Expt. Sta. Bui. 307,

31 pp.

KETZER, J. L., GLASSEY, T. ^Y., GOFF, A. M., and

HARRADINE, F. F.

1951. SOIL SURVEY OF THE STOCKTON AREA, CALIFORNIA. U.S. Dept. Ai^r. in coop. Univ.

Calif. Agr. Expt. Sta. Ser. 1939 No. 10, 121

pp.

REYNOLDS, E. B.

1954. RESEARCH ON RICE PRODUCTION IN TEXAS.

Tex. Agr. Expt. Sta. Bui. 775, 29 pp.

SENEWIRATNE. S. T., and MIKKELSEN, D. S.

(31)

1961.

SHAPIRO

1954.

PHYSIOLOGICAL FACTORS LIMITING GROWTH

AND YIELD OF ORYZA SATIVA UNDER FLOODED

CONDITIONS. Plant and Soil 14 : 127-146.

R. E.

THE EFFECT OF FLOODING ON AVAILABILITY OF

SOIL PHOSPHORUS YIELD. AND PHOSPHORUS

AND NITROGEN X^PTAKE BY RICE. FoUl'th luternatl. Rice Comn. Proc, Tokyo. [Mimeographed paper.]

STURGIS, M. B.

V,):M\. CMAN(iES IN THE OXlDATlON-KElK ( TlON EQUILIBRIUM IN SOILS xiS RELATED 'i'( ) 1 HE PHYSICAL PKOPEUriES OF THE SOILS AND THE

GROWTH OF KITE. La. Agr. P]xpt. Sta. Bui.

271, 37 1)}).

(32 1

11)57. MANAGING SOILS FOR RICE. /// Soil, U.S.

Dept. Agr. Yearl)()ok of Agr., pp. 658-663.

(33) TENNEY, F. G., and WAKSMAN, S. A.

1930. COMPOSITION OF NATURAL ORGANIC MATERIALS

AND T1H:IR DECO^^IPOSITTON IN THE SOIL. V.

DECOMl'OSITION OF VARIOUS CHEMICAL CONSTITUENTS U\ PLANT MATERIALS, UNDER

ANAEROBIC CONDITIONS. Soil Sci. 30: 143-

160.

(34) THOMPSON, L., MAPLES, R., WELLS, J., and others.

19r]2. RECOMMENDATIONS FOR RICE FERTILIZATION IN

socTHERN STATES. Rice Jour. 65(1) : 5, 6,

and 40.

( 35 ) WALKER, R. K., and MIEARS, R. J.

1957. THE COASTAL PRAjRUis. lu Soil, U.S. Dept.

Agr. Yearbook of Agi\, pp. 531-534.
CULTURE

By T. H. JOHNSTON and M. D. MILLER

Rice has been grown as a commercial crop in

the United States since the Latter part of the

17th century. Rice cultural methods used from

that time until the present have been reviewed

by Adair, Miller, and Beachell (5).i They

traced the evolution of cultural methods from

the use of hand labor for clearing timber from

the land, for digging canals and ditches, for

plowing with a hoe, for seeding, harvesting, and

threshing, through the use of animal power

(oxen, mules, and horses) for binding and threshing the rice. Then came steam-powered threshers. Today, several large "rice-special" dieseland gas-powered tractors and self-propelled combines may be used on one farm. Much of the

seeding and most of the fertilizing and spraying

is now done by airplanes that can cover several

hundred acres a day.

Much of the increase in rice production i^er

acre can be attributed to imi)roved cultural methods made possible by the invention and manufacture of the specialized equipment. The major

rice areas of the United ¡States are now described

as the most highly mechanized farming areas in

the world.

Along Avith improvements in machinery and

farming methods have come other innovations,

including use of reservoii's for im])ruved water

supply and, more recently, underground pipelines

to eliminate man}' open canals.

Rotation or cropping systems; land leveling

and seedbed prepaiation; seed and seeding; irrigating (ñg. 28) ; and harvesting, drying, and

storing methods have been develoi)ed and improvecl through research. ]\Iany branches of

science have contributed to the development and

adaptation of new and improved methods, equipment, and facilities now used in rice culture.

Rotation or Cropping Systems

In most rice-producing areas of the United

States, crops are rotated because under continuous cropping the soil usually becomes dej^leted

in fertility and in organic matter. The resulting

deterioration of the physical condition of the soil

makes seedbed preparation esi^ecially difficult. In

addition, the soil usually becomes progressively

1 Italic numbers in parentheses refer to Selected References, p. 106.

74

Ficu'EE 28.—A ricefield showing the canal that supplies the

irrigation water.

infested with weeds and diseases that lower the

yield and quality of the rice.

In the early 3'-ears in the Carolinas, rice was

grown continuously in the same field with only

occasional rest (4-4) • Later, ricefields in that

area sometimes were planted to oats in the fall,

followed by })otatoes the next year. Some farmers grew rice and cotton in alternate years. This

helped to control weeds in both crops.

In the early years in the South Central States,

fields were cropped to rice year after year until

the rice yields became low and the quality poor

because of the mixtures of weed seed and red

rice ill the threshed grain. Fields then were

allowed to lie idle for 1 or 2 years, and then

were again put back into rice. This helped to

increase rice yields but did not control the weeds

satisfactorily. Therefore, ricefields were grazed

during the years that they were "laid-out." This

practice helped to control grass and weeds but

did not control red rice. Some farmers practiced

summer-fallowing for a year or two between rice

crops and in this way controlled weeds and red

rice more effectively than when the fields were

idle.

Modern riceland cropping systems are based

on information gained from controlled experiments and from groMer experience. The preferred system for any farm depends on soil type.
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 75

local climatic conditions, and economic considerations.

Arkansas

Rotation experiments Avere begun in 1927 at

the Rice Branch Experiment Station, Stuttgart,

Ark. Because of the numerous factors knoAvn to

affect rice yields, many rotations were tried,

along with several combinations of delayed seeding, tillage for weed control, and summer-fallowing. Results included the following {93^ 94) :

(1) In 2-, 3-, and i-year rotations, best yields

were obtained when rice was grown not more

than half the time.

(2) Rice rotated with fallow or early planted

soybeans (for beans or hay) or lespedeza (for

hay) produced 1,000 pounds more rice per acre

in the year it was grown than when rice was

grown continuousl5\ Over a 7-3?'ear period of

continuous cropping, rice yields declined 180

pounds per acre.

(3) The best 3-year rotation was 1 3^ear of

soybeans, followed by a winter vetch cover crop,

and 2 years of rice. Rice yield increase was

greatest the first year.

(4) As compared to continuous rice, 4:-yeav

rotations of soybeans-oats-rice gave large jdeld

increases in the first year of rice, but only half

as large an increase in the second year of rice.

(5) Rice yields Avere significantly increased bj^

plowing down legume green manure crops, including soybeans, lespedeza, and hairy vetch

(Vida vUJosa Roth) immediately preceding the

rice crops. All green manure treatments increased rice yield more than did chemical fertilizer applied to the preceding crop in the rotation.

Simmons {115) reviewed x^^rkansas rice rotation research, discussing 3-, 5-, 6-, and 8-year

systems. These systems mvolvecl rice on the land

for half of the time or less and soybeans, oat«,

lespedeza, or hairy vetch the rest of the time.

Perkins and Lund (100) listed ways in which

good rotations would benefit the farmer, but cautioned that these rotations would not replace

mineral plant food elements such as phosphorus

and potassium. They stated that legumes may

supply considerable nitrogen, but more nitrogen

may be needed. They also stated that rotations

will aid in disease and insect control, but other

control measures may be required.

In 1947 the order of frequency of crops in the

Arkansas rice area was rice, oats, lespedeza, soybeans, corn, and cotton {120), The most prevalent cropping systems on small rice farms in

Arkansas were 4 or 6 years long, with rice being

grown on the land for 2 or 3 consecutive years

(ÖÖ, 91), These systems included growing rice

and leaving the land idle, a rotation of rice, oats,

and lespedeza, and a rotation of rice and soybeans. Returns to the operators were slightly

higher with only one-third of the land in rice

than with one-half of the land in rice, if other

crops such as oats, lespedeza, and soybeans were

grown and harvested to supplement income.

Forty percent of the operators of large rice

farms followed a cropping system including rice

and oats, with the oats in many cases being overseeded with lespedeza; and almost all operators

had some fallow and idle land. Approximately

25 percent of the farmers produced so^^beans, and

about 35 percent produced beef cattle. The second most common rotation was rice-oats-lespedeza-soybeans, with 42 percent of the land being

used for rice under this cropping system.

In 1962, the crops most often grown in rotation with rice in Arkansas were soybeans and

oats. Legume green manure crops were used infrequently. In recent years, 1 or 2 years of lespedeza in a rice rotation has sometimes led to

considerable damage to rice from the so-called

lespedeza worm, grape colaspis, Maecolaspis

ßavida (Say). However, chemical controls for

this insect have been developed by Rolston and

Rouse (iö7).

The rotation of rice with reservoirs used for

fish production and as a source of irrigation water has been practiced in Arkansas {46). In

some instances, the rotation has produced substantial increases in rice vields, even without the

use of commercial fertilizer on the rice crops.

The rotation may include 2 years of fish and 2

years of rice or 1 year of fish and 1 or 2 years of

rice. Leaving a reservoir in fish for longer than

2 years is usually unsatisfactory because the accumulated fertility results in excessive vegetative growth of the rice the first year after fish.

In some cases, even 2 years in fish results in excessive vegetative growth and severe lodging of

the following rice crop.

Experiments by Sims {117. 118) indicate that

a large part of the increased vegetative growth

of rice may be attributed to the accumulation of

ammonium nitrogen in the soil during the period

the reservoirs were in water and fish. Excessive

vegetative growth of rice may be avoided by

growing a row crop such as soybeans, grain

sorghum, or corn in the rotation the first year

following fish or water and then growing rice

the second year. In one field test on a clay soil

that had been in fish 2 years, all of these crops reduced the ammonium nitrogen content of the

soil from 175 pounds per acre at seeding time to

40 pounds per acre at harvest. Rice grown on

the experimental area the second year did not

lodge.

In ricefields where high soil fertility resulted

in excessive early vegetative growth, draining

the fields and allowing them to dry thoroughly

before the development of the rice panicles

(heads) at the early jointing stage of growth
7G AGRICULTURE HANDBOOK 2 8 9, U.S. DEFT. OF AGRICULTURE

helped retard later vegelalive o-rowth of the rice

and helped reduce lodging.

Green (45) reviewed the problems of fish farming and stated that haphazard raising of fish

must be supplanted by more scientific production

and marketing practices.

Green and White (^7) recently have compared

three selected 4-year rice rotations in eastern

Arkansas. These rotations were fish-fish-ricerice, soybeans-soybeans-rice-rice, and idle-fallowrice-rice. Combinations of buffalo and bass were

the fish species most commonly stocked. These

studies indicated that a total of 881 pounds of

buffalo and 181 pounds of bass per acre must be

produced and marketed during the 2-year fish

period for this system of land management to be

as profitable as the soybean-rice rotation. This

level of production is considerably higher than

that reported by the 35 fish-rice farmers whose

operations were included in the study.

Preliminary experiments conducted at the Rice

Experiment Station at Crowley, La., showed that

good-quality catfish could be produced under

conditions similar to those in flooded ricefields

without major disease or parasite problems

{128). To help answer some of the complex

problems encountered in the growing of fish and

in the use of fish-rice rotations, a Fish Fanning

Experimental Station was established in 1961 at

Stuttgart, Ark., by the Fish and AVildlife Service of the U.S. Department of the Interior. In

cooperation with the University of Arkansas, experiments have been initiated to determine suitable management and fertilization practices

{116),

Sullivan (136) reported that some Arkansas

farmers in recent years have started to rotate

water and crops. Their fields are kept flooded 1

or 2 years and then seeded to rice. According to

Sullivan, benefits under this system include increased organic matter content of the soil, improved physical soil characteristics, improved

weed control, and improved recreational and

wildlife facilities.

Louisiana

Reporting on early experiments in rice production in southwestern Louisiana, Chambliss

and Jenkins {19) in 1925 stated: ''Good drainage, good tillage, and proper rotation make unnecessary the application of any commercial fertilizer to the Crowley silt loam at the present

time." Results obtained at the Crowley Rice

Experiment Station from 1913 to 1923, inclusive, showed that rice in rotation with soybeans

averaged 2,384 pounds per acre, as compared

with 1,243 pounds per acre for continuous rice.

Efficient drainage and good tillage, supplemented

by the organic matter added to the soil by plowmg under mature soybean plant remnants after

harvest, gave greater returns than were obtained

from commercial fertilizer applied to the rice

crop. In addition, the soil was left in a loose,

friable condition, which facilitated the preparation of a better rice seedbed.

Jenkins and Jones {62) in 1944 pointed out

that the rice crop, like other cereals, responds to

appropriate cultural methods and rotation systems. At the time their experiments were started

in 1934, the rice crop normally was grown in

alternate years or once in 3 years on land fallowed or îeft in stubble pasture for 1 or 2 years.

In 2-year rotations, the highest yields of rice

were obtained following Italian ryegrass, clovers, or stubble pasture. Another experiment

demonstrated how other crops grown in the rotation may influence rice yield. The average

yield of rice following cotton that had been

dusted with calcium arsenate was 30 percent

below the yield following cotton that had not

been dusted. The reduced yield apparently was

due to the adverse residual effect of the calcium arsenate upon the ensuing rice crop. Reed

and Sturgis {lOJf) in 1936 showed that arsenic

toxicity symptoms in the rice plants are similar

to those of straighthead in which case florets

may be distorted and seed set may be reduced

markedly.

The average yields of cotton and soybeans in

a 3-year rotation of cotton, soybeans, and rice

were too low to be profitable, and the average

yields of rice was slightly less from this rotation

than from the better 2-year rotations.

In 4-year rotations consisting of rice 2 years

followed either by 2 years of cotton (fertilized

and not fertilized) or hj 2 years of native pasture (fertilized and not fertilized), the yields of

rice were not increased hj fertilizing; but the

rice following native pasture jnelded somewhat

more than did the rice following cotton.

In 10-year rotations of 5 successive i*ice crops

following 5 years each in (1) improved pasture,

(2) native pasture, (3) corn plus soybeans, or

(4) cotton, the 4-year average yield per acre of

rice was 2,192 pounds following improved pasture; 2,120 pounds following native pasture;

2,052 pounds following corn plus soybeans; and

1,444 pounds following cotton dusted with calcium arsenate.

On land cropped continuously to rice for 49

years, the average annual yields for successive

5-year periods during the la*st 30 of the 49 years

ranged from 1,102 to 1,440 pounds per acre. Fluctuations in the 5-year average yields apparently

were due to variations in climatic conditions and

were not the result of depletion of the soil fertility, according to Jenkins and Jones {62).

Walker and Sturgis {IJ^l) reported in 1946

that pasture-rice rotation experiments begun in

1938 and conducted on three soil types of the
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 77

prairie rice area of Louisiana showed that a 12-

month grazing program could be developed. They

stated that up to that time the rotation of improved pasture with rice definitel^^ was the best

means found of increasing rice yields and of

improving the soil productivity of the area. Also,

where proper management practices were used,

yields of beef from improved pxistures exceeded

yields from unimproved pastures by more than

150 pounds per acre. In addition, turning under

improved-pasture sod ahead of rice crops increased rice yields 1,000 to 1,800 pounds per acre.

Black and Walker (16) reported in 1955 on a

5-year rotation experiment that Avas established

at five locations in Louisiana, from 1946 to 1953,

on four soil types. The results of these five experiments substantiated earlier work on pasturerice rotation in southwest Louisiana. Thej' found

that if improved pastures are established, it is

desirable to provide contour levees and irrigation during dry periods, so that full benefits can

be received from the relatively large investment

required to establish improved pastures. Also,

it was necessary to obtain a minimum of 3 years'

grazing from an improved pasture before planting it to rice, since an improved pasture produces

only about two-thirds as much in the first year

as in the second and third years, and the initial

cost of an improved pasture is fairly high. Black

and Walker concluded that in southwest Louisiana a long-time rotation of improved pasture

and rice is superior to the more common rotation

of 1 year of rice followed by 1 3^ear of native

pasture.

Davis, Sonnier, and White (¿i) in 1963 described an experiment initiated in 1953 to determine the optimum length of time for pasturerice rotations in southwest Louisiana. Rotations

included 1 year native or improved pasture and

1 year rice; 2 years improved pasture and 1 year

rice; 3 j^ears improved pasture and 2 years rice;

and 4 years improved pasture and 2 j'Cars rice.

Fertilization practices varied according to needs

shown by soil tests and good agronomic practices.

In this study, length of rotation and pasture

treatment had little effect on yield of rice. This

is believed to be the result of using more fertilizer

and the fact that existing soil conditions were

somewhat better in this experiment than in earlier

experiments in the area. Improved pastures in

the rotation increased the yield of beef more than

500 percent.

In reporting on an economic appraisal of farm

practices and rotation programs on Louisiana

rice farms, MuUins (88) in 1954 pointed out that

the most common rotation at that time was 1 year

of rice and 1 or 2 years of native pasture. Some

longer rotations were being used such as rice 2

years and improved pasture 3 or 4 years. In the

longer rotations a smaller proportion of the cropland was in rice each year, but the increase in

rice jnelds was sufficient to maintain about the

same total volume of rice production on the

farm.

A rotation of rice for 2 years and temporary

pasture for 3 years gave an average rice yield of

2,600 pounds per acre, as compared with 1,950

pounds per acre from rice alternated with native

pasture in a 2-year rotation. When rice was

grown for 2 years following 3 years of temporary pasture, the estimated average rice yield

for the 2 years was about 3,250 pounds per acre.

Leaving land in pasture for a fourth year added

an additional 150 pounds per acre to this average rice yield. In addition, the quality of rice

improved and this, combined with higher production of beef feeding on the temporary pasture, gave substantially higher net return to rice

farmers.

Mississippi

Thompson and Waller (137) in 1952 suggested

using rotations of rice-soybeans-soybeans or ricelespedeza( for haj^ or grazing)-soj^beans in Mississippi. As recently as 1962, Anderson and

McKie (11) cautioned growers about substantially decreased yields from growing continuous

rice and suggested that a field be held out of rice

for 2 to 4 years, during which time the weed

population should be reduced. Rice was commonly grown 2 years and was followed by fallow or soybeans. Some growers also used wheat

and oats in the rotation.

:\Iullins (89) m 1960 pointed out that in Mississippi rice is grown in the delta area on clay

soils. When a relatively short rotation period

of 2 to 3 years is used, farmers generally summer-fallow about as much land as they seed to

rice. The fallowed land requires little preparation for seeding the next spring. Rice is not

grown on the same field for the second year in

such rotations, and rotational crops such as soybeans or small grains usually are omitted.

Some growers use a 5- or 6-year rotation, with

rice 2 years and then no rice for 3 or 4 years.

When delta rice farmers use longer crop rotation systems, at least half of the rice each year

is seeded on land that grew either rice or other

crops the previous year. Where rice followed

rice, a few operators burned the stubble to facilitate land preparation for the second year of rice.

In these longer rotations, the major crop grown

in rotation with rice was soybeans. The next

most commonl)^ grown crop was wheat. On a

small number of farms, oats were grown.

Where adequate surface drainage was available, wheat and oats were well adapted to the

clay soils of the rice farms in Mississippi. These

small grain crops fit reasonablly well into the rice

rotation programs. They usually were seeded on
78 AGRIGULTLiRE HANDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE

land that had lain idle and had been fallowed the

previous summer or on land from which earlymaturing soybeans had been harvested. Small

grains following soybeans did not always produce satisfactory yields because there was only a

short time to prepare a suitable seedbed. This

sometimes delayed seeding of small grains and

the delay often led to damage from winterkilling. AVliere the harvesting of small grain was

not delayed, it was possible to double crop the

land with late-planted soybeans. Because of the

risk, some growers preferred to summer-fallow

the land before seeding rice or soybeans the following spring.

Missouri

Experiments in Missouri reported by King

{7Jf) in 1937 demonstrated that crop rotation

was essential to continued high rice yields on

Wabash clay (gumbo) soils. In a 6-year period,

yields on continuous rice plots dropped to 450

pounds per acre because of infestation with

weeds. Rice yields were as high from a 2-year

rotation of rice and so5^beans as from 4-year

rotations that included rice and other crops such

as soybeans, wheat, clover, and corn.

Texas

In a review of research on rice production in

Texas, Reynolds {105) stated: ''High yields of

rice have not been sustained by growing rice on

the same land every year. Xor has the growing

of cultivated crops in rotation with rice proved

practical in most of the Texas rice belt.''

It is a common practice to grow rice 1 or 2

years and to follow tliis with several years of

§razing beef cattle on volunteer vegetation,

ometimes the land is mereh^ left idle for 2 years

or more. When rice follows unimproved pasture

or idle land, the improved physical condition and

the increased organic matter content of the soil

increase rice yields.

Workers at the Beaumont station started research on rotations and cropping systems in 1913.

From 1931 to 1941, a number of rotations were

tried. The average yields of rice per acre were

as follows: continuous rice, 1,072 pounds; continuous rice with fall-seeded sourclover (MelUotiis indica (L.) AIL), 1,194 pounds; rice 1 year

and idle 1 year, 1,613 pounds; rice 1 year, fallow 1 3^ear, 1,635 pounds; rice 1 year,^ cotton 1

year, 1,707 pounds; rice 1 year, soybeans 1 year,

1,618 pounds; rice 1 year, sesbania 1 year, 1,725

pounds; rice 1 year, crotalaria 1 year, 1,642

pounds.

^ Studies from 1943 to 1945 indicated that rotations of alyceclover for pasture and rice were

more satisfactory than were other rotations. Rice

following alyceclover produced 2,500 to 2,860

pounds per acre, as compared with 1,800 pounds

where the rice did not follow clover. These results led to investigations started in 1946 on the

rapid, low-cost conversion from rice to improved

pasture in rice-pasture systems.

As reported by Reynolds (105), Moncrief and

Weihing found it practical to convert from rice

to pasture by broadcasting grass and clover seed,

without seedbed preparation, in standing rice at

the last draining about 10 days before harvest

and in rice stubble after harvest. The levees

and drainage ditches used to irrigate and drain

the rice w^ere used to irrigate and drain the

improved pastures. In the more humid areas a

mixture of dallisgrass and clover (Louisiana

white, Persian, and large hop) was successful.

In drier areas Hubam sweetclover w^as a more

satisfactory legume. It was found that bermudagrass usually volunteered. Ryegrass, tall fescue,

and cereals were seeded successfully at the last

draining of the ricefields and in the rice stubble.

Lespedeza could be established by broadcasting

the seed in rice stubble in late February or early

March.

Rice yields following improved pastures were

increased by 20 percent or more. In addition, as

much as 200 pounds of annual beef gains per acre

were obtained on the improved pastures, as compared with less than 50 pounds on unseeded, unfertilized pasture fields. The clovers and bermudagrass, and sometimes dallisgrass, volunteered after the rice crop to provide grasses and

legumes for the next pasture period. In some

cases, pasture seed and hay could be harvested

from these fields.

In summary, Reynolds (105) stated: ''The several possible rice-pasture systems of farming have

not been fully evaluated. However, such systems as 2 years rice, 3 years pasture; 2 or 3 years

rice, several years pasture; 1 year rice, 2 to 3

years pasture seem to be worth considering in

systems to maintain and improve soil tilth and

productivit}^ between rice crops, as well as for

providing j^ear-long grazing of nutritious forage

for beef cattle on rice farms.''

In a report on their studies of year-long grazing in the rice-pasture system of farming, Weihing, Moncrief, and Davis (146) reported that

the unimproved pastures were grazed only 201

days during the j^ear, whereas the improved pastures were gi'azecl the full 365 days. In addition,

the carrying capacity of the improved pastures

was about three times that of the unimproved

pastures from April 14 to November 7, 1949; and

gains on the improved pastures were nearly four

times those on unimproved pastures. Management practices, including fertilization and inoculation of clover seed, were important in establishing improved pastures.
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 79

Evatt and Weihing (33) reported that rice following improved pastnres prodnced 650 to 800

pounds more per acre than did rice following

unimproved pastnres when eqnal amounts of fertilizer were used. The rotations hiclnded in this

study were (1) rice and nnimpro^'ed pasture in

alternate j^ears; (2) improved pasture 3 years,

rice, unimproved pasture, rice; (3) improved

pasture 4 years, rice 2 j^ears; and (4) improved

pasture 5 years, rice 3 years.

Katooning is the harvesting of a second grain

crop from regrowth of the first rice stubble. The

practice is only possible when well-adapted shortseason varieties are grown and the area enjoys

about 280 frost-free days (41). About 35 percent of Texas rice acreage was ratooned in 1963.^

Evatt and Beachell [Sß) discussed ratoon cropping of short-season rice varieties in Texas. They

reported that the technique appears to be a practical means of increasing rice yields, provided

varieties that mature the first crop in 100 to 105

days are used. It requires about 70 to 80 days

to produce the second crop if all operations are

properly executed.

Although ratooning now appears to be a practical and possibly profitable operation in United

States areas having a suitable climate, expert

management is recjuired. Evatt and Beax?hell

(33) have shown that the stubble of the first

crop should be at least 16 to 18 inches high. Leaving a shorter stubble delays recovery. Significant

yield increases have been obtained from the ratoon crop by applyin«: up to 120 pounds of nitrogen per acre immediately after the first harvest.

The stubble is reflooded when regrowth is 18 to

20 inches high. Usmg the early variety Nato,

these authors reported 4,048 pounds per acre

from the first crop and 2,382 pounds per acre

from the ratoon harvest, for a total of 6,430

pounds per acre from a ¿ingle seeding.

California

Xo clear-cut rotation pattern has yet become

established for California riceland (6*8) for the

following reasons :

(1) The soil used for rice production generally

is inherently quite fertile. Hence, with the relatively short cropjping history as compared with

other rice States, soil nutrient depletion, with

the exception of nitrogen, has not yet proved a

limiting factor.

(2) No serious rice disease has appeared to

date to force a rigid crop rotation program for

disease control purposes.

(3) The rapidly advancing knowledge of weed

control, crop fertilization, and other improved

cultural practices has made it possible to crop

2 EVATT, N. S. Texas A & M University, Beaumont, Tex.

1964. [Correspondence.]

ricelands for a period of 3 to 10 years continuousl}^ aud still obtain increasing yields. In 1920,

California's average rice yield was 2,205 pounds

per acre; in 1003, it was 4,505 i^ounds per acre.

A number of cash crops are well adapted for

growing in rotation with rice in California. The

ones most commonly grown are those providing

the best immediate economic advantage. One

rotation involves rice; s^Dring- or early summerplowed fallow; and fall-sown wheat, oats, or

oats and vetch. Another includes rice; springsown grain sorghum or field beans; and fallsown wheat, oats, or oats and vetch. Safflow^er

may be grown in rotation with rice but production usually is more successful when this crop is

grown the second, rather than the first, j^ear after

rice.

Two rotational cash crops are sometimes harvested the same j^ear. Wheat or oats may be

followed by irrigated grain sorghum, field beans,

or safläower. For successful double cropping on

riceland, all operations must be expertly timed.

Other crops used occasionally on the better

quality, medium-textured riceland soils include

sugarbeets, melons for seed, tomatoes, and alfalfa,

Williams, Finfrock, and Miller (JW) reported

that purple vetch (Ticla atívpurpurea Desf.),

burclover [Medicago hispida Gaertn.), horsebeans (Yicia' faha L.), and field peas {Pisum

œrvense L.) were commonly used in ricelands for

winter-grown cover crop and green manure. They

reported that leguminous green manures were

grown and turned under on about one-fifth of

California's riceland and that the practice is expanding rapidly.

Land Leveling and Seedbed Preparation

Jones and others {69) reported that most land

on which rice is grown is comparatively level,

with a gentle slope toward the drainage channels. The cost of developing for irrigation lands

with from 0.01- to 0.50-percent slope usually is

economical. A competent surveyor is employed

to locate the irrigation canal, drainage ditches,

and field levees. Improper location of canals,

ditches, and levees may cause serious losses, since

it may result in faulty irrigation and poor drainage. Irrigation canals should be large enough to

supply ample water promptly when needed.

Drainage ditches should likewise be large enough

to dispose of water rapidly.

Land Grading and Leveling

A general discussion of land leveling for irrigation has been published by Bamesberger {IJf).

Technical reports of land grading (land forming)

for surface irrigation by Gattis, Koch, and McVey

{JfO) and Marr {82) discuss the factors to consider before land grading is undertaken. These
82 AGRICULTURE HANDBOOK 2 8 9, U.S. DEFT. OF AGRICULTURE

" '^py'oß't"':

FIGURE 31.—Preparing the .seedbed : A, Moldboard plow ;

B, field cultivator with spike-tooth harrow attached ;

0, disk harrow.

ally it is not necessary to ploAV in the spring the

fields that were plowed the previous summer or

fall, except on poorly drained soil or during

seasons of heavy rainfall.

In general, land plowed in the spring should

be disked and harrowed as soon as possible after

plowing to break up any large lumps and clods,

to prevent baking or crusting, and to avoid subsequent difficulty in preparing the seedbed. In

Texas, experience has shown that heavy soils,

such as Beaumont clay and Lake Charles clay,

generally require more subsequent tillage, such

as disking and harrowing, to obtain a desirable

seedbed when plowed in the spring than when

plowed in the fall or early winter {105).

Usually California ricelands are spring plowed

to a depth of -t to 6 inches, after the stubble of

the previous crop has been partly reduced by

burning. The straw may be burned in the fall

inmiediately after rice harvest if dry weather

continues long enough. Spring-plowed soils make

a better seedbed if allowed to dry for a week to

10 days after plowing before beginning the final

seedbed operations. Davis {26) reported that

water-seeded rice germinates better, has more

seedling vigor, and produces a heavier crop when

sown on a seedbed that is dry during the finishing operations. A seedbed prepared under moist

conditions for water seeding induces algae (scum)

development, increases weed problems, and frequently results in a poor stand because of poor

germination and seedling vigor.

Finfrock and Miller {36) reported that a good

winter-grown vetch cover crop aids in drying out

riceland soil, thereby making it possible to prepare the seedbed earlier. Cover crops turned under for green manure are usually plowed down

with a moldboard or a disk plow. For best results in California, the plant material should be

completelj' covered with 4 to 6 inches of soil,

according to Williams and others {lJp8^ H^).

Seedbed Preparation as Related to Method

of Seeding

Rice may be seeded either by drilling on dry

ground, or by broadcast seeding with an endgate

seeder or airplane on dry ground or in flooded

fields. The final seedbed preparation is influenced by the method of seeding to be used. If

fields are to be water seeded, growers sometimes

are able to prepare a fairly good seedbed in the

late fall or winter and to erect their levees at

this time. When this is possible, very little land

preparation other than harrowing is necessary in

the spring. In the Southern States, if the field

is to be dry seeded with a drill or Avith an endgate seeder or broadcast by airplane, the final

preparation of the field includes working over

the levees while the field is worked. When rice

is to be seeded, the final preparation just ahead

of the drill usually is clone with a spring-tooth

or disk harrow behind which is drawn a spiketooth harrow. This gives a mellow firm seedbed,

and the moisture is held near the surface so the

seed usually will germinate soon after seeding

without irrigating the field. A roller-packer may

be used in order to break up clods before drilling

and to firm the soil after drilling to help retain

moisture. Usually, the levees are reseeded after
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 83

they have been parti}' rebuilt, and the seed then

is covered by the final building of the levees with

a levee disk or a pusher-type levee maker.

If rice is to be broadcast seeded on dry ground,

the final seedbed preparation leaves the surface

rough and somewhat cloddy. The seed usually is

covered by a shallow working with a springtooth, spike-tooth, or disk harrow^ Seed on the

levees is covered by the final working with the

levee disk or pusher. In most cases, precipitation following seeding is necessary to bring

about germination and emergence of the rice

seedlings.

If a field is to be water seeded, the final seedbed preparation depends somewhat on soil type.

On sandy or silt loam soil, a mellow, firm seedbed similar to that for drilling should be prepared. Levees are constructed and are seeded

just before the final working with a levee disk

or pusher. The renuiinder of the field is worked

between the levees with a spring-tooth harrow,

which leaves fairly deep furrows into which the

seeds fall as they settle through the water.

TVlien rice is water seeded on clay or very fine

silt loam soil, the seedbed should be fairly rough

with a clod size ranging up to 4 inches in diameter. This is done in California by harrowing

twice with a heavy spike-tooth harrow followed

by dragging with a heavy wooden di'ag. A

rough seedbed helps prevent drifting of watersown seed. As the clods slake down ¡ifter Hooding and seeding, a fine film of soil may cover the

seed. In the South, the levees usually are seeded

separately. In California, the levees are considerably higher and larger and are not seeded.

Some farmers have been successful in preparing their land in relatively stale water by drawing spring-tooth or spike-tooth harrows through

the fields in the mud or in fairly deep water.

Other growers who have attempted this method

have found it very unsatisfactory.

Construction of Levees

Ricefields are divided by levees into subfields,

called paddies or bays (cuts). Levee construction is an important operation in preparation for

growing rice because levees are the kev device for

regulating water depth in ricefields. They must

be located accurately and must be well constructed

in order to maintain a uniform depth of water

within each paddy (fig. 32).

FIGURE 32.—Making levees with {A) disk, (Ü) pusher, and (C) plastic.
84 AGRICULTURE llANI>l^>OOK 2 8 9, U.8. DEFT. OF AGRICULTURE

The levees are constructed on the contour, that

is, on lines of equal elevation. They should be

located by an experienced surveyor or operator

who uses an accurate instrument. Because a

smooth soil surface is needed for accurate location

of the levees, the surveying should be done immediately after the held has been floated. On flat

land, the difference in elevation between levees is

0.1 to 0.2 foot, and on steep, sloping land it is 0.3

foot {37. 69). In fields where the levees run

parallel to the direction of the prevailing wind,

it is desirable, especially if the paddy is large, to

build wind levees at right angles to the direction

of the prevailing wind. These levees are not tied

into the border or contour levees. Their function

is to reduce the effect of the wind and thereby

decrease wave action and reduce the possibility of

levees being washed out.

The levee should be compact and high enough

to hold the water at an average depth of 3 to 6

inches in the paddy. In the Southern States, the

levees have gently sloping sides, so that they may

be crossed with cultivating and harvesting equipment. Here, the levees are completed after the

rice is drilled. Levees of this type are considered

very efficient, for an entire field can be cultivated,

seecled, and harvested as a single unit.

In California, the levees are higher and have

steep sides so as to hold a deeper flood; and the

areas between pairs of levees must be harvested

as a field or unit. This increases farming costs

because it increases machinery-maneuvering time.

In addition, the land area devoted to high levees

is nonproductive.

In the Southern States, the base of the levee

commonly is made by plowing one round with a

3-bottom plow. Levees are constructed with a

levee disk usually mounted on the rear of a large

tractor, or commonly with a single- or doubleblade puslier on clay soils. The levee base is

built as early as possible, so that it will become

compact before flooding time. This is especially

important on hea^\y clay soils on Avhich levee construction often is difficult. Compact, well-settled

levees reduce seepage and are less likely to be

washed out by excess water from heavy rains.

Well-constructed levees, properly repaired after

seeding, facilitate irrigation and eliminate much

expensive hand shoveling. Much of the vrork of

installing levee gates and closing the gaps at the

ends of the levees is done with pickup blades or

scoops mounted on small tractors. This eliminates much of the hand labor formerly required.

In California, a V-type diker or soil crowder

that is 14 to 16 feet wide in front and 4 feet wide

in the back is used to build levees. Two or more

heavy-duty, crawler-type tractors are used to pull

the diker. The levees usually are from 30 to 36

inches high when freshly made and settle to between 16 to 20 inches. Levees usually are made

m the fall with a base of 5 to 6 feet and are

allowed to settle during the winter. A bulldozer

or a tractor wáth a front-end scoop is used to

close the gap at the water control boxes and at

the end of each levee.

Lewis and others {75) and Scott ancl others

{113) reported on the possibility of using rice

ievees made of plastic film in lieu of levees made

of soil. Their studies show^ that plastic levees

are physically feasible. Their commercial feasibility^ probably depends on the development of

a machine to 'economically install the plastic

levees. Prototype, privately developed machines

to install plastic levees mechanically were operated experimentallv in California in 1962 and in

1963.

Seed and Seeding

The choice of seed and the use of suitable seeding methods are an important part of rice culture.

To achieve a high level of production, the variety

to l:)e grown must be adapted for the area. After

deciding on the variety, it is necessary to select a

lot of rice seed that is free from varietal mixtures,

does not contain red rice and weed seed, is high in

percentage of viable seed, and has high bushel

weight. All rice-producing States now have a

rice seed certification program designed to provide high-quality seed for the rice industry.

Before 1941, when combine harvesting, artificial

drying, and bulk storage Avere begun in the southern rice area, there was little incentive to develop

a seed rice industry. Varietal mixtures resulting

from handling were not serious when binders,

stationary threshers, and sack storage were used.

Seed rice usually was saved from fields or parts

of fields of known varietal purity. Weed seeds

and trash were removed by fanning mills and

disk or cylinder graders usually owned and operated by private or grower organizations. However, as combine harvesting, artificial drying, and

bulk storage deA^eloped, varietal mixtures became

serious. It was at this time that seed production

and processing developed into a specialized business. Today, much of the seed rice sown in the

Southern States is given specialized attention

during growing, harvesting, drying, and processing. As a result, the seed rice industry is well

developed today. Foreign demand for seed of

high quality has further stimulated the development of the seed rice industry. Substantial quantities of seed rice are exported annually to Central

and South American countries.

Seed Quality

Numerous w^orkers have stressed the desirability

of using seed rice of good quality {18, 27, 70, lU)^

Good seed should be well matured and free from

red rice, immature and hulled or broken grains,
RICE IN THE UNITED STATES ! VARIETIES iVND PRODUCTION

seed of other varieties, and weed seeds. The seed

should be cleaned and graded to remove hulls,

trash, and other foreign matter. Also, good seed

should germinate satisfactorily and should produce strong sprouts. Using seed that germinates

poorly may result in uneven stands, uneven ripening, and low field yields of poor milling quality.

Smith [12If) reported in 1940 that seed lots

used on 29 farms were examined, and only 4 were

found to be free of weed seeds and red rice.

Today, most rice seed is thoroughly cleaned and

graded. Consequently, it is free of weed seed and

has only a trace of hulled or poorly filled grains.

Much emphasis has been placed on the importance of eliminating red rice from planting seed

(3, 70). Red rice is objectionable because the red

bran is not completely removed in milling. This

results in an unattractive appearance when milled.

Also, the grain size, shape, and milling quality

are inferior. Red rice tillers profusely and shatters easily, and seeds that have become buried in

the soil have been known to remain viable for

several years {19, J/.S). '\A^ien rice seed containing

red rice was seeded several years in succession on

the same land and red rice was not controlled,

over 50 percent of the harvested grain was red

rice (3). In a ricefield in Louisiana, over 500 red

rice grains were found in the top 6 inches of each

square foot of soil.^

The importance of using seed free from red rice

cannot be overemphasized l>ecause as long as red

rice is being sown, it cannot be eliminated from

the fields. Based on a seeding rate of 80 pounds

per acre, seed containing 5 red rice grains per

pound would probably result in approximately

200 red rice plants per acre. At the Beaumont

Rice-Pasture Research and Extension Center,

land was cropped 2 consecutive years, in 1946

and 1947, and seed was used that contained approximately two red rice grains per pound. The

grain harvested the first year contained about 18

red rice grains per pound and that harvested the

second year contained over 125 grains.'^

Seed rice free from red rice was nearly nonexistent until 10 years ago. Screen graders,

which effectively grade seed rice on a grain

diameter basis, have been effective in removing

the broader red rice grains from long-grain varieties. The screen graders, along with the production and increase of seed stocks free from red

rice, have effectively controlled red rice. In a

few instances, slender red rice grains that cannot be separated from long-grain varieties have

been observed. Whenever a seed lot that contains such types is observed, it should be discarded immediately.

^BAKEE, J. B, Louisiana State Univ., Baton Rouge,

La. 1963. [Correspondence.]

^BEACHELL, H. M. Rice-Pasture Research and Extension Center, Beaumont, Tex. 1963. [UnpubUshed data.]

Red rice grains are difficult to remove from

short- and medium-grain varieties because of the

similarity in diameter between tliose varieties and

red rice. Since red rice grains cannot be effectively removed from the medium- and short-grain

varieties, it is essential to use seed free from

red rice!

The origin of high-quality seed rice and the

certihcation of rice seed is discussed in the section on ''Eice Breeding and Testing Methods in

the Ignited States/' p. 56.

Source of Seed

Jones and others (67) studied the effect of environment and source of seed on yield and other

characters of a group of varieties at four rice experiment stations in Arkansas, Louisiana, Texas,

and California. They concluded that seed source

had no appreciable effect on grain test weight,

germination of seed, average grain and kernel

weights within a variety, proportion of hulls, and

milling quality. In summary, they stated that

''local seed of good qualit}^, free of mixtures and

weed seed, is as productive as that obtained from

other rice-producing States.''

Seed Treatment

Finfrock and Miller (36) reported that California growers usually soak their rice seed in a

sodium hypochlorite solution at the rate of 1 gallon of household bleach (5.25 percent of NaOCl)

per 100 gallons of water. In addition to providing some protection against seedling diseases, the

chemical deactivates germination inhibitors located in rice hulls.

Mikkelsen and Sinah (54) reported the presence of six compounds in the hulls of Caloro rice

that diffuse into the embryo and inhibit germination when present in large amounts. Compounds

identified included vanillic acid, ferulic acid,

p-hydroxybenzoic acid, p-coumoric acid, p-hydroxybenzaldehyde, and possibly idoleacetic acid.

In low concentrations, these chemical substances

stimulate germination and ensuing growth.

Leaching the seed by soaking with water reduces

the concentration to stimulatory levels. The

probable action of sodium hypochlorite solution

is to modify these inhibitors so that seedling

growth is stimulated.

Garrison (39) reported on work with other

small grains conducted by Earhart. Results

showed that there is a definite need for all small

grain seed to be completely processed, including

thorough cleaning and treating. For every 100

field-run seeds put in the ground, only 58 healthy

plants were produced. '\'\^ien seed from the same

lot was cleaned, 65 healthy plants were produced;

and when the seed was both cleaned and treated,

72 healthy plants were produced. Field experiments comprising two rice varieties, sown at two
86 ItírUGULTOTvE HANDBOOK 2 8 9. U.S. DEFT, OF AGPaCULTURE

dates at each of three locations for 2 years,

showed an average survival of 01 percent for

seed treated with two commonly used seed-treatment chemicals, compared with 52 percent for

untreated seed (Í2).

Information on the treatment of rice seed to

prevent seedling blight is given m the section

^^Rice Diseases," p. 113.

Time of Seeding

Seeding of rice in the United States begins

when the weather becomes warm enough for

germination and seedling growth. In Arkansas,

Mississippi, Missouri, and California, where the

growing season is comparatively short, seeding

usually is done in April and May, within a period

of 3 to 5 weeks. Near the Gulf Coast in Louisiana and Texas, rice can be sown from early March

to late June—although most seeding is done in

April.

The length of seeding period depends mostly

on the length of life cycle of the available varieties. Essentially it is the difference between the

lensrth of the ofrowino; season for rice in an area

and the shortest ¡period of time rec|uired to mature a crop.

Seeding time also is influenced, directly or indirectly, by favorable weather conditions for land

preparation and seeding operations, methods of

seeding, fertilizer practices, availability of fresh

water, temperature of water, cold tolerance of

varieties, and time of maturity of varieties in relation to date of seeding.

Adair and Cralley (5) stressed that the proper

seeding date for each variety is important. They

stated that no rice variety should be sown until

the mean daily temperature rises to about 70° F.

They and Johnston and others (ö5, 66) reported

that because of the relatively long growing period

of several of the varieties then available, it was

necessary to seed these varieties in Arkansas by

late April or early May. Other, shorter season

varieties had a wider range of seeding dates.

However, when any variety then available was

sown in Arkansas after the first week in June,

there was a risk that the crop might fail to mature if there was an early frost. However, with

the development of the very early-maturing varieties Belle Patna and Vegold, mid-June seedings

appear to be relatively safe, even in northern Arkansas. Johnston and others (64) suggested that

these two varieties be seeded in northern Arkansas from about June 1 to 10, in central Arkansas

from about June 1 to 20, and in southern Arkansas from June 1 to 25. Johnston, Cralley, and

Henry (66) emphasized that a relatively ^''safe^'

seeding date may depend to a considerable extent

on anticipated water management and fertilizer

practices. They pointed out that heavy rates of

nitrogen fertilization, particularly when applied

late, tend to delay maturity.

Results from date of seeding experiments indicate that there is a comparatively long period in

the South during which rice can be sown and still

produce satisfactory yields. It is possible and

often advisable to spread the seeding time of certain varieties so that the harvest can be extended

over a longer period. However, Adair (4), who

studied the effect of time of seecling on yield and

milling quality in Arkansas, concluded that most

of the early and midseason varieties produced rice

of better milling quality when they matured late

in September or early in October than when they

matured before September 15. Jodon (63) stated

that since the approximate number of days required from seeding to maturity is known for all

commercial varieties, it may be desirable to base

the date of seeding on the number of days rec^uired for maturity, so that the rice will mature

in the fall when the weather is usually dry and

pleasant for harvest. Rice maturing after the

temperatures have lowered somewhat may be of

better milling quality. When rice matures during

extremely hot weather, considerable sun checking

may result and low head rice yields may be produced when the grain is milled.

Chambliss (18) stated that in the prairie areas

of Louisiana and Texas, most of the rice is sown

from April 1 to May 15. However, he pointed

out that May 1 was approximately the best date

for sowing rice on the prairie because of the cold

weather that sometimes prevails during April.

According to Jones and others (69)^ rice usually

is sown in the Southern States from April 1 to

May 80. Rut if conditions are favorable, some

seeding is done in March and as late as June 30.

Rice germinates more quickly when sown in the

late spring, when temperatures are relatively

high, than when sown earlier. Also, late seeding

has an advantage in that the weeds that have

started growth can be killed by cultivation before

seeding of the rice crop.

Reynolds (Wo) stated that time of seeding rice

in Texas ranges from March 1 to late June but

that most of the rice acreage is seeded in April

and ]\iay. He pointed out that the actual time

of seeding may depend on several factors, such

as the weather, method of seeding, soil condition,

and maturity group of the variety. Some varieties can tolerate cool weather in the spring better

tlum others and will thereby produce better stands

when seeded relatively early. He further reported that the yield of certain varieties showed

a marked decrease when seeding was delayed

beyond certain dates. He concluded from tests

at Beaumont that the late-maturing varieties

should be seeded as early as practicable to insure

satisfactory yields.
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 87

In California, the period for seeding rice is

more concentrated than it is in the South. Some

rice is sown in California soon after April 1 and

some as late as June 15, but most of it is sown

from April 15 to May 15 (36). When rice is

sown as late as May 30 in California, it should

be fertilized at a moderate rate, and preferably

a short-season variety such as Colusa should be

orrown.

Very early seeding entails certain hazards sucli

as loss of stands due to seedling blight or drowning out of drilled rice. Early growth is slow,

prolonging the period from seeding to harvesting.

Isolated early-maturing fields may be attacked

by concentrations of insects, rodents, or birds.

Rice that matures early during hot and dry

weather tends to have lower milling cjuality.

Relatively early seeding in the Southern States

helps assure an adequate supply of water to

mature the crop before a summertime shortage of

water or, in limited areas where it occurs, before

the intrusion of salt water. Water is available

for early-seeded rice in all areas, although in

California the water may be too cold. Earljseeded rice may tiller more, may compete more

effectively with weeds, and may escape insects and

diseases to some extent. AA'lien rice can be harvested early in the season, it usually is possible

to avoid seasonal congestion at the driers and to

find a ready market. Also, early seeding of shortseason varieties usually allows time for the production of a stubble crop in southern Louisiana

and Texas. Because of the somewhat shorter

growing season and cooler fall temperatures,

results and observations indicate that such double

cropping (ratoon cropping) is not a safe practice

in Arkansas in most years (ßJ/.).

However, even the customary April seeding

often is subjected to unfaworable conditions for

establishing stands. Varieties that have short

growing seasons mature during hot weatlier if

seeded at the average time, ancl in some seasons

the quality is poor. Localized summer wind

storms and rainstorms may cause lodging with

resulting loss of yield and increased cost of

combining. Often at the peak of the season more

rice is ready for harvest than the driers have

capacity to process, and the rice that waits in the

fiekl is in danger of deteriorating.

Rice matures in a shorter time when sown late

than when sown early. Delaying seeding or using

varieties that require long growing seasons permits harvesting to be done in the normally cool

autumn weather when there may be fewer showers and when the driers are less likely to be

crowded. Later maturing rice usually is better

quality as long as the temperatures are not too

low for normal development of the grain. Delaying seeding also allows time for additional

cultivation to reduce weed and red rice infestation. On land that has been in winter or perennial pasture crops, a delay in date of seeding

provides a hunger grazing period and makes possible the preparation of a better seedbed.

Late seeding also has disadvantages. There

may be a greater possibility of injury by root

maggots, armyworms, and stem borers. Weather

conditions may be more favorable to the blast

fungus at the time the young plants are susceptible. Stem rot may be more severe late in the

season. The crop is exposed to early fall storms,

likely to be the most damaging of the season.

Cold weather may reduce quality and yield if

harvest is extremely late. Isolated late-maturing

fields probably are more exposed to damage by

concentrations of birds and other pests than are

extra early fields.

Clearly, there is no ideal time for seeding. In

Louisiana and Texas especially, where the seeding period is long and there are several varieties

to choose from, the date of seeding demands careful consideration. This is true whether one field

is to be seeded to a single variety or a large acreage is to be allotted among two or more varieties.

Rate of Seeding

Factors that enter into a determination of the

proper rate of seeding include seed size and quality, condition of the seedbed, fertility of the soil,

date of seeding, and variety. In the southern rice

area, the seeding rate is about 90 to 110 pounds

per acre when drilled and about 115 to 150 pounds

per acre when sown broadcast on dry soil or in

the water. In California, when rice is sown in

the water, seeding rates average about 150 pounds

and range from 125 to 200 pounds (dry weight

basis) per acre.

The number of rice seeds ranges from 14,000 to

22,000 seeds per pound, depending on the variety.

With a seeding rate of 150 pounds per acre, seeds

are sown at the rate of about 50 seeds per square

foot. Excellent yields have been obtained from

populations ranging from 8 to 30 plants per

square foot. Seeding rates that provide plant

populations between these extremes apparently

do not influence yields. Extremely dense stands

lodge more readily than do optimum stands. Kice

in dense stands heads and matures more uniformly than does rice in thin stands with abundant tillering. Weed control is more difficult in

thin stands, so seeding rates should be higher in

fields infested with weed seed. Relatively high

seeding rates usually are used on land on which

many rice crops have been grown previously.

In early tests in Arkansas, Nelson (93) tried

11 rates of seeding, using recleaned seed, seeded

with a grain drill. The results showed no marked

preference for any rate. Although denser stands

and fewer weeds were obtained from the higher

rates of seeding, higher yields resulted from the
AGRICULTURE HANDBOOK 28 9, U.S. DEPT. OF AGRICULTURE

lower rates of seeding. The higliest average

yields were obtained from sowing approximately

70 pounds of seed per acre.

Simmons {115) reported that later studies

at the Arkansas Rice Branch Station at Stuttgart

indicated that the best rate for drill seeding was

90 to 110 pounds per acre and that about 110 to

135 pounds per acre was best when the seed was

broadcast.

Chambliss [18), reporting on early experiments

at the Crowley, La., Rice Experiment Station,

found that the largest yields and the best quality

of milled rice were obtained from the Honduras

variety by drilling SO pounds of seed to the acre.

Other varieties available at that time could be

seeded at a slightly lower rate. He pointed out

that less seed may be used when the crop is sown

in late 3iay if the seedbed is well prepared, smce

better germination is obtained with higher tem-

¡Jeratures prevailing. The quantity to be sown

depends on the method of seeding, variety, character of the seedbed, soil fertility, and vitality or

germination of the .seed. If rice is broadcast on

wet land or on a poorly prepared seedbed, the

rate of seeding should be increased. If seed of

low vitality is used, then the seeding rate should

be increased accordingly. Seeding at too low

a rate resulted in excessive tillering, irregular

ripening, and reduced grain yields.

Reynolds {105) stated that in Texas the rate of

seeding ranges from 60 to 125 pounds per acre,

with the average about 00 pounds. The rate of

seeding varies greatly in different parts of the

rice belt of Texas. In the more humid areas,

higher rates of seeding are u.sed than m the western counties where rates as low at 60 pounds per

acre frequently are used. At Beaumont, from

1914 to 1918, seeding 100 pounds per acre produced slightly higher yields of rough rice than

seednig 60 and 80 pounds per acre. Experiments

were conducted there from 1950 to 1952 to determine the oi^timum rate of seeding rice under

several levels of soil fertility. Bhiebonnet 50 was

broadcast at rates of 45, 90, 1P,5, and 180 pounds

per acre. Fertilizers were applied on the surface

with a fertihzer-grain drill at the time of seeding

There were no significant differences in the average yields of rough rice from the seedino; rates of

90, 135, and 180 pounds per acre, but the yields

from these rates were significantly higher" than

those from the 45-pounds per acre rate As in

earlier experiments, the optimum rate of seeding

was about 90 pounds per acre. Where weeds are

troublesome, heavier rates of seeding usually mve

better results. ^

Jones and others {69. 70), summarizing rate of

seeding experiments with drilled rice under

iavorable conditions, indicated that 80 pounds of

seed per acre usually is sufficient to give good

stands. Yields are seldom materially increased

and sometimes may be reduced if more than 80

pounds i)er acre is sown. They pointed out that

under ordinary conditions, 90 to 100 pounds of

recleaued viable seed sown with a drill or 110 to

150 ¡rounds sown broadcast is sufficient to give

good stands. They stated that the rate of seeding should be sufficiently high to produce stands

that are thick enough to help check weed growth

and also to i^revent late tillering. The latter

often results in irregular ripening and grain of

inferior quality.

Method of Seeding

SeA'eral methods are used to seed rice in the

United States. On dry soil rice may be sown fi/^

to 2 inches deep with a grain drill, or broadcast

and disked or harrowed to cover. TVlien soil

moisture is not sufficient for germination and

growth, the field may be flushed. The water is

drained immediately becau.se the rice seedling

cannot emerge through both 1 to 3 inches of soil

and 4 to 8 inches of water. Rice also is broadcast

in water by airplanes (fig. 33). Several modifications of the water-seeding method are used. Rice

is not transplanted in the United States.

Simmons {115) reported in 1940 that the two

methods of seeding being used in Arkansas at the

time of his report were the broadcast and the drill

methods. The broadcast method had been most

popular since it did not require much machinery,

and it was u.sed extensively in new rice areas. He

pointed out that drilling"was being used widely

FiGTTRE 3.3.—Airplane being loaded with seed rice, with

tanlis u.sed for soaking seed in the foreground, and

ricefields ready to be seeded on each side of landing strip.
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 89

on old riceland. Advantages of drilling over

broadcast seeding were that less seed was required

for a good stand and that the seed could be put

clown at a uniform depth and rate, which make a

more uniform stand possible. Simmons pointed

out that uniform stands are important because

they insure even maturity. Grain maturing

evenly will have a better grade, and consequently

will usually command a better price. lie further

stated that when rice was seeded with a grain

drill, a depth of 1 to 2 inches normally should be

used. Deeper seeding sometimes resulted in a

poor stand, especially if the soil was clay textured, cold, or inclined to crust after rains.

Jones and others [69) also reported that shallow seeding is preferable to deep seeding on a

rough seedbed or a fine mellow seedbed that is

inclined to crust after rain. Surface crusts may

be broken by a light harrowing or by irrigating

to permit the seedlings to emerge.

Xelson (94) reported in 1944 in Arkansas that

seeding rice broadcast on the surface of the soil

and irrigating immediately gave large increases

in yields of rice over the usual method being used

at that time. He pointed out that even larger

average increases in yield were obtained when the

soil was flooded and the seed broadcast in the

water. He indicated that both methods could be

used to produce higher yields of rice if the practical difficulties involved in seeding large areas

by these methods could be overcome. The yield

increase apparently was due to the control of

grass.

Mullins (89) found that in Mississippi, where

ground equipment was common, rice was seeded

after the first levee-building operation was performed and before the levees were raised to the

desired height. Seeding was done with endgate

seeders by approximately 50 percent of the farmers who were surveyed, and grain drills were used

by the remainder of those using ground equipment. By 1958, about 20 percent of the farmers

seeded some rice in the water with planes, and

the practice appeared to be more common in 1959.

Water seeding often was used during the later

weeks of the planting season when quick germination and effective grass control are particularly

important. Some farmers reseeded their levees

after the final levee-building operation, but the

majority did not.

Reynolds (105) reported that a depth of 1 to 2

inches was best when rice was seeded with a grain

drill. In experiments conducted at Beaumont,

Tex., from 1914 to 1918, placing the seed 2 inches

deep produced slightly higher yields of rice than

placing the seed 1 or 3 inches deep. There

usually was less rotting from shallow seeding than

from deep seeding, especially if irrigation was

necessary to germinate the rice seed. Seed could

be planted deeper on sandy soils, such as Katy

and Hockley soils, than on clay soils, such as

Beaumont clay and Lake Charles clay.

Iveynolds (105) pointed out that rice usually was

seeded m Texas with a grain drill but that aerial

seeding was increasing rapidly and that 110,000

acres were seeded by plane in 1953. He stated

that broadcast seeders were used to some extent.

On rough, dry seedbeds, rice frequently was

broadcast with endgate seeders or with a drill

with the disks removed. In either case, the land

was then harrowed after seeding and was irrigated. When seeding was done on dry land,

fields usually were harrowed after seeding and

then flushed to bring about germination. The

fields were resubmerged in time to control the

growth of weeds and grass.

The seeding of rice in water was started in

California as a way to control barnyardgrass

(EchinochJoa spp.) (6). At first rice was sown

with a tractor-drawn endgate broadcast seeder,

but this method was not very satisfactory. Airplane seeding was attempted first near Merced,

Calif., in 1929, for reseeding a field of rice. A

fair stand of rice and a satisfactory yield were

obtained. Several growers in California seeded

their rice from an airplane in 1930. Now airplane seeding is the common practice on California's 300,000 acres of rice.

According to Finfrock and Miller (S6)^ the

usual practice in California (19(31) is to soak the

seed for 18 to 24 hours in a sodium hypochlorite

solution (see ''Seed Treatment,*' p. 85), drain for

24 to 1^ hours, and seed by airplane into fields

that have just been flooded to a depth of 6 to 8

inches. Seed rice will absorb the maximum

amount of water in 18 to 24 hours.

Soaked seed is used instead of dry seed. Soaking starts the germination process before seeding.

More important, because it is heaAW, the soaked

seed sinks into place when it hits the water. Thus

the seed does not drift and unseeded areas are not

left in the field. Fields remain continuously

flooded until drainage for harvest.

Modifications of water-seeding methods broadly

adapted to use in the sourthern rice area have

been developed. Slusher (119^ 120) extensively

discussed the use of aircraft to seed rice in

Arkansas,

Adair and Engler (6) described the waterseeding method as used in Arkansas as follows:

The land usually is plowed in winter and a seedbed is prepared in the spring by disking two or

three times and then harroAving. Frequently, the

soil also is tilled to a depth of about 8 inches with

a field cultivator to provide aeration and space

for applying cool irrigation water that contains

dissolved oxygen. Oxygen is essential for early

root development. The levees are completed after

the soil is worked with the field cultivator and

the field is then cultivated between the levees with
90 AGRÍCULTURE HANDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE

a spring-tootli harrow, which leaves shallow furrows and ridges that help to reduce drifting of

the seed. The IcA^ees may or may not be seeded

before final going over with the levee disk.

Floodgates are then put in, the field is submerged to a depth of 4 to 6 inches, and the rice

is sown from an airplane. Seeding is done as

promptly as possible, since poor stands usually

are obtained when the water has been on the

field longer than about 4 days before seeding.

The airplane operator is guided by flagmen,

one at each end of the field, who pace off the

distance (about 30 feet) that the plane can sow

in one trip across the field. Depending on the

length of growing season of the variety being

grown and the desires of the operator, the water

may be drahied from the field after 5 weeks or

more to control the rice water weevil, to prevent

straighthead, or to provide dry soil for topdressmg with fertilizer (6"). Occasionally, draining

at an earlier date may be necessary. However,

unless specific conditions exist that require early

draining, it is advisable to drain late because

high grain yields have been obtained when flood

water was left on fields until shortlv before harvest (93).

From tests with water-seeded rice on clay soil

in Arkansas, Hall (SO) suggested the following:

(1) A disk harrow is eff'ective in preparing the

seedbed. On the last trip over, a spring-tootli

harrow should follow the disk harroAV so that

prominent furrows are left in the seedbed to

catch the seed and reduce the drift.

(2) The field should be flooded as rapidly as

possible with a minimum of 4 to G inches of

water to control grass. All levees should have

a gate or spillway so as to make and maintain

a constant level of water and prevent the levees

from breaking because of added pressure from

heavy rains.

(3) The field should be seeded immediately

after the 4- to 6-inch depth of water is obtained.

In the test conducted, there was no significant

difference in plant stand densities obtained due

to seeding in clear or in muddy water that

cleared within 24 hours after seeding. Likewise,

presoaking the seed showed no significant difference from seeding with dry seed. It was found

that seed treated with a fungicide or insecticide,

or both, had less tendency to float than did untreated dry seed.

(4) After seeding, the full flood of 4 to 6

inches of water should be maintained for 5 to 6

weeks. Lowering the water depth or draining

the field soon after seeding allows grass to become established with the rice, thus defeating

the purpose of water seeding. A rate of 135

pounds of seed per acre gives a sufficient number

of plants, so that the loss due to wave action is

much less than loss from weeds due to drahiing

the field.

(5) After a period of 6 weeks or more, the

field may be drained for midseason nitrogen

fertilization.

A few growers in Arkansas pregermmate the

seed by soaking it before seeding. In one method

the seed is placed in a grain cart such as that

used to haul the rice from the combine at harvesttime. The grain cart is filled with water, or

water is kept running through the seed for several hours. Then the water is drained and the

rice is left in the grain cart overnight. The following day it is angered into the hopper of the

plane for seeding. In another method the seed

is soaked in bags in a canal for a somewhat

longer period, up to 3(3 hours.

Faulkner (34) compared different practices for

water seeding rice in Louisiana. These included

(1) pregerminated seed compared with dry seed,

(2) cloddy seedbed compared with seedbed that

had been smoothed in water, and (3) draining

irrigation water 3 to 5 days following seeding

compared with leaving a full flood of water and

allowing the rice to emerge through the water.

He reported slightly higher grain yields when

the seed was soaked to ])regerminate it before

seeding in the water. He found that a small

percentage of the dry seed floated in the water

and settled in low spots, whereas the pregerminated seed remained well in place on both the

cloddy and smooth seedbeds. However, he

pointed out that pregerminating seed requires

additional labor and expense and also requires

a short interval between germination and seeding.

Faulkner found that the average yield of rice

produced from the smooth or the rough seedbeds

was approximately the same. However, there

were some indications that the working of the

soil in w^ater reduced the germination of grass

seed and thereby reduced the resulting competition. Also he found that soils that were worked

in the water dried more quickly when the water

was drained and caused the top one-fourth inch

of soil to curl, thereby pulling the young seedlings from their root anchorage. Such conditions

would require that the area be flushed.

In this series of experiments, Faulkner found

that good stands of rice, along Avith excellent

control of red rice and grasses, could be obtained

by leaving a full flood of water on the field until

the rice had emerged through the water and was

strong enough to stand free from the water.

The yield results from 1959 indicated that about

500 pounds more rice per acre was produced

\yhere the water w^as allowed to remain on the

field than where it w^as drained a few days after

seeding. Faulkner thought that on the clay soils

it might be more difficult to obtain a good stand

of rice using the continuous flooding method, but
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 91

that additional experiments would be necessaiy

to determine this.

The most common method of land preparation

for water seeding in Texas in 1954, according to

Eeynolds (105)^ was plowing and disking to kill

the vegetation. The land was then left in a

rough condition until seeding, at which time the

field was irrigated until the water barely covered the land. It Avas then liarrowed to muddy

the water. HarroAving to muddy the water before seeding is seldom done early in the season,

because dry north winds cause the soil surface

to dry rapidly. This drying curls and cracks

the soil surface before the seedlings become

rooted. The seed usually was soaked in bags in

a canal for 24 to 36 hours, removed from the

water and allowed to drain, and then sown by

airplane on the water. Some farmers drained

their fields as soon as possible after sowing,

whereas others might delay draining as much as

36 hours. Experiments conducted by Wyche and

Cheaney (150) during 1954 at the Rice-Pasture

Research and Extension Center showed that

under the conditions of the test, soaking the

seed, muddying up the water, time of removing

the water after seeding, and depth of the water

up to 8 inches had no eflFect on the yield of

water-seeded rice. They felt that it would be a

good farm practice to leave the surface of the

soil slightly rough in order to lessen the drift

of seed vrhen water seeding rice.

From observations made on experimental tests

and on commercial fields, little if any difference

in suitability to water seeding has been noted

among varieties. However, in Arkansas where

the soils are alkaline, or the water contains excess salts, the medium-grain varieties in general

have been damaged less from these adverse conditions when water seeded than have the longgrain varieties, especially the Bluebonnet group.

Hall and Thompson (5T) pointed out that these

problem areas that are colloquially referred to

as alkaline have been brought about, on cultivated lands, by the use of well water containing

excess salts combined with restricted internal

drainage of the soil. Some of these troublesome

soils have shown a pH of 7.0 to 7.5, whereas

others have been below 7.0. This indicates that

pH alone is not a complete!}^ reliable indicator

of such problem soils.

Nelson {92) conducted an investigation to determine the uniformity of distribution of seeds

and fertilizers from airplane distributors and

studied the extent to which rate of application,

materials distributed, and flight altitude affected

uniformity of distrilDution. He concluded that

a fairly good distribution is possible with welldesigned equipment if a few precautions are fol-,

lowed. Characteristic deposit patterns should

be determined before a new or modified distributor is first used. From the deposit ]jatterns

obtained, optimum flagging intervals can be determiiied that will allow for an overlaj) sufficient

to maintain a uniform application or seeding

rate. For proper overlapping of swatlis, a

ground crew is necessary. For uniform distribution a flagman should be stationed at eacli end

of the field, and each flagman should be equipped

with two long markers comiected with a rope or

chain length equal to the flagging interval distance. It is necessary that the flagging interval

be measured correctly and that the airplane fly

directly over the two flags. Recently, many

growers have measured these flagging distances

or intervals and have marked them with stakes

or small flags on wires so that the flagman will

not need to measure the distance.

Transplanting Rice

Yields of direct-seeded and transplanted rice

were compared in a stud}^ conducted b}^ Adair

and others (7) in the major United States rice

areas during a 3-year period starting in 1937.

Tliree varieties were included in the experiment

at three rice experiment stations in the Southern

States, and two varieties were included at the

California Rice Experiment Station. High jàelds

of transplanted rice often obtained under intense

culture in certain countries had led to a more or

less common belief that yields of transplanted

rice generally are higher than those from direct

seeding. Advantages claimed for transplanting

were listed and discussed. It was pointed out

that high-quality, stiff-strawed varieties already

were being grown by machine methods in several

countries. During the 3 years of these tests, the

average yields of some of the varieties at some

locations were significantly higher from direct

seeding than from transplanting. None of the

varieties at any of the stations produced significantly higher average yields when transplanted

than when directly sown. These workers concluded that the principal reasons for transplanting are not to increase 3àelds but to better use

land and labor in densely populated countries in

which the tillable land area is limited and the

labor supply is plentiful.

Irrigating and Draining

Flood irrigation is used for all rice grown in

the United States. The soil is submerged in 4 to

8 inches of water most or all of the time from

seeding or shortl}^ after, until the grain is nearly

ripe. This period may extend from 60 to 90 or

more days, depending on method of seeding and

variety grown (5, 69). Although the water requirement for rice is high, Jones and others (69)

stressed that good surface drainage is as necessary for successful rice culture as is a dependable

supply of fresh irrigation water.
92 AGîiI'!/'UUiVrUKE HANDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE

Haskell (J¿) pointed out m HUn tliat a plentiful and easily a('eessil)le water su})])ly is tlie ñrst

requisite wliere rice is to be oTown. He also emphasized the importance of i)ro]:)er use of avadable water. He su<:<;-ested that under certain conditions, it was beneficial to control the fiow of

fresh water so that it traveled the entire leno-fh

of each cut. This circulation resulted in more

uniform water temperature and liel])ed to control alo-ae (scum) and insects. He also stressed

the importance of judicious water niana^i'ement

in reducing the effects of certain diseases and

other production hazards.

Amount of Water Required

The water requirement of the Ignited States

rice crop is comparatively high liecause the fields

are continuously flooded for so mucli of the growing season. Rice will not produce a profitable

crop on stored soil moisture or infreijuent rains,

as will other cereals (8). When tried in the

united States or when used elsewhere, the upland system of rice culture generally results in

yields of only ;><) to 7<) i)ercent of those ol)tained

from flooded rice grown under similar soil and

climatic conditions.

Senewiratne ami Mikkelsen {IJ.Í) suggested

that differences in groAvtli res])onses of flooded

and unflooded rice may l)e due to differences in

auxin metabolism. They found that plants grown

under unflooded conditions had a low catalase

activity and a high peroxidase activity, which

favored accelerated auxin degradation. They

suggested that high manganese levels in plants

grown under unflooded conditions affect the indolacetic oxidase meclianism and result in retarded growth and deju'essed grain yields. Kice

grown with ammonium nitrogen (flooded) collected small amounts of manganese, wliereas

plants grown with nitrate nitrogen (typical of

upland rice) contained much more manganese.

Clark, Neari)ass, and Specht ( j/), however, concluded that ''the better growth of rice in submerged as compared to uidand culture in at least

some soils is due to greater iln availability under

submerged soil conditions."

Jones and others {69) indicated that from 2.8

to 3.8 acre-feet of water normally was recjuired

to produce a rice crop in the Southern States.

About one-third of this is supplied by rainfall

during the growing season. Robertson (106) reported from early observations that the total seasonal use of water for rice in California normally

ranged from 4.3 to 14.8 and averaged 8.2 acrefeet. After a ricefield is flooded, a considerable

amount of water is required to maintain an optimum depth in the field. Water is added periodically to conqjensate for losses due to transpiration

by plants, evaporation from the water surface,

deep percolation, and spillage. These losses will

vary depending on amount of plant growth, solar

radiation, temperature, wind, relative humidity,

soil type, and rate of inflow of water into the

field. " A rate of flow^ equal to 1 cubic foot per

second (450 gallons per minute) for each 50

acres being irrigated usually is required to maintain watei^levels on ricefields in California (37).

The apparently lower water requirement for

rice in the Southern States as compared to California is related to naturally occurring climatic

differences in the évapotranspiration losses from

ricefields between the two areas. Whereas the

relative humidity during the growing season is

cjuite higli in the Southern States, it is comparatively low in California. In California, a vegetation-free water surface will lose from 5 to 6

acre-feet in 12 months, whereas this loss in southern rice areas may be less than half this amount.

Source of Water

It is estimated that 30 to 35 percent of the 1962

rice acreage in the United States was irrigated

from wells. iVdair and Engler (6) stated that

over 40 percent of the 1953 rice acreage received

well water. Since that time, however, numerous

additional reservoirs have been constructed.

Many of these reservoirs were constructed in

Arkansas. The reservoirs are filled with runoff

water before the ricegrowing season. Other

important sources of irrigation water are rivers,

bayous, lakes, and draiuAvays.

Adair and Engler (6) discussed the early irrigation of rice and reported that in 1894 the first

large irrigation plant was established near

Crowley, La. After failures of some pumps, a

somewhat larger centrifugal pump was installed

in 1896. This pump delivered 5,000 gallons of

water per minute, which was enough for the rice

acreage planted at that time. During the next

few years, many pumping plants were installed

on the streams in southwestern Louisiana and

southeastern Texas. By 1901 some pumping

plants in operation delivered up to 45,000 gallons

of water per minute.

Diesel engines came into common use for pumping water after 1919 (6), Convenience, IOAV labor

recpiirements, and reasonable initial and operating

costs have since caused a shift to electric power

and natural gas power for irrigating rice. In

Arkansas in Í955, nearly 50 percent of the 1,800

irrigation installations were powered by electricity. In Louisiana, of a total of 1,06Í wells,

450 were powered by diesel engines, 212 by natural gas, 105 by electric motors, and the remainder by other units. In some cases water is

pumped or relifted by means of the power takeoff unit on tractors.

Historically, most areas in the world where

water is pumped from wells have experienced

declining water tables. This problem, as related
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 93

to Arkansas nee production, was studied by

Engler, Thompson, and Kazmann {30), Suggested remedies included the use of deep weíls

(900 to 1,000 feet) that normally supply more

water than shallow wells (100 to' 150 feet) and

the use of small reservoirs. Engler {;29) reported

that during a oO-year period, the decline in Avater

level for the Grand Prairie area of Arkansas

averaged about three-fourths foot per year, which

caused an annual decline in capacity of shallow

wells of 20 to 25 gallons per minute. Various

methods of replenishing underground water supplies on the farm are discussed by Muckel (57).

GerloAv and Mullins (4-) pointed to the value

of small, 20- to 40-acre farm reservoirs in conserving surface runoff water to supplement or

replace well water for rice irrigation. Another

development designed to conserve water (whether

from wells or elsewhere) has been the increasing

use of underground concrete or Incite irrigation

pipelines (laid about 30 inches beneath the soil

surface) to transport irrigation water for rice

and the accompanying rotational crops. Pipeline irrigation greatly reduces the rodent damage

that characterizes open irrigation systems. In

addition, it greatly reduces evaporation and seepage losses. Aside from the important aspect of

water conservation, it has been calculated that,

for each 1,000 feet of open canal replaced with a

pipeline, 2.S acres of land are returned to crop

production (3),

Adair and Engler (6) pointed out that pumping from bayous supplies most of the surface

water in Louisiana and Texas. According to

Anderson and ^NIcKie (Í7), sources of rice irrigation water in Mississippi are shallow^ "wells (90

to 100 feet) and surface water from lakes or

streams. Diversion from large streams is the

main source of water for rice irrigation m California. It is estimated that less than 5 percent

of the California rice acreage is irrigated from

wells.

Quality of Water

For successful rice production it is very important that the available water be of suitable quality.

Sice irrigation water should be relatively free of

dissolved salts that are toxic to rice plants. The

characteristics of irrigation w^ater that determine

quality include (1) total concentration of so]u))le

salts; (2) relative proportion of sodium to other

cations; (3) concentration of boron or other toxic

elements; and (4) under some conditions, the

bicarbonate concentration as related to the concentration of calcium plus magnesium. Other

hnportant factors to consider are the initial salinity of the soil, the effect of internal drainage on

the flooded soil, and the total salt content of the

soil. Finfrock and others {37} described goodquality rice irrigation water thus:

Speciiic Electrical Conductivity

(K A 10«) 1 less than 750

Boron, parts per million lesstlian 1

S.A.K. index (tendency to form

^alkali soil) I less than 10,0

When high sodium \vater is regularly used

each growdng season, it may deflocculate the soil,

so that stickiness, compactness, and impermeability increase. The deflocculated soil is difficult

to r'ultivate and usually produces IOAV yields.

Pearson {96\ 97) described the point of greatest importance as the nature of the soil solution

or saturation extract found in the zone of rice

roots. If soil saturation extracts have a conductivity index of 4 to 8 millimhos, the yield of

Caloro rice may be reduced 50 percent.

Rice is very tolerant of salt durino- irermination, out rice seedlings are very sensitive to salinity during early development (1 to 2 leaves) and

are progressively less so at 3 to 6 w^eeks of age

[96, 99). When soils are strongly saline, having

an excessively high concentration of sodium, calcium, or potassium, the concentration of salts in

tlie soil solution (including the standing water)

may be so great that it wdll injure or kill the

seedling rice (98). Excessive salt concentration

results in restriction in dowui^vard percolation;

therefore, the floodwater is subject to a longer

period of evaporation wdth an ensuing increase

in salt concentration. Thus, w^ater having: a

higlier salt concentration enters the soil, and the

salt concentration of tlie soil solution is increased.

Adair and Engler {(J) reported that salt water ]uit on dry soil damages a ricefield more than

if salt water is used to replenish the water supply in a field that has been watered with fresh

water. The reason given was that the salt was

more concentrated in the dry soil, and more of

it moved into the root zone, where it ^vas taken

up by the plants. They indicated that rice

grown on clay soils may not be injured as much

by salt water as is rice grown on lighter soils,

because less water is used and less is lost by

seepage.

The rice plant can tolerate higher concentrations of salt in the later stages of growth, although veiy high concentrations may kill the

plants or make them sterile. Some varieties of

rice are more tolerant to salt than are others

and may make satisfactory yields when the water contains salt concentrations of 75, 150, 200,

and 250 grains per gallon in the tillering, jointing, booting, and heading stage, respectively. It

is Ijelieved that some of the newer varieties

Avould be damaged seriouslv bv such amounts of

salt(ö).

Irrigation water pumped for rice from shallow Avells in Arkansas and other States frequently has a comparatively high sodium con-
9^ MWÄ ULTURE HANDBOOK 289, U.S. DEPT. OF AGRICULTURE

tent as compared with water coming from surface

streams. Kapp (71) suggested tliat the source

and chemical composition of rice irrigation water should be considered from both the immediate effect on the current crop and the longrange productivity of the soil. In greenhouse

and field experiments he found that sodium

chloride added to rice soil injured germination

and resulted in lowered production of vegetation

and grain. The addition of 5,700 parts per million of sodium cliloride to the soil only slightly

reduced vegetation, but completely prevented

grain formation. In field trials, 825 pounds of

sodium chloride per acre hindered germination,

and 3,300 pounds per acre reduced rice gram

yield.

Water from the shallow wells in Arkansas

containing 75 parts per million calcium and 22

parts per million magnesium has caused some

riceland soils to increase in alkalinity from an

original pH of about 5.0 up to as high as 8.0.

The change from a highly acid to a highly alkaline reaction is due to the annual addition of

about 1,500 pounds per acre of limestone equivalent. The increase in alkalinity has lowered the

availability of phosphorus in the soil. If a new

source of water low in dissolved minerals is obtained, such changes may be reversed (ö). Such

water may be obtained from installing a deep

well or constructing a reservoir and catching surface runoff water. However, as long as the unfavorable soil condition exists, delaying the initial flood and following a routine of alternate

draining and reflooding at 4- or 5-da3^ intervals

until the plants are about 6 weeks old haA^e given

fairly satisfactory relief in Arkansas.

When the rainfall is below normal in the

Gulf Coast area of Louisiana and Texas, the

water level in the streams that supply irrigation

water often is so low that brackish water encroaches from the Gulf. The concentration of

chloride salts may become so high that the yield

and quality of rice is reduced or the crop is

ruined. Adair and Engler (6) pointed out that

several workers had shown that water containing more than 35 grains of salt per gallon (600

parts per million) should not be used to irrigate

young rice if the soil is dry and if the water is

to remain on the field. Rice watered continuously with water containing 35 and 75 grains of

salt per gallon was reduced in yield about 25 and

70 percent, respectively, and the rice was of

lower quality than when water containing only

25 grains per gallon was used.

Water quality in California ricefields was studied by Stromberg and Yamada (135). They

found that water that contained a high total of

soluble salts killed rice plants. However, when

a field showing initial symptoms of dying was

immediately flushed out with quantities of water low in total salts, the plants soon recovered.

Water low in total salts w^as used for the remainder of the season, and a normal crop of

grain was produced.

In California, rice culture has proved useful

in reclaiming saline soils, provided the fields to

be reclaimed are first engineered to drain well.

Mackie (77) reported that one rice crop grown

m Imperial clay near Imperial, Calif., reduced

the saline content 72 percent to a depth of 6 feet.

In his experiments he found the usual reduction

in saline content from the first rice crop to be

one-third to two-thirds. Overstreet and Schulz

(95), in a series of San Joaquin Valley tests,

concluded that rice culture serves as an efficient

means of reclaiming nonsaline soil containing 15

percent or more of exchangeable sodium.

Water Temperature and Oxygen Content

The temperature of water with which rice is

irrigated has a profound effect on the plants.

Adair and Engler (6") reported that the temperature of rice irrigation water pumped from

wells and from streams frequently is 65^ F. or

lower. When such cool water goes directly into

the field, the rice growing near the water inlet

usually is retarded and may ripen as much as

7 to 10 days later than the rest of the field.

Kaney, Hagan, and Finfrock (103) showed that

with the building of high dams on the major

California streams, the temperature of water

available for rice irrigation from surface streams

had dropped to 51° or less.

The temperature of the irrigation water should

be not less than 70'' F. nor more than 85° for

best results. Raney (102) showed that the critical seasonal threshold of water temperature for

normal growth of Caloro rice Avas near 69°.

When the mean temperature was 5° lower, maturity was delayed 30 days beyond the normal

160 days. Rice yield was highest when the mean

water temperature was 80°. At water temperatures aljove 85°, yield was reduced and root develoi)ment was poor, probably because of low

oxygen content of the water.

Chapman and Peterson (£0) studied underwater rice seedling establishment in relation to

temperature and dissolved oxygen. Under laboratory pot culture they found water temperatures in the range of 77° to 8-t° F. most favorable

for the effective establishment of rice in static

culture. Emergence of the shoot from the water

was most rapid at 8J:°, but the development of

the root system and the penetration of the soil

were favored by temperatures as low as 68°.

Exposure to a water temperature of 104"° for

12 hours or more was lethal to pregerminated

Caloro rice seed. They concluded that it seemed

unlikely that dissolvecl oxygen deficiency would
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 95

^.k .j,»* -*>«* fc..

H^^' ^^'. ^;^* "j*f*,>i»-. „ ^ -

FiGUBE 34.—Headgate that controls flow of water from canal into ricefield.

be a limiting factor in seedling establishment in

the field even at 95°, if currently recommended

seeding rates were used and the water had an

initial oxygen content of at least 5 to 6 parts per

million.

Ehrler and Bernstein {28) reported that at a

constant root temperature of 64.4° F., Caloro

shoot growth was twice that at 86° and root

growth was one and a half times as great; however, grain yield was only three-fourths as much

at the lower root temperature. No significant

interaction was found between root temperature

and cationic concentration or cationic rates.

Seeds germinate slowly when the temperature

is less than 70° F. Water now available for rice

irrigation in some areas, including northern California, may be colder than this, ranging down

to 51° or less. Such cold water will retard and

lower the germination of rice sown in the water

and will retard the development of plants so that

the stand may be thin and crop maturity will be

delayed near the inlet to the field. According to

Raney, Hagan, and Finfrock {103), field studies

over a 3-year period showed that plant-free

water-warming basins, 6 to 12 inches deep, equal

in size to 2 percent of the area to be served,

successfully and economically raised the mean

water temperature of 60° to 70°.

Water Control Methods

Methods of transporting and controlling irrigation water for rice production have evolved

over the years. They vary in different riceproducing areas but tend to follow a general

pattern.

In most cases water is conveyed from the

pumps, streams, or reservoirs in canals from

which it is diverted into laterals, into field

ditches, and finally into the field checks or paddies. Water is usually delivered to the highest

point in the field by canals or pumps. It passes

into successively lower paddies through metal

levee gates or levee control boxes or openings in

the levees. These gates or boxes provide permanent control of maximum water depth in each

paddy.

Water that overflows or is drained from the
96 AGRICULTURE HANDBOOK 28 9, U.S. DEFT. OF AGRICULTURE

lowest paddy may be caught in drainage ditches

or canals and recirculated or moved into other

canals or drainage ditches. Some fields have a

canal along one side so that each paddy can be

watered separately from this canal. Finfrock

and others {37) described in detail the rice irrio-ation control structures used m California.

^ CANAL GATES.—Gates in the irrigation canals

of the California ricegrowing areas are simple

structures of wood or concrete (fig. 34). In the

vertical fixed portion of the structure, slots are

provided so that short planks (flash boards) can

be inserted or removed as desired to raise or

lower the water level at the diversion point into

the field. Inlet structures to the field may consist of similar slotted wooden structures or screwtype metal gates. The latter commonly are used

in the southern rice area.

LE^^EE BOXES OR GATES.—Water is controlled

within the field with boxes or gates set at convenient locations in the levees. In the southern

rice area, metal levee gates with acljustable panels are in common use in some localities (fig. 35).

Variations that may be used include single planks

or boards or metal panels which are forced into

the soil across a narrow cut through a levee to

keep the water at the desired level. In California, the levees are usually considerably larger

than those in the Southern States. The wooden

or metal boxes are placed along the more accessible side of the field. Flash boards of various

widths are added or removed to regulate the

water to the desired depth. Boxes must be

properly constructed and installed so they will

not be washed out (fig. 36).

DEPTH STAKES.—To gage the water level in a

paddy or check, a depth stake is driven into the

soil within a suitable distance of the levee box

or gate. The stake is set so that the bottom of

an 8-inch red band is at the average elevation

of the ground surface in the paddy. If a 5-inch

flood is desired, then 3 inches of the red band is

•y?»^>

FIGURE 35.—A ricefleld in Arkansas that is irrigated and readj' to be seeded, showing the gates used to regulate the

flow of water from one check to another. (Photo by Copeland.)
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 97

^..-»Ç%*

PiGTiEE 36.—Levée box used in California to regulate

flow of water from one check to another in ricefleld.

left showing. The stake is painted white at the

top, so that if an 8-inch flood is desired, only the

white band is left exposed.

Construction of access roads around ricefields

helps to (1) cut production costs because equipment can be moved more easily into the field;

(2) control water better and more economically :

and (3) control mosquitoes by reducing seepage

problems, by making it easier to control weeds

where mosquitoes breed, and by enabling mosquito abatement employees to reach troublesome

spots.

PROTECTION OF IRRIGATION SYSTEM.—Once they

are engineered and installed, riceland irrigation

and drainage structures are subject to damage

from use, the elements, and insect or animal

pests; but countermeasures can be employed. In

large, flat paddies or checks, wind levees may be

constructed between the normal-interval levees to

decrease wave action. Their judicious placement in areas subject to strong winds may be

very beneficial. So-called alkali levees built

from soil high in sodium and other salts frequently are subject to washouts or breaks when

fields are flooded. Heavy applications of gypsum on such areas before pulling the levees help

to stabilize the soil and greatly reduce the chances

of breaks. Plastic sheeting or various types of

laminated paper also ,can be used to cover weak

areas in levees. Soil is plowed or shoveled onto

the edges of the material to prevent its floating

when the field is flooded. Certain pests, such as

muskrats, field mice, Norway rats, crayfish, and

large insects, often inhabit canal and drainage

ditchbanks, as well as contour levees. Their burrowing? may result in levee or bank leaks or

breaks and heavy water loss. Major structures,

such as weirs, can be protected to some extent by

trapping or poisoning the pests. In California

fields where the large levees sometimes are inhabited by crayfish and muskrats, the problem

has been solved by using sheep to graze the

vegetation from the levees.

Water Management

The application and management of water is a

key operation in rice farming (89). The principal functions of water cover are to control weeds,

to condition the soil and provide a favorable

environment for rice growth, and, especially in

California, to serve as a temperature regulator by

minimizing the effect of the large variations between daytime and nighttime air temperatures.

Systems of water management for rice production vary widely, depending on method of seeding, soil type, climate, crop rotation, diseases, and

insects. A very important aspect of water management is good drainage. This includes drainage of winter rainwater as well as periodic drainage during the growing season. In years when

riceland is used for rotational crops, the crops

may be drowned if drainage is poor. Seedbed

preparation and fall harvest can be expedited by

a good drainage system. Drainways around and

through the field that connect with main drainage.

ditches leading to natural drainage channels are

essential. These ditches should be large enough

and deep enough to allow the removal of large

quantities of water quickly. When it is necessary

to preirrigate or to flush irrigate to bring about

emergence of rice, good drainage plays a key role

in getting a good stand quickly by expediting

fieldwork and reducing seed rot losses (5, 69).

Good drainage of ricefields and adjacent areas

and ditches also is of prime importance in eliminating mosquito-breeding areas.

Essentially there are two broad systems of

water management, depending on the method of

seeding. The first broad system of water management revolves around drilling or broadcast

seeding on "dry" ground. Where necessary, seeding is followed by flushing to bring about uniform emergence, and the first flood is applied

later. This system is often used in the southern

rice area. With the second broad system of water

management, fields are flooded just before aerial

seeding and usually remain flooded until they are

drained for harvest. This system is used in California, and with modification also is used in the

southern rice area. In the southern rice area

(especially in Texas), where rice is water seeded

on heavy soils, some growers drain as soon as

possible after seeding; others may delay draining

for 36 hours. After stand establishment, irrigation practices are essentiallj^ the same as for

drilled rice (8).

Unless rice is water seeded and the flood is

maintained, a flood is applied about as soon as the
98 AURIC ULTÜTURE HANDBOOK 2 8 9, U.S. DEFT. OF AGRICULTURE

crop is old enough to withstand submergence. As

a means of Aveedy grass control, ricefields on the

lighter soils in Arkansas often are flooded as soon

as the rice has emerged. If the fields are free of

weedy grasses or if these grasses have been

chemically controlled, the land may not be submerged until the rice seedlings reach a height of

4 to 6 inches. Jones and others (69) indicated

that at this stage the land is submerged to a depth

of 2 to 4 inches. As the plants grow taller, the

depth of water gradually is increased until it

reaches 4 to 6 inches. During the rest of the

grooving season or until the land is drained before

harvesting (except for special reasons), the water

may be held on the land at a depth of about 5

inches. To maintain this constant depth, additional water should be applied to replace that lost

by evaporation, transpiration, and seepage.

Eeasons for draining ricefields during the

growing season and allowing the soil to dry include (1) control of algae (scum) ; (2) control of

rice water weevil; (3) prevention of straighthead

(blight); (4) control of aquatic weeds such as

mudplantain (ducksalad) ; and (5) application

of nitrogen fertilizer. On saline or alkaline soils

it may be necessary to drain fields several times

early In the growth of the rice to allow the plants

to become well established.

ARKANSAS.—Adair, Miller, and Beachell (8)

reported that water management is similar in

Arkansas and Louisiana. Depending on growing conditions and grass control methods being

used, the first flood may be applied as the rice is

emerging, or it may be delayed for 2 or 3 weeks.

The majority of ricegrowers in Arkansas drain

their fields about midway in the growth of the

rice and allow the soil to dry before applying

nitrogen fertilizer. The fields are then reflooded,

and observations indicate that nitrogen is taken

to the rice roots as the water soaks into the soil.

This results in more efficient use of the fertilizer.

Hall (50) described the water-seeding method

used by some Arkansas growers. Seed is broadcast by plane into fields immediately after the

application of 4 to 6 inches of water. The flood

may be held for about 6 weeks before draining for

the midseason application of nitrogen fertilizer.

Other growers may drain their fields soon after

the seed is sprouted and reflood after a few days.

If fields are left drained for several days, heavy

stands of grass weeds may become established.

When rice is water seeded on heavy clay soils,

this early draining is a common practice. The

fields then are reflooded after about 3 days and

the flood is maintained until midseason.

In a series of greenhouse experiments. Hall

(49) found that unless rice plants were fertilized,

the practice of draining and drying the soil and

then reflooding did not increase grain production on soil low in organic matter.

LOUISIANA.—Jenkins and Jones (62) found

that in date-of-submergence experiments in Louisiana, the highest average yields were obtained on

land submerged 20 days after the seedlings had

emero-ed. In a discontinuous and continuous submergence experiment, early continuous submergence (10 days after seedling emergence) of the

land gave higher average yields than did intermittent drying of the land followed by continuous

submergence.

In Louisiana, water seeding is not common; but

where it is practiced, the water is drained when

the rice seedlings are one-half inch long, according to Wasson and Walker (14^). It then is

allowed to groAv until flooding is needed. Drilled

rice may be flushed if necessary for uniform germination. Normally the rice is not flooded until

it is 6 to 8 inches tall, and then only to a depth

of 41/4 inches. Fields are drained as necessary

for topdressing with fertilizer and for pest

control.

MISSISSIPPI.—Mullins (S9) stated that rice in

the delta area of Mississippi is kept flooded for

90 to 120 days during the growing season, depending on variety and seeding date. The first flood

is applied as early as possible after the rice seed

germinates and a stand is established. This may

be about 2 weeks after seeding or, if germination

is slow, possibly 3 weeks after seeding. Application of the first flood requires close attention to

avoid breakage of levees and to stabilize the water

at the desired level. If the levees are accurately

located and well constructed, relatively little time

is required to apply the first water; otherwise,

labor requirements may be much higher. Mullins

reported that most fields were drained after 3 to

4 weeks under flood and the soil was allowed to

dry for several days. This permitted the roots

of the rice plant to become more firmly established and also stimulated additional tillering.

He suggested that if grass was well under control

at this time, fertilizer could then be applied.

TEXAS.—Reynolds (105) stated that where rice

is seeded with a grain drill on heavy soils, the

fields usually are flushed (irrigated) for germination if water is available and if the soil has not

been saturated by rain. Flushing usually is

practiced in areas irrigated from canals, since the

fields can be covered rapidly. Sandy soils and

soils irrigated from wells usually are not flushed.

After fields are flooded, irrigation water may be

drained off once or twice during the growing

season to permit fertilization and to control water

weeds and insects. The time and number of

drainings may vary, depending on the length of

maturity of the variety, the presence of weeds

and insects, and the supply of irrigation water.

Where there is a shortage of water for reflooding,

the fields usually are not drained. If irrigation

is required to germinate the seed, the field is
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 99

promptly drained after this flushing. Where rice

is seeded with an endgate seeder, the Land is then

harrowed and irrigated and the irrigation water

is drained off shortly thereafter. It has been

found from tests and general observations that

satisfactory rice stands-are not obtained if seeds

are covered by both soil and water, so that draining water from fields where the seed is covered

with soil is extremely important.

Morrison (85) found little difference in the rice

yields at Beaumont when the total amount of

water used ranged from 46 to 73 inches. He concluded that the use of 45 to 50 inches of water

would be just as satisfactory as the use of larger

amounts. These results generally agree with

those reported by Jones and others {69), It was

further concluded (85) that the depth of water

does not seem to be of much importance where

weeds are not a problem. Draining ricefields once

during the growing season increased the yield of

rice considerably.

Evatt (31) reported that preliminary tests conducted at the Rice-Pasture Research and Extension Center in 1956 and 1957 showed significantly

reduced rough rice yields of the Century Patna 231

variety with use of deep water (10 to 12 inches),

compared with use of average depths of water of

from 4 to 6 inches from late tillering to maturity.

He found that the temperature variation was 2 to

4° F. greater under the shallow water than under

the deep water. Yields from superimposed fertilizer factorials showed no significant fertilizerwater depth interactions in 1956. However, in

1957 yields were less from both nitrogen and

phosphorus treatments under the deeper water.

CALIFORNIA. —In California where japonicaderived varieties predominate, ricefields normally

are rapidly flooded to a depth of 6 to 8 inches just

before seeding. Then they are seeded with presoaked seed immediately after flooding to enable

the developing young rice plants to compete efficiently with soil organisms for available oxygen

and with weeds for space and nutrients (36),

The water is maintained at that depth until it is

drained for harvest. Water may be lowered to

about a 3-inch depth for weed control and at

stand-establishment time during cool weather.

If the soil in the field contains excessive amounts

of salts, the water may become sufficiently saline

as to be toxic to the rice seedlings. In such cases

the water may be drained from the field and fresh

water applied immediately. The continuous flood

system comonly used in California was developed

to control weeds, principally watergrass, and to

fit the fertilizer requirements of rice (55, 83).

Draining for Harvest

Draining at the proper time before harvest is

necessary to dry the soil enough to sup^Dort harvesting equipment. It is equally important to

hold the water on the land long enough to permit

the rice to reach proper maturity.

The time to drain depends on the type of soil,

drainage facilities, and seasonal weather conditions. Some soils dry and crust quickly after

drainage; others dry slowly. Less time is required to dry the soil early in the season when

temperatures are higher and the days are longer

than is required later in the fall. Growers soon

familiarize themselves with the drying time of

their soil, so that they can judge when to drain

the fields to permit harvesting and yet not let the

crop suffer for lack of soil moisture.

Usually the land may be drained when the rice

is fully headed and the heads are turned down

and are ripening in the upper parts. This stage

ordinarily will be about 2 to 3 weeks before the

crop is ready to cut. The date when the rice will

be ready for harvest can be estimated by observing the date of first heading (when approximately one-tenth of the rice heads have emerged).

Rice in the South normally requires 35 to 45 days

from first heading to maturity. In California,

crops of average yield will be ready for harvest

about 45 days from the first heading. Heavy

crops with yields of 5,000 pounds or more per

acre may require as many as 55 days from first

heading to maturity.

Water intake should be discontinued a few days

before final drainage. The water already on the

field will then recede slowly. This lessens lodging

and does not overtax the drainage system with

excessive water. In the South the field may be

drained by removing the levee gate panels or by

"cutting" the comparatively small levees with

hand shovels. Levee gates sometimes are upended

or may be removed from the fields before harvest.

Dynamite is used quite extensively in California

for opening levees to permit draining of ricefields

before harvest. The levees are blown where they

cross the drains that are installed within the

fields. The dynamiting, which requires experienced powdermen, is started at the lower end of

the field.

Harvesting, Drying, and Storing

Harvesting

Most rice grown in the United States now is

directly harvested with self-propelled combines.

It is then dried artifically before storing or milling. A small amount of seed rice is cut, swathed,

and threshed from the windrow when the seed

has dried down to 12 percent moisture or less.

Direct combining and artificial drying is the

most efficient and economical way of harvesting

rice. Careful adjustment of the combine and

proper drying methods result in grain having

highest milling quality and commercial value.
100 AGRICULTURE HANDBOOK 289, U.S. DEFT. OF AGRICULTURE

Before adoption of direct combining, the

United States rice industry used three other harvest methods, according to Smith {12Ji)> These,

in order, were (1) harvesting by hand with a

sickle or cradle, and then stationary threshing;

(2) cutting with team-drawn or ultimately with

tractor-drawn grain binders, handshocking the

bundles, and then engine-powered stationary

threshing; and (3) cutting with a tractor-drawn

header or swather, followed by threshing from

the windrow (when the grain was dry) with a

pickup combine.

Direct combining was first tested in Arkansas

and Texas in 1929 {1'26). According to Bamer

{13), approximately 3,000 acres of rice were harvested by combines in 1929 m California, and

nearly 35,000 acres in 1931. The combined harvester-thresher had been developed primarily for

wheat, and the first models were not well suited

to ricefield conditions. Low wet spots, weed

patches, and high, narrow levees made combine

harvesting difficult.

At the same time that combine harvesting was

first being tried, tests were being conducted on

artificial drying of rice {126). ^ Even with the

problems encountered in combining and artificial

drying of rice, numerous advantages were cited.

These included: (1) In one operation rice is removed from fields with no danger of weather

damage; (2) very little loss of rice is sustained

through shattering; (3) rice of high milling

quality can be obtained regardless of weather

conditions at harvest; and (4) all the rice can be

thoroughly and uniformly dried, making it safe

for storage either in bulk or in sacks. Also, it

was pointed out that artificially dried rice usually

is more uniform in quality because of the thorough mixing during the drying operations.

Additional advantages of the combine method

over the binder, as pointed out by Slusher and

Mullins {121) were (1) the elimination, to a large

extent, of the need for outside labor for harvest ;

(2) less chance for loss from destructive wildlife,

principally blackbirds and ducks; (3) possibility

of salvaging a much higher percentage of crop in

case of storm or wind damage; and (4) reportedly less field loss. These authors found that

hand labor used in harvesting was reduced from

slightly more than 11 hours per acre with the

binder to from 2.4 to 3.6 hours with the combine

method, depending on the size of the machine

used. They reported that 400 acres of rice approaches the maximum seasonal acreage that a

grower can safely plan on harvesting with one

12-foot self-propelled combine. Slusher {120)

indicated that the usual crew for the self-propelled combine method consisted of one man on

the combine, one man with a tractor and grain

cart to haul grain from the combine to the truck,

and two men and trucks to haul grain to the drier

or elevator. One such crew usually could harvest

about 16 acres of rice per 10-hour day.

Mullins {89) emphasized that the time required

and the cost of harvesting depend largely on the

weather at harvesttime. Heavy rams and wind

often cause excessive lodging and create unfavorable surface conditions for operating combines

and other equipment. Severely lodged rice may

be harvested with combines that have adjustable

pickup reels. When this is necessary, the combine

must be operated at a much lower speed across a

field, which greatly increases the time required

for harvesting.

In a study of a large number of samples that

included the effect of method of harvest on rice

mill yield and grade, it was concluded that there

was little difference between the combine method

and the binder-thresher method of harvest as it

related to the market value of the rice obtained.

Most rice now is handled in bulk {122), although some, especially that being saved for seed,

still is sack dried. The conversion from sacking

rice in the field to bulk handling was accentuated

by increasing costs and scarcity of sacks and hand

laboi".

Today the self-propelled rice combine harvesters are equipped with relatively large bins or

hoppers for collecting the threshed grain (fig.

37, A ). The hoppers then are emptied by mechanically augering the rice into self-propelled "bankouts" or tractor-drawn carts that take the rice to

waiting field-side trucks (fig. 37, B), Rice then

is hauled to driers (figs. 37, C and 37, D) or to

aeration bins (fig. 38) where it is unloaded by use

of grain augers or other bulk-handling methods.

Hurst and Humphries {61) discussed harvesting of rice with combines and pointed out that

care should be taken not to crowd the feed. Because rice straw is heavy and green at harvest, the

ground speed of the machine should be slow

enough to avoid clogging. Since the rice kernel

is very susceptible to cracking, the cylinder should

be run at a slower speed than for other cereal

crops. Allowing a small percentage of kernels to

crack maj^ be necessary to thresh out a maximum

yield.

Special self-propelled rice combines used in

California are equipped with crawler tracks that

enable the machine to cross wet spots, small

ditches, and low levees. In rainy seasons, wide

wooden mud cleats are bolted on to the tracks to

increase the support for the harvester. Selfpropelled combines used in the ricefields in the

South usually are equipped with large tires with

mud lugs so that they can be operated over the

sloping levees.

In recent years, specially designed rice combines have been built by the major farm machinery manufacturers in the United States and

are being used in the ricefields of the South and
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 101

FIGURE 37.—A, Cutting and threshing rice with a combine harvester that is loading the rice into a "bank-out" or

grain cart ; B, transferring the rice from the "banli-out" into a truclc in a road at field side : C, trucks loaded with

rice waiting to unload at a farm drier ; Z>, unloading the rice at the drier.

the West. These high-powered machines commonly have 12- to 16-foot headers and can be

operated under extremely muddy conditions.

They can be adjusted to do a thorough job of

threshing with a minimum of shelling and cracking of the grain. Most combines now are

equipped with straw choppers, which cut up the

rice straw as it leaves the combine, and a distributor, which spreads the straw particles uniformly over the stubble to facilitate plowing

under.

The effect of combine adjustment on harvest

losses of rice was studied by McNeal (79). He

found that there were four types of combine losses

—cutter bar, cylinder, rack, and shoe. To obtain

maximum grain yields, it was necessary for the

cylinder bars and the concave to be in good condition and for the concaves and other parts of

the combine to be properly adjusted. He concluded that combine ground speed should be reduced to one-half mile per hour when the rice

is badly lodged. He indicated that the operator
102 AGRICULTURE HANDBOOK 28 9, U.S. DEFT. OF AGRICULTURE

FiGTJEE 38.—Bin drying combined rice on the farm.

is the most important factor in preventing higli

combine losses. The height at which the rice was

cut was very important, since the proper amount

of straw served as a cushion to the grain in the

threshing process, and resulted in a lower cylinder loss and less hulling and breakage.

Curley and Goss {^2) found that combine

losses also may be due to overloading or improper

machine adjustment or a combination of the two.

Overloading as a result of excessive ground speed

usually is the major cause for excessive loss in all

sizes of combines.

Their tests in rice indicated that total combine

loss including reel shattering should be less than

5 percent of the gross yield if the machine is

properly adjusted and operated. Thus, the loss

from a 6,000 pound per acre yield should not

exceed 300 pounds. A high loss of unthreshed

grain usually resulted from improper cylinder or

concave adjustments, or from both. High loss of

threshed seed came from poor separation in the

straw walkers and cleaning shoe. They found

that under California conditions reel shattering

losses normally were insignificant in rice as compared with other small grains.

Curley and Goss suggest that several loss checks

should be made on a machine in a given area to

determine the effect of adjustment or change in

ground speed. Detailed recommendations for machine and procedural adjustments for harvesting

rice under California conditions also are listed by

these workers.

MOISTURE CONTENT OF GRAIN AT HARVEST.—

Smith and others {127) pointed out that rice must

be of high milling quality to command a premium

price, and that for this high quality and for

maximum grain yields, rice must be cut at the

proper stage of maturity. If the crop is harvested when immature, field yields usually are

reduced and the breakage in combining and milling is excessive because of the light, chalky kernels. If the crop is left in the field until" overripe, the kernels may check. This causes severe

breakage during combining and milling and a

reduction in the yield of head rice (whole kernels). Smith and others emphasized that when

rice has reached the proper stage, harvesting

should proceed rapidly, since loss of moisture in

standing rice may be very rapid. In rice harvested at the proper stage, the grains were fully

mature in the upper portions of the panicle and

in the hard-dough stage at the base. Few, if any,

chalky kernels were found in rice harvested at

this stage of maturity. When such rice was properly dried, germination was satisfactory for seed

purposes.

Bainer {13), Davis {26), Rester {72), McNeal

{80), and Smith and others {125, 126, 127) have

reported results of research relating sta^e of

maturity (moisture content) of the gram to

proper ' harvesttime. Although their findings

varied, they were in general agreement that maximum yield of head rice was obtained when rice

was harvested at a moisture content of about 18

to 24 percent and then immediately dried to between 13 and 14 percent.

Varieties differ in the range of harvesttime

moisture content at which they yield the best

quality milled rice. McNeal {80) reported that

a range in moisture content of 16 to 22 percent

provided the highest yield of head rice for Rexark and that a range of 17 to 23 percent provided

the highest yield for Zenith. Davis {25) reported

that the best range for Caloro was 20 to 25 percent, and Kester {72) and Rester and Pence {73)

reported that the best range for Calrose was 22 to

27 percent. Their work showed that for every

1-percent reduction in kernel moisture while the

unharvested grain was left in the field, the decline

in head rice yield from the maximum was 1.4

percent for Caloro, 0.9 percent for Calrose, and

1.0 percent for Colusa.

Most ricegrowers determine the moisture content of hand-harvested samples of their rice before beginning harvest. Determinations usually

are made with electrically operated moisture

meters, which they own or which are available at

the commercial driers.

Although kernel moisture content at harvesttime strongly influences rice quality and milling

characters, environmental factors that affect the

plant physiologically during the growing season

also influence quality. Halick {Jf8) has shown

that a variety that ripened under lower temperatures (81° to 84° F.) produced higher head rice

milling yields than did rice that ripened earlier

in the season under higher temperatures (90° to

94°). Stansel, Halick, and Rramer {m)io\mà.

that high temperatures (90° day and 80° night)

increased chalkiness in all four varieties studied

(Century Patna 231, Bluebonnet 50, Toro, and

a glutinous variety). California rice quality
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 103

studies (73) showed that certain crop fertilization

practices could result in declines in kernel characters such as weight, water uptake, hot-paste

viscosity, and whiteness. Thus, when harvesting

for maximum quality, many factors must be considered; but certainly moisture content of grain

at harvesttime is among the most important.

PREHARVEST CHEMICAL DRYING.—Results from

experiments with the preharvest application of

chemical desiccants to speed the drying of rice in

the field have been reported by Addicott and

Lynch (9), Hinkle (57, 58, 59), Smith, Hinkle,

a¿d Williams (123), Tullis (139), and Williams

{U7). All materials were applied as sprays when

the rice contained from 20 to 27 percent moisture. Materials tested at varying concentrations

included (1) sodium chlorate-borate mixtures;

(2) magnesium chlorate; (3) disodium 3,6-

endoxohexahydrophthalate (alone and with ammonium sulfate) ; (4) sodium monochloroacetate ;

(5) S, S, S,-tributyl phosphorotrithioate; (6)

sodium pentachlorophenate; (7) di-nitro-O-secbutylphenal compounds (alone and in combination with aromatic oils) ; and (8) aromatic oils

alone. Some of the chemicals studied by these

investigators hastened the drying of rice in the

field. However, none were entirely satisfactory

because the milling quality was reduced, the kernels were discolored, or the chemical imparted an

off-flavor to the rice.

Desiccants are used occasionally to hasten the

drying of seed rice. However, no grower should

use a desiccating chemical on his maturing rice

crop until he has checked with his local agricultural authorities to determine its legal status with

reference to chemical residue tolerances. Laws

are strictly enforced in this regard, and an entire

crop could be impounded if it exceeds the legally

established chemical residue tolerances.

Drying and Storing

For the proper drying of rice, moisture must beremoved from inside the kernel (23). If rice is

dried too rapidly or if the temperature of the

drying air is too high, quality is seriously impaired. To prevent internal checking or breaking

of the kernels from drying too rapidly, drying

usually is done in three to five stages. In each

stage the rice passes through the drier and then

is tempered in a bin, so that the kernel moisture

will equilibrate.

Bainer (13) published one of the earliest accounts of artificial drying of combine-harvested

rice. He concluded that rice could be dried successfully by artificial means but that the temperatures in the drier should not exceed 100° F.

Smith and others (126) reported on early research on artificial drying of rice in Arkansas and

Texas. They concluded that a drying-air temperature of 120° F. could be used without injuring the rice if the moisture content was reduced

only about 2 percent at each drying operation and

the rice was allowed to remain in storage 12 to 24

hours between drying periods. However, when

necessary to dry a given lot of rice in one operation, the drying-air temperature should not exceed

110°.

From experiments conducted with combined

rice in 1944, 1945, and 1946, McNeal (78) concluded that in most cases the head rice yield was

increased and the total drying time was decreased

as the number of dryings was increased from one

to four at temperatures ranging from 100° to

150° F.; and the tempering period between dryings was important, since it gave the moisture m

the grain an opportunity to equalize and thereby

reduced drying time. On the basis of more recent

experiments, McNeal (81) concluded that the

most desirable drying combination appeared to be

four dryings at 120°.

In 1953, Aldred (10) summarized research on

drying and storing rough rice in the Southern

States. This summary covered work conducted

by the Agricultural Experiment Stations in

Arkansas, Louisiana, and Texas, and by the U.S.

Department of Agriculture. This author gives

information on volume of air used in columntype and bin-type driers; number of stages to

use in drying rice; temperature of the air for

drying; depth of rice when dried in bins; length

of time rice can be held before drying; and the

use of fumigants to protect rice from storage

insects.

A comprehensive review of research in the

United States on conditioning and storing rough

and milled rice through 1958 (23) was published

in 1959. This reidew cited 74 specific references

and included participation by 36 contributors.

TYPES OF DRIERS.—Driers can be classified by

type as (1) continuous flow, including mixing and

nonmixing; and (2) batch, including bins and

potholes. Driers can also be classified as multipass and uni-pass. Multi-pass is a continuousflow system; uni-pass is a batch system.

Wasserman and others (1^2) reported that

mixing-type driers are of many designs. Two of

the most popular mixing-type driers are the baffle

design and the Louisiana State University (LSU)

design (1), In the baffle design, rice is conducted

downward in a zigzag path by means of baffles,

while heated air is forced through the grain. In

the LSU design of the baffle drier, layers of

inverted-V-shaped air channels are installed in

a bin with alternating air-inlet and air-exhaust

channels. Each layer is offset, so that the tops of

the inverted Vs split the streams of grain as it

flows down between the channels. Drying air

passes from the air-inlet channels through the rice

and out the air-exhaust channels (142).

Wasserman and others {H2) stated that the
104 AORÏCULTURE líANDBOOK 2 8 9, U.S, DEFT, OF AGRICULTURE

nonmixing columnar type drier is the simplest

and most commonly used. In this drier, rice

descends between two parallel screens set 4 to 6

inches apart while heated air is blown through

the screens and intervening rice. No appreciable

mixing occurs, and the effect is similar to drying

in a static bed with a depth equal to the distance

between the screens.

According to Morrison, Davis, and borenson

(<?(?), bin drying refers to drying grain in storage

bins usually at depths of 6 to 8 feet. Normally

the grain is dried in the same bin in which it is

stored, which makes the method particularly

suited to on-farm installations. In contrast, aeration is defined as the procedure used to cool and

ventilate grain during storage to maintain quality. This is accomplished by turning the gram

at frequent intervals, by transferring the gram

from one bin to another, or by circulating air

through the stored grain. Although drying may

be accomplished with unheated (normal atmospheric) air under favorable conditions, a source

of supplemental heat should be available during

periods of high humidity.

Bin drying, consisting of drying with unheated

air but supplemented with artificial heat, is used

in on-farm installations, especially for seed rice.

Supplemental heat refers to heat added to atmospheric air for limited temperature rise, usually

less than 20° F., to accomplish drying within a

maximum permissible time to prevent spoilage.

Barr and others (16), Henderson (53, 54, 55),

Hildreth and Sorenson (5Ö), Sorenson (129,130),

and Sorenson and Davis {131), all discuss the

requirements for successful bin drying and its

limitations.

Sorenson, Davis, and Hollingsworth (132)

pointed out that some rice for seed is dried in pothole-type sack driers.

McNeal {81) describes two distinct procedures

in use for commercial rice drying. These are the

multi-pass system and the uni-pass system. In

the multi-pass driers, air heated to approximately

120° F. is passed through a continuously moving

column of rice in three or more passes. During

the first pass a predetermined amount of moisture

is removed; then the rice is stored for about 24

hours to allow the moisture to equilibrate

throughout the individual kernels. As many additional passes are used as are necessary to reduce

the moisture content of the rice to a safe storage

level.

In uni-pass driers, air heated to 110° F. or

higher is passed continuously through the column

of rice in one operation until the moisture content

of the grain is reduced to safe storage level. This

system employs a pack 10 inches thick, and the

direction of the heated drying air is reversed at

regular intervals and the dryfng is accomplished

in one pass.

SOURCES OF HEAT FOR DRIERS.—The amount of

heat required for warming the air used by a rice

drier depends on the initial temperature and moisture content of the air. The approximate quantity of lieat required to raise the temperature of

each 1,000 cubic feet of air and its moisture 1° F.

is about 18.1 B.t.u.'s. To take care of initial air

temperature, heat losses, and periods of above

average humidity, results of experiments at

Crowley, La., indicated that the heat source

should provide 2 B.t.u.'s per minute for each cubic

foot of air used. The most satisfactory source of

heat was found to be natural or butane gas. It

was pointed out that gas burners are relatively

inexpensive and are easily regulated to maintain

a desired air temperature. Also, since a clean

flame is produced, the burner can be directed

toward the inlet to the blower and the products of

combustion allowed to pass through the drier {1),

DRYING RATE AND TEMPERATURE.—Unlike most

cereals, rice is consumed primarily as unbroken

kernels, so that the market value for whole kernels is much greater than that for broken kernels.

Therefore, to avoid breaking the rice kernels,

much more care is required in drying rice than in

drying other cereals. The drying rate of rice

depends on the rate of migration of moisture

from the inside to the outside of the kernel. As

the rice kernel is dried, the outer portion shrinks,

setting up stresses and strains. When too much

moisture is removed too rapidly, checking or

shattering of the kernel results. To reduce this

effect, rice is dried with air at 100^ to 130° F. in

two or more stages or passes through the drier.

Between passes through the drier, the grain is

held in a bin to allow the moisture to equilibrate

throughout the individual kernels. This tempering relieves stresses and strains and facilitates

drying in the next pass. Laboratory-scale studies

witii California-grown rice showed how dryingair temperature and number of passes through

the drier affected head rice yield and total drying

time. The relation of these factors has been

represented on a single diagram to serve as an

operating guide in the drying of rice {142).

EFFECTS OF HIGH TEMPERATURES ON SEED VIABILITY.—McFarlane, Hogan, and McLemore {76)

studied the effects of heat treatment on the viability of rice. They also surveyed the literature

iuA^olving rice and other grains. Germination

tests confirmed that the effects of high temperatures on the viability of naturally moist rough

rice were much the same as for other kinds of

seed similarly treated. General observations included the following: (1) For a given sample of

rice, the zone of heat damage (beginning of heat

damage to loss of viability) is narrow; (2) the

resistance of rough rice to impairment of its viability by heat varies inversely as its moisture

content; and (3) when viability of rice is dam-
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 105

aged by heat, loss in germination vigor is apparent before loss in germination capacity.

In artificial drying experiments with seed rice,

good results were obtained by continually rotatnig the seed from bin to drier to another bin until

dry. An inlet air temperature of 120'' F. and a

20-minute drying period were used. This method

reduced drier capacity somewhat but eliminated

the possibility of mold or fungus attacking the

germ of warm, damp rice between drying periods

(i). MclSTeal (75) showed that germination percentages were reduced when rice was dried at air

temperatures above 130°.

I]MPRO^^[NG EFFICIENCY OF COMMERCIAL DRIERS.

—Eecent studies have shown how commercial

drier capacity could be increased by about 50 percent and head rice yield by 2.5 percent without

significant additional capital outlay or increased

operating costs {101^ 133^ i^5, IH)- Depending

on the physical characters of the drying equipment, a combination of increased rate of flow

through the driers (up to 50 percent) and higher

drying temperatures (up to 150° F. for Caloro

rice) IS used to achieve increased drier efficiency.

The findings are based on tests with rice varieties in southern areas as well as in California.

Calderwood and Hutchinson {17) conducted a

series of experiments at Beaumont, Tex., to determine how best to hold freshly harv-ested rice

until it could be dried. These studies, as well as

those of Hutchinson and Willms (60)^ also included the use of unheated air to effect economies

in rapidly cooling rice during the tempering

periods between passes in the heated air column

driers. Long-grain rice, with an initial moisture

content below 20 percent, aerated with 0.43 cubic

feet per minute per 100 pounds, showed no change

in grade when held in temporary aerated storage

for 10 days before drying. Medium-grain Gulfrose, with an initial moisture content of 23 percent, aerated with 0.43 cubic feet per minute per

100 pounds, was not damaged when stored for 3

days. Another lot, with an initial moisture content of 22 percent, aerated with 1.24 cubic feet

per minute per 100 pounds for 7 days before drying, showed a sharp drop in grade.

INFRARED DRYING OF ROUGH RICE.—As long ago

as the early 1940's, Texas and California ricegrowers experimented with industrial infrared

lights as a heat source for drying rice. By 1948

California workers had reached the conclusion

that infrared rice drying was no faster than convection-type driers, and was not as efficient.^ In

their six experiments, 7,300 B.t.u.'s were required

to remove 1 pound of water from rice, whereas

convection-type sack rice driers then in use were

using 2,000 B.t.u.'s.

^ Unpublished reports from the University of California,

Department of Agricultural Engineering.

Infrared drying of rice has not yet become established commercially but interest continues.

Schroeder {109, 110) and Schroeder and Rosberg

{111^ 112) reported on laboratory rice-drying

experiments. Varieties apparently respond differently. The drying rate for the 15-, 20-, and 25-

second irradiation periods ranged from 1.2 to 1.9

grams of water removed per second of irradiation

for Nato and from 1.3 to 1.6 grams for Magnolia.

Tilton and Schroeder [138) found that rice weevils and lesser grain borers in rough rice could be

controlled by irradiation with infrared lights.

They postulated that using gas-fired infrared

heating for drying rough rice would have the

additional benefit of killing all stages of these

stored-rice insects during the rice-drying process.

In utilizing on-farm bin drying and storing, the

rice farmer is assuming considerable responsibility for items that he pays someone else to assume

when he employs commercial facilities. These

include (1) considerable supervision over a long

period of time to oversee the drying, particularly

if he uses unheated air; (2) greater chance of rice

deterioration; (3) protection of the rice from

insect, bird, and animal pests; and (4) protection against rain or ñood damage. Offsetting

these are usually lower cash outlays per unit volume of rice dried and stored.

Dachtler {23) emphasized that the use of the

proper airflow rate to dry rice with unheated air

is of primary concern in bin drying rice. Air

must be supplied at a rate to complete drying

before the rice is damaged by mold growth or

other causes. Recommendations developed from

tests in the Southern States and in California are

summarized by Dachtler {23). Supplemental

heat is not recommended as a standard practice

for bin drying. However, it is desirable to have

the necessary equipment available for use during

prolonged periods of adverse weather. This normally will include extended periods of high humidity (above 75 percent). The temperature of

the air entering the rice may be raised 10"^ to 15°

F. above the ambient temperature. A maximum

of 95° is recommended in Texas, and a maximum

of 80° to 85° in California. Supplemental heat

should be used until the moisture content of the

top foot of rice is reduced to 15 percent. After

the moisture is reduced to this level, unheated air

should be used to complete the drying to a safe

storage level. During the time unheated air is

used, the fan should be operated only when the

relative humidity is less than 75 percent, which

usually will be during daylight hours on clear,

bright days.

AERATING STORED RICE.—According to Hutchinson and WiUms {60), the practice of aerating

grain came into widespread use in the Southwest

between 1955 and 1960, They indicate aeration

is used (1) to maintain the quality of undried
106 A'JMâCITi;iTJitE HANDBOOK 289, U.S. DEPT. OF AGRICULTURE

grain until it can be moved through the drier, (2)

to remove harvest or drier heat, (3) to remove

small amounts of moisture (1 to 2 percent), and

(4) to maintain the quality of grain during storage. Aeration is defined as the moving of air

through stored grain at low airflow rates (generally between one-tenth and one-fifth cubic feet

per minute per 100 pounds) for purposes other

than drying, to maintain or improve its value.

Several types of aeration systems are described,

as-are methods of operation and controls.

Aldred {10) presented the following conclusions regarding storage and aeration of rice :

(1) Based on information to date (1952), rice

in bulk storage should be turned once every 2

months during the winter and at least once a

month during the summer.

(2) With proper aeration, rice with a moisture

content of IS to 24 percent can be kept for a

week or 10 days without spoilage.

(3) For retaining rice with a moisture content

of 18 to 24 percent before drying, 2 cubic feet

per minute per 100 pounds is adequate. After the

rice has been parth^ dried, one-half cubic foot

per minute per 100 pounds is adequate.

(4) Eice with a moisture content below 16 percent can be kept several months in either cool or

warm weather with the aid of aeration.

As pointed out by Dachtler (¿-i), practically

all rough rice is stored in bulk, although sack

storage is practical for relatively small lots and

for seed rice. A maximum moisture content of

12 percent is recommended for seed rice, but up to

14 percent usually is safe in bulk storage. The

length of the storage period for rice depends on

market conditions, but it usually is from 5 to 8

months. For any common-type storage bin, any

type of construction material is satisfactory if it

results in a storage structure that will keep the

grain dry, cool, and free of insects and other pests

and if it provides job safety and convenience

while moving and inspecting the grain. Dachtler

warned that if dried rough rice is to be stored for

a few months or longer or if damp rice is to be

held before drying, the storage structure should

be equipped for aeration.

IxsECT INFESTATION OF STORED RICE.—Insect

infestation generally occurs after rice is in storage, since most rice han^ested and dried by modern methods is relatively free of insects upon entering storage (23), Insect control practices that

are used before and during storage have been

developed through research and are widely applied. Emphasis now is being placed on the use

of protective treatment. Chemicals are now

available that can be mixed with or sprayed on

the rice as it is stored and that will protect it

against invading insects yet leave no residues

harmful to human beings {108, 11^0), For information about the use of these diemicals, contact

your local agricultural authorities.

Stored rice is subject to attack by a number of

insects. The lesser grain borer {Rhyzopertha

dommwa (F.)), the Angoumois grain moth

{Sitotro^a cerealeUa (Oliv.) ), and the rice Aveevil

{SitophiJ'us oryzcie (L.) ) attack sound rough rice

kernels. The cadelle {Tenehroides mauritanicus

(L.) ), the saw-toothed grain beetle {Oryzat ^hilus

sni'inameiisis (L.) ), the flat grain beetle {Cryptolestes piis'dJus (Schon.) ), the red flour beetle (T'nhoUum castaneum (Herbst)), and the confused

flour beetle {T, confusiwi (Duv.)) attack broken

or dehulled kernels. Moths that infest the surface of Ijulk or bagged rough rice and spin webbing in profusion include the Indian-meal moth

{PJocUa interpuncteIJa (Hbn.) ), the almond moth

{E'phestia cauteUa (Wlkr.)), and the rice moth

{Coreyra eephalonka (Staint.) ). In storing bran

and milled rice, control of the bran bugs, including the flour beetles, is important {108, 11¡.0),

(1)

(2)

Selected References

ANONYMOUS.

1947. RICE DKYING AND STOKAGE IN LOUISIANA. LIL

Agr. Expt. Sta. Bui. 416, 22 pp.

(3)

1949. STOP—DON'T PLANT RED RICE

52(li) : 20.

Rice Jour.

196: Rice Jour. 65(9)

(41

( o )

(6)

(7)

(8)

(9)

(10)

(11 )

(12)

(13)

ADAIR, I

1940

1950.

UNDERGROUND IRRIGATION.

22, 23, ilUis.

C. R.

EFFECT OF TIME OF SEEDING ON YIELD, MILLING QI-^ALITY, AND OTHER CHARACTERS IN

RICE. Auier. Soe. Agron. Jour. 32: 697-70(1

and CRALLEY, E. M.

1949 RICE YIELD AND DISEASE CONTROL TESTS.

Ark. Agr. Expt. Sta. Rpt. Ser. 15, 20 pp.

and ENGLER, KYLE.

THE IRRKiATlON AND CULTURE OF RICE. hi

Water, U.S. Dept. Agr. Yearl)onk of Agr.,

pp. 389-894.

BEACHELL, H. .AI., JODON, N. E., and others.

COMPARATIVE YIELDS OF TRANSPLANTED AND

DH^ECT SOWN RICE. Auicr. Soc. AgroD. Jour.

34: 129-187.

:MTLLER, :M. I)., and BEA( HELL, H. M.

RICE IMPROVEMENT AND CULTURE IX THE

uxriED STATES. Adv. in Agron. 14: 61-108,

illus.

ADDK'OTT, F. T., and LYNCH, R. S.

1957. DEFOLIATION AND DESICCATION : HARVEST-AID

PRACTICES. Adv. in Agron. 9: 67-93.

ALDRED, F. L. (editor).

19o8. RECENT RESEARCH ON DRYING AND STORAGE OF

ROUGH RICE. South. Coop. Ser. Bul. 29, 29

pp., illus.

ANDERSON. K. L., and MCKIE, J. W.

196-!. GROWING RICE IN THE MISSISSIPPI DELTA.

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1959. LAND GRADING FOR SURFACE IRRIGATION. Ark.

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1937. THE UTLLIZATI0N OF WABASK CLAY' ( GUMBO j

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1950. WHEN TO HARVEST RICE FOR BEST MILLING

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1957. GRADING LAND FOR SURFACE IRRIGATION.

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1958. RICE FERTILIZATION. Calif. Agr. Expt. sta.

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1961. GERMINATION INHIBITION IN ORYZA 8ATIVA

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1953. RICE IRRIGATION TESTS AT THE BEAUMONT

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1959. REPLENISHING UNDERGROUND WATER SUPPLIES ON THE FARM. U.S. Dept. Agr. Leaflet

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1954. ECONOMIC APPRAISAL OF FARMING PRACTICES

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1950. COMPAEISON OF FARMING SYSTEMS FOR SMALL

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1951. COMPARISON OF FARMING SYSTEMS FOR LARGE

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1961. AERIAL APPLICATIONS OF GRANI'LAR AND PELLETED MATERIALS AND SEEDS. RICE JOUT.

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1931. PRELIMINARY REPORT ON CULTURAL AND FEK

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1944. ROTATION, CPILTUBAL AND IRRIGATION PRACTICES AFFECTING RICE PRODPCTION. Ark.

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195S. THE EFFECT OF RICE CLOTURE ON A NONSALINE SODIC SOIL OF THE FRESNO SERIES.

Hilgardia 27(12); 319-332, illus

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1959. FACTORS INFLUENCING SALINITY OF SUBMERGED SOILS AND GROWTH OF CALORO RICE.

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1961. THE SALT TOLERANCE OF RICE, Internat!.

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1960. RICE AS A CROP FOR SALT-AFFECTED SOIL IN

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1959 SALINITY EFFECTS AT SEVERAL GROWTH

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1950. CROP ROTATION ON EICF FAr^MS. Alk. A^T.

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1961. IMPEO^^EMENTS IN COMMERCIAL DRYING OF

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1959. WARMING BASINS AND WATER TEMPERATURE.

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1957

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1936. TOXICITT FROM ARSENIC COMPOUNDS TU KI-:E

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1954. RESEARCH ON RICE PRODUCTION IN TEXAíTex. Agr. Expt. Sta. Bui. 775, 29 pp., lllu^^.

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1917. IRRIGATION OF RICE IN CALIFORNIA. Calif.

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1960. CONTROL OF GRAPE COLASPIS AND RICE WATER

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1958. INSECTS ... IN FARM-STORED RICE. Ark

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1960. INFEA-EED DRYING OF ROUGH RICE. II.

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1959.

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1961, PHYSIOLOGICAL FA^;TORS LIMITING GROWTH

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1940. RICE PRODUCTION AND RICELAND USES IN ARKANSAS, Ark. Agr. Ext Serv. Cir. 424,

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1953 THE USF. ot AIRPLANES ON RICE FAEMS IN

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1955. DRYING AND STORING ROUGH RICE IN FARM

STORAGE BINS, 1954-55. Tex. Agr. Expt. Sta.

Prog. Rpt. 1819, 8 pp.

DAVIS, W. C, and HOLLINGSWORTH, J. P.

1948. DRYING RICE IN SACKS. Tex. Agr. Expt.

Sta. Prog. Rpt. 1138, 4 pp.

SPADARO, J. J.

1961. EVALUATION OF WRRL DRYING METHODS ON

SOUTHERN RICE. Second Conf. on Rice Utilization Proc, May 18-19. U.S. Dept. Agr.,

Agr. Res. Serv. ARS 74-24, pp. 22-23.

STANSEL, J. W., HALICK, J. V., and KRAMER, H. H.

1961. INFLITENCE OF TEZ^IPERATURE ON HEADING

DATES AND GRAIN CHARACTERISTICS OF RICE.

Rice Tech. Working Group Proc, June 29

to July 1, Lafayette, La. MP 488, pn

14-15.

STROMBERG, L. K., and YAMADA, H.

1955. WATER Qt^ALITY IN RICE FIELDS. Calif Agr

9(3) : 10.

SLTLLIVAN, K. B.

1960. WATER IS A 'CROP' WITH ROTATION RESERVOIRS. Ark. Farmer 62(8) : 4, illus.

THOMPSON, W. R., and WALLER. T. :S1.

1952. GROWING RICE IN THE MISSLSSIPPI DELTA.

Miss. Agr. Ext. Serv. Pub. 219, 0 pp.

TELTON, E. W., and SCHKOEDER, H. W.

1961. THE EFFECT OF INFRARED RADIATION ON IMMATURE INSECTS IN KERNELS OF ROUGH RICE

Rice J

TLTLLIS, E. C.

1951. HERBICIDES FOR ACCELERATING MATURATION

OF RICE. South. Weed Conf. Proc 4: 1-2.

UNITED STATES DEPARTMENT OF AGRICULTI^RE.

1957. CONTROLLING INSECT PESTS OF STORED KIC E.

U.S. Dept. Agr. Agr. Handb. 129, 30 pp

illus.

(141) WALKER, R. K., and STURGIS, M. B.

1946. A TWELVE-MONTH GRAZING PROGRAM FOR THE

RICE AREA OF LOUISIANA. La. Agr. Expt

Sta. Bui. 407, 19 pp.

(142) WASSERMAN, T., FERREL, R. E., BROWN, A. H., and

SMITH, G. S.

1957. COMMERCIAL DRYING OF WESTERN RICE. CEreal Chem. Today 2(9) : 251-254.

(143) FERREL, R. E,, KAUFMAN, V. F., and others.

1958. IMPROVEMENTS IN COMMERCIAL DRYING OF

WESTERN RICE. I. MIXING TYPE DRYER

LOI^ISIANA STATE UNIVERSITY DESIGN. Rice

Jour. 61(4) : 30-32, 34-36, 38; 61(5) : 40

42-46.

(144) FERREL, R. E., KAUFMAN, V. F., and others.

1958. IMPROVEMENTS IN COMMERCIAL DRYING OF

W^ESTERN RICE. II. NON-MIXING COLUMNARTYPE DRYER. Rice Jour. 61(7) : 9-12 14

(145) WASSON, R. A., and WALKER, R. K.

1955. LOUISIANA RICE. La. Agr. Ext. Serv Ext

Pub. 1182, 16 pp., illus.

(146) WEIHING, R. M., MONCRIEF, J. B., and DAVIS, W. C.

1950. YEARLONG GRAZING IN THE RICE-PASTURE SYSTEM OF FAEMING. Tex. Agr. Expt Sta

Prog. Rpt. 1280, 4 pp.

(147) WILLIAMS, A. H.

1952. PRE-HARVEST DRYING OF RICE BY CHEMICAL

TREATMENT. Down to Earth 8(2) : 2-3

(148) and FINFROCK, D. C.

1962. EFFECT OF PLACEMENT AND TIME OF INCORPORATION OF \^TCH ON RICE Y^IELDS. AgrOD

Jour. 54(6) : 547-549.

(149) FINFROCK, D. C, and MELLER, M. D.

1957. GREEN MANURES AND CROP RESIDUES IN

MANAGING RICE SOILS. Calif. Agr. Expt

Sta. Ext. Serv. Leaflet 90, 6 pp.

(150) WYCHE, R. H., and CHEANEY, R. L.

1955. WATER SEEDING OF RICE. Tex Agr Expt

Sta. Prog. Rpt. 1778, 3 pp.

CAUTION.—If pesticides are handled or applied

improperly, or if unused parts are disposed of improperly, they may be injurious to humans, domestic animals, desirable plants, pollinating insects, fish or other wildlife, and may contaminate

water supplies. Use pesticides only when needed

and handle them with care. Follow the directions

and heed all precautions on the container label.
WEEDS AND THEIR CONTROL

By R. J. SMITH, JR., and W. C. SHAW

Losses in the rice crop clue to Aveed competition

amount to more than $60 million each j^ear. In

addition, farmers spend almost $24: million each

year to control weeds. Among the weeds that

cause severe losses in rice are barnyardgrass

[EchinochJoa spp.), red rice [Oryza sativa L.),

sigiialgrass {Brachiaria spp.), sprangletop {LeptocKloa spp.), sesbania {Seshania exaltata (Raf.)

Cory), curly indigo {Aeschynomene virginica

(L.) B.S.P.), Mexican-weed [Caperonia castaneaefolki (L.) St. Hil.), gooseweed [Sphenodea

zeylanica Gaertn.), redstem {Ammannia coccínea Rottb.), ducksalad [Heteranthem spp.),

bulrush [Scirpus ^^^.)^ umbrellasedge {Cyperus

spp.), spikerush [Eleocharü spp.), and various

species of algae.

Conditions favorable for growth of rice also

are favorable for growth of these weeds. Weeds

in rice produce an abundance of viable seeds; and

once weeds infest the soil, they are difficult to

remove. The best approach to weed control is to

prevent Aveed infestations by seeding weed-free

rice and by removing scattered weed seedlings

from the field before they produce seed. Even

after weeds infest the soil, however, they can be

effectively controlled by selected cultural and

chemical methods.

Weed control is the primary aim of many cultural practices. Herbicides—notably propanil

and the phenoxy herbicides—have been used in

conjunction with good farming practices for controlling weeds and have greatly increased the

effectiveness of the cultural practices. As chemical methods of weed control change—and they

are changing rapidly—cultural practices also will

change.

Certain young grass and broadleaf weeds in

rice were effectively controlled in 1959 bj^ propanil [3,4-dichloropropionanilide]. Propanil is

very selective, and rice is not injured by high

rates applied soon after emergence. In 1961 rice

farmers in the major ricegrowing States used propanil as a postemergence weed killer in commercial fields on about 20,000 acres. Because propanil controlled grass weeds so effectively in 1961,

and because it was recommended by the agricultural experiment stations in Arkansas, Mississippi, and Texas, rice farmers treated approximately 250,000 acres in 1962. Overall, goodytoexcellent grass and weed control and significant

improvement in rice yields were obtained in more

than 90 percent of the fields treated in 1962.

Propanil controls barnyardgrass, including

the species EchinochJoa cmsgaUi (L.) Beauv., E,

colonum (L.) Link, and E. cmispavonis (H.B.K.)

Schult.; and other grasses, including crabgrass

{Digitaria spp.), Texas-millet {Paniciim texanum

Buckl.), paragrass {P. puiyurascens Raddi), and

signalgrass {Brachiaria spp.). Propanil also controls certain young annual broadleaf weeds including sesbania, curly indigo, gooseweed, and

redstem; and young annual sedges, including

spikerush, umbrellasedge, and Fimhristylis spp.

Propanil controls all these weeds most effectively

when they are in the early vegetative stage of

growth.

Propanil kills the cells of grass-weed and

broadleaf-weed plants by contact action. It is

usually applied when both the weeds and the rice

are in the early stages of development. Barnyardgrass and other grass weeds are controlled

most eft'ectively when propanil is applied in the

2- to o-leaf stage, or when the grass is 2 to 3

inches tall. However, rapidlj^ growing grass

weeds in highly fertile soil and deep water may

be controlled satisfactorily when the grass weeds

have four or more leaves,

Propanil should be applied according to the

developmental stage of the grass weed rather than

that of the rice. However, a reasonably heavy

stand of rice should be growing before treatment;

otherwise if replanting is necessary, the effectiveness of the herbicide is lost.

Irrigation stimulates the .?:rowth of grass weeds

and makes them more susceptible to propanil, but

water should not be standing on fields when propanil is applied because propanil cannot reach

weeds covered with water. Fields treated with

propanil should be flooded 1 to 4 days after treatment to increase the activity of the herbicide on

barnyardgrass and to prevent barnyardgrass and

other grass-weed plants from reinfesting the field.

Propanil may be applied with either ground or

aerial equipment. Aerial equipment has the

advantage because fields may be sprayed when

the soil is too wet to support- ground equipment,

and also levees do not present a problem as with

ground equipment. The spray solution of propanil should cover the weeds adecjuately and uniformly but should not be allowed to drift onto

nearby areas where it can injure field crops such

111
112 MnacuvrvKï^ HANDBOOK 289, u.s. DEPT. OF AGRICULTURE

as cotton nnd soybeans and certain horticultural

and ornamental plants. Young cotton and soybean plants are susceptible to propanil mitil they

are 8 to 10 inches tall and can be killed or injured

severely enou^ih to reduce yields greatly.

Postemergence treatments with phenoxy herbicides control most broadleaf and aquatic Aveeds

and many sedges that infest rice. Grass weeds

are not controlled. Phenoxy herbicides are often

used by commercial ricegrowers, and more thaii

half of the rice crop in the United States is

sprayed each year for broadleaf-weed control.

Phenoxy herbicides used for controlling broadleaf weeds in rice include 2,4-D [2,4-dichlorophenoxyacetic acid], MCPA [2-methyl-4-chlorophenoxyacetic acid], 2,4,5-T [2,4,5-trichlorophenoxyacetic acid], and silvex [2-(2,4,5-trichlorophenoxy)propionic acid]. These herbicides are

applied as either amine salt or low-volatile ester

formulations at rates of i/o ^^ IV2 pounds per acre

acid equivalent. The rate depends on the weed

species and the stage of growth of the rice.

Response of rice to phenoxy herbicides is affected chiefly by the stage of development of the

rice plant. ^Very young rice is injured severely

or even killed by^ 2,4-D, MCPA. 2,4,5-T, and

silvex. Rice in late-jointing, boot^ing. or heading

stages may be injured severely, üice 111 ine latrtillering or prejointing stages is usually uninjured by phenoxy herbicides. Rice responds

differently to these various postemergence herbicides. It^ is most ^^tolerant^' to 2,4,5-T, less '^tolerant'' to silvex and MCPA, and least ^^tolerant'^

to 2,4-D.

Weeds also respond differently to 2,4-D,

MCPA, 2,4,5-T, and silvex. When several species varying in susceptibility to a herbicide are

present 'in one ricefiekh mixtures of phenoxy

herbicides may be used advantageously. Weeds

are usually most susceptible to phenoxy herbicides when they are young and growing rapidly.

Therefore, it is important to treat weeds as soon

as the rice is adequateh^ ''tolerant" to the herbicide—usually about 7 weeks after rice emerges.

Water management affects the response of

weeds to phenoxy herbicides. Herbicides are

less effective in reaching weed plants that are

covered by water, and herbicides cannot effectively control weeds that are growing slowly because of dry soil. Therefore^ herbicides should

be applied soon after draining, while weeds are

o-rowing rapidly. If the field is flooded too soon

after spraying or if rain falls immediately after

spraying, 'the herbicide is washed off the weed

plants and cannot control their growth.

Phenoxy herbicides are sprayed uniformly to

the field with low-gallonage sprayers attached to

ground or aerial equipment. Care must be taken

not to injure other crops such as cotton, soybeans, and tomatoes and valuable trees, shrubs,

and ornamental plants. All major rice-producing States strictly regulate aerial applications of

phenoxy herbicides. Most States regulate ground

applications. These laws prohibit the use of

high-volatile esters of 2,4-D, MCPA, 2,4,5-T, and

silvex. Definite regulations as to equipment,

herbicide formulations, wind velocity, records,

responsibility, and liability must be observed.

Before spraying rice with postemergence herbicides, farmers and custom applicators should become familiar with State laws so they can comply with them.

CAUTION.—Before being used for applying insecticide or fungicide, spray equipment that has been used

for applying 2,4-D, 2,4.5-T, MCPA, or silvex should be

given a special cleansing with ammonia or with actiyaied charcoal and detergent. For detailed instructions, consult your State extension weed specialist.

Certain algae maj^ be controlled with applications of small copper sulfate crystals applied in

the early stages of scum development. Differences in the species of algae and in local water

and soil conditions determine the amount of control possible. Copper may be toxic to fish, so

care must be taken if water from treated ricefields is collected in reservoirs containino; fish.
RECE DISEASES

Bv J. (T. ATKINS

Rice diseases are economically important in

the rice crop in the southern rice area (o).^ Except for seedling disorders, these diseases are of no

importance in California. Annual losses in Louisiana and Texas average about S percent. Diseases are important in rice, but they are not as

disastrous in rice as in many other crops. Although average losses in most fields are rather

low, losses in individual fields from specific diseases are sometimes high.

Most of the world's important rice diseases are

known to occur in the Ignited States. Exceptions are the rice dwarf and rice stripe viruses,

bacterial leaf blight, and certain physiological

disturbances reported from Japan and other Asiatic countries. A few^ minor diseases caused by

fungi are also not known to occur ni the United

States.

The severity of specific diseases is influenced by

varietal susceptibility, fertilization, soil type, and

environmental conditions. Losses from certain

diseases can be reduced or held to a low level by

the use of resistant varieties, better cultural and

management practices, and seed treatment. Diseases shift in prevalence and severity with

changes in varieties. The reaction of 18 rice

varieties to some diseases in the ITnited States

are shown in table 19.

TABLE 19.—Reaction of rice varieties to some diseases of rire in the United States

[R = resistant; MR = moderately resistant; ]\IS = moflerately susceptible; S = susceptible; VS = very susceptible]

Grain type and variety Blast Browm leaf

spot

Narrow brown

leaf spot Straighthead White tip Hoja blanca

Sîiort-èTain :

Caloro S

S

S

s

VS

R, S

S

s

s

R, S

S

MS

S

s

MS

S

s

s

S

S

MS

S

MS

MS

MS

MS

S

MS

S

S

s

s

s

s

s

s

S

S

S

s

MS

R

S

MS

S

s

S

s

MS

y S

s

VS

MS

MS

S

S

S

s

s

s

s

MS

MR

S

R

R

VS

VS

VS

R

R

VS

S

S

S

VS

VS

s

s

s

s

s

R

R

R

R

R

R

R

R

S

Cody

Colusa

S

R

MediurD-grain : Arkrose R

Cairose S

Gulfrose R

MagnoUa S

Nato S

Northrose

Zenith

MR

S

Long-grain ;

Belle Patna S

Bluebonnet 50

Century Patna 231 __

Rexoro

S

s

s

Sunbonnet

Texas Patna

Toro

TP 49

s

s

s

s

Major Diseases

Slast

Blast, caused by the fungus Piricidaria oryzae Cav., occurs in all ricegrowing areas of the

world and is the most damaging disease of rice

(fig. 39). Blast in the United States is about as

old as the rice crop itself—it caused trouble

1 Italic numbers in parentheses refer to Selected References, p. 120.

shortl}^ after rice was introduced into South

Carolina [M) and then into Louisiana [18).

Losses from blast were light from about 1985 to

1955; however, in the southern rice area, particularly Louisiana, seriously infested fields have

l)een found each year since *1955 (5). Blast has

Ijeen one of the chief factors in preventing successful rice culture in southern Florida»

When the fungus attacks the leaves, the disease results in leaf blast. Symptoms are elono-ated or spindle-shaped leaf spots with grayish

113
114 AGRICULTURE HANDBOOK 289, U.S. DEFT. OF AGRICULTURE

FIGURE 39.—The long, narrow spots on the leaves and the

infection at the hase of the panicle, which caused it to

break over, are typical symptoms of blast. (Photo courte.sy of G. E. Templeton. )

centers and brown margins. Under severe disease conditions, nearly all leaves are killed and

many young plants are killed or severely damaged. Young plants are also killed by infection

of the sheath tissues, which turn brown. Generally, all plants in a ricefield are not uniformly

affected. In some areas the plants are killed,

but in others they are affected less severely.

The leaves are susceptible from the seedling

through the early-tillering stage of growth. Under flooded soil conditions, the leaves are less

susceptible in the late-tillering stage of growth

and at heading. As a result, severely diseased

fields of young rice appear to recover later when

the plants become older and progress through

the vegetative growth stages.

Head blast, also called rotten neck, results

from the attack of the fungus after emergence

of the panicle (head) from the boot or top leaf

sheath. The peduncle (the top node and internode) and the branches of the panicle are very

susceptible to attack. Typically, the peduncle

shows a necrotic, brown area that prevents movement of food into the developing grain. The

grain produced in affected panicles varies from

nearly normal amounts to none, depending on

the time of infection in relation to flowering.

As infection weakens the structural tissues of

the peduncle, the panicles frequently break over

to give the condition known as rotten neck.

Atmospheric moisture conditions are of primary importance in infection and spread of the

fungus that causes blast (19). Frequent rains,

heavy nightly dews, and high relative humidities

favor disease development. Severe outbreaks of

the disease occur after periods of rainy weather.

Eice plants under high levels of nitrogen fertilization are susceptible to blast. Plants growing under nonflooded or upland conditions are

more susceptible than those growing under

flooded or irrigated conditions {19). For this

reason, blast is often heavier on the levees and

on or around knolls or other high areas in the

ricefield than it is on the low areas.

All United States rice varieties are susceptible

to one or more of the 10 pathogenic races of P.

oryzae known to occur in the southern rice area

(^, 20). However, Rexoro, Texas Patna, and TP

49 usually escape infection because they are late

maturing. Under average field conditions. Bluebonnet 50 and Sunbonnet are less severely infected than are several other varieties, and losses

are lighter. Arkrose, Caloro, Calrose, Colusa,

Nato, and Northrose are consistently susceptible.

Gulfrose and Zenith are resistant to most races.

The reaction of 18 varieties to 10 races is given

in table 20.

Brown Leaf Spot

Brown leaf spot of rice is caused by HelminthosfO'ñum oi^zae B. de Haan, the same fungus

that causes seedling blight. The spots occur

chiefly on the leaves but are frequently on the

hulls (fig. 40). The leaf spots are oval to circular and grayish brown to black.

Brown leaf spot is prevalent in the southern

rice area. Under good cultural conditions, damage is slight on vigorous plants. Weak plants

with yellowish leaves, caused by low nitrogen

levels, root damage, or other factors unfavorable

for good nitrogen nutrition, are often severely

damaged by brown leaf spot.

All commercial rice varieties are susceptible to

brown leaf spot. Bluebonnet 50 is generally

more susceptible than are most other varieties.

Management and fertilizer practices that promote good growth reduce losses.

Narrow Brown Leaf Spot

Narrow brown leaf spot in rice, caused by the

fungus Cercospora oryzae I. Miyake, is one of

the most prevalent rice diseases in the southern

rice area. The leaf spots are narrow or linear

and light to dark brown (fig. 41). When severe, the leaves die, one after another, beginning

with the lower leaves. In most seasons, infection does not become severe until late August or

September. Early-maturing rice varieties, when

sown early, tend to escape heavy infection.

Rice varieties show marked differences in susceptibility. Several pathogenic races or strains

of 0. oryzae occur in the United States [îS).

Bluebonnet 50, Rexoro, and Texas Patna are

susceptible varieties. Under average field conditions. Century Patna 231, Gulfrose, Nato, Toro,

and TP 49 are fairly resistant.
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 115

TABLE 20.—Reaction of rice varieties to the races of Piricularia oryzae Cav. in the United States

[R = resistant : MR = moderately resistant ; S = susceptible]

Grain type and variety

Short-grain :

Caloro

Cody

Colusa

Medium-grain :

Arkrose

Calrose

Gulfrose

Magnolia

Xato

Xorthrose

Zenith

Long-grain ;

Belle Patna

Bluebonnet 50

Century Patna 231-

Rexoro

Sunbonnet

Texas Patna

Toro

TP49

Race

R

R

R

R

R

S

R

R

R

S

S

s

s

s

s

s

s

s

s

MR

S

s

s

R

R

R

S

R

R

R

R

R

R

R

R

R

S

S

s

s

s

R

S

s

s

R

S

s

s

s

s

s

s

s

s

s

s

s

s

R

R

R

S

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

S

S

S

s

s

R

S

s

s

R

S

s

s

s

s

s

s

s

s

s

s

s

s

s

s

s

s

s

s

MR

s

s

s

s

s

s

s

s

s

s

R

R

R

R

R

S

R

R

S

S

s

s

s

10

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

R

16

R

S

S

S

R

R

S

R

R

R

S

R

FiGUEE 40.—Oval to circular lesions on rice leaves are

symptoms of brown leaf spot.

II.

'4'

ä J

FIGURE 41.-

Root Rot

-Linear lesions on rice leaves are symptoms of

narrow brown leaf spot.

Root rot of rice is a general diseased condition in which the roots grow poorly, darken with

necrosis, or die. As decay progresses, the leaves

cease to grow normally and turn yellow. Affected plants generally show heavy brown leaf
116 AGRICULTURE HANDBOOK 289, U.S. DEFÏ. OF AGRICULTURE

spot because of their impaired physiological

condition.

Several soil fungi may cause root rot. Damage

is more severe when nematodes and. root maggots feed on the roots. Plants growing ni sahne

soil and alkali spots in ñelds are also affected.

Losses from root disorders can be held to a

mimmum through good cultural and fertilizing

practices that maintain the plants in a vigorous

condition. Draining the field and permitting the

soil to dry stimulates growth of new roots. For

many years growers have used this ]:iractice to

control' root maggots and straighthead hi conjunction with topdressing applications of nitrogen.

Seedling Bligh*)

Fungi in the soil and on or in the seed cause

seedling blight of rice (fig. 42). These fungi

reduce emergence and kill or weaken tlie plant

after emergence. Low soil temperature and high

soil moisture, combined with seedlwrne fungi, or

combinations of tne two, make stand establishment difficult.

Satisfactory stands are generally obtained

through use of good-quality seed treated with a

fungicide and seeded under conditions favorable for rapid emergence. Atkins, Cralley, and

Chilton (7) reported that thiram, chloranil,

dichlone. and a number of organic mercuii'S gave

best results. Seedling blight caused by Helmmthospor/iim nryzne—the fungus that causes

brown leaf spot—can be partly controlled by

using one of the mercury fungicides. Each of

the chemicals listed is available m différent

preparations.

WARNING

The materials recommended here for treating rice

seed should be considered poisonous to man and animals. Care should be taken in handling and using

them. Read the label placed on each container by the

manufacturer and follow his instructions regarding

safet}' measures. All workmen operating seed-treating

equipment should be carefully taught how to use the

chemicals and should be warned against carelessness.

Sacks of treated seed should always be properly labeled. Care should be taken to prevent any treated

seed from being used as food or feed.

Stem Rot

The stem rot fungus Leptospluteriu salvinU

Catt. {Sderothim oryzae C'att.) lives in the soil

as sclerotia from one season to another up to 6

years (SO) (fig. 4?,). Typically, rice plants are

attacked in the advanceil-growth stages. Initially, the fungus invades the sheath tissues near

the water level and produces dark areas. The

FIGURE 42.—Three blighted rice seedlings and, at right,

a healthv seedling.

FIGURE 43.—Rice culms showing sclerotia of the stem

rot fungus. (Photo courtesy of G. E. Templeton.)
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 117

ñuigus progresses inward to the culm. The

nodes aucl internodes turn dark and weaken.

Many of the plants lodge because of rotten culms.

The plants are weakened or killed before maturity. Little gi-ain is produced and its quality

is reduced.

None of the rice varieties are highly resistant

to stem rot {H). Rexoro is jjerhaps the most

susceptible variety. Some of the medium-grain

varieties are resistant or intermediate in reaction.

The early-maturing varieties tend to escape severe damage if seeded early. High rates of

nitrogen fertilizer increase the susceptibility of

plants to stem rot damage, but potassium fertilizers reduce damage.

Straighthead

Straighthead, sometimes called blight, is a nonparasitic or physiological disease of rice. Diagnostic symptoms are observed only in the panicles.

The panicles remain upright at maturity because

of lack of grain development (fig. 44) ; hence,

the common name of straighthead. The shape

of the palea and lemma, which later form rhe

hulls, is distorted, particuarly in the long-grain

varieties. It is similar to a parrot beak, crescent,

or half moon. Hull distortion may or may not

be conspicuous in the short- and medium-grain

varieties.

Straighthead is caused by unknown soil conditions associated with prolonged submergence

of the soil with water. TJndecayed organic material and arsenic in the soil are also factors. In

general, rice grown on the lighter or sandy soils

is more subject to straighthead than nee grown

on the heavier clay soils.

For many years, ricegrowers have followed the

practice of draining and drying the soil to prevent straighthead {'27). The fields are drained,

dried, and reflooded just before panicle formation. This period is about 50 days after seedling

emergence for Century Patna 2.31, a susceptible,

early-maturing variety [1^). However, the best

control measure is to use resistant varieties.

The numerous rice varieties have been classified as to straighthead reaction [6). Belle Patna,

Bluebonnet 50, Lacrosse, Texas Patna, and Toro

are resistant. Nato is intermediate in reaction

and is seldom affected.

White Tip

White tip of rice is caused by an ectoparasitic,

foliar nematode, Aphelenchoides hevseyl Christie

(fig. 45). The nematodes are seedborne and live

from one crop to the next in the seed rice. After

rice is sown, the nematodes become active and

move into the growing point of the young rice

plants. In this protected location, the nematodes

feed and reproduce. The feeding by large numbers of nematodes injures the developing leaves

and panicles before emergence. The nijury is

later observed as white, necrotic leaf ú\y?> and

small, usually sterile panicles. Grain yields in

susceptible plants are greatly reduced.

Several methods may be used to control white

PiGUBE 44.—Erect panicles with sterile florets are typical of rice plants affected with straighthead.

FIGURE 45.—Left, healthy rice panicle; right, panicle

affected with white tip.
118 AGRICULTURE HANDBOOK 2 8 9, U.S. DEPT. OF AGRICULTURE

tip Resistant varieties or nematode-free seed

may be sown. Cralley (16) and Todd and Atkins (S5) have described hot-water treatments

that control white tip very effectively. They are

not practical for general use. However, they

can be used by the rice experiment stations for

treating small lots of base seed used in foundation seed programs. Emergence through water

following water seeding controls white tip (16).

This practice can also be used to clean up small

lots for seed production.

Several rice varieties are resistant to white tip

(table 1). In general, the long-grain varieties

are resistant and most of the short- and mediumgrain varieties are susceptible (12). Although

white tip was an economically important disease in the southern rice area for many years, it

is no longer important.

Minor Diseases

Bordered Sheath Spot

Bordered sheath spot in rice is caused by

Rhizoctonia oryzae Ryker & Gooch. The sheath

spots are large, 2 to 6 centimeters long, and frequently encircle the sheath. The margins of the

spots are reddish brown. During wet weather,

the leaves of rice plants in small areas, 2 to 6

feet in diameter, are killed by Rhizoctonia spp.

Hoja Blanca

Hoja blanca, or white leaf, is a virus disease

of rice that is transmitted by a planthopper,

Sogata orizicola Muir. Leaf symptoms are one

or more white stripes along the leaf blade or a

whitening of the entire leaf blade (fig. 46).

Diseased plants are generally reduced in height.

The panicles are reduced in size and often fail

to emerge completely from the boot. The palea

and lemma are generally distorted in shape and

later turn brown. Most florets are sterile. Since

the diseased plants produce few, if any, seed, the

panicles remain upright instead of bending over

like those of normal plants (fig. 47).

Hoja blanca occurs only in the Western Hemisphere. Leaf symptoms are similar to those of

the stripe virus disease of Japan, but the two

diseases differ (5). Hoja blanca was first recognized as a new rice disease in 1956 {2). Severe

yield losses were reported from Cuba, Venezuela,

"and other countries of Latin America. The disease and insect vector were found in 1957 in

f'lorida (5), in 1958 in southern Mississippi (iO),

and in 1959 in Louisiana {11). An eradication

program was initiated after each finding of the

insect vector. In 1960 and 1961, neither the disease nor the insect vector was found in the southern rice States. In 1962, ,6'. orizicola was again

found and collected in southern Louisiana \l).

Yield losses from hoja blanca in the United

States have been negligible. LTnless the disease

and insect vector become established and cause

economic losses, no control measures need be conFiGUEE 46.—Rice leaves affected with hoja blanca. FiQUEE 47.—Rice panicles affected with hoja blanca.
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 119

sidered by individual rice producers. Arkvose,

Colusa, and Gulfrose are resistant to hoja blanca.

Kernel Smut

Kernel smut of jice is caused by one of the

smut fungi, Neovossici harclayana Bref. (SI).

Part or all of the endosperm is replaced by a

black mass of smut spores (fig. 48). One to several grains per panicle are affected. Other plant

parts are not affected. The disease is easily overlooked in the field. It can be seen when rains

wash the black spores over portions of the panicle or when the smut spore mass expands between

the two hulls with absorption of moisture from

dew or rain.

The black smut spores germinate and produce

sporidia. When the rice flowers open at pollination, the sporidia enter. The fungus then invades

the developing grain, grows, and produces its

spores. Infection is not systemic in the rice

plant, as it is with several other cereal smut fungi

{2I^). Although the smut spores are seedborne

(that is, they are carried into a field along with

the seed), they are not directly responsible for

later smut infection. Kernel smut is more prevalent in rainy seasons and in fields receiving fairly

high rates of nitrogen fertilizer {"25). Nitrogen

applied late in the season also increases the incidence of kernel smut.

No satisfactory controls for kernel smut are

known at present. Seed treatment by chemicals

or hot water is ineffective. All long-grain varieties are susceptible. Most of the medium-grain

Strunk) Clemoryzae are the

[29). Feeding

varieties, except Nato, generally show less kernel

smut.

Kernel Spots

Discolored or dark areas and spots occur on

the kernels of brown and milled rice. This kernel discoloration is generally associated with

dark, discolored hulls. Ourvularia lunata

(Wakk.) Boed., Fusarium spp., Altemariaj.p]).,

Trichoconis caudata (Appel &

ments, and Helminthosporium

fungi most commonly isolated , - ,

punctures of the immature grains by stink bugs

also cause kernel spots {17).

At the time of some of the earlier studies

{21, 26. 29), rice was binder harvested and

placed in shocks. The change in harvesting

methods from the binder to the combine has

probably reduced losses from kernel spots.

Leaf Smut

Leaf smut, caused by EntyJoma oryzae H. & P.

Syd., is a common but minor rice disease in the

southern rice area (fig. -19). The disease may be

recognized by numerous, small, black sori on the

leaves. The disease becomes more prevalent as

the rice plants approach maturity.

i '<

Í

FiouKE 48.—Rice panicle with several florets affected by

kernel smut.

j

P^ ' '

1 •! \

.ñ,

FiGUBE 49.—Leaf smut on rice leaves.
120

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

(12)

(13)

(14)

(15)

A';mTr'Fi;nTKE HANDBOOK 2 89, U.S. DEFT. OF AGRICULTURE

Selected References

ANONYMOUS

1962. INSECT CAKKIER OF HOJA BLANCA KICK DISEASE BEAPPEARS IN LOUISIANA. Rice Jour.

65(12) : 22.

ADAIK, C. R., and INGRAM, J. W.

1957. PLANS FOR THE STUDY OF HOJA BLANCA—A

NEW RICE DISEASE. Rice Jour. 60(4) : 12.

ATKINS, J. G. _ ,

1958. RICE DISEASES. U.S. Dept. Agr. Farmers

Bui. 2120, 14 pp.

1962. PREVALENCE AND DISTRIBUTION OF PATHOGENIC RACES OF PIRICITLARIA OEYZAE IN THE

UNITED STATES- Pîiytopathology 52 : 2.

and ADAIE, G. R.

1957. RECENT DISCO\^RY OF HOJA BLANCA, A NEW

RICE DISEASE IN FLORIDA, AND VARIETAL RESISTANCE TESTS IN CUBA AND VENEZITELA.

Plant Dis. Rptr. 41: 911-915.

BEACHELL, H. M., and CRANE, L. E.

1956. REACTION OF RICE VARIETIES TO STRAIGHTHEAD. Tex. Agr. Expt. Sta. Prog. Rpt.

1865, 2 pp.

CRALLEY, E. M., and CHILTON, S. J. P.

1957. UNIFORM RICE SEED TREATMENT TESTS IN

ARKANSAS, LOUISIANA, AND TEXAS. Plant

Dis. Rptr. 41: 105-108.

GOTO, K., and YASITO, S.

1961. COMPARATIVE REACTIONS OF RICE VARIETIES

TO THE STRIPE AND HOJA BLANCA VIRUS

DISEASES. Internl. Riœ Conin. Newsletter

10Í4) : 5-8.

JoDON, N. E., and BOLLICH, C. N.

1962. TESTING AND BREEDING FOR BLAST-RESISTANT

RICE. La. Agr 5(4): 14-15.

KRAMER, J. P., and HENSLEY. S. D.

1958. HOJA BLANCA AND ITS INSECT VECTOR FOUNT

ON RICE IN A SECOND AREA IN THE UNITED

STATES. Plant Dis. Rptr. 42: 14Ui

XEWSO^í. L. D., SPINK, W. T.. and others,

1960. OCCl^RRENCE OF HOJA BLANCA AND ITS VECTOR, SOGATA ORIZICOLA MUIR, ON RICE IN

LOUISIANA. Plant Dis. Rptr. 44: 390-393.

and ToDD, E. H.

1959. WRITE TIP DISEASE OF RICE. TIT. YIELD

TESTS AND VARIETAL RESISTANCE. PhytOpatholog^^ 49 : 189-191.

CHEANEY, R. L.

1955. EFFECT OF TIME OF DRAINING OF RICE ON THE

PREVENTION OF STRAIGHTHEAD. TeX. Agr.

Expt. Sta. Prog, Rpt. 1774, 5 pp.

CRALLEY, E. M.

1936. RESISTANCE OF RICE VARIETIES TO STEM ROT.

Ark. Agr. Expt. Sta. Bui. 329, 31 pp.

(16)

(17)

(18)

(19)

(20)

(21)

(22)

(23)

(24)

(25)

(26)

1949. WHITE TIP OF RICE.

pathology 39: 5.

(Abstract) Phyto1956. A NEW CONTROL MEASURE FOR WHITE TIP.

Ark. Farm Res. 5(4) : 5.

DOUGLAS, W. A., and TULLíS, E. C.

1950 INSECTS AND FUNGI AS CAUSES OF PECKY

RICE. U.S. Dept. Agr. Tech. BuL 1015, 20

PPFULTON, H R.

1908 DISEASES AFFECTING RICE IN LOUISIANA. LA.

Agr. Expt. sta. Bul. 105, 28 pp.

KAHN, R. P., and LIBBY, J. L.

1958. THE EFFECT OF ENVIRONMENTAL FACTORS AND

PLANT AGE ON THE INFECTION OF RICE BY

THE BLAST FUNGUS, PIRICULARIA OEYZAE.

Phytopathology 48: 25-30.

LATTEEELL, 'FRANCES M., TULLíS, E. C, and COLLIER, J. W.

I960 PHYSIOLOGIC RACES OF PIRICULARIA ORYZAE

CAV. Plant Dis. Rptr. 44: 679-683.

MARTIN, A. L., and ALSTATT, G. E.

1940. BLACK KERNEL AND WHITE TIP OF RICE.

Tex. Agr. Expt. Sta. Bui. 584, 14 pp.

METCALF, H.

1906. A PRELIMII^AEY REPORT ON THE BLAST OF

RICE WITH NOTES ON OTHER RICE DISEASES.

S.C. Agr. Expt. sta. Bui. 121, 48 pp.

RYKER, T. C.

1943. PHYSIOLOGIC SPECIALIZATION IN CERCOSPORA

ORYZAE, Phytopathology 33 : 70-74.

TEMPLETON, G. E.

1961. LOCAL INFECTION OF RICE FLORETS BY THE

KERNEL SMI^T ORGANISM, TILLETIA HÓRRIDA.

Phytopathology 51 : 13(V131.

JOHNSTON, T. H., and HENRY, S. E.

1960. KERNEL SMUT OF RICE Ark. Farm Res.

9(6) : 10.

TiSDALE, W. K.

1922. SEEDLING BLIGHT AND STACK-BURN OF RICE

AND THE HOT-WATER SEED TREATMENT. U.S.

Dept. Agr. Dept. Bui. 1116, 11 pp.

and JENKINS, J. M.

1921. STEAIGHTHEAD OF RICE AND ITS CONTROL.

U.S. Dept. Agr. Farmers' BuL 1212, 16

pp.

ToDD, E. H., and ATKINS, J. G.

1959. WHITE TIP DISEASE OF RICE. II. SEED TREATMENT STUDIES. Phytopathology 49: 184-

188.

TULLíS, E, C,

1936. FUNGI ISOLATED FROM DISCOLORED RICE KERNELS. U.S. Dept. Agr. Tech. Bui. 540, 11

pp..

and CRALLEY, E. M.

1941. LONGEVITY OF SCLEROTIA OF THE STEM-ROT

FUNGUS LEPTOSPHAERIA SALVINII. PhytOpathology 31: 279-281.

(31) and JOHNSON, A. G,

1952, SYNONYMY OF TILLERTIA HÓRRIDA AND NEOvossiA BAEci^YANA. Mycologla 44: 773-

788.

(28)

(29)

(30)
INSECTS AND THEIR CONTROL

By TRAVIS EVERETT

Rice Water Weevil

The rice water weevil {L/sso)'hopfnts oryzophilvs Kuschel) occurs in most of the ricegrowing areas of the United States. The adult

weevil (fig. 50) is grayish brown and about oneeighth inch long. It overwinters in finely matted

grasses growing in the vicinity of ricefields. In

the spring it migrates into the ricefields and

feeds on newly emerged plants, making slitlike,

longitudinal feeding scars on the upper surface

of the leaves. Eggs are laid in the leaf sheaths

of rice plants. Larvae feed on the roots of rice

plants and cause severe injury by pruning the

root svstem. The voung larvae, or root maggots

as they are commonly called, are milky white,

legless, and about one-half inch long when fully

grown.

Since the innnature stages of the rice water

weevil are spent entirely under water among the

rice roots, many of the larvae may be destroyed

by drainage (6).^ However, this practice is not

recommended for controlling the root maggots

because it is unreliable and also impractical in

areas where water supplies are not abundant.

1 Italic numbers in parentheses refer to Selected References, p. 124.

The rice water weevil can be effectively controlled with insecticides.

Rice Stink Bug

Practically all ricefields in Arkansas. Louisiana, and Texas are infested with tlie rice stijik

bug (Oebalufi pugnax (Fabricius) ). The adult

stink bug (fig. 51) is a straw-colored, shieldshaped insect about one-half inch long. It passes

the winter as an adult in the refuse near the surface of the ground in clum])s of grass. It emerges

from winter quarters in the spring and feeds on

grasses and sedges. Two or tliree generations

may be produced tliere before it migrates to rice

soon after the rice begins to head. The eggs,

shaped like short cylinders, are deposited on the

leaves, stems, or heads of the rice, on grass, on

Mexican-weed, and on other weeds. The eggs

are usually laid in clusters of 10 to 40 in 2 rows,

FIGURE 50.—Adult rice water weevil. riGURE 51.—Adult rice stink bug.

121
122 AGRICULTURE HANDBOOK 289, U.S. DEFT. OF AGRICULTURE

are green when first laid, and change to reddish

black before hatching. The freshly hatched

nymph is nearly round, about IV2 millimeters

long and 1 millimeter wide. The head, thorax,

legs, and antennae are black; the abdomen is red

with two elongate black spots running crosswise.

The young stink bugs remain together near the

eggshells until after the first molt. Then they

seek separate feeding places, generally on grass

or on rice panicles, where they suck the juice

from the developing kernels. Feeding in the

milk stage of rice produces empty glumes, whereas feeding in the soft-dough stage causes "peckiness" of grain or seed sterility (4-)-

Since infestations build up on grasses earlier

in the season, control of grasses in the field and

mowing the areas around the field help reduce

the potential population for infesting rice. Two

hymenopterous egg parasites, Ooencyrtus anasae

(Ashm.) and Telenomus podIs/ Ashm., are at

times very helpful in reducing stink bug populations late in the season.

Grape Colaspis

The grape colaspis [Maecolaupis fa vida

(Say)), called lespedeza worm by ricegrowers,

sometimes reduces plant stands severely in Arkansas and Louisiana (9). It passes the winter in

the young larval stage. In the spring the larvae

make their way toward the soil surface where

they feed on germinating seeds or seedlings.

Heavy infestations may reduce stands so severely

that reseeding is necessary. The larvae pupate

in the soil and emerge as pale brown, elliptical

beetles about one-eighth inch long. Adults of

the grape colaspis lay their eggs in the soil

around the roots of grasses growing in lespedeza

or other leguminous crops. Rice planted following these crops is subject to damage.

Other Pests of Rice

Several otner pests occasionally cause serious

damage to rice.

The rice leaf miner {HydreUia gríseola var.

scapula.vs Loew) is a pest of rice in California

(7). Maggots of this fly feed in the leaves of

young rice plants and destroy the leaf tissue.

Infested leaves turn brown and lie prostrate on

the water. This pest is seldom present in sufficient numbers to warrant control measures.

Gra.sshoppers are found in nearly all ricefields

but seldom are present in sufficient numbers to

cause severe damage (í2). They feed on the

leaves, culms, and grain of rice.

Sporadic outbreaks of the fall armyworm

{^podoptera jrugiperda (J. E. Smith)) (fia 50)

have been recorded at irregular intervals and ni

PiGUKE 52.—Fall armyworm : A, Male moth ; B, right

front wing of female moth ; C, moth in resting position ; D, pupa ; E, full-grown larva. A, B, D, E about

X 2 ; C Slightly enlarged.

widely separated localities. It feeds on leaves

and stems of unflooded rice. Submerging the

rice crop is usually effective in controlling this

insect.

The rice stalk borer {Chilo plejadeUus Zincken)

(fig. 53) and the sugarcane borer {Diatraea saccharaUs (Fabricius) ) (fig. 54) both occur in riceFiQUEE 53.-Rice stalk borer: A, Adult; B, larva.

About X 3.
RICE IN THE UNITED STATES : VARIETIES AND PRODUCTION 123

IS

FiQtTRE 54.—Adult female sugarcane borer.

fields in Louisiiinii and Texas {S). These borers

tunnel inside the stem throughout the growing

season and interfere with normal growth and

development of the plant. They may also weaken

the stem so that it breaks off" or lodges before

harvest. Stalk borer damage is first noticeable

on the rice plant at time of heading when sterile

heads with white panicles, or white heads as they

are commonly called, appear. The eggs of both

species of borers are parasitized by the minute

wasp (Trichogramma minutum Riley), which

helps reduce insect populations. Plowing under

rice stubble in the spring destroys some of the

overwintering borers. Grazing with cattle or

flooding rice stubble fields reduces the number of

hibernating borers. Eicefields should be separated

as far as possible from corn and sugarcane because these two crops serve as a breeding place

for the sugarcane borer.

The planthopper (Sogata orizicola Muir

potentially a very important pest of rice. It is

the only known vector of hoja blanca, the rice

disease that has become the scourge of rice production in several Latin American countries.

*S', orizicola was first reported in the United

States in 1957. Although the planthopper was

found in Mississippi in 1958 and in Louisiana in

1959 [1) and in 1962, neither it nor the disease it

transmits has become established in the United

States. Apparently the vector cannot survive the

cold weather that sometimes occurs in the ricegrowing areas of this country.

The chinch bug (Blissus leucopterm (Say))

(fig. 55) is present in Arkansas, Louisiana, and

Texas (S). It has entered ricefields in large

numbers and seriously injured the young rice

plants before they were submerged. Both adults

and nymphs attack rice. The feeding of bugs

causes the plants to wither and die. Chinch

bugs feed mainly on the stems, just above the

surface of the ground. They may be controlled

by submerging the infested field. The insects

spend the winter in dry grass, straw, and other

material that affords them shelter. Plowing under such material in the fall or winter reduces

1^

/

FiGxniE 55.—Chinch bugs. Enlarged.

the number of bugs emerging the following

spring.

The tadpole shrimp (Triops Jongicaudittus

(LeConte) ). although not an insect, is sometimes

a pest in California (10). Damage occurs shortly

after fields are flooded and when eggs laid in

fields the previous year hatch. Shrimp larvae

at first feed on organic matter in the soil; but

as they mature, they dislodge and feed on young

rice piants. The shrimp matures in 8 to 10 days

and may produce a second generation.

For information on the insecticides currently

recommended for control of rice insects, consult

your county agent. State agricultural experiment

station, or "the U.S. Department of Agriculture,

Washington. D. C. 20250.

PRECAUTIONS

Insecticides are poisonous. Use them only

when needed and handle them with care. Follow the directions and heed all precautions on

the container label. Insecticides should be kept

in closed, well-labeled containers, in a dry place

where they will not contaminate food or feed

and where children and pets cannot reach them.

Avoid repeated or prolonged contact with skin

and inhalation of dusts and mists. Methyl

parathion and phosphamidon should be applied

only by persons experienced in handling and applying poisonous chemicals. Operators exposed

to sprays containing methyl parathion and phosphamidon should wear half masks equipped with

cartridges of a type approved by the U.S. Department of Agriculture. "Wear clean, dry clothing, and wash hands and face before eating or

smoking. When handling concentrates, avoid

spilling them on the skin and keep them out of

the eyes, nose, and mouth. If any is spilled,

wash it off the skin and change clothing immediately. If it gets in the eyes, flush with plenty
124- .u;i:ií'iM;n .LV:;i>nOi)K 2SÖ, L.S. DEFT. Oi^ A(;RICULTURE

of water for IT) niiiiutes and i^et mcMlical attention.

Avoid drift of insectic'id.e s())-ays or dusts to

nearby crops, livestock, or bee yards. Sp/^ays or

dusts applied hy airplane and olher power equipment are especially likely M) drift. J>o not allow

poultry, dairy animals, jr meat animals to feed

on plants or drink water contaminated by drift

of insecticides. Do not clean spraying equipment

or dump excess spi'cy material near streams,

lakes, or ponds.

Do not apply—

Aldrin or maiathion within 7 da3's before

harvest.

(\irbaryl (Sevm) '^ within l-i days before

harvest.

Metliyl parathion witlim IT» days before harvest.

Phosphamidon witliin :il days before harvest.

Diekirin within oO days before harvest.

Do not apply DDT to rice after heads start

to form.

Do not feed rice straw to dairy animals or animals being finished for slaugliter if the rice straw

has been treated with DDT, phosphamidon, or

toxaphene.

Do not feed rice stravr to livestock if the rice

straw was treated with aldrin within 30 days of

harvest or with diekirin within ::!i) davs of harvest.

2 Sevin should not be applied to rice that has been or

will be treated with DPA herbicide.

Seiected References

(1) ATKINS, J. G., NEWSOM, L. D., SPINK, W. T., and

jthers.

IÍM;(). 0<'(_ rKKKNCK OF HOJA BLANCA AND ITS INSECT

VECTOE, SOGATA ORIZICOLA MUIR, ON EICE IN

LOUISIANA. Plant Dis. Rptr. 44: 390-393.

(2) BOWLING, C. C.

19()(). CONTROL OF lííCE STINKBUGS AND GRASSHOPPERS ON RICE. Tex. Agr. Expt. Sta. Prog

Rpt. 2132, 6 pp.

^3) DouGiAs, W. A., and INGRAM, J. W.

1942. RICE FIELD INSECTS. U.S. Dept. Agr. Cir

632, 32 pp.

(4) and TULLíS, E. C.

1950. INSECTS AND FUNGI AS CAUSES OF PECKY

RICE. U.S. Dept. Agr. Tech. Bui. 1015, 20

pp.

(5) GRIGARICK, A. A., LANGE, W. H., and FINFROCK

D.C.

1961. CONTROL OF THE TADPOLE SHRIMP, TRIOPS

LONGICAUDATUS, IN CALIFORNIA RICE FIELDS.

Jour. Econ. Ent. 54: 36-40.

(6) IsELY, DwiGHT, and SCHWARDT, H. H.

1934. THE RICE WATER WEEVIL. Ark. Agr. Expt

sta. Bui. 299, 44 pp.

(7) LANGE, W. H., JR., INGEBRETSEN, K. H., and DAVIS

L. L.

1953. RICE LEAF MINER. Calif. Agr. 7(8) : 8-9.

(8) PoRTMAN, R. F., and WILLIAMS, A. H.

1952. CONTROL OF MOSQUITO LARVAE AND OTHER

PESTS IN RICE FIELDS BY DDT. Jo'ir. Econ.

Ent. 45: 712-716.

(9) RoLSTON, L. H., and ROUSE, PHIL.

1960. CONTROL OF GRAPE COLASPIS AND RICE WATER

WEEVIL BY SEED OR SOIL TREATMENT. Ark.

Agr. Expt. Sta. Bui. 624, 10 pp.

(10) ROSENBERG, L. E

1947. APUS AS A PEST IN CALIFORNIA RICE FIELDS.

Calif. Dept. Agr. BuL 36(2) : 42-48.

'U.S. GOVERNMENT PRINTING OFFICE: 1966- ' 780-396