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Danielson, L.L., and W.A. Gentner. 1966. A versatile logarithmic sprayer for small experimental plots. U.S. Dep. res. Serv. 34:87. 7pp.

Derr, J.F., and B.L. Appleton. 1988. Herbicides injury to trees and shrubs. Blue crab press. Virginia Beach, VA. pp.72.

Eagle, D.J. 1981. Diagnosis of herbicide damage to crops. ISBN chemical publishing. London. pp.70.

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Freed, V.H., and J.E. Davies. 1980. Classification and toxicology of pesticides, pp.130-150 in Pest and pesticide management in the Caribbean [E.G.B. Good,ed]. Proc. Seminar & Workshop 3-7 Nov., 1980. Bridgetown, Barbados, Vol. II.

Gomez, K.A., and A.A. Gomez. 1984. Statistical Procedure for Agricultural Research. 2nd. ED. John Wiley & Sons, Inc. New York.

Hill, M., and G. Barclay. 1987. Southern Herb Growing. Shearer Publishing, Texas. pp196.

Ikerd, J.E. 1989. Sustainable Agriculture. Annual Agricultural Outlook Conference, November 29. USDA, Washington.
Kaspova, G.Y., V.I. Semak, S.B. Kaltypina, and A.D. Yakubovich. 1980. Long term use of simazine in lavender plantations [in Russian]. Khim. Sel'sk. Khoz. 18(1):53-57.

Lewis, Y.S. 1984. Spices and herbs for the food industry. Food trade Press, England.

Ministry of agriculture, fisheries, and food. 1980. Culinary and medicinal herbs. Her majesty's Stationary Office, reference book 325. pp69.

Morris, K.S., and L.E. Craker. 1990. Herb gardens in America. p.43-46. Proceedings of the Fifth Annual International Herb Growers and Marketers Association.

Nagy, F. and P. Szalay. 1977. Development of modern chemical weed control technology in lavender [in Hungarian]. Herb a Hung. 16(3):59-75.

Neal, J.W. Jr. 1976. A manual for determining small dosage calculations of pesticides and conversion tables. Entomol. Soc. Amer. 71 P.

Talbert, R.E., R.E. Frans, T.L. Gulley, and M.E. Terhune. 1983. Field screening of new chemicals for herbicidal activity, 1982. Ark. Agric. Exp. Stn. Mimeo Ser. 301, 16pp.

Weir, D., and M. Schapiro. 1981. Circle of poison; pesticides and people in a hungry world. Institute for food and development policy, San Francisco. 103p.
# PRODUCTION OF WEST INDIAN HOT PEPPER SEED

Brian Cooper and Monica Gordon
CARDI, P.O. Box 766, St. John's Antigua.

## Abstract

The paper describes efforts in Antigua during the last four years to produce good quality seed of West Indies type hot peppers with both red and yellow fruit suitable for export to Europe and North America. Activities have included characterization of Scoth Bonnet and lantern type peppers, selection for suitable fruit shape, sampling and analysis of plant tissues for virus infection and development of methods for seed extraction. Good yield of high quality seed, treated for TMV type viruses have been produced and made available throughout the O.E.C.S. countries.

## INTRODUCTION

Hot peppers have been grown in the West Indies since pre-Columbian times and were probably brought to this region from the main centres of diversity in Peru and Mexico by the Amerindian peoples as they populated the region (Purseglove 1968). They are an important part of West Indian cuisine and are used either as an ingredient during cooking or processed as pepper sauce. Flavour and pungency are the most important characteristics that determine household acceptance.

Demand for hot pepper within the region can be easily met from local production. In Antigua, 1-2 ha is adequate to supply the requirements of 60,000 people for fresh peppers sauce. Local markets can therefore become quickly saturated.

However, the migration of Caribbean people to the metropolitan countries in North America and Europe in the last few decades has created a significant demand for hot peppers in these temperate countries. This has been further stimulated by the more recent "crossing over" of ethnic foods into the mainstream population with a particular emphasis on spicy foods.
With growing efforts being made to diversify their agriculture, the Organization of East Caribbean States (OECS) countries have been looking for additional crops that have export potential. Hot pepper appears to be one such crop and several countries within the Caribbean have been stepping up production of hot pepper, for export to Europe and North America.

A number of problems were experienced in expanding pepper production in the OECS that appeared to be related to poor seed quality. CARDI was asked to assist in producing good quality seed for the OECS countries and since 1989 has been producing hot pepper for seed extraction. The following report identifies some of the problems encountered and the successes achieved.

## Traditional Sources of Seed.

Hot peppers are grown on a small scale by many Caribbean Farmers for local consumption. In addition, Jamaica has a history of pepper production for export. Barbados, Trinidad, Grenada and St. Lucia also have significant exports. However, in all these countries there has been no commercial or organized production of seed. All seed has been farmer produced often with little regard for plant selection or disease and other factors. In some cases, exporting agencies have made seed available to farmers by extracting it from fruit arriving at collection centres or packing stations, where any reference to the mother plants is impossible.

For this reason quality of seed has been very variable in several respects- genetic content, seed health and viability. These aspects will be dealt with in more detail later. In addition, supply has also been very limited and has acted as a constraint to increased production.

## Varietal Identification and Selection

The botanical nomenclature surrounding *Capsicum peppers* is very confusing and there has been considerable disagreement over segregation of species. Some authorities have preferred to group all *Capsicums* into just two species, *C. annuus* and *C. frutescens* (Purseglove 1968), while other authorities have identified several
<figure><img src="image_34.png" /><figcaption>Figure 1. west Indian hot Pepper types produced in Antigua seed production programme</figcaption></figure>
(Heiser & Smith 1953). The IBPGR has recently accepted five *Capsicum* species (ie. *C. annuum*, *C. baccatum*, *C. chinense*, *C. frutescens*, and *C. pubescens* (IBPGR, 1983). Hot peppers are found in at least four of these species. Previously most hot peppers were assigned to *C. frutescens* and this is the name commonly used in the literature. West Indies hot peppers are classified as *Capsicum chinense* (Jean Andrews, personal communication; Pickersgill, 1989).

In the food trade, hot pepper is considered as spice and is generally referred to as chilli pepper. There are many different types of chillies and Jalapeno, Anasheim and Tabasco are examples of well known commercial varieties. West Indian chillies are less common and somewhat atypical, having lantern or bonnet shaped fruit (Figure 1) with strong flavours and aroma as well as a high levelof pungency, consequently they occupy a special position in the chilli market. Scotch Bonnet is the only named West Indian pepper in the trade. The commercial pepper variety Habanero is also a *C. chinense* and is frequently linket to Scotch Bonnet pepper. However, the Habanero fruit is not bonnet shaped and although very pungent, does not have the characteristic Scotch Bonnet Flavour.

The authors have been unable to find any descriptions in the literature for any of the West Indies hot peppers and no named varieties are commercially produced. The Scotch Bonnet pepper is perphaps the best known and has been reported in Jamaica since at least the late 18th century, (Miller, 1768). It is also well known throoghout the West Indies and in the chilli trade. The name, however, has been used for a wide variety of West Indian pepper types with both bonnet and lantern shaped fruit. In order to avoid confusion, it would be better if the name Scotch Bonnet is used only for the yellow, truly bonnet-shaped peppers with distinctive pungency and aroma.

## Seed Production Activities.

In the absence of any kind of pure lines, red pepper seed production was started in 1989 from a sample of seed obtained from an export agency. Yellow pepper seed (Scotch Bonnet Type) was obtained from Jamaica. Red and yellow populations were grown in isolation. Selections were made from plants with the characteristic of fruit shape, colour, flavour and pungency that we required. Off types were rogued
out and discarded. This process has now been repeated through 4 generations, and we have obtained relatively homogeneous populations of a red lantern-shaped pepper and yellow, bonnet-shaped pepper, which we are calling West Indies Red and West Indies Yellow respectively.

Production of West Indies hot peppers is similar to that of other chillies, but there are some important differences which seem to be related to specific features of *C. chinense*.

Germination of seeds is slow and complete germination requires more than 14 days. This has been observed in both germination tests and in seedling production with seed of good vigour. Initial growth of seedlings also tends to be slow, especially with Scotch Bonnet and seedlings have regularly taken more than eight weeks to be ready for transplanting.

Harvesting can begin 12 to 14 weeks after transplanting and has continued for at least five months and may last longer, depending on the build up virus infection. Seed production plots have produced the equivalent of 20,000 kg fresh fruit/ha after five months of harvest, of which 30-50% was suitable for seed extraction. Selected fruit yielded about 2% of fresh weight as dry seed. Table 1 shows details of production plots.

Fruit production is not uniform, but fluctuales under rainfed conditions in Antigua with a 3-5 week cycle (Figure 2). Other conditions may produce different behaviour.

<table><caption>Tabla 1. Production of fresh fruit from West Indies Red Seed production Plots.</caption><thead><tr><th>Crop Number</th><th>1</th><th>2</th><th>3</th><th>4</th></tr></thead><tbody><tr><td>Area (ha)</td><td>0.04</td><td>0.09</td><td>0.09</td><td>0.09</td></tr><tr><td>Date Planted</td><td>January 1989</td><td>December 1989</td><td>April 1991</td><td>October 1991</td></tr><tr><td>Harvest Period Commenced</td><td>April, 1989</td><td>March, 1990</td><td>July, 1991</td><td>January, 1992</td></tr><tr><td>Duration (weeks)</td><td>27</td><td>26</td><td>21</td><td>25</td></tr><tr><td>Fruit Yield (Kg/ha)</td><td>13,300</td><td>21,827</td><td>23,750</td><td>23,325</td></tr></tbody></table>
<figure><img src="image_35.png" /><figcaption>Figure 2. Weekly and cumulative yields of whole West Indies Red pepper fruits.</figcaption></figure>

Since the beginning of the programme, CARDI has produced 50 kg of pepper seed, mostly West Indies Red, which has been sold to several OECS countries, primarily Grenada and St. Lucia.

## Disease Management/Seed Health

One of the major concerns at the beginning of this project was the management of pepper virus diseases. Virus diseases in both sweet and hot peppers are common throughout the region (Charles 1976) and both TMV and PVY viruses have been reported on peppers (Phelps and Haque, 1973; Lloyd-Tomas, 1982). When infections build up to serious levels, severe losses can result. Reports indicated that in several instances there were significant levels of virus infection in seedlings produced from farmer saved seed.

For this reason, particular care was taken to monitor the disease situation in the seed production plots. Plants showing signs of leaf curling, distortion or mottling were rogued out as early as possible. In addition, through a linkage with the Tropical Virus Project, funded by the UK Overseas Development Administration (ODA), a virologist at Rothamsted Agricultural Experimental Station in the UK was able
to identify the viruses found in leaf samples taken from the seed production plots. Subsequently, additional samples of seeds and fruit tissue were analyzed.

The results of these analyses have shown that our plots have been generally free of virus up to the beginning of the harvest period. As the crop ages, however, incidence of virus usually increases. For this reason we have not continued our seed crops for more than 5 months, although fruit production was still vigorous at this stage.

Pepper Mild Mottle Virus (PMMV), a TOBAMO virus, has been found in almost all cases of virus infection. Pepper Mottle Virus (PMV), a POTY virus, was found in a few cases (Jones and Cooper, 1991). PMV is not known to be borne, but PMMV is carried on the seed coat and can easily be transmitted by seed. For this reason, we have treated all seed with a 30 minute soak in 10% trisodium phosphate to reduce or eliminate PMMV infection through the seed.

## Seed Extraction and Treatment.

Seed extraction has been carried out by hand. Selected fruit are cut, so as to remove the stem end of teh fruit. The central placenta is then cut out, leaving as little flesh as possible adhering. A coring machine was constructed in order to assist with the removal of the placenta, but this did not work well and needs modification.

During initial stages of the project, the placentae with seeds attached were placed in the shade or indirect sun to dry. This process takes about 10-14 days, depending on the weather. The seeds were then rubbed off in a hand-operated peanut sheller. This was time consuming and inefficient, and also produced large quantities of very pungent dust.

After the introduction of the trisodium phosphate treatment, it was discovered that direct treatment of the freshly cut placenta resulted in the efficient detachment of the seeds, which, after careful washing, could then be dried in a few hours instead of days. This treatment did not result in any significant decrease in germination percentage and
storage test showed satisfactory germination for up to six months, following this treatment (Table 2).

Using these methods, high quality seeds have been obtained with germination levels of 75-85% and very little impurities. Vigour of seedlings has been good, and fruit production has been excellent. There have been very few reports of seedlings problems. Seeds are treated with Captan and Malathion dust before storage or shipment.

<table><caption>Table 2 Effect of trisodium phosphate treatment and storage times on germination of hot pepper seed (Average of four replicates).</caption><thead><tr><th rowspan="2">Seed Treatment</th><th rowspan="2">Storage Time (mths)</th><th colspan="5">Germinating seed Condition (%)</th></tr><tr><th>Normal</th><th>Adnormal</th><th>Dead</th><th>Fresh</th><th>Hard</th></tr></thead><tbody><tr><td>Control</td><td>0</td><td>82</td><td>8</td><td>2</td><td>6</td><td>2</td></tr><tr><td>Sodium Phosphate</td><td>3</td><td>78</td><td>15</td><td>2</td><td>5</td><td>0</td></tr><tr><td>Treated</td><td>6</td><td>65</td><td>5</td><td>10</td><td>20</td><td>0</td></tr><tr><td></td><td>12</td><td>45</td><td>20</td><td>20</td><td>15</td><td>0</td></tr></tbody></table>

## Conclusions.

Although the amount of seed production appears small, even by caribbean farming standards, it has made an important contribution to the production of hot pepper in several of the OECS islands. The seed produced and distributed has been sufficient to plant approximately 100-150 ha. While exact statistic are difficult to obtain, this represents a significant proportion of the area presently planted to hot pepper in these countries. A preliminary characterization of the germplasm has been made, but a great deal more remains to be done. Pepper mild mottle virus has been virtually controlled in the seed.

## Acknowledgements

The expertise and assistance of Dr. Phil Jones, Plant Pathologist, Rothamsted Agricultural Experimental Station, UK., in identifying and describing the viruses found in our pepper plots, is very gratefully acknowledged. The assistance of various funding agencies who have
given financial support for various aspects of the work, is also acknowledged. These have included the United States Agency for International Development, the Overseas Development Administration (UK), Barclays Bank International Development Fund and the European Development Fund. The fortitude of our field station staff in tolerating high levels of capsaicin in the environment is sincerely appreciated. Without their assistance week after week, there would have been very little seed produced. Finally the support and encouragement of the late Dr. Gordon Muller, CARDI's Programme Leader in Crop Production, must also be acknowledged. In particular, his assistance in facilitating the linkage with Rothamsted and other virologists was invaluable.

## References.

* Andrews, J. (1985) Peppers - The domesticates *Capsicums*, Texas University Press, Austin, TX.

* Charles, W.B., (1976) "Pepper Growing", Extension Bull. No. 12, Univ. of the West Indies, St. Augustine, Trinidad, 9 p.

* Heiser, C.B. and Smith P.G. (1953) The cultivated *Capsicum pep-pers*, Econ. Bot. 7 (3) 214-227. IBPGR (1983) Genetic resources of Capsicum, Rome, 49 p.

* Jones, P. and Cooper, B.R. (1992). Virus free seed production in the Eastern Caribbean, Proceedings Summary, plant Virology in the Tropics, Assoc. Appl. Biol./Brit. Soc. Plant Pathology, York, April, 1992

* Lloyd Thomas, O.S. (1982) Hot pepper Mosaic - an important disease in the West Indies, Tropical Pest Management, 28 88-89

* Miller, P. (1968) The Gardener's and Botanist's Dictionary, 8th ed., London (quoted by Andrews, 1985)

* Phelps R. and Haque, S.Q. (1973) Some diseases of important food crops in the Southern Caribbean, FAO Report, Dept of crop Science, UWI, Trinidad.
Pickersgill, B. (1989) Genetic resources of *Capsicum* for tropical regions, In: Tomato and Pepper production in the Tropics. Proc. Intl. Symp. on Integrated Management Practices, AVRDC, p 1-9

Purseglove, J.W. (1968) Tropical Crops, Dicotyledons, 1st edition
Longmans, London Tindall, H.D. (1983) Vegetables in the Tropics-
Solanaceae, Hot pepper, Macmillan.
# TOMATO GERMPLASM EVALUATION FOR GROWTH AND PRODUCTIVITY IN THE VIRGIN ISLANDS.

Charles D.Collingwood, Stafford M.A.Crossman
and Manuel C. Palada

Agricultural Experiment Station
University of the Virgin Islands
St. Croix, U.S. Virgin Islands

## ABSTRACT

Five tomato (Lycopersicon esculentum) cultivars, Calypso, Celebrity, Caraibo, Floradade and UH-N69, were field grown during two seasons (spring of 1991 and 1992) to evaluate their growth characteristics and productivity in the U.S. Virgin Islands. In 1991, highest total yields of 44.9, 41.7 and 40.3 ton/ha were produced by UH-N69, Floradade and Celebrity; respectively. Cultivars UH-N69 and Floradade produced the largest quantity of marketable fruits (41.8 and 38.2 ton/ha, respectively). The mean fruit size of Floradade (174 g), Celebrity (170 g), Calypso (169 g) and UH-N69 (163 g) were all significantly larger than fruits of Caraibo (125 g). Fruits of Celebrity and Calypso contained the highest percentage of total soluble solids of 4.5 and 4.7%, respectively. In 1992, yields of all cultivars were generally lower than those obtained in 1991 due to severe infestation of whiteflies and disease infection. Cultivars UH-N69 and Celebrity produced high marketable yields of 32.3 and 30.0 ton/ha, respectively. These cultivars displayed more vigorous growth resulting in plants that were taller than other cultivars. Fruits produced by Celebrity, Calypso and Floradade were larger than Caraibo. In these trials, Celebrity, Floradade and UH-N69 were the best cultivars for fresh market tomato production in the Virgin Islands.

## INTRODUCTION

Tomato (Lycopersicon esculentum) is one of the most important cash crops in the world. An estimated 45 million tons are produced on 2.2

Paper presentet at the 28th Annual Meeting of the Caribbean Food Crops Society, August 9-15, 1992, Santo Domingo, Dominican Republic.
million hectares annually, of this only 15% are produced in the tropics (Villareal, 1980). Tomato is the highest value crop in the United States after potato (McCollum and Ware, 1968). Compared to other fruits and vegetables, tomatoes are not very nutritious and they do not rank high in the concentration of any particular dietary components. However, because of the large consumption of tomatoes in the United States, tomato ranks 3rd in the actual source of vitamins A and C (Adams and Richardson, 1977). In the Virgin Islands and the wider Caribbean, tomato is the most popular vegetable and its culinary uses, including fresh and processed, are endless.

Tomato, unlike many other vegetables requires many costly inputs therefore selecting the best cultivars is a very important step in increasing the returns of these inputs. Many cultivars are available for the fresh market, each with its own characteristics and value, therefore it is very important that farmers select cultivars that will bring the best economic returns. Although tomato is classified as a warm season crop it requires warm days (25-30°C) and cool nights (15-20°C). Two of the most limiting factors in tomato production in the tropics are the high (above 20°C) night temperature and the seasonal rainy conditions. High temperatures severely limit the fruit setting process which results in poor yield (Villareal, 1980). Heavy tropical rains can cause fruit cracking or checking unless fruits are tolerant to these disorders (Scott and Jones, 1991). Hot, rainy conditions are also ideal for the development of several tomato diseases including bacterial spot and bacterial wilt (Pilgrim and Francis, 1984). In the Virgin Islands tomato is usually grown during the winter months of December through April when climatic conditions (near optimum temperatures and low rainfall) are most favorable. The selection of tomato cultivars by local farmers is subject to the availability of seeds in the local market. Presently the most commonly grown varieties in the Virgin Islands are Calypso and Celebrity. These varieties have been traditionally grown by farmers in the Virgin Islands. There is a need to evaluate new and improved cultivars for seasonal adaptability and production in the Virgin Islands.

The objective of this two year study was to determine the best cultivars for the Virgin Islands at the most favorable growing period of the year.
# MATERIALS AND METHODS

This study was conducted at the University of The Virgin Islands Agricultural Experiment Station on St. Croix. The soil is a Fredensborg clay loam. This series consists of a well drained soil formed over limestone or marl (Rivera et al., 1970).

Tomato seeds of five cultivars (Celebrity, Floradade, Caraibo, Calypso and UH-N69) were planted in Pro mix (Premier brands Stamford Ct.) in February 1991 and January 1992. Seedlings were transplanted in the field plots thirty days after seeding. The experimental design was a randomized complete block with four replications. Each replication contained three rows 5.5 m long with plant spacing of 45 cm between plants and 1.2 m between rows. A trellis system made of "goat wire" and metal fencing post were used as plant support. Tomatoes were tied, suckered and pesticides applied based upon standard commercial recommendations. The irrigation system consisted of submains of 19 mm polyethylene hose and laterals of bi-wall (15) tubing (Hardie Irrigation El Cajon, Ca.). Soil moisture levels were maintained at field capacity. A complete fertilizer of 12-12-12 was band applied in a split application at the rate of 215 kg/ha, one at transplant and the other at the first harvest. Fruits were harvested at the turning-to-ripe stage, with the first harvest approximately eight weeks after transplanting. In the first year, fourteen harvests were made and in the second year, due to a heavy infestation of pin worms and whiteflies, ten harvests were made. Total and marketable yield data were collected along with plant height, stem diameter, fruit size, total soluble solids and juice acidity (pH). All data were analyzed using the ANOVA and GLM procedures of SAS (SAS Institute, Cary N.C.).

# RESULTS AND DISCUSSION

In 1991, UH-N69, Floradade, and Celebrity produced total yields of 44.9, 41.7, and 40.3 ton/ha, respectively. The total yield from UH-N69 was significantly higher (P<0.05) than the total yield of Caraibo. UH-N69 produced significantly higher (P<0.05) marketable yields than all cultivars except Floradade (Table 1). Celebrity had the highest amount of non-marketable fruits (23%) due to a high
incidence of fruit cracking. Fruits from the cultivar Caraibo with a mean weight of 124.7 g were significantly smaller than the other cultivars (Table 1). No differences were observed in pH or total soluble solids content (Table 4).

Total marketable yields for all cultivars were generally lower in 1992 due to a severe infestation of whiteflies and pinworms. UH-N69 and Celebrity produced marketable yields of 32.3 and 30.0 ton/ha, respectively (Table 2). Fruits of Caraibo with a mean weight of 113.5 g were significantly smaller than the other cultivars (Table 2). Plants of cultivar Celebrity and UH-N69 were taller than the other cultivars (Table 3). UH-N69 had the smallest stem diameter; however, this characteristic did not affect yield. In 1991, fruits of Celebrity and Calypso had the highest percent of total soluble solids of 4.5 and 4.7%, respectively (Table 4). Percent total soluble solids were lower in 1992 compared to 1991. Increased percentage of total soluble solids is responsible for improved flavor in fruits of tomato cultivars (Casas Diaz et al., 1987). The five tomato cultivars can be separated based on their weekly production levels. Calypso, Caraibo and UH-N69 produce higher yields in week two and three, while Floradade and Celebrity produce higher yields after week three. This late yielding characteristic of Celebrity and Floradade makes them very susceptible to pests and diseases which becomes more severe in the latter part of the growing season. Harvesting of Caraibo fruits demanded more labor than other cultivars due to a combination of larger number of significantly ($P < 0.05$) smaller fruits and shorter plants (Tables 1, 2 and 3).

Based on this study UH-N69, Celebrity and Floradade can be recommended as the best cultivars for fresh market production in the Virgin Islands.

## REFERENCES

Adams, C. F., and Richardson, M. (1977) Nutritive value of foods. Home and Garden Bulletin no.72. Washington,D.C.
Diaz Casas, A. V. Hewitt, J. and Lapushner, D. (1987) Effects of parthenocarpy on fruit quality in tomato. J. Amer. Soc. Hort. Sci. 112 634-636.

McCollum J. P. and Ware G. W. (1968) Producing vegetable crops. 558p. Interstate Printers and Publishers, Inc. Danville Illinois.

Pilgrim, R. N. and Francis, R. L. (1986) On farm evaluation of five tomato cultivars (Lycopersicon esculentum) for yield and fusarium wilt (Fusarium oxysporum f.lycopersici) tolerance in St. Lucia. Proceedings of CFCS 22nd annual meeting August 25-29, 1986 St. Lucia W. I.

Rivera, L. H., Frederick, W. D., Farris, C., Jensen, E. H., Davis, L., Palmer, C. D., Jackson, L. F. and Mckinie W. E. (1970) Soil Survey of the Virgin Islands of the United States USDA Soil Conservation Service.

SAS Institute Inc., (1988). SAS/STAT User's Guide, Release 6.03 Edition. SAS Institute Inc., Cary N. C.

Scott, J. W. and Jones, J. B. (1991). Methodology for developing multiple resistant, heat tolerant tomatoes. Achievements in Tropical and Subtropical Agricultural Research Under PL89-106 Special Research Grants Caribbean Basin Administrative Group.

Villareal, R. L. (1980) Tomatoes in the Tropics. 173p. Westview Press Inc. Boulder Colorado
<table><caption>Table 1. Yield and fruit size of tomato cultivars (1991)</caption><thead><tr><th>Cultivar</th><th>Total yield (ton/ha)</th><th>Marketable yield (ton/ha)</th><th>Fruit size (g)</th></tr></thead><tbody><tr><td>Calypso</td><td>36.9 c</td><td>33.0 c</td><td>168.5 a</td></tr><tr><td>Caraibo</td><td>37.3 bc</td><td>35.8 bc</td><td>124.7 b</td></tr><tr><td>Celebrity</td><td>40.3 ab</td><td>31.1 c</td><td>169.5 a</td></tr><tr><td>Floradade</td><td>41.7 ab</td><td>38.2 ab</td><td>173.5 a</td></tr><tr><td>UH-N69</td><td>44.9 a</td><td>41.8 a</td><td>163.2 a</td></tr></tbody></table>

Mean separation by Duncan's multiple range test, P=0.05.

<table><caption>Table 2. Yield and fruit size of tomato cultivars (1992).</caption><thead><tr><th>Cultivar</th><th>Total Yield (ton/ha)</th><th>Marketable Yield (ton/ha)</th><th>Fruit size (g)</th></tr></thead><tbody><tr><td>Calypso</td><td>27.9 a</td><td>23.8 a</td><td>181.0 a</td></tr><tr><td>Caraibo</td><td>29.6 a</td><td>26.5 a</td><td>113.5 b</td></tr><tr><td>Celebrity</td><td>34.7 a</td><td>30.0 a</td><td>182.5 a</td></tr><tr><td>Floradade</td><td>26.0 a</td><td>22.4 a</td><td>157.8 a</td></tr><tr><td>UH-N69</td><td>36.0 a</td><td>32.3 a</td><td>148.0 a</td></tr></tbody></table>

Mean separation by Duncan's multiple range test, P=0.05.

<table><caption>Table 3. Plant height and stem dia. of tomato cultivars (1992)</caption><thead><tr><th>Cultivar</th><th>Plant ht. (cm.)</th><th>Stem dia. (cm.)</th></tr></thead><tbody><tr><td>Calypso</td><td>83.2 ab</td><td>15.2 ab</td></tr><tr><td>Caraibo</td><td>70.5 c</td><td>15.1 ab</td></tr><tr><td>Celebrity</td><td>88.5 a</td><td>15.9 a</td></tr><tr><td>Floradade</td><td>74.8 bc</td><td>15.7 a</td></tr><tr><td>UH-N69</td><td>86.1 ab</td><td>13.6 b</td></tr></tbody></table>

Mean separation by Duncan's multiple range test, P=0.05.
<table><caption>Table 4. Total soluble solids and pH of tomato cultivars.</caption><thead><tr><th>Cultivar</th><th>Total Soluble (1991)</th><th>Solids (%) (1992)</th><th>pH</th></tr></thead><tbody><tr><td>Calypso</td><td>4.5 a</td><td>3.2 a</td><td>4.3 a</td></tr><tr><td>Caraibo</td><td>3.6 a</td><td>3.1 a</td><td>4.2 a</td></tr><tr><td>Celebrity</td><td>4.7 a</td><td>3.5 a</td><td>4.0 a</td></tr><tr><td>Floradade</td><td>3.4 a</td><td>3.3 a</td><td>4.2 a</td></tr><tr><td>UH-N69</td><td>3.6 a</td><td>3.4 a</td><td>4.2 a</td></tr></tbody></table>

Mean separation by Duncan's multiple range test, P=0.05.
CARACTERIZACION AGRONOMICA DE ALGUNOS TIPOS DE GUANDUL (*Cajunus Cajan*, Millsp)<fnref n="1" />.

F. Saladín, M. Herrera, J. C. Nin, F. Henríquez y J. Cedano.
CESDA. Programa Leguminosas Comestibles. Apdo. 24, San Cristóbal y Estación Experimental de Arroyo Loro, San Juan de la Maguana, Rep. Dominicana.

RESUMEN

Nuevas variedades de guandul han sido introducidas al país para su utilización en la industria de enlatado y consumo fresco. Es necesario por lo tanto obtener informaciones básicas sobre las características agronómicas para dar las recomendaciones adecuadas a los agricultores. Con este fín se llevaron a cabo ensayos en las locadidades de San Cristóbal y San Juan de la Maguana para determinar el marco de plantación más adecuado y así optimizar la producción. Las variedades bajo estudio fueron Kaki Blanco, Puerto Rico y Sagarateado; como testigo utilizamos la variedad Kaki comercial.

Los resultados en San Cristóbal fueron significativamente superiores en cuanto al rendimiento de las cuatro variedades a los obtenidos en San Juan de la Maguana. Con un marco de 1.50 mt., entre hileras y plantas se logró mayor rendimiento en San Cristóbal para todas las variedades.

1.- INTRODUCCION

El cultivo del guandul ocupa en estos momentos un lugar de importancia socioeconómica, por ser alternativa de la habichuela para la producción de proteína a más bajo costo.

Las industrias instaladas en varios lugares de nuestro país han introducido nuevas variedades de guandul para ser usadas para el enlatado, así como también para el consumo y exportación en verdeo.

<footnote n="1">¹Trabajo preliminar presentado en la XXVIII Reunión Anual de la Sociedad Caribeña de Cultivos Alimenticios.</footnote>
Las informaciones básicas sobre características agronómicas de estas nuevas variedades son muy importantes, para poder dar recomendaciones a nuestros agricultores.

## 1.1 OBJETIVOS.

a) Evaluar el marco de siembra más apropiado para la consecusión de rendimientos económicos.

b) Realizar caracterización agronómica de los cultivares.

## II. MATERIALES Y METODOS.

### 2.1 Materiales.

#### 2.1.1 Descripción del Área.

El experimento fue realizado en el Centro Sur de Desarrollo Agropecuario (CESDA) y la Estación Experimental de Arroyo Loro (EEAL) San Juan de la Maguana, cuya características geoclimáticas se presentan en el cuadro 1.

<table><caption>Cuadro 1. Características geoclimáticas de los sitios experimentales.</caption><thead><tr><th rowspan="2">Característica</th><th colspan="2">Lugar</th></tr><tr><th>CESDA</th><th>EEAL</th></tr></thead><tbody><tr><td>Latitud</td><td>N 18° 25'</td><td>N 18° 48'</td></tr><tr><td>Longitud</td><td>W 70° 06'</td><td>W 71° 14'</td></tr><tr><td>Altitud</td><td>44 msnm</td><td>415 msnm</td></tr><tr><td>Temperatura Media</td><td>25.9°C</td><td>24.9°C</td></tr><tr><td>Precipitación Anual</td><td>1756.7 mm</td><td>961.4 mm</td></tr></tbody></table>

Fuente: Dirección Nacional de Meteorología.
### 2.1.2 Material Biológico.

Se utilizaron las variedades de guandul Kaki Blanco, Puerto Rico, Sañarateado y como testigo la variedad Kaki comercial.

### 2.1.3 Marcos de Plantación.

Se utilizaron los siguientes marcos de plantación:

2.00 m x 1.50 m

1.50 m x 1.50 m

## 2.2 Métodos.

### 2.2.1 Manejo Experimental.

Utilizamos un diseño de bloques completos al azar con cuatro (4) repeticiones en un arreglo factorial 2 x 4 en parcelas divididas, generando un total de 8 tratamientos correspondiendo los marcos de siembras al factor de parcela y las variedades a los tratamientos de subparcelas.

Cada tratamiento consistió en 4 surcos de 6m de longitud.

<table><tr><td>Separación entre repeticiones</td><td>= 2.00 m</td></tr><tr><td>Separación entre parcelas grandes</td><td>= 2.00 m</td></tr><tr><td>Area total del ensayo</td><td>= 58.00 m x 30.00 m<br>= 1,740 m<sup>2</sup><br>= 2.8 ta.</td></tr></table>

### 2.2.2 Siembra y Labores Culturales.

La siembra en la EEAL fué el día 27/5/91 y en el CESDA en fecha 10/6/91.

Durante el ciclo del cultivo se realizaron unas 5 labores de deshierbo en ambas localidades. El raleo fué realizado a los 50 días después de la siembra dejando dos plantas por golpe.
En la EEAL fué necesario dar dos riegos suplementarios para garantizar la germinación y crecimiento.

### 2.2.3 Observaciones Durante el Ciclo.

El color de las flores y legumbres, así como las ramificaciones aparecen en el cuadro 2.

<table><caption>Cuadro 2. Color de la flor, ramificaciones y color de las legumbres de las variedades en estudio.</caption><thead><tr><td>Variedad</td><td>Color Flor</td><td>Ramificaciones</td><td>Color Legumbres</td></tr></thead><tbody><tr><td>Kaki</td><td>Amarilla</td><td>Colgante</td><td>Verdes</td></tr><tr><td>Puerto Rico</td><td>Biscolor</td><td>Oblicuas</td><td>Jaspeadas</td></tr><tr><td>Kaki Blanco</td><td>Biscolor</td><td>Oblicuas</td><td>Jaspeadas verdes</td></tr><tr><td>Sagarateado</td><td>Saragateada</td><td>Colgantes</td><td>Jaspeadas</td></tr></tbody></table>

### 2.2.4 Cosecha.

Las legumbres fueron cosechadas en verdeo, realizando cinco cosechas en las tres variedades en estudio y el testigo.

### 2.2.5 Evaluaciones.

#### a) Días a floración.

Cuando el 50% de las plantas en cada tratamiento presentó una flor abierta, se dice que la variedad en estudio está en floración, ésta información sólo fué recopilada en la localidad de San Juan de la Maguana.

#### b) Rendimiento en verdeo.

Para el estudio de granos en verdeo fue tomada una muestra de 500 gramos de vainas cosechadas procediendo a su desgrane y posteriormente se determinó el porcentaje de granos verdes en cada tratamiento.
### 2.2.6 Análisis de Datos.

Se utilizó la técnica del análisis de varianza y la prueba de rango múltiple de Duncan, para las comparaciones entre medias de tratamientos y con un nivel de significancia (alfa) de 0.05.

## III. RESULTADOS Y DISCUSION.

### 3.1 Días a floración.

Los resultados del análisis de varianza, tabla 1, muestran que no hubo diferencia estadística para marcos de siembra; mientras que para variedades hubo diferencia altamente significativa y para la interacción marcos por variedades solamente resultó ser significativa.

La variedad Kaki resultó la más precoz al igual que la Sagarateado, pero superando a las variedades Puerto Rico y Kaki Blanco, siendo esta última la más tardía, según Duncan al 5% en la tabla 2. En la tabla 3 se observa que la variedad Sagarateado con marcos de siembra de 1.50m x 1.50m conjuntamente con el testigo (Kaki) con cualquiera de los marcos estudiados, resultaron superiores, siendo la más tardía la Kaki Blanco.

<table><caption>Tabla 1. Análisis de varianza para días a floración de cuatro variedades de guandul.</caption><thead><tr><th>Fuente devar.</th><th>GL</th><th>SC</th><th>CM</th><th>FC</th><th>Prob.</th></tr></thead><tbody><tr><td>Repeticiones</td><td>3</td><td>278.500</td><td>92.833</td><td>3.0149</td><td>0.1945</td></tr><tr><td>Marcos</td><td>1</td><td>0.125</td><td>0.125</td><td>0.0041</td><td></td></tr><tr><td>Error (a)</td><td>3</td><td>92.375</td><td>30.792</td><td></td><td></td></tr><tr><td>Variedades</td><td>3</td><td>2419.250</td><td>806.042</td><td>14.3976</td><td></td></tr><tr><td>Marcos x Var.</td><td>3</td><td>915.125</td><td>305.042</td><td>5.4462</td><td></td></tr><tr><td>Error (b)</td><td>12</td><td>672.125</td><td>56.010</td><td></td><td>0.0003**<br>0.0135*</td></tr></tbody></table>

CV. = 4.70%
<table><caption>Tabla 2. Días a floración de las variedades de guandul.</caption><thead><tr><td>Variedad</td><td>Días a floración</td></tr></thead><tbody><tr><td>Kaki</td><td>149.5 a</td></tr><tr><td>Sagarateado</td><td>154.3 ab</td></tr><tr><td>Puerto Rico</td><td>161.1 b</td></tr><tr><td>Kaki Blanco</td><td>172.6 c</td></tr></tbody></table>

$$DMS = 8.153$$

<table><caption>Tabla 3. Días a floración de los diferentes tratamientos sobre variedades y marcos de siembra.</caption><thead><tr><td>Marcos (m)</td><td>Variedad</td><td>Días a floración</td></tr></thead><tbody><tr><td>1.50 x 1.50</td><td>Sagarateado</td><td>148.3 a</td></tr><tr><td>2.00 x 1.50</td><td>Kaki</td><td>148.5 a</td></tr><tr><td>1.50 x 1.50</td><td>Kaki</td><td>150.5 a</td></tr><tr><td>1.50 x 1.50</td><td>Puerto Rico</td><td>157.8 a b</td></tr><tr><td>2.00 x 1.50</td><td>Sagarateado</td><td>160.3 a b</td></tr><tr><td>2.00 x 1.50</td><td>Kaki Blanco</td><td>164.5 b</td></tr><tr><td>2.00 x 1.50</td><td>Puerto Rico</td><td>164.5 b</td></tr><tr><td>1.50 x 1.50</td><td>Kaki Blanco</td><td>180.8 c</td></tr></tbody></table>

$$DMS=11.53$$

## 3.2 Altura de Planta.

Los resultados del análisis de varianza; tabla 4, muestran que hubo diferencia estadística altamente significativa entre localidades para altura de planta y diferencia significativa para la interacción, localidad por variedad; mientras que para las interacciones localidad por tratamiento, localidad por marco, marco por variedad y localidad por marco por variedad, no hubieron diferencias estadísticas. Tampoco hubo diferencia entre marcos ni entre variedades.

En la localidad de San Cristóbal las variedades estudiadas tuvieron un porte más alto según la prueba de Duncal al 5%, siendo el marco de
2.00m x 1.50m entre hileras y plantas, donde se logró mayor altura como podemos ver en las tablas 6, 7 y 8.

### 3.3. Diámetro de Copa.

Los resultados del análisis de varianza, tabla 5, muestran que no hubo diferencia estadística entre las localidades, pero hubo diferencia significativa para los marcos. No hubo diferencia estadística para la interacción localidad por marco, en cambio se encontraron diferencias altamente significativas entre las variedades e interacción localidad por variedad.

No hubo diferencia estadística para las interacciones marcos por variedad por localidad, ni localidad por marcos por variedad.

En la localidad de San Cristóbal se logró mayor diámetro de copa según Duncan al 5% con un marco de siembra de 2.00m x 1.50m, como podemos ver en las tablas 6, 7 y 8. Al comparar las medias de las variedades en las dos localidades podemos ver, exceptuando la variedad Puerto Rico, las demás tuvieron un diámetro de copa similar como podemos apreciar en la tabla 9.

<table><caption>Tabla 4. Análisis de varianza para altura de planta de cuatro variedades de guandul.</caption><thead><tr><th>Fuente de var.</th><th>GL</th><th>SC</th><th>CM</th><th>FC</th><th>Prob.</th></tr></thead><tbody><tr><td>Rep. en loc.</td><td>6</td><td>0.758</td><td>0.126</td><td>1.8821</td><td>0.1100</td></tr><tr><td>Loc. x trat.</td><td>1</td><td>9.158</td><td>9.158</td><td>136.4718</td><td>0.0000**</td></tr><tr><td>Marco</td><td>1</td><td>0.165</td><td>0.165</td><td>2.4593</td><td>0.1253</td></tr><tr><td>Loc. x Marco</td><td>1</td><td>0.197</td><td>0.197</td><td>2.9343</td><td>0.0951</td></tr><tr><td>Variedad</td><td>3</td><td>0.316</td><td>0.105</td><td>1.5681</td><td>0.2135</td></tr><tr><td>Loc. x Variedad</td><td>3</td><td>0.764</td><td>0.255</td><td>3.7962</td><td>0.0181*</td></tr><tr><td>Marco x Variedad</td><td>3</td><td>0.095</td><td>0.032</td><td></td><td></td></tr><tr><td>Loc. x Marco x Var.</td><td>3</td><td>0.154</td><td>0.051</td><td>0.4714</td><td></td></tr><tr><td>Error</td><td>37</td><td>2.483</td><td>0.067</td><td>0.7651</td><td></td></tr></tbody></table>

CV. = 11.54%
<table><caption>Tabla 5. Análisis de varianza para diámetro de copa de cuatro variedades de guandul.</caption><thead><tr><th>Fuente de var.</th><th>GL</th><th>SC</th><th>CM</th><th>FC</th><th>Prob.</th></tr></thead><tbody><tr><td>Rep. en loc.</td><td>6</td><td>0.507</td><td>0.085</td><td>2.2112</td><td>0.0637</td></tr><tr><td>Loc. x trat.</td><td>1</td><td>9.145</td><td>9.145</td><td>3.8024</td><td>0.0388*</td></tr><tr><td>Marco</td><td>1</td><td>0.280</td><td>0.280</td><td>7.3137</td><td>0.0103*</td></tr><tr><td>Loc. x Marco</td><td>1</td><td>0.088</td><td>0.088</td><td>2.2959</td><td>0.1382</td></tr><tr><td>Variedad</td><td>3</td><td>0.604</td><td>0.201</td><td>5.2652</td><td>0.0040**</td></tr><tr><td>Loc. x Variedad</td><td>3</td><td>0.839</td><td>0.280</td><td>7.3138</td><td>0.0006*</td></tr><tr><td>Marco x Variedad</td><td>3</td><td>0.178</td><td>0.059</td><td>1.5506</td><td>0.2177</td></tr><tr><td>Loc. x Marco x Var.</td><td>3</td><td>0.072</td><td>0.024</td><td>0.6268</td><td></td></tr><tr><td>Error</td><td>37</td><td>1.414</td><td>0.038</td><td></td><td></td></tr></tbody></table>

$$CV = 11.51\%$$

<table><caption>Tabla 6. Altura y diámetro de copa del guandul en las localidades de San Cristóbal y San Juan de la Maguana.</caption><thead><tr><th>Localidades</th><th>Altura (m)</th><th>Diámetro (m)</th></tr></thead><tbody><tr><td>CESDA</td><td>2.623 a</td><td>1.747 a</td></tr><tr><td>EEAL</td><td>1.867 b</td><td>1.652 b</td></tr><tr><td>DMS =</td><td>0.235</td><td>0.029</td></tr></tbody></table>

<table><caption>Tabla 7. Altura y diámetro de copa de guandul para los marcos de siembra en San cristóbal y San Juan de la Maguana.</caption><thead><tr><th>Marcos de siembra (m)</th><th>Altura (m)</th><th>Diámetro (m)</th></tr></thead><tbody><tr><td>2.00 x 1.50</td><td>2.623 a</td><td>1.765 a</td></tr><tr><td>1.50 x 1.50</td><td>2.194 a</td><td>1.633 b</td></tr><tr><td>DMS =</td><td>0.235</td><td>0.029</td></tr></tbody></table>
<table><caption>Tabla 8. Altura y diámetro de copa de guandul para la interacción localidad por marco de siembra en San Cristóbal y San Juan de la Maguana.</caption><thead><tr><th>Localidad</th><th>Marco de siembra (m)</th><th>Altura (m)</th><th>Diámetro (m)</th></tr></thead><tbody><tr><td>CESDA</td><td>2.00 x 1.50</td><td>2.619 a</td><td>1.850 a</td></tr><tr><td>CESDA</td><td>1.50 x 1.50</td><td>2.628 a</td><td>1.644 b</td></tr><tr><td>EEAL</td><td>2.00 x 1.50</td><td>1.973 b</td><td>1.681 b</td></tr><tr><td>EEAL</td><td>1.50 x 1.50</td><td>1.761 c</td><td>1.622 b</td></tr><tr><td>DMS =</td><td></td><td>0.1854</td><td>0.1396</td></tr></tbody></table>

<table><caption>Tabla 9. Altura y diámetro de copa de guandul para las variedades de guandul en las localidades de San Cristóbal y San Juan de la Maguana.</caption><thead><tr><th>Variedad</th><th>Altura (m)</th><th>Diámetro (m)</th></tr></thead><tbody><tr><td>Kaki</td><td>2.328 a</td><td>1.707 a</td></tr><tr><td>Puerto Rico</td><td>2.153 a</td><td>1.539 b</td></tr><tr><td>Kaki Blanco</td><td>2.203 a</td><td>1.759 a</td></tr><tr><td>Sagarateado</td><td>2.296 a</td><td>1.792 a</td></tr><tr><td>DMS =</td><td>0.1854</td><td>0.1396</td></tr></tbody></table>

<table><caption>Tabla 10. Altura y diámetro de copa de guandul para la interacción localidad por variedad en San Cristóbal y San Juan de la Maguana.</caption><thead><tr><th>Localidad</th><th>Variedad</th><th>Altura (m)</th><th>Diámetro (m)</th></tr></thead><tbody><tr><td>CESDA</td><td>Kaki</td><td>2.856 a</td><td>1.668 a</td></tr><tr><td>CESDA</td><td>Sagarateado</td><td>2.638 a b</td><td>1.700 a</td></tr><tr><td>CESDA</td><td>Kaki Blanco</td><td>2.619 a b</td><td>1.850 a</td></tr><tr><td>CESDA</td><td>Puerto Rico</td><td>2.381 b</td><td>1.750 a</td></tr><tr><td>EEAL</td><td>Sagarateado</td><td>1.955 c</td><td>1.884 a</td></tr><tr><td>EEAL</td><td>Puerto Rico</td><td>1.925 c</td><td>1.329 b</td></tr><tr><td>EEAL</td><td>Kaki</td><td>1.800 c</td><td>1.726 a</td></tr><tr><td>EEAL</td><td>Kaki Blanco</td><td>1.788 c</td><td>1.668 a</td></tr><tr><td>DMS =</td><td></td><td>0.2622</td><td>0.1975</td></tr></tbody></table>
<table><caption>Tabla 11. Altura y diámetro de copa del guandul para la interacción variedad por marco en San Cristóbal y San Juan de la Maguana.</caption><thead><tr><th>Variedad</th><th>Marco siembra (m)</th><th>Altura (m)</th><th>Diámetro (m)</th></tr></thead><tbody><tr><td>Kaki</td><td>2.00 x 1.50</td><td>2.420 a</td><td>1.842 a</td></tr><tr><td>Sagarateado</td><td>2.00 x 1.50</td><td>2.380 a</td><td>1.780 abc</td></tr><tr><td>Kaki</td><td>1.50 x 1.50</td><td>2.236 a</td><td>1.571 cd</td></tr><tr><td>Sagarateado</td><td>1.50 x 1.50</td><td>2.213 a</td><td>1.804 ab'</td></tr><tr><td>Kaki Blanco</td><td>1.50 x 1.50</td><td>2.204 a</td><td>1.697 abc</td></tr><tr><td>Kaki Blanco</td><td>2.00 x 1.50</td><td>2.203 a</td><td>1.820 ab</td></tr><tr><td>Puerto rico</td><td>1.50 x 1.50</td><td>2.181 a</td><td>1.619 bcd</td></tr><tr><td>Puerto Rico</td><td>2.00 x 1.50</td><td>2.125 a</td><td>1.460 d</td></tr></tbody><tfoot><tr><td>DMS =</td><td></td><td>0.2622</td><td>0.1975</td></tr></tfoot></table>

<table><caption>Tabla 12. Altura y diámetro de copa del guandul para las interacciones localidad por variedad por marco en San Cristóbal y San Juan de la Maguana.</caption><thead><tr><th>Loc.</th><th>Variedad</th><th>Marco de Siembra (m)</th><th>Altura (m)</th><th>Diámetro (m)</th></tr></thead><tbody><tr><td>CESDA</td><td>Kaki</td><td>2.00 x 1.50</td><td>2.888 a</td><td>1.850 abc</td></tr><tr><td>CESDA</td><td>Kaki</td><td>1.50 x 1.50</td><td>2.825 a</td><td>1.525 de</td></tr><tr><td>CESDA</td><td>Kaki Blanco</td><td>1.50 x 1.50</td><td>2.750 ab</td><td>1.700 abcd</td></tr><tr><td>CESDA</td><td>Sagarateado</td><td>2.00 x 1.50</td><td>2.725 ab</td><td>1.725 abcd</td></tr><tr><td>CESDA</td><td>Sagarateado</td><td>1.50 x 1.50</td><td>2.550 ab</td><td>1.675 abcd</td></tr><tr><td>CESDA</td><td>Kaki Blanco</td><td>2.00 x 1.50</td><td>2.488 ab</td><td>2.000 a</td></tr><tr><td>CESDA</td><td>Puerto Rico</td><td>1.50 x 1.50</td><td>2.388 bc</td><td>1.675 abcd</td></tr><tr><td>CESDA</td><td>Puerto Rico</td><td>2.00 x 1.50</td><td>2.375 bc</td><td>1.825 abc</td></tr><tr><td>EEAL</td><td>Sagarateado</td><td>2.00 x 1.50</td><td>2.035 cd</td><td>1.835 abc</td></tr><tr><td>EEAL</td><td>Puerto Rico</td><td>2.00 x 1.50</td><td>1.987</td><td>1.413 de</td></tr><tr><td>EEAL</td><td>Kaki</td><td>2.00 x 1.50</td><td>1.952</td><td>1.835 abc</td></tr><tr><td>EEAL</td><td>Kaki Blanco</td><td>2.00 x 1.50</td><td>1.918</td><td>1.640 bcd</td></tr><tr><td>EEAL</td><td>Sagarateado</td><td>1.50 x 1.50</td><td>1.875</td><td>1.933 ab</td></tr><tr><td>EEAL</td><td>Puerto Rico</td><td>1.50 x 1.50</td><td>1.862</td><td>1.245</td></tr><tr><td>EEAL</td><td>Kaki Blanco</td><td>1.50 x 1.50</td><td>1.658</td><td>1.695 abcd</td></tr><tr><td>EEAL</td><td>Kaki</td><td>1.50 x 1.50</td><td>1.648</td><td>1.617 bcd</td></tr></tbody><tfoot><tr><td>DMS =</td><td></td><td>0.3709</td><td></td><td>0.2793</td></tr></tfoot></table>
### 3.4 Porcentaje de Granos Verdes.

Los resultados del análisis de varianza tabla 13 muestran que hubo diferencia significativa para los marcos; mientras que para las variedades e interacción marcos por variedades, no hubo diferencia estádística.

El marco de siembra de 1.50m x 1.50m se obtuvo mayor cantidad de granos en verdeo, según Duncan al 5% en la tabla 14. En las tablas 15 y 16 podemos ver que las cuatro variedades tuvieron un comportamiento similar para cualquiera de los marcos usados.

<table><caption>Tabla 13. Análisis de varianza para el porcentaje de granos verdes del guandul.</caption><thead><tr><th>Fuente de Variación</th><th>GL</th><th>S.C.</th><th>C.M.</th><th>FC.</th><th>Probabilidad</th></tr></thead><tbody><tr><td>Repeticiones</td><td>3</td><td>47.844</td><td>15.948</td><td>22.8507</td><td>0.0144*</td></tr><tr><td>Marcos</td><td>1</td><td>11.281</td><td>11.281</td><td>16.1642</td><td>0.0276*</td></tr><tr><td>Error (a)</td><td>3</td><td>2.094</td><td>0.698</td><td></td><td></td></tr><tr><td>Variedades</td><td>3</td><td>6.094</td><td>2.031</td><td>0.7057</td><td></td></tr><tr><td>Marcos x Variedades</td><td>3</td><td>3.844</td><td>1.281</td><td>0.4451</td><td></td></tr><tr><td>Error (b)</td><td>18</td><td>51.813</td><td>2.878</td><td></td><td></td></tr></tbody></table>

$$CV = 3.20\%$$

<table><caption>Tabla 14. Granos en verdeo del guandul para los marcos de siembra.</caption><thead><tr><th>Marcos de siembra (m)</th><th>Granos en verdeo (%)</th></tr></thead><tbody><tr><td>1.50 x 1.50</td><td>53.625 a</td></tr><tr><td>2.60 x 1.50</td><td>52.438 b</td></tr></tbody></table>

<table><caption>Tabla 15. Porcentaje de granos verdes del guandul para las variedades.</caption><thead><tr><th>Variedades</th><th>Granos en verdeo (%)</th></tr></thead><tbody><tr><td>Kaki Blanco</td><td>53.75 a</td></tr><tr><td>Kaki</td><td>53.00 a</td></tr><tr><td>Sagarateado</td><td>52.75 a</td></tr><tr><td>Puerto Rico</td><td>52.63 a</td></tr></tbody></table>

$$DMS = 1.782$$
<table><caption>Tabla 16. Porcentaje de granos verdes del guandul para la interacción marco por variedad.</caption><thead><tr><th>Variedad</th><th>Marco de siembra (m)</th><th>Grano en verdeo (%)</th></tr></thead><tbody><tr><td>Kaki Blanco</td><td>1.50 x 1.50</td><td>54.50 a</td></tr><tr><td>Kaki</td><td>1.50 x 1.50</td><td>53.75 a</td></tr><tr><td>Puerto Rico</td><td>1.50 x 1.50</td><td>53.50 a</td></tr><tr><td>Kaki Blanco</td><td>2.00 x 1.50</td><td>53.00 a</td></tr><tr><td>Sagarateado</td><td>2.00 x 1.50</td><td>52.75 a</td></tr><tr><td>Sagarateado</td><td>1.50 x 1.50</td><td>52.75 a</td></tr><tr><td>Kaki</td><td>2.00 x 1.50</td><td>52.25 a</td></tr><tr><td>Puerto Rico</td><td>2.00 x 1.50</td><td>51.75 a</td></tr></tbody></table>

$$DMS = 2.520$$

### 3.5 Rendimiento Grano Verde.

Los resultados del análisis de varianza, tabla 17, muestran que hubo diferencia altamente significativa entre localidades, mientras que para marcos y la interacción localidades por marcos, la diferencia fue solamente significativa. Los efectos entre variedades y demás interacciones no resultaron significativos.

Con el marco de siembra de 1.50 m x 1.50m se obtuvieron los mejores rendimientos, según Duncan al 5%, siendo la localidad de San Cristóbal con cualquiera de los marcos estudiados, donde se obtuvieron los mejores rendimientos en las cuatro variedades como podemos ver en las tablas 19, 20 y 22.

<table><caption>Tabla 17. Análisis de varianza para rendimiento grano en verdeo.</caption><thead><tr><th>Fuente de var.</th><th>GL</th><th>SC</th><th>CM</th><th>Fc</th><th>Prob.</th></tr></thead><tbody><tr><td>Repet. en loc.</td><td>6</td><td>70446281.659</td><td>11741046.943</td><td>5.8035</td><td>0.0002**</td></tr><tr><td>Localidad</td><td>1</td><td>516323873.144</td><td>516323873.144</td><td>255.2134</td><td>0.0000**</td></tr><tr><td>Marcos</td><td>1</td><td>10937976.149</td><td>10937976.144</td><td>5.4065</td><td>0.0251*</td></tr><tr><td>Loc. x Marcos</td><td>1</td><td>114151380.706</td><td>114511380.706</td><td>5.6603</td><td>0.0221*</td></tr><tr><td>Variedades</td><td>3</td><td>9517621.023</td><td>3172540.341</td><td>1.5682</td><td>0.2117</td></tr><tr><td>Loc. x Var.</td><td>3</td><td>6341067.448</td><td>2113689.144</td><td>1.0448</td><td>0.3830</td></tr><tr><td>Marcos x Var.</td><td>3</td><td>4846280.319</td><td>1615426.773</td><td>0.7985</td><td></td></tr><tr><td>Loc. x Mar. x Var.</td><td>3</td><td>12180345.355</td><td>4060115.118</td><td>2.0069</td><td>0.1280</td></tr><tr><td>Error</td><td>41</td><td>82947377.741</td><td>2023106.774</td><td></td><td></td></tr></tbody></table>

$$CV. = 24.99\%$$
<table><caption>Tabla 18. Rendimiento en verde de guandul en las dos localidades.</caption><thead><tr><th>Localidad</th><th>Rendimiento en verde (gr/AU)</th></tr></thead><tbody><tr><td>CESDA</td><td>8530.969 a</td></tr><tr><td>EEAL</td><td>2850.278 b</td></tr></tbody></table>

$$DMS = 718.434$$

<table><caption>Tabla 19. Rendimiento granos verdes de guandul para los dos marcos.</caption><thead><tr><th>Marco</th><th>Rendimiento grano verde (gr/AU)</th></tr></thead><tbody><tr><td>1.50m x 1.50</td><td>6104.031 a</td></tr><tr><td>2.00m x 1.50</td><td>5277.216 b</td></tr></tbody></table>

$$DMS = 718.434$$

<table><caption>Tabla 20. Rendimiento granos verdes de guandul para la interacción localidad por marco.</caption><thead><tr><th>Localidad</th><th>Marco</th><th>Rendimiento grano verde (gr/AU)</th></tr></thead><tbody><tr><td>CESDA</td><td>1.50m x 1.50m</td><td>9367 a</td></tr><tr><td>CESDA</td><td>2.00m x 1.50m</td><td>7695 b</td></tr><tr><td>EEAL</td><td>2.00m x 1.50m</td><td>2860 c</td></tr><tr><td>EEAL</td><td>1.50m x 1.50m</td><td>2841 c</td></tr></tbody></table>

$$DMS = 1061$$

<table><caption>Tabla 21. Rendimiento granos verdes de guandul para las variedades.</caption><thead><tr><th>Variedades</th><th>Rendimiento grano verde (gr/AU)</th></tr></thead><tbody><tr><td>Kaki</td><td>6215 a</td></tr><tr><td>Sagarateado</td><td>5851 a</td></tr><tr><td>Puerto Rico</td><td>5520 a</td></tr><tr><td>Kaki Blanco</td><td>5176 a</td></tr></tbody></table>

$$DMS = 1016$$
<table><caption>Tabla 22. Rendimiento grano verde del guandul para la interacción localidad por variedad.</caption><thead><tr><th>Localidad</th><th>Variedad</th><th>Rendimiento grano verde(gr/AU)</th></tr></thead><tbody><tr><td>CESDA</td><td>Sagarateado</td><td>9017 a</td></tr><tr><td>CESDA</td><td>Kaki</td><td>4015 a</td></tr><tr><td>CESDA</td><td>Kaki Blanco</td><td>8226 a</td></tr><tr><td>CESDA</td><td>Puerto Rico</td><td>7866 a</td></tr><tr><td>EEAL</td><td>Kaki</td><td>3415 b</td></tr><tr><td>EEAL</td><td>Puerto Rico</td><td>3175 b</td></tr><tr><td>EEAL</td><td>Sagarateado</td><td>2686 b</td></tr><tr><td>EEAL</td><td>Kaki Blanco</td><td>2125 b</td></tr></tbody></table>

$$DMS = 1436$$

<table><caption>Tabla 23. Rendimiento granos verdes del guandul para la interacción variedad por marco en San Cristóbal y San Juan de la Maguana.</caption><thead><tr><th>Variedad</th><th>Marco (m)</th><th>Rendimiento (gr/AU)</th></tr></thead><tbody><tr><td>Sagarateado</td><td>1.50 x 1.50</td><td>6725 a</td></tr><tr><td>Kaki</td><td>1.50 x 1.50</td><td>6541 ab</td></tr><tr><td>Kaki</td><td>2.00 x 1.50</td><td>5889 ab</td></tr><tr><td>Puerto Rico</td><td>1.50 x 1.50</td><td>5833 ab</td></tr><tr><td>Kaki Blanco</td><td>1.50 x 1.50</td><td>5318 ab</td></tr><tr><td>Puerto Rico</td><td>2.00 x 1.50</td><td>5208 ab</td></tr><tr><td>Kaki Blanco</td><td>2.00 x 1.50</td><td>5033 b</td></tr><tr><td>Sagarateado</td><td>2.00 x 1.50</td><td>4978 b</td></tr></tbody></table>

$$DMS = 2031$$
<table><caption>Tabla 24. Rendimiento granos verdes del guandul para las interacciones localidad por variedad por marco en San Cristóbal, San Juan de la Maguana.</caption><thead><tr><th>Localidad</th><th>Variedad</th><th>Marco (m)</th><th>Rendimiento (gr/AU)</th></tr></thead><tbody><tr><td>CESDA</td><td>Kaki</td><td>1.50 x 1.50</td><td>10520 a</td></tr><tr><td>CESDA</td><td>Sagarateado</td><td>1.50 x 1.50</td><td>10040 a</td></tr><tr><td>CESDA</td><td>Kaki Blanco</td><td>1.50 x 1.50</td><td>8584 abc</td></tr><tr><td>CESDA</td><td>Puerto Rico</td><td>1.50 x 1.50</td><td>8331 abc</td></tr><tr><td>CESDA</td><td>Sagarateado</td><td>2.00 x 1.50</td><td>7996 bc</td></tr><tr><td>CESDA</td><td>Kaki Blanco</td><td>2.00 x 1.50</td><td>7869 bc</td></tr><tr><td>CESDA</td><td>Kaki</td><td>2.00 x 1.50</td><td>7513 c</td></tr><tr><td>CESDA</td><td>Puerto Rico</td><td>2.00 x 1.50</td><td>7401 c</td></tr><tr><td>EEAL</td><td>Kaki</td><td>1.50 x 1.50</td><td>4266 d</td></tr><tr><td>EEAL</td><td>Sagarateado</td><td>1.50 x 1.50</td><td>3412 d</td></tr><tr><td>EEAL</td><td>Puerto Rico</td><td>1.50 x 1.50</td><td>3335 d</td></tr><tr><td>EEAL</td><td>Puerto Rico</td><td>2.00 x 1.50</td><td>3015 d</td></tr><tr><td>EEAL</td><td>Kaki</td><td>1.50 x 1.50</td><td>2563 d</td></tr><tr><td>EEAL</td><td>Kaki Blanco</td><td>2.00 x 1.50</td><td>2198 d</td></tr><tr><td>EEAL</td><td>Kaki Blanco</td><td>1.50 x 1.50</td><td>2053 d</td></tr><tr><td>EEAL</td><td>Sagarateado</td><td>2.00 x 1.50</td><td>1960 d</td></tr></tbody></table>

$$DMS = 2031.$$

IV. CONCLUSIONES Y RECOMENDACIONES

1) Las variedades Kaki (testigo) y Sagarateado, resultaron con mayor precocidad a la floración, mientras que la Kaki Blanco resultó la más tardía.

2) El mayor desarrollo en altura de planta y diámetro de copa de presentó en la localidad de San Cristóbal con marcos de plantación de 2.00m x 1.50m, mientras que con marcos de 1.50m x 1.50m se obtuvieron los mejores rendimientos.

3) Las variedades introducidas no superaron al testigo en cuanto al porcentaje de granos a la cosecha, ni rendimiento total, en verdeo.

4) Continuar los estudios con estos materiales pero, incluyendo otros marcos de plantación.
BIBLIOGRAFÍA

1.- Investigaciones Agropecuarias (1973-1984). Secretaría de Estado de Agricultura, Santo Domingo, R.D. 199 p.

2.- Herrera, M. (1989). Comportamiento del guandul (Cajanus cajan, L.) variedad UASD, en diferentes épocas y marcos de plantación 2da. Jornada Agrometeorológica. Santo Domingo, R.D. 12 p.

3.- Herrera, M. (1990). Número e intervalos de cosechas del guandul (Cajanus cajan, L) variedad UASD, en primavera. 3era. Jornada Agrometeorológica, Santo Domingo, R.D. 22p.

4.- Freddy, S.G. (1991). El cultivo del guandul (Cajanus cajan, L) Programa Nacional de Leguminosas Comestibles. Santo Domingo, R.D. 44p.
# THE INFLUENCE OF VARIED STEM MATURITY ON ROOTING OF CARIBBEAN OREGANO

(Lippia micromera S.)

J.R. Espaillat, E.C. French, and S.H. West

University of Florida, IFAS

Agronomy Department

304 Newell Hall

Gainesville, Florida, 32611

## ABSTRACT

Different stages of vegetative maturity influence rooting potential of stem cuttings. Oregano is in high demand in the international herb market. Four experiments were conducted in spring and fall of 1990 and 1991 to: 1) determine optimum stem maturity stage for cutting propagation of Caribbean oregano (Lippia micromera S.), and 2) determine seasonal differences in its rooting capabilities. Hardwood main stems, hardwood secondary stems, softwood stem tips, and semi-hardwood stem tips were placed upright in perlite using a hotbed. Bottom heat temperature was 28°C for all exp. At 21 days, shoot growth (SG), and root length (RL) ratings and rooting percent data showed highly significant difference between stem cuttings. Soft-wood stem tips gave plants with the best shoot growth and root system regardless of the season. Increased wood maturity negatively influenced rooting potential for fall propagated cuttings.

## INTRODUCTION

Caribbean oregano (Lippia micromera S.) belongs to the family Verbenaceas. There are 760 species in this family, mainly in temperature and tropical climates. Liogier (1974) considered Caribbean oregano to be original from the Antilles. It can be described as a bush type plant of 1-2 m high, perenne, highly branched, small oval leaves of 6-12 cm, and white or pink flowers in terminal bunch. Rodriguez (1980) listed the uses of this oregano in the antilles. Fresh and dry leaves are used as seasoning. Medicinal properties are attributed to
its volatile essential oils. The te is used as astringent, as antiseptic, to cure dysentery and against cold.

Tucker (1990) reports that almost every culture of the temperate and tropical zones utilizes plants high in phenol carvacrol and often these plants are substituted for each other. There is the need to understand the name oregano as a particular spice flavor, and not to refer to any one particular species. When considering the commercial value of the different oreganos, the Caribbean oregano is highly appreciated. The plant propagates both by seeds and stem cuttings. Seed germination is low, having the seedlings a long juvenile stage and great genetic segregation. Stem cuttings has been used for long time in the Caribbean. However, Rodriguez (1980) reports poor rooting results. Because of the highly branched growing habit, there are always tips and branches of different maturity and under different growing conditions.

When propagating perennials by cuttings the type of plant material to be selected at different seasons is an important consideration. Raviv et al. (1983) found that winter cuttings of laurel taken from lower and juvenile parts rooted better than those taken from older parts. During the summer rooting differences were not significant. This changes in rooting ability with season and stage of growth can be related to dormancy and/or change in the balance between rooting promoters and inhibitors. Hartman and Kester (1983) concluded that during dormancy rooting is generally poor.

Moe (1988) claims, seasonal variations in rooting may be related to changes in irradiance level, light quality and photoperiod. Short days induce dormancy in many species and flowering in short day plants generally inhibit rooting and lateral branching. Long days induce flowering in long day plants (LDP) inhibiting rooting and lateral branching. Temperature can modify the effect of photoperiod and/or irradiance on lateral branching and rooting.

Heide (1968) demonstrated that mother plants grown at high temperature and long days (LD), a combination which is favorable for rooting of its cuttings, had a higher auxin activity than those from SD and low temperature. Therefore, cuttings should be obtained from
healthy, turgid, disease and insect-free stock plants with no nutritional deficiencies.

According to Rak and Nowak (1988) for snapdragon which seedlings possess a long and vulnerable juvenile stage, cuttings propagation omits that first very critical stage of seedling growth. Van de Pol and Van Hell (1988) considered a clear sample the Musaceas, which propagation by seeds is undesirable due to a prolonged period of juvenility of about 4 years and a great degree of genetic variation.

There is an optimum range of environmental conditions for propagation to ensure good rooting results. Loach (1988) emphasized the propagation environment is controlled through use of shading, polyethylene enclosures, variation of the misting frequency, humidity and temperature regulation through heating or evaporative cooling. It is adequate to mention that optimal conditions are often specified in terms of the individual environmental components in an specify location.

As specified by Moe (1988) the goal of all plant propagator is to obtain high quality young plants in the shortest possible time. This implies that cuttings must root quickly and be capable of forming adventitious buds, good lateral branching and fast subsequent growth after rooting. That is why it is so important to know the best wood-hardiness of the stems for cuttings propagation.

The objectives of this research were defined as follow: 1) determine optimum stem maturity stage for cutting propagation of Caribbean oregano, and 2) determine any difference in the rooting capabilities of Caribbean oregano during spring and fall propagation seasons.

## MATERIALS AND METHODS

Four rooting experiments were conducted during the spring (May) and fall (September) of 1990, and during the spring (April) and fall (September) of 1991 using Caribbean oregano stem cuttings at different vegetative maturity. Randomized complete block designs with four replications were used. The treatments (trt) under consideration
were the following: 1) hardwood main stems, 2) hardwood secondary stems, 3) softwood stem tips, and 4) semi-hardwood stem tips.

Cuttings from clonally propagated mother plants were separated based on mentioned wood hardiness treatments and surface disinfected with a 5% solution of chlorine. Leaves were removed from the basal 2.5 cm of the cuttings. While wet, the basal end of the cuttings were dipped into hormodin No 1 (1 % of Indole-3-butyric Acid) root inducing substance.

The experiments were conducted in a glass greenhouse with 50 % shading. The rooting media was horticultural perlite on a hotbed. Temperature (T) and relative humidity (R.H.) in the greenhouse and in the hotbed were kept constant for the four experiments. Temperature in the hotbed was set at 28° C. Diurnal T in the greenhouse fluctuate from 26 to 29°C, while night T fluctuate from 20 to 26°C. Adequate moisture was maintained by misting irrigation when necessary according with a moisture detector placed in the middle of the experiments. Efforts were made to keep environmental conditions constant during rooting.

After 21 days, cuttings were taken out and rooting data recorded. The data collected included ratings of shoot growth (SG), and root length (RL) in an scale of 1 to 5 (5 = the best) and rooting percentage (R %). Statistical analyses included, two way analysis of variance (ANOVA) and mean separation by least significant difference test (LSD).

## RESULTS

Results of the four rooting experiments will be commented independently. Also, similarities and differences in the performance of treatments due to seasonal and environmental variations will be evaluated.

In experiment # 1 (May, 1990) SG and RL ratings were highly significant affected by the treatments. Softwood stem tips had the quickest shoot growth among all treatments and no differences were observed between hardwood secondary stems, hardwood main stem, and semi-hardwood stem tips (Table 1). Rooting percentage did not
showed significant difference among treatments. However, there was
a trend of softwood stem tips having the best root system.

In experiment #2 (September, 1990) SG, RL, and R % showed highly significant differences among treatments. Softwood stem tips had the quickest shoot growth, the strongest root system, and the greatest rooting percentage among all treatments (Table 2). Semi-hardwood stem tips, hardwood secondary stems and hardwood main stems followed in that order for the three variables under evaluation. The order in which these treatments followed each other is different from experiment # 1. During the fall the efficiency of the cuttings seems to be more closely related to the tenderness of the tissue, the more tender the better they root. From this preliminary results, it appears that a dormancy mechanism in this tropical plant shows low hormonal activity during the fall. If this is true, the rooting capabilities will be reduced as the tissue matures.

In experiment # 3 (April, 1991) SG and R % showed a highly significant difference among treatments. Softwood stem tips had the quickest shoot growth and the greatest rooting percentage among all treatments (Table 3). Rooting percentage did not had significant differences among treatments. The results of this second spring experiment were very similar to the results obtained in experiment # 1 with the treatments following the similar trend.

In experiment # 4 (September, 1991) SG and RL showed highly significant differences among treatments (Table 4). Rooting percentage did not showed significant differences among treatments. However, a trend exist among treatments. Softwood stem tips had the quickest shoot growth, strongest root system, and the greatest rooting percentage among all treatments. Semi-hardwood stem tips, hardwood secondary stems and hardwood main stems followed for root length and rooting percent.

The results of the two experiments performed during the spring (Experiments # 1 and # 3) were very similar. Regardless of significant differences or not, the treatments followed similar trend of performance for the three variables under evaluation in which, softwood stem tips were the best lippia cuttings for an efficient plant production.
For example, this is the case of rooting percent, the variable in which we are more interested. Semi-hardwood stem tips gave the worst rooting percent and the smallest root system.

The results of the two experiments performed during the fall (Experiments #2 and #4) were very similar. In the experiment conducted in 1991 the difference among treatments was more evident except for rooting percentage. When comparing the results obtained during the spring and the fall, it is obvious that the use of soft tissue is more convenient during the fall. While during the spring, cuttings from actively growing plants, although fairly woody will root and growth in a satisfactory manner. In both seasons, spring or fall, the newly growth tissue rooted the best.

## CONCLUSIONS

Under the prevailing conditions of these experiments, it can be concluded that there is difference in the rooting ability of varied stem maturity cuttings of Caribbean oregano. Herb growers interested in clonally propagate this oregano, should use stem cuttings which still green and soft without forming a brown cortex.

For the three variables under evaluation, which characterizes a good stock plant, softwood stem tips were better than any other more mature cutting regardless of the season. These type of cuttings gave plants with a strong root system and have a single shoot growing fast which allow an easy configuration of the plant by pruning while harvesting. The use of semi-hardwood stem tip cuttings, will give plants with acceptable shoot growth, but with smaller root systems and lower rooting percentage.

Although with certain degree of variability, the rooting percentage results were consistent for both experiments carried out during the spring and the fall. These results implies that rooting percentage could be the best variable to be measured when performing this type of rooting experiments. Finally, it can be concluded that increased wood maturity negatively influenced rooting potential for fall propagated cuttings.
<table><caption>Table 1. Root Lenght (RL), Shoot Growth (SG), and Rooting Percentage (R %) of Caribbean oregano (Lippia micromera S.) at different vegetative maturity in experiment # 1.</caption><thead><tr><th>Treatment</th><th>RL</th><th>SG</th><th>R %</th></tr><tr><td></td><td colspan="2" style="text-align: center;">----rating----</td><td>%</td></tr></thead><tbody><tr><td>Hardwood main stems</td><td>3.5 b</td><td>3 b</td><td>85</td></tr><tr><td>Hardwood secondary stems</td><td><strong>3.7 ab</strong></td><td>3 b</td><td><strong>97</strong></td></tr><tr><td>Softwood stem tips</td><td>4.7 a</td><td>5 a</td><td><strong>97</strong></td></tr><tr><td>Semi-hardwood stem tips</td><td>2.2 c</td><td>3 b</td><td>72</td></tr><tr><td>ANOVA</td><td>**</td><td>**</td><td>NS</td></tr></tbody></table>

<table><caption>Table 2. Root Lenght (RL), Shoot Growth (SG), and Rooting Percentage (R %) of Caribbean oregano (Lippia micromera S.) at different vegetative maturity in experiment # 2.</caption><thead><tr><th>Treatment</th><th>RL</th><th>SG</th><th>R %</th></tr><tr><td></td><td colspan="2" style="text-align: center;">----rating----</td><td>%</td></tr></thead><tbody><tr><td>Hardwood main stems</td><td>1.2 sc</td><td>1.7 b</td><td>67 b</td></tr><tr><td>Hardwood secondary stems</td><td>2.5 b</td><td>2.2 b</td><td>90 a</td></tr><tr><td>Softwood stem tips</td><td>4.5 a</td><td>4.7 a</td><td>100 a</td></tr><tr><td>Semi-hardwood stem tips</td><td>4.2 a</td><td>4.0 a</td><td>94 a</td></tr><tr><td>ANOVA</td><td>**</td><td>**</td><td>**</td></tr></tbody></table>

<footnote>*Values followed by the same letter are not significant different as LSD test at 5% level. N S, *, ** = Non significant, or significant at the 5 and 1 % level respectively.</footnote>

<footnote>ª Values followed by the same letter are not significant different as LSD test at 5% level. N S, *, ** = Non significant, or significant at the 5 and 1 % level, respectively.</footnote>
<table><caption>Table 3. Root Lenght (RL), Shoot Growth (SG), and Rooting Percentage (R %) of Caribbean oregano (*Lippia micromera* S.) at different vegetative maturity in experiment # 3.</caption><thead><tr><th>Treatment</th><th>RL</th><th>SG</th><th>R %</th></tr><tr><td></td><td colspan="2" style="text-align: center;">----rating----</td><td>%</td></tr></thead><tbody><tr><td>Hardwood main stems</td><td>3.5 ab</td><td>3.5 b</td><td>79 ab</td></tr><tr><td>Hardwood secondary stems</td><td>3.7 ab</td><td>2.5 b</td><td>92 a</td></tr><tr><td>Softwood stem tips</td><td>4.5 a</td><td>4.7 a</td><td>95 a</td></tr><tr><td>Semi-hardwood stem tips</td><td>3.0 b</td><td>3.5 b</td><td>73 b</td></tr><tr><td>ANOVA</td><td>**</td><td>**</td><td>**</td></tr></tbody></table>

<table><caption>Table 4. Root Lenght (RL), Shoot Growth (SG), and Rooting Percentage (R %) of Caribbean oregano (*Lippia micromera* S.) at different vegetative maturity in experiment # 4.</caption><thead><tr><th>Treatment</th><th>RL</th><th>SG</th><th>R %</th></tr><tr><td></td><td colspan="2" style="text-align: center;">----rating----</td><td>%</td></tr></thead><tbody><tr><td>Hardwood main stems</td><td>2.2 sd</td><td>2.7 c</td><td>81</td></tr><tr><td>Hardwood secondary stems</td><td>3.5 c</td><td>2.0 d</td><td>88</td></tr><tr><td>Softwood stem tips</td><td>5.0 a</td><td>5.0 a</td><td>93</td></tr><tr><td>Semi-hardwood stem tips</td><td>4.2 b</td><td>4.0 b</td><td>71</td></tr><tr><td>ANOVA</td><td>**</td><td>**</td><td>NS</td></tr></tbody></table>

<footnote><sup>*</sup> Values followed by the same letter are not significantly different as LSD test at 5% level. N S, *, ** = Non significant, or significant at the 5 and 1 % level respectively.</footnote>

<footnote><sup>*</sup> Values followed by the same letter are not significantly different as LSD test at 5% level. N S, *, ** = Non significant, or significant at the 5 and 1 % level, respectively.</footnote>
REFERENCES

Hartmann, H.T. and D.E. Kester. 1983. Plant propagation. principles and practices. Third Edition. Prentice-hall, Inc., Englewood Cliffs, N.J.

Heide, O.M. 1968. Auxin level and regeneration of begonia leaves. Planta 81:153-159.

Liogier, A.H. 1974. Diccionario botánico de nombres vulgares de La Española. Universidad Nacional Pedro Henríquez Hureña. pp.813.

Loach, K. 1988. Characterisation of Optimal Environments for Rooting Leafy Cuttings. International Symposium on Propagation of Ornamental Plants. pp. 403-412. Netherlands.

Moe, R. 1988. Effect of stock plant environment on lateral branching and rooting. International symposium on propagation of ornamental Plants. pp.431-444. Netherlands.

Rak, J. and J. Nowak. 1988. The effect of plant hormones on rooting and growth of snapdragon. Acta Hort. 226:503-505.

Raviv, M., E. Patievsky, U. Ravid, D. Senderovitch, N. Snir, and R. Ron. 1983. Bay Laurel as on Ornamental Plant. Acta Hort. 132:35-42.

Rodríguez, N.R. 1980. Cultivos agroindustriales no tradicionales en República Dominicana. Editora Taller, Sto. Dgo. pp.324.

Tucker, A.O. 1990. The Oregano mystery: A quide to the Oreganos. pages 8-9 in J.E. Simon, A. Kestner, and M.R. Buehrle, eds. Proceedings of the fifth national herbs growing and marketing conference, Baltimore, Maryland, 1990, IHGMA.

Van de Pol, P.A., and T.F. van Hell. 1988. Vegetative Propagation of Strelitzia reginae. Acta Hort. 226:581-586.
# ENSAYO DE HIBRIDOS Y VARIEDADES DE MAIZ
(Zea mays L.) DEL PROGRAMA UNPHU DE
MEJORAMIENTO

Pedro Comalat Rodes<fnref n="1" />

José Richard Ortiz<fnref n="1" />

## RESUMEN

Con el objetivo principal de buscar un aumento substancial de rendimiento en el cultivo del maíz en la República Dominicana, a fin de poder competir con los precios a que se vende el maíz importado a través de la Ley PL-480, en la Finca Experimental de Nigua de la Universidad Nacional Pedro Henríquez Ureña, se ha efectuado una evaluación de 41 materiales de maíz correspondientes a híbridos y variedades obtenidos en su mayor parte en la propia finca.

Para el fin perseguido se está trabajando sobre los efectos aditivos utilizando métodos de selección recurrente, en la obtención de nuevos híbridos convencionales mediante el cruzamiento de líneas seleccionadas y con buena habilidad combinatoria, además utilizando ambos procedimientos para juntar en materiales el mejoramiento debido a efectos aditivos y el correspondiente al vigor híbrido mediante el cruzamiento de líneas cuyas fuentes han sido de variedades mejoradas trabajando sobre los efectos aditivos. Nueve de los híbridos generados y una variedad de polinización abierta, ambas obtenidas en la Universidad, han superado al híbrido simple comercial introducido 3214, tropical pero originario de una empresa semillera de los Estados Unidos de Norteamérica.

## INTRODUCCION

En el transcurso del tiempo las necesidades del maíz en la República Dominicana han aumentado en progresión geométrica. El consumo humano no es muy grande, pero el uso del maíz transformado en

<footnote n="1">¹/ Fitomejoradores del Programa de Mejoramiento de Maíz de la Universidad Nacional Pedro Henríquez Ureña y Secretaría de Estado de Agricultura. Apartado Postal No. 25047 (El Embajador) Santo Domingo, Rep. Dom.</footnote>
carne, principalmente en la industria avícola y porcina, es bastante elevado. A medida que aumenta el consumo del cereal en el país, se perfila un estancamiento en la producción nacional. Este retroceso que se presenta en nuestra producción es debida a diversos factores entre los que hay que resaltar los bajos rendimientos de las variedades de siembra tradicionales, al elevado costo de producción del cultivo y a la competencia desleal con el cereal procedente de los Estados Unidos, el cual es subsidiado e importado por el Gobierno Dominicano a través de la PL-480.

Los Programas de Mejoramiento de Maíz de la Universidad Nacional Pedro Henríquez Ureña (UNPHU) y de la Secretaría de Estado de Agricultura, realizan importantes esfuerzos con el fin de lograr maíces, variedades e híbridos más rendidores que los materiales utilizados actualmente por el agricultor dominicano. La meta es aumentar la producción, mejorando la rentabilidad del cultivo y poder competir con el maíz importado de los Estados Unidos que se vende más barato que el producido en la República Dominicana. El aumento del potencial de rendimiento es buscado tanto por la obtención de nuevas variedades trabajando sobre los efectos aditivos mediante la utilización de diversos métodos de selección recurrente, como mediante el cruzamiento de líneas con el fin de obtener un buen vigor híbrido o bien usando ambos procedimientos.

## Revisión de Literatura

La manifestación de heterosis en cruzamientos de variedades hechos por Beal (1880) en la Estación Experimental Agrícola de Michigan, alertó a otros investigadores de los posibles beneficios de los cruces varietales, y estableció un plan mediante el cual el agricultor podría obtener su propia semilla mediante cruzamientos.

Hayes y Olson (1919) observaron que los mayores aumentos en rendimiento se dieron en los cruzamientos con parentales de diferentes orígenes que presentaron caracteres contrastantes que en una serie de cruzamientos mostraban el mayor grado de heterosis, lo cual permitía el mayor rendimiento obtenido en relación a los parentales de los mismos.
Moll et al. (1962) y Moll et al. (1965), estudiaron los cruces producidos entre variedades con diferentes niveles de diversidad genética estando estos influenciados por el origen geográfico de las variedades parentales.

Comalat y Germán (1986), presentaron en el PCCMCA resultados experimentales en que la variedad UNPHU-301C, el doble híbrido XL-678 y el cruce intervarietal UNPHU-301C y UNPHU-302D superaron en rendimiento a seis híbridos dobles y a la variedad Across-7728.

Pérez y Comalat (1982), concluyen que la baja productividad del maíz en la República Dominicana es debida principalmente al bajo potencial de rendimiento de las variedades bajo cultivo en el país.

Comalat y Tirado (1988), informaron que en una evaluación de 30 cultivares de posible introducción y de 6 desarrollados en la República Dominicana, el híbrido simple dominicano $NO_2 \times NO_7$ rindió un 11% más que el también híbrido simple-comercial 3214 y un 21% sobre el testigo H-5, siendo entre las variedades de polinización abierta la UNPHU-301C la más rendidora.

Cockerham (1954) y Kempthorne (1954) citados por Hallauer y Miranda (1981), desarrollaron la teoría general sobre las partes que determinan la variación hereditaria y consideraron que la varianza genética total podía ser descompuesta en varianza aditiva (efectos aditivos), varianza de dominancia (efectos de dominancia) y varianza epistática (interacción de efectos aditivos y de dominancia).

Alfaro, Pérez y Alvarado (1987), detectaron cruzas simples origina-
das a partir de líneas generadas de las poblaciones 24, 26, 27 y 36 del
Programa de Híbridos del CIMMYT, con un alto potencial de
rendimiento que superaron en este carácter al híbrido 3214 en un 25%.

Compton et al. (1965); Gardner (1963); Lindsey et al. (1962); Lonnquist (1961); Robinson y Comstock (1955) y Sprague (1966), citados por Sprague y Eberhart (1977), resumen que generalmente la variabilidad genética de los más importantes caracteres es debida en gran parte a la varianza genética aditiva y que la varianza no aditiva
debida a la dominancia y a la epistasis es comúnmente inferior en magnitud.

## Materiales y Métodos

El ensayo fue llevado a cabo en la Finca Experimental "Nigua" de la Universidad Nacional Pedro Henríquez Ureña (UNPHU), localizada a 18 grados 21' latitud Norte y 74 grados 04' longitud Oeste a 14 metros de altitud.

### a) Material Genético.

NO₂. Proveniente de un sintético de Florida. Posee más de 10 generaciones de autogamia (o endocría por autopolinizaciones). Buena habilidad combinatoria general. Buen productor de polen y de óvulos no abortados que producen semilla. Posee manchas en las hojas quizás debido a la concentración de genes recesivos. Plantas de mediana altura. Hojas verde claro. En promedio florece a los 62 días.

NO₃. Origen no completamente conocido, pero proviene de materiales dominicanos originarios de raza Chandelle. Más de 10 generaciones de autogamia. Buena habilidad combinatoria general. Plantas altas y con poca uniformidad. Grano cristalino que fácilmente revienta en la maduración inhabilitándolo para la siembra como hembra en la formación de híbridos. Hojas verde oscuro. Florece a los 59 días.

NO₅. Originaria del doble híbrido de Pioneer X-304A. 5 generaciones de autogamia. Habilidad combinatoria general no del todo buena. Plantas bajas con hojas verde oscuro y poco vigorosas. Floración a los 60 días.

NO₆. Proveniente de la variedad Mayorbela de Puerto Rico. Más de 10 generaciones de autogamia. Plantas altas no muy uniformes. Susceptible al achaparramiento (Corn stunt), pero en cruces con NO₂ posee buena habilidad combinatoria específica y resistente a dicha enfermedad. Florece a los 61 días.
**NO7.** Originaria de material cubano procedente de la raza Chandelle. Más de 10 generaciones de autogamia. Las cruzas con NO₂ han resultado muy inestables. En promedio florece a los 59 días.

**NO8.** Originaria de una contaminación de polen extraño con la NO7. Más de 8 generaciones de autogamia. Florece a los 59 días.

**DK-12.** Originaria de una cruza de varios híbridos tropicales de Dekalb. Más de siete generaciones de autogamia. Los híbridos simples que contienen esta línea son malos rendidores, pero de plantas muy uniformes. Posee mala habilidad combinatoria general. Florece a los 59 días.

**DK-14 y DK-19.** Igual origen que DK-12. Más de siete generaciones de autogamia. Plantas bajas y uniformes. Buena habilidad combinatoria general. Florecen a los 59 y 62 días respectivamente.

**T66.** Proveniente del híbrido doble de los Northrup King T66. Excelente habilidad combinatoria general. Más de 7 generaciones de autogamia. Plantas altas y bastante uniformes. Buena productora de polen y de óvulos fértiles capaces de producir semilla. Aporta color morado al tallo, carácter dominante. Florece en promedio a los 65 días.

Las líneas JC49 y JC53 pertenecen a Pioneer Hi-Bred International, Inc.

Las variedades utilizadas y sus características más relevantes se destacan a continuación:

**San Cristóbal-8328.** Originaria de selecciones sucesivas de la población 28 Amarillo Dentado. Procede de una mezcla genética de germoplasma caribeño, mexicano, centroamericano y brasileño. Sometida posteriormente al método de selección de mazorcas por hilera y liberada como variedad en 1983. De alto rendimiento, pero muy susceptible al achaparramiento. Ciclo de 125 días.

**UNPHU-301C.** Originaria de un cruzamiento de Across-7728 por CNIA-12. Un ciclo de selección masal estratificado y ocho ciclos por
selección recurrente utilizando el método de mazorca por hilera. Muy resistente al acame. Alto rendimiento. Ciclo 120 días.

UNPHU-303C. Originaria de un cruce entre CESDA-88 x DK-12. Tres ciclos de selección de "mazorca por hilera" fueron completados.

UNPHU-304C. Originada de un cruzamiento entre las variedades CESDA-88 y NB-6. Cuatro ciclos de selección recurrente por el método mazorca por hilera. Un ciclo de selección para la eliminación de los segregantes blancos por endogamia y por cruzamiento con maíz blanco. Altamente resistente al achaparramiento. Buena rendidora. Ciclo vegetativo de 120 días.

CESDA-88. Originaria de un policruzamiento de las poblaciones del CIMMYT 24, 26 y 28 con Francés Largo. Mejorada con varios ciclos de selección recurrente por progenies S1.

Los híbridos XL-678C y XL-679 pertenecen a la compañía Dekalb-Pfizer Genetics.

Los híbridos 3214 y 3204 pertenecen a la compañía Pioneer Hi-Bred International, Inc.

STR es el nombre primitivo de la variedad CESDA-88.

### b) Siembra.

El ensayo fue sembrado utilizando un diseño en Bloques al Azar con cuatro repeticiones. Las parcelas fueron de 2 surcos de 5 metros de largo y una separación entre ellos de 0.8 metros.

### c) Manejo.

No se aplicó herbicida. La fertilización fue efectuada a los 15 días después de la germinación a razón de 120 kg/ha de Nitrógeno en forma de Urea. Para el control de insectos, se ejecutaron dos aplicaciones a base de Pounce 1.5 G a razón de 11 kg/ha dirigido básicamente al control de *Spodoptera frugiperda* Smith. Se efectuaron dos desyer-
bos antes de la floración. Debido a las pocas precipitaciones, se practicaron cuatro riegos.

### d) Variables evaluadas.

Las variables evaluadas fueron: Días a Flor, Altura de Plantas y Mazorca, Acame de Raíz y Tallo, Peso de Campo, Plantas Establecidas, Plantas Cosechadas, Número Total de Mazorcas, Número de Mazorcas Podridas, % de Humedad, Número de Plantas con Corn Stunt, Aspecto de Planta y Mazorca, Cobertura de Mazorca, Dureza de Grano y Rendimiento en Grano al 15% de Humedad.

### e) Método estadístico.

Se realizó el análisis de varianza bajo el siguiente modelo:

$$X_{ijk} = \mu + E_i + B_j + \text{eijk} \\ \text{en el que,}$$

$X_{ijk}$ = Valor fenotípico observado en el tratamiento aplicado en el bloque donde está la observación en el orden indicado.

$\mu$ = efecto de la medida general

$E_i$ = efecto de tratamiento

$B_j$ = efecto del bloque

$\text{eijk}$ = efecto del error experimental

## Resultados y Discusiones

En el Cuadro 1, se especifican los datos tomados y su valoración. En el Cuadro 2, se presentan los cuadrados medios de las variables evaluadas en este ensayo y las diferencias ($p<a = 0.01$ ó $p<a = 0.05$) significativas y las no significativas para los efectos de tratamientos, y su partición en híbridos, variedades y la comparación de híbridos vs. variedades. En el Cuadro 3 se presentan las medias y LSD para cada variable evaluada.
<table><caption>Cuadro 1. Datos tomados y valoración de los mismos</caption><tr><td>Días Flor (flor)</td><td>Desde siembra (riego o lluvia) en días hasta que el 50% de las plantas esparzan polen.</td></tr><tr><td>Altura Pta. (aip)</td><td>Distancia en cms desde el suelo hasta la base de la inflorescencia masculina.</td></tr><tr><td>Altura Mazorca (almz)</td><td>Distancia en cms desde el suelohasta el nudo de la mazorca superior o principal.</td></tr><tr><td>Acame Raíz (acr)</td><td>Número de plantas acabadas con una inclinación de tallo a partir de los 45 grados.</td></tr><tr><td>Acame Tallo (act)</td><td>Número de plantas quebradas por debajo de la mazorca.</td></tr><tr><td>Plantas estab. (ptst)</td><td>Número por parcela útil.</td></tr><tr><td>Plantas cos. (ptcos)</td><td>Número por parcela útil.</td></tr><tr><td>Número Mazorcas (#mz)</td><td>Número por parcela útil.</td></tr><tr><td>Aspecto Planta (aspt)</td><td>Escala 1 (excelente) 9 (mala)</td></tr><tr><td>Aspecto Mazorca (aspmz)</td><td>Escala 1 (excelente) 9 (mala)</td></tr><tr><td>Cobertura Maz. (cob)</td><td>Número de mazorcas con mala cobertura.</td></tr><tr><td>Dureza Endosperma (dur)</td><td>Escala 1 (cristalino) 9 (suave)</td></tr><tr><td>% achap. (% achap)</td><td>En % por parcela</td></tr><tr><td>% maz. Podridas (%mzp)</td><td>En % por parcela</td></tr></table>

Conclusiones

Exceptuando las variables acame de tallo y % de mázorcas podridas, en las que no se encontró diferencias significativas, todas las demás variables mostraron diferencias para los efectos de entradas evaluadas. Con respecto a la comparación entre híbridos y variedades, el análisis de varianza mostró diferencias entre ambos tipos de materiales.
Es interesante señalar el bajo coeficiente de variación obtenido para la variable rendimiento = 5.57%.

El híbrido simple dominicano NO₃ x T₆₆, (comercial, RD-36691), como en otros ensayos, sigue mostrando su potencial en comparación con otros materiales. En este trabajo estuvo entre los primeros lugares, seguido de cerca por otros nueve materiales entre los que se encuentra la nueva variedad UNPHU-304C, generada por nuestro Programa de Mejoramiento.
<table><caption>Tabla 2. Cuadrados medios de las variables significativas evaluadas en el estudio de Hifridos y variedades del Programa UNPHU de Miérjoramiento.</caption><thead><tr><th>Fuente</th><th>G.L.</th><th>Rend.</th><th>Fibr.</th><th>Alt. pfa.</th><th>Alt. mr.</th><th>Acima R.</th><th>Acima T.</th><th>Pta. Est.</th><th>Pta. Cen.</th><th>#Mt.</th></tr></thead><tbody><tr><td>Rep</td><td>3</td><td>1.32**</td><td>17.52**</td><td>95.52**</td><td>87.46**</td><td>3.78**</td><td>0.18**</td><td>20.92**</td><td>30.31**</td><td>27.66*</td></tr><tr><td>Trt</td><td>40</td><td>2.87**</td><td>16.10**</td><td>349.47**</td><td>449.85**</td><td>4.31**</td><td>0.41**</td><td>27.31**</td><td>28.21**</td><td>28.73**</td></tr><tr><td>*Hib</td><td>35</td><td>1.55**</td><td>15.25**</td><td>353.32**</td><td>479.61**</td><td>3.67**</td><td>0.39**</td><td>6.50**</td><td>7.51**</td><td>11.79**</td></tr><tr><td>*Var</td><td>4</td><td>9.67**</td><td>10.55**</td><td>361.25**</td><td>301.88**</td><td>5.18**</td><td>0.50**</td><td>175.75**</td><td>179.20**</td><td>123.93**</td></tr><tr><td>*H vs V</td><td>1</td><td>21.80**</td><td>68.21**</td><td>167.70**</td><td>0.04**</td><td>23.11**</td><td>0.62</td><td>161.73**</td><td>148.96**</td><td>240.77**</td></tr><tr><td>Error</td><td>120</td><td>0.18</td><td>1.35</td><td>85.00</td><td>137.45</td><td>1.31</td><td>0.38</td><td>4.26</td><td>4.13</td><td>7.54</td></tr><tr><td>Media General</td><td></td><td>7.54</td><td>62</td><td>218.5</td><td>113.3</td><td>1.0</td><td>0.3</td><td>38.9</td><td>38.0</td><td>37.2</td></tr><tr><td>Media Hfb.</td><td></td><td>7.68</td><td>63</td><td>218.8</td><td>113.3</td><td>0.9</td><td>0.3</td><td>39.3</td><td>38.3</td><td>37.7</td></tr><tr><td>Media Var.</td><td></td><td>6.57</td><td>61</td><td>215.8</td><td>113.3</td><td>2.1</td><td>0.5</td><td>36.3</td><td>35.4</td><td>34.0</td></tr><tr><td>C.V.</td><td></td><td>5.57</td><td>1.87</td><td>4.22</td><td>10.35</td><td>109.67</td><td>184.00</td><td>5.31</td><td>5.35</td><td>7.38</td></tr><tr><td>Min.</td><td></td><td>4.12</td><td>59</td><td>200.0</td><td>92.5</td><td>0.0</td><td>0.0</td><td>24.5</td><td>23.5</td><td>24.8</td></tr><tr><td>Max.</td><td></td><td>9.02</td><td>66</td><td>232.5</td><td>131.3</td><td>3.5</td><td>1.3</td><td>40.8</td><td>40.8</td><td>41.3</td></tr></tbody></table>

<table><caption>Tabla 2. (Continuada)</caption><thead><tr><th>Fuente</th><th>Asp Pfa.</th><th>Asp Mz.</th><th>Cob Mz.</th><th>Durza</th><th>% Achup.</th><th>% Mt.Puf.</th></tr></thead><tbody><tr><td>Rep</td><td>0.09**</td><td>0.01**</td><td>2.37**</td><td>0.01**</td><td>22.25**</td><td>20.48**</td></tr><tr><td>Trt</td><td>0.31**</td><td>0.68**</td><td>18.22**</td><td>3.01**</td><td>116.33**</td><td>8.19**</td></tr><tr><td>*Hib</td><td>0.30**</td><td>0.56**</td><td>19.94**</td><td>2.81**</td><td>126.86**</td><td>8.61**</td></tr><tr><td>*Var</td><td>0.27**</td><td>1.27**</td><td>1.58**</td><td>4.94**</td><td>14.75**</td><td>5.67**</td></tr><tr><td>*H vs V</td><td>0.78**</td><td>2.74**</td><td>24.94**</td><td>2.16**</td><td>153.78**</td><td>3.35**</td></tr><tr><td>Error</td><td>0.10</td><td>0.01</td><td>1.65</td><td>0.05</td><td>12.49</td><td>5.66</td></tr><tr><td>Media General</td><td>1.3</td><td>1.4</td><td>1.7</td><td>2.3</td><td>4.4</td><td>1.9</td></tr><tr><td>Media Hfb.</td><td>1.2</td><td>1.4</td><td>1.8</td><td>2.3</td><td>4.7</td><td>2.0</td></tr><tr><td>Media Var.</td><td>1.5</td><td>1.8</td><td>0.6</td><td>2.6</td><td>1.8</td><td>1.5</td></tr><tr><td>C.V.</td><td>25.42</td><td>7.36</td><td>77.91</td><td>9.38</td><td>80.58</td><td>123.67</td></tr><tr><td>Min.</td><td>1.0</td><td>1.0</td><td>0.0</td><td>1.1</td><td>0.0</td><td>0.0</td></tr><tr><td>Max.</td><td>2.3</td><td>2.5</td><td>11.8</td><td>5.0</td><td>28.6</td><td>5.7</td></tr></tbody></table>

* = Diferencias estadísticas a = 0.05

** = Diferencias estadísticas a = 0.01

ns = No diferencias estadísticas
<table><caption>Círculo 3. Medidas de los variables agrupacionales del módulo de la variables 7 y variables MínimosMAXIMOS</caption><thead><tr><th>Gas</th><th>RESID</th><th>FLOA</th><th>ALP</th><th>ALM2</th><th>ACR</th><th>ACT</th><th>FSTT</th><th>FTCO</th><th>Fb</th><th>ASFT</th><th>ASUM</th><th>COB</th><th>DUR</th><th>SACIN</th><th>Wakyl</th></tr></thead><tbody><tr><td>RESID/167/1</td><td>9.22</td><td>219</td><td>65</td><td>125</td><td>4.3</td><td>0.5</td><td>41</td><td>40</td><td>39</td><td>2.1</td><td>1.0</td><td>0.0</td><td>4.0</td><td>0.0</td><td>1.3</td></tr><tr><td>NOCEM/167/1</td><td>8.96</td><td>224</td><td>128</td><td>129</td><td>0.5</td><td>0.0</td><td>40</td><td>40</td><td>39</td><td>1.3</td><td>1.0</td><td>1.3</td><td>1.6</td><td>3.3</td><td>0.0</td></tr><tr><td>RESID/167/2</td><td>8.96</td><td>215</td><td>129</td><td>119</td><td>0.3</td><td>0.0</td><td>40</td><td>40</td><td>39</td><td>1.4</td><td>1.0</td><td>1.5</td><td>3.0</td><td>3.8</td><td>0.0</td></tr><tr><td>NOCEM/167/3</td><td>8.47</td><td>63</td><td>221</td><td>113</td><td>2.5</td><td>0.3</td><td>40</td><td>40</td><td>39</td><td>1.4</td><td>1.1</td><td>0.5</td><td>2.5</td><td>1.3</td><td>1.9</td></tr><tr><td>NOCEM/167/4</td><td>8.47</td><td>62</td><td>206</td><td>100</td><td>0.3</td><td>0.0</td><td>40</td><td>40</td><td>39</td><td>1.0</td><td>1.0</td><td>2.5</td><td>2.5</td><td>6.1</td><td>2.4</td></tr><tr><td>NOCEM/167/5</td><td>8.14</td><td>64</td><td>220</td><td>118</td><td>0.3</td><td>0.3</td><td>39</td><td>37</td><td>37</td><td>1.0</td><td>1.3</td><td>3.3</td><td>1.4</td><td>8.7</td><td>1.9</td></tr><tr><td>NOCEM/167/6</td><td>8.13</td><td>64</td><td>213</td><td>124</td><td>0.8</td><td>0.3</td><td>42</td><td>39</td><td>39</td><td>1.1</td><td>1.0</td><td>0.0</td><td>2.0</td><td>0.0</td><td>0.0</td></tr><tr><td>NOCEM/167/7</td><td>8.07</td><td>63</td><td>228</td><td>129</td><td>2.8</td><td>0.3</td><td>41</td><td>40</td><td>39</td><td>1.5</td><td>1.0</td><td>0.0</td><td>2.6</td><td>0.3</td><td>1.2</td></tr><tr><td>NOCEM/167/8</td><td>8.07</td><td>62</td><td>214</td><td>100</td><td>0.0</td><td>0.0</td><td>40</td><td>40</td><td>39</td><td>1.0</td><td>1.1</td><td>5.3</td><td>2.0</td><td>1.0</td><td>0.0</td></tr><tr><td>NOCEM/167/9</td><td>8.01</td><td>59</td><td>200</td><td>94</td><td>0.5</td><td>0.8</td><td>41</td><td>40</td><td>39</td><td>1.3</td><td>1.0</td><td>0.3</td><td>2.5</td><td>0.5</td><td>1.2</td></tr><tr><td>Tiwa</td><td>7.99</td><td>62</td><td>233</td><td>119</td><td>0.5</td><td>0.3</td><td>36</td><td>35</td><td>39</td><td>1.1</td><td>1.5</td><td>1.8</td><td>2.5</td><td>5.3</td><td>3.4</td></tr><tr><td>RESID/167/10</td><td>7.97</td><td>60</td><td>200</td><td>131</td><td>3.5</td><td>1.3</td><td>40</td><td>39</td><td>39</td><td>2.3</td><td>2.0</td><td>3.5</td><td>2.6</td><td>9.2</td><td>0.6</td></tr><tr><td>NOCEM/167/11</td><td>7.94</td><td>65</td><td>220</td><td>125</td><td>2.0</td><td>0.0</td><td>41</td><td>40</td><td>39</td><td>1.4</td><td>1.5</td><td>1.0</td><td>2.5</td><td>0.6</td><td>0.6</td></tr><tr><td>NOCEM/167/12</td><td>7.92</td><td>66</td><td>223</td><td>129</td><td>0.8</td><td>0.0</td><td>38</td><td>37</td><td>37</td><td>1.1</td><td>2.0</td><td>0.8</td><td>2.0</td><td>1.9</td><td>1.3</td></tr><tr><td>NOCEM/167/13</td><td>7.81</td><td>65</td><td>221</td><td>113</td><td>0.8</td><td>0.0</td><td>40</td><td>40</td><td>39</td><td>1.1</td><td>1.5</td><td>0.3</td><td>2.3</td><td>0.6</td><td>2.0</td></tr><tr><td>NOCEM/167/14</td><td>7.74</td><td>59</td><td>229</td><td>126</td><td>1.3</td><td>0.3</td><td>39</td><td>38</td><td>38</td><td>1.4</td><td>1.5</td><td>0.3</td><td>2.1</td><td>0.6</td><td>2.7</td></tr><tr><td>NOCEM/167/15</td><td>7.68</td><td>60</td><td>216</td><td>100</td><td>1.0</td><td>0.0</td><td>40</td><td>40</td><td>39</td><td>1.4</td><td>1.0</td><td>0.3</td><td>0.6</td><td>1.9</td><td>1.9</td></tr><tr><td>NOCEM/167/16</td><td>7.68</td><td>63</td><td>223</td><td>116</td><td>0.8</td><td>0.8</td><td>40</td><td>40</td><td>39</td><td>1.4</td><td>1.5</td><td>1.0</td><td>2.8</td><td>0.6</td><td>0.6</td></tr><tr><td>NOCEM/167/17</td><td>7.68</td><td>65</td><td>229</td><td>111</td><td>1.5</td><td>0.5</td><td>40</td><td>40</td><td>39</td><td>1.3</td><td>1.0</td><td>0.8</td><td>2.0</td><td>1.3</td><td>1.3</td></tr><tr><td>NOCEM/167/18</td><td>7.56</td><td>66</td><td>211</td><td>110</td><td>0.0</td><td>0.3</td><td>38</td><td>38</td><td>39</td><td>1.1</td><td>1.0</td><td>3.5</td><td>2.5</td><td>9.2</td><td>3.7</td></tr><tr><td>NOCEM/167/19</td><td>7.62</td><td>62</td><td>210</td><td>106</td><td>0.5</td><td>0.3</td><td>39</td><td>38</td><td>38</td><td>34</td><td>1.1</td><td>1.0</td><td>1.6</td><td>0.0</td><td>1.3</td></tr><tr><td>NOCEM/167/20</td><td>7.58</td><td>64</td><td>229</td><td>129</td><td>1.3</td><td>0.5</td><td>40</td><td>37</td><td>37</td><td>36</td><td>1.3</td><td>1.0</td><td>1.3</td><td>4.0</td><td>1.3</td></tr><tr><td>NOCEM/167/21</td><td>7.54</td><td>65</td><td>211</td><td>130</td><td>0.0</td><td>0.5</td><td>40</td><td>39</td><td>39</td><td>1.3</td><td>1.5</td><td>5.0</td><td>2.1</td><td>0.0</td><td>2.4</td></tr><tr><td>NOCEM/167/22</td><td>7.45</td><td>62</td><td>215</td><td>113</td><td>2.0</td><td>0.8</td><td>37</td><td>40</td><td>39</td><td>1.5</td><td>1.0</td><td>2.0</td><td>3.0</td><td>6.9</td><td>2.6</td></tr><tr><td>NOCEM/167/23</td><td>7.41</td><td>65</td><td>233</td><td>128</td><td>0.3</td><td>0.3</td><td>38</td><td>40</td><td>39</td><td>1.0</td><td>1.5</td><td>0.0</td><td>2.0</td><td>0.0</td><td>3.8</td></tr><tr><td>NOCEM/167/24</td><td>7.32</td><td>60</td><td>711</td><td>104</td><td>0.5</td><td>0.0</td><td>38</td><td>40</td><td>39</td><td>37</td><td>1.0</td><td>1.5</td><td>3.8</td><td>1.0</td><td>10.1</td></tr><tr><td>NOCEM/167/25</td><td>7.31</td><td>62</td><td>199</td><td>96</td><td>0.0</td><td>0.0</td><td>38</td><td>39</td><td>39</td><td>39</td><td>1.0</td><td>1.6</td><td>0.5</td><td>1.1</td><td>0.6</td></tr><tr><td>NOCEM/167/26</td><td>7.30</td><td>62</td><td>229</td><td>110</td><td>1.3</td><td>0.3</td><td>38</td><td>36</td><td>36</td><td>1.3</td><td>1.0</td><td>3.5</td><td>2.0</td><td>10.1</td><td>0.7</td></tr><tr><td>NOCEM/167/27</td><td>7.24</td><td>63</td><td>218</td><td>106</td><td>0.3</td><td>0.0</td><td>38</td><td>38</td><td>38</td><td>36</td><td>1.3</td><td>1.5</td><td>1.8</td><td>2.5</td><td>4.7</td></tr><tr><td>NOCEM/167/28</td><td>7.21</td><td>64</td><td>203</td><td>100</td><td>0.5</td><td>0.5</td><td>40</td><td>40</td><td>39</td><td>37</td><td>1.0</td><td>1.5</td><td>1.8</td><td>2.0</td><td>4.9</td></tr><tr><td>NOCEM/167/29</td><td>7.16</td><td>61</td><td>219</td><td>103</td><td>0.0</td><td>0.5</td><td>40</td><td>40</td><td>39</td><td>39</td><td>1.0</td><td>1.5</td><td>2.3</td><td>1.1</td><td>5.9</td></tr><tr><td>NOCEM/167/30</td><td>7.08</td><td>64</td><td>216</td><td>100</td><td>0.8</td><td>0.3</td><td>38</td><td>39</td><td>39</td><td>39</td><td>1.3</td><td>1.5</td><td>0.3</td><td>1.5</td><td>0.6</td></tr><tr><td>NOCEM/167/31</td><td>6.99</td><td>61</td><td>204</td><td>106</td><td>1.3</td><td>0.3</td><td>38</td><td>38</td><td>38</td><td>39</td><td>1.3</td><td>1.0</td><td>0.5</td><td>2.6</td><td>1.3</td></tr><tr><td>NOCEM/167/32</td><td>6.91</td><td>61</td><td>209</td><td>114</td><td>0.3</td><td>0.3</td><td>38</td><td>37</td><td>37</td><td>37</td><td>1.0</td><td>1.5</td><td>0.5</td><td>2.1</td><td>3.3</td></tr><tr><td>NOCEM/167/33</td><td>6.73</td><td>60</td><td>204</td><td>91</td><td>0.3</td><td>0.3</td><td>38</td><td>40</td><td>39</td><td>38</td><td>1.3</td><td>1.0</td><td>2.3</td><td>5.0</td><td>5.8</td></tr><tr><td>NOCEM/167/34</td><td>6.59</td><td>61</td><td>215</td><td>95</td><td>1.0</td><td>1.0</td><td>38</td><td>38</td><td>38</td><td>35</td><td>1.4</td><td>1.5</td><td>0.8</td><td>2.0</td><td>1.9</td></tr><tr><td>NOCEM/167/35</td><td>6.57</td><td>59</td><td>220</td><td>104</td><td>0.5</td><td>0.5</td><td>40</td><td>40</td><td>39</td><td>35</td><td>1.0</td><td>1.3</td><td>1.0</td><td>2.0</td><td>3.6</td></tr><tr><td>NOCEM/167/36</td><td>6.11</td><td>59</td><td>215</td><td>100</td><td>1.0</td><td>0.3</td><td>38</td><td>37</td><td>37</td><td>35</td><td>1.6</td><td>1.3</td><td>1.0</td><td>1.5</td><td>1.8</td></tr><tr><td>NOCEM/167/37</td><td>4.12</td><td>40</td><td>223</td><td>128</td><td>3.3</td><td>0.8</td><td>25</td><td>24</td><td>25</td><td>1.8</td><td>2.5</td><td>0.0</td><td>4.5</td><td>0.0</td><td>1.9</td></tr><tr><td>RESID/167/48</td><td>0.6</td><td>2</td><td>13</td><td>16</td><td>1.6</td><td>0.9</td><td>3</td><td>3</td><td>4</td><td>0.4</td><td>0.1</td><td>1.8</td><td>0.3</td><td>4.9</td><td>3.3</td></tr></tbody></table>

F1= variables F1=varianclal
Referencias

Alfaro, O., D. Pérez y A. Alvarado. 1987. Aptitud Combinatoria General y Específica de Líneas Tropicales de Maíz de grano amarillo y Predicción de Rendimiento de Híbridos Dobles y Triples. Resumen de la XXXIII Reunión Anual del PCCMCA.

Beal, W. J. 1880. Rep. Michigan Board Agric. Pp 287-88.

Comalat, Pedro y P. M. Germán. 1986. Primera Etapa para la Obtención de las Nuevas Variedades UNPHU-301C y UNPHU-302D. Informe UNPHU 17:1.

Comalat, P. y G. Tirado. 1988. Evaluación de 30 Cultivares de Maíz de Posible Introducción y 6 Desarrollados en la República Dominicana. XXXIV Reunión del PCCMCA.

Hallauer, A. R. y J. B. Miranda. 1981. Quantitative Genetics in Maize Breeding. Iowa State University Press. Ames, Iowa.

Hayes, H. K. y P. J. Olson. 1919. First Generation Crosses between Standard Minnesota Corn Varieties. Minnesota Agric. Exp. Stn. Bull. 183.

Moll, R. H.; W. S. Salhuana y H. F. Robinson. 1962. Heterosis and Genetic Diversity in Variety Crosses of maize. Crop Sci. 2:197-198.

Pérez, R. y P. R. Comalat. 1982. Resultado del Segundo Ciclo de Evaluación de Variedades de Maíz y Cruzamientos Intervarietales. XXVIII Reunión Anual del PCCMCA, San José, Costa Rica.

Sprague, G. F. y S. A. Eberhart. 1977. Corn Breeding. In Corn and Corn Improvement, G. F. Spargue (ed) Pp 305-324. Am. Soc. Agron., Madison, Wis.
# THE USE OF FULL-SIB RECURRENT SELECTION IN THE IMPROVEMENT OF AN OPEN POLLINATED CORN POPULATION FOR USE IN SUSTAINABLE AGRICULTURAL SYSTEMS

J. R. Espaillat, R. N. Gallaher, and S.H. West

University of Florida, IFAS

Agronomy Department

304 Newell Hall

Gainesville, Florida, 32611

## ABSTRACT

Synthetic varieties of Corn (Zea mays L.) are better buffered against environmental stresses in sustainable agricultural systems than cultivars with a narrow genetic base. A full-sib (FS) recurrent selection (RS) program was started at the University of Florida using a tropical open pollinated corn population. The goal was to develop a synthetic with a broad genetic base suitable to be grown during the fall in north-central Florida under conservation practices. Full-sib crosses were made in the spring of 1987. Then, in August a progeny test was planted in a randomized complete block design with six replications. Collected data included: ear, husk, and grain weight, insect damage (ID), whole plant yield (WY), seed and leaf N percent, and plant height. Analyses included ANOVA, correlations (r), heritabilities, and frequency distribution. There were differences between FS families for most of the traits. Ear weight (EW) was highly positively r (+r) with yield and plant height traits. Ear weight was negatively r (-r) with ID and +r with leaf N percent of FS families. Tip ID was -r with husk weight. Heritability varied for all traits. The mean EW of the FS were higher than the parents and the Pioneer hybrid X-304C. Selection for EW improved WY, earworm (Heliothis zea L.) tolerance and N uptake.

## INTRODUCTION

The genetic improvement of corn (Zea mays L.) within the concept of sustainable agricultural systems must receive high priority. Duvick
(1981) reported that the diverse gene pool contained in synthetic varieties serves as a buffer against environmental stresses allowing their use in many areas of the world. Synthetic varieties of corn are proposed by CIMMYT (international maize and wheat improvement center) (1984) for areas of the world where farmers do not have the means to secure high yields that justify the cost of hybrid seeds. Ikerd (1989) explained the need for more sustainable, energy efficient production systems and the development of more adapted cultivars.

Sinha and Swaminathan (1984) say plant breeders will have to anticipate the changes which are likely to take place in the major farming systems of the world. Crosson and Rosenberg (1989) predict researchers will have to develop many new technologies for expanding food production while preserving land, water, and genetic diversity. Within the mentioned concepts Fehr (1987b) defined plant breeding as the genetic adjustment to the physical, biological, technological, economic, and social component of the environment.

## Recurrent Selection and The Selection Criteria

Synthetic varieties are obtained by bulking the product from each cycle of recurrent selection and allowing random interbreeding in succeeding generations. According to Briggs and Knowles (1977) the initial stock for a recurrent selection program may be an open pollinated variety, a successful single-cross or double-cross hybrid, or a synthetic variety. Inbred lines are convenient to use as components of a synthetic variety because they are not difficult to maintain. Random crossing of the components (parents) is assumed, and each should contribute the same amount of inheritance to the next generation.

As pointed out by Tingey and Singh (1980) a synthetic variety is a mixture of many genotypes, hence it has been subjected to changes from selection pressure. The degree of inbreeding decreases as the number of unrelated families mated to form the synthetics is increased. The number of families may range from 2 to more than 100. Busbice et al (1972) suggested that the use of more than 16 unrelated families provides little additional advantage. In the case of related parents or those whose relationships are unknown, the use of more than 16 families may be advisable.
Fehr (1987a) pointed out that the methods used to identify superior individuals for use in a synthetic cultivar involve both phenotypic and genotypic selection. Johnson (1981) emphasized that many characteristics can be evaluated in the development of new cultivars. Breeders must be able to determine which ones are important in later selection cycles. Phenotypic and genetic correlations are useful in plant breeding because they facilitate the interpretation of results and provide the basis for planning more efficient breeding programs. Falconer (1960) stated there are two causes of correlation between characters, genetic and environmental. The degree of genetic correlation expresses the extent to which two characters are influenced by the same gene(s). The genetic and environmental factors will give the phenotypic correlation. Sherrard et al (1984) proposed correlating physiological traits and growth parameters to predict yield, nutrient assimilation, and pest resistance.

One of the most important characteristics needed for a fall Corn cultivar is resistance to earworm (Heliothis zea L.). Bullard and York (1985) found resistance to be associated with husk length and thickness. Brewbaker and Kim (1979) associated earworm and fall armyworm (Spodoptera frugiperda L.) resistance with husk number. Cameron and Anderson (1966) found that long husks by itself are of no value in insect resistance unless they are compressed over the tip (small silk-channel diameter). As a result of studies done by Ullstrup (1978), it is recognized that a positive correlation exists between weevil infestations, earworm damage and bird damage to maize hybrids.

The traits of a good silage cultivar include high yields, proper maturity, and excellent standability. Theoretically, multiple-eared plants should be more efficient than single-eared types. Non-tillering types usually are for grain; heavy-tillering is useful for silage and green feed. Here, there is a problem in developing a variety for both purposes, grain and silage production. However, evaluations for both uses were important.

In an effort to achieve some of the above guidelines, a full-sib recurrent selection (RS) program was started in March 1987 at the University of Florida to develop a synthetic variety using conservation
agriculture practices. The objectives were the following: I) Develop a synthetic cultivar with a broad genetic base suitable to be grown during the fall in a succession no-tillage cropping system, II) Determine the degree of correlation among all traits and use these correlations to predict yield, III) Determine the heritability of traits contributing to yield and quality, and IV) Evaluate the synthetic against commercial hybrids and the parental population.

# MATERIALS AND METHODS

## The Mass Selection Program

This corn program had its origin in 1982, when Dr. Raymond N. Gallaher, Professor of Agronomy at the University of Florida went on a trip to Central America. He collected three ears from a farm in the Limon province of eastern Costa Rica. The corn had been grown on a subsistence farm, where low or no inputs had been used.

When he returned to Florida Dr. Gallaher began a mass selection program with the Costa Rica germplasm crossed with temperate and tropical hybrids. The objective was to create a diverse genetic population adapted to Florida. Various degrees of low input agriculture prevailed. A total of six mass selection cycles were accomplished in a 5-yr period under no-tillage double cropping management.

## The Full-sib Recurrent Selection Program

A recurrent selection program was started in 1987 to increase the frequency of genes for yield. The program was conducted under the no-tillage late summer environmental conditions prevailing at the Green acres agronomy farm located 13 miles west of Gainesville, Florida.

A nursery was established in early spring (march). The plot was rectangular (0.18 ha) with no replications. The area had been under no-tillage for the last 3 yr. Weed control was done before seedling emergence with Paraquat (paraquat) (1,1 dimethyl,4',4' bipyridiniumion) at a dosage of 0.5 kg a.i. ha⁻¹. Broadcast preplant fertilization included 23 kg K as KCl, 5 kg of K₂SO₄, 10 kg S and 10 kg Mg as
MgSO₄. Ammonium nitrate was sidedressed preplant at a rate of 152 kg ha⁻¹. When plants were about 33 cm tall N as Ammonium nitrate was sidedressed by hand. Insect pests were controlled with Furadan 10G (carbofuran) (2,3-dihydro-2,2-dimethyl 7-benzofuranyl methyl-carbamate) at a rate of 2 kg a.i. ha⁻¹. Irrigation was done with overhead sprinklers.

The genetic pool included Flopup'86, Flopdown'86, two Levy County open-pollinated cultivars, and 6 open-pollinated varieties from the Central America and the Caribbean. This blend of 10 different germplasms was called Population 1 (P1). The tassel-bag method (Jugenheimer, 1976) was the technique used to make the 65 hand pollination full-sib crosses. Ears were harvested at physiological maturity, dried to 12% moisture, and shelled. The grain was cleaned and placed in storage bags.

## The Progeny Test

The full-sib progeny test was planted in early August (fall), at the Green Acres Agronomy farm in soil classified as Arenic and Glossa-renic Paleudults. A Randomized complete block (RCB) design with six replications was used. Single row plots were 6.00 m long. The parents, the cycle 6 of the mass-selected population and a tropical hybrid (Pioneer brand X304C), were used as control.

A jab-type planter was used to establish a plant population of 65,000 seed ha⁻¹. A preplant application of 300 kg N ha⁻¹ as anhydrous ammonia was applied. Also P, K, Mg, S, and micronutrients were broadcast. Weed control was with a preemergence spray of Atrazine (Atrazine) (2-chloro-4ethylamino-6-isopropylamino-s-triazine) at a dosage of 2.2 kg a.i. ha⁻¹, Paraquat at a dosage of 0.5 kg a.i. ha⁻¹, and Lasso (Alachlor) (2-Chloro-2¹-6¹-diethyl-N-methoxymethyl) acetani-lide at a dosage of 2.2 kg a.i. ha⁻¹ Also post-directed Paraquat sprays with a CO₂ backpack sprayer were used as needed. Fall armyworm and earworm were controlled with 5 applications of Furadan (carbo-furan) directly to the whorl with a bottle (bazooka) at a dosage of 1.0 g m⁻². Irrigation was provided as needed.
## Selection Methodology

Although it was not possible to calculate the genotype x environment interaction, other parameters of performance were determined to achieve the selection goals. Data collection included the evaluation of 18 traits in the field and postharvest. Field data collection corresponded to Traits 6, 7, 9, and 10 at the 50% silking stage and Traits 16 and 17 at harvest time (Table 1). Post-harvest data collection corresponded to Traits 1, 2, 3, 4, 5, 8, 11, 12, 13, 14, 15 and 18 (Table 1).

Four categories were considered for the ear insect damage evaluations. No insect damage, tip damage, body damage and total insect damage were considered as indicative of insect attack. The number of harvested ears was calculated by adding the number of ears showing no insect damage and the total insect damage. Whole plant dry matter was calculated using six plant samples taken at random. The fresh weight was recorded and samples dried for 2 days at 70°C in a forced air oven. The dried samples were weighed to calculate the dry weight percentage. The micro-Kjeldahl N analysis method was used to determine the N concentration in leaves and seeds. The amount of ammonium sulfate in the solution was determined using a technicon autoanalyzer following the procedure by Schuman et al. (1973).

There was a 33°F freeze on 2^nd^ and 3^rd^ December at 106 days after planting; at this point some of the families had reached the black layer stage. Considering the black layer stage as physiological maturity, ears were harvested with an average moisture of 18%.

Several statistical parameters were used to analyze the data. The analysis of variance (ANOVA) of a randomized complete block (RCB) design for all traits was obtained. Traits showing differences at the 5% probability level were assumed to have real differences between the full-sib family means. Correlation coefficients (r) between all traits were determined. In every case the selection of the dependent variable was based on highly significant differences among full-sib families. Also, those traits having a probability lower than 5% when correlated with the selected trait and showing a r value greater than 0.50 in the case of positive correlations (+r), or greater
than -0.50 in the case of negative correlations (-r), were selected for further analyses and comparisons.

Since only one year and one location was tested, full-sib families and error were used to obtain the genetic component of variance ($\sigma^2_t$). The formula for the expected mean square as adopted from Allard (1966a) is expressed as follows:

$$\sigma^2_t = (MS_t - MS_e) \div r$$

In which: $\sigma^2_t$ = the genetic variance, $MS_t$ = mean square for FS families,

$MS_e$ = mean square error, and $r$ = replications.

Heritability ($h^2$) is defined as the ratio of the genotypic variance ($\sigma^2_t$) divided by the total (phenotypic) variance ($\sigma^2_p$). It provides a measure of the effectiveness by which selection can be expected to exploit the genetic variability. The total variance was used as the denominator in the following $h^2$ formula:

$$h^2 = \sigma^2_t / [\sigma^2_t + (\sigma^2_e / r)]$$

In which: $\sigma^2_e$ = expected error mean square ($MS_e$).

After identifying the desired full-sib families, the expected genetic gain ($G_g$) was calculated. Then, the mean of all FS families was added to obtain the expected mean of the second FS cycle formed by the selected full-sib families.

The frequency distribution of the FS families in classes was for ear weight. Ear weight was selected as the results of ANOVA, correlations, $h^2$, and expected genetic gain. Also, its use in selection for yield performance is desirable based on ease of data collection in order to save time and resources. In order not to erode the genetic diversity of the populations, taking into consideration that only one environment has been evaluated, it was necessary to be flexible in the intensity of selection. The top 27% of the full-sib families were selected for the creation of the next cycle.
## RESULTS AND DISCUSSION

Analyses of variance (ANOVA) for a RCBD showed a highly significance difference ($P = 0.01$) among full-sib families in $P_1$ for 15 of the 18 traits evaluated. Body insect damage, grain weight, and lodging percent showed differences at the 0.05 probability level (Table 1). The lowest coefficients of variation (CV) were found for N traits (from 4.26 to 6.45%). Ear weight had a CV of 23.70%.

Ear weight was $+r$ with 13 of the traits (Table 2). Acceptable $r$ were with whole plant dry matter, grain weight, number harvested ears, stalk weight, and tassel height with $r$ values of 0.94, 0.89, 0.63, 0.58 and 0.53, respectively with $P<0.01$. Total insect damage and tip insect damage were $-r$ with ear weight $r = -0.25$, and $-0.19$, respectively with $P<0.01$. Tip insect damage was $-r$ with husk weight, having $r = -0.30$ and $P = 0.01$. Lodging per cent is a function of tassel height and silk height showing $r = 0.26$ and 0.21 respectively with $P = 0.01$.

The best $h^2$ was given by parent's seed N and the full-sib leaf N with 99 and 98%, respectively (Table 3). Yield traits had $h^2$ ranging from 54% for husk weight to 29% for grain weight. Ear weight had $h^2$ of 41%. Both plant height traits showed the same $h^2 = 52\%$. Ear insect damage had $h^2$ fluctuating from 48% for total insect damage to 32% for body insect damage.

The highest $G_g$ was given by the stalk weight (11.4%), followed by ear weight (6.1%). Since they were positively correlated ($r = 0.58$) any improvement in ear weight will result in a general improvement of the quality of the plant. Also, because ear weight had adequate $\sigma_1^2$ and $h^2$ coefficients, it was decided to use it as the main selection criterion.

The ear weight data shows a phenotypic distribution characteristic of mixed populations (Figure 1). This assumption is supported by two distinctive peaks in the frequency distribution, corresponding to 560 and 650 $g m^{-2}$. The ear weight of the top 15 full-sib families ranged from 675 to 823 $g m^{-2}$ with a $\bar{x}$ of 710 $g m^{-2}$. The ear weight mean of the selected families has $92 g m^{-2}$ (10%) increase over the
population **mean**. The population x̄ was found in Class 6. The x̄ of the two parents, Flopup'86 and Flopup'87, was 515 and 531 g m⁻², respectively. Cenia-12 and hybrid Pioneer brand X-304C had almost the same ear weight equal to 496 and 490 g m⁻², respectively.

## CONCLUSIONS

The contributions of the temperate and tropical hybrids, used in the mass selection program, to the diversity of the Costa Rican germplasm is unknown. However, free mating occurred as well as a reduction in plant height, improved grain yield, and changes in grain type, texture and color (Gallaher, 1986).

The full-sib breeding technique used was successful. Significant differences among full-sib families were obtained for most of the traits. Increases in yield performance are expected in future selection cycles for both populations.

Traits were correlated, suggesting the control by many genes having nearly equal effects. According to Simmonds (1979) non-independence of characters and especially of fitness characters is not uncommon and most breeders encounter them frequently. Ear weight was the trait that most positively correlated with other yield and plant height traits. Therefore, selection for high ear weight should result in both improved grain and whole plant yield. Tip insect damage was negatively correlated with husk weight in both populations. These results imply the effect of the weight and thickness of the husk in preventing insect larvae entrance, a well known mechanism of resistance studied by Wiseman (1985).

Heritability estimates for the evaluated traits varied. In general the N and plant height traits had the largest h², indicating either the precision of the evaluation procedure or the genetic variance was larger than for the other traits. The yield and insect damage traits, in most of the cases, had acceptable h² coefficients.

The mean of all full-sib families was better than the mean of the parents. Also, the mean of all full-sib families was better than the control hybrid Pioneer brand X-304C. Since this hybrid is recommen-
ded for planting during the late summer, its use as a control is recommended in future selection cycles. An interesting performance was given by Cenia-12, a parent. This improved variety from the Dominican Republic was highly tolerant to earworm damage.

<table><caption>Table 1, Analysis of variance of full-sib families in Population 1.</caption><thead><tr><th>Trait</th><th>Computed F</th><th>Probability Value</th><th>Signif.</th><th>CV</th></tr></thead><tbody><tr><td colspan="5">Insect damage traits:</td></tr><tr><td>1- Harvested ears</td><td>1.90</td><td>0.000</td><td>**</td><td>18.50</td></tr><tr><td>2- No damage</td><td>1.70</td><td>0.004</td><td>**</td><td>66.60</td></tr><tr><td>3- Tip damage</td><td>1.80</td><td>0.001</td><td>**</td><td>23.90</td></tr><tr><td>4- Body damage</td><td>1.50</td><td>0.024</td><td>*</td><td>52.00</td></tr><tr><td>5- Total damage</td><td>1.90</td><td>0.000</td><td>**</td><td>10.90</td></tr><tr><td colspan="5">Nitrogen conc. traits:</td></tr><tr><td>6- Parent's seed</td><td>79.50</td><td>0.000</td><td>**</td><td>4.30</td></tr><tr><td>7- FS family leaf</td><td>23.20</td><td>0.000</td><td>**</td><td>6.45</td></tr><tr><td>8- F5 family seed</td><td>2.40</td><td>0.000</td><td>**</td><td>6.10</td></tr><tr><td colspan="5">Plant height traits:</td></tr><tr><td>9- Tassel</td><td>2.00</td><td>0.000</td><td>**</td><td>6.85</td></tr><tr><td>10- Silk</td><td>2.10</td><td>0.000</td><td>**</td><td>13.50</td></tr><tr><td colspan="5">Yield component traits:</td></tr><tr><td>11- Ear weight</td><td>1.70</td><td>0.003</td><td>**</td><td>23.70</td></tr><tr><td>12- Grain weight</td><td>1.40</td><td>0.042</td><td>*</td><td>27.80</td></tr><tr><td>13- Husk weight</td><td>2.20</td><td>0.000</td><td>**</td><td>23.90</td></tr><tr><td>14- Cob weight</td><td>1.90</td><td>0.000</td><td>**</td><td>33.20</td></tr><tr><td>15- Shelling percent</td><td>1.80</td><td>0.000</td><td>**</td><td>27.30</td></tr><tr><td>16- Stalk dry weight</td><td>2.20</td><td>0.000</td><td>**</td><td>28.90</td></tr><tr><td>17- Lodging percent</td><td>1.50</td><td>0.018</td><td>*</td><td>147.80</td></tr><tr><td>18- Whole plant DN</td><td>1.70</td><td>0.003</td><td>**</td><td>23.80</td></tr></tbody></table>

<footnote>(*, **)= different at the 95% and 99% level of significance, respectively.</footnote>
<table><caption>Table 2. Correlation matrix of all traits in Population 1.</caption><thead><tr><th></th><th>1</th><th>2</th><th>3</th><th>4</th><th>5</th><th>6</th><th>7</th><th>8</th><th>9</th><th>10</th><th>11</th><th>12</th><th>13</th><th>14</th><th>15</th><th>16</th></tr></thead><tbody><tr><td>1</td><td>1.00</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>2</td><td>0.81</td><td>1.00</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>3</td><td>0.84</td><td>-0.56*</td><td>1.00</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>4</td><td>0.81</td><td>-0.82</td><td>0.78**</td><td>1.00</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>5</td><td>0.85</td><td>-0.82**</td><td>0.82**</td><td>1.00</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>6</td><td>0.88</td><td>-0.15*</td><td>0.84</td><td>0.83</td><td>-0.04</td><td>1.00</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>7</td><td>0.84</td><td>-0.81</td><td>0.84</td><td>-0.85</td><td>0.83</td><td>0.84</td><td>1.00</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>8</td><td>0.81</td><td>0.04</td><td>-0.18*</td><td>0.17*</td><td>-0.88</td><td>0.13</td><td>-0.04</td><td>1.00</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>9</td><td>0.85</td><td>-0.88</td><td>-0.83</td><td>-0.88</td><td>-0.87</td><td>0.82</td><td>0.88</td><td>-0.11</td><td>1.00</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>10</td><td>0.87</td><td>-0.86</td><td>-0.85</td><td>-0.88</td><td>-0.85</td><td>-0.87</td><td>-0.89</td><td>0.86**</td><td>1.00</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>11</td><td>0.85**</td><td>0.82**</td><td>-0.81**</td><td>0.84</td><td>-0.25**</td><td>0.82</td><td>-0.11</td><td>-0.13</td><td>0.51**</td><td>0.49**</td><td>1.00</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>12</td><td>0.86**</td><td>0.17*</td><td>-0.09</td><td>0.17*</td><td>-0.17*</td><td>0.82</td><td>-0.12</td><td>-0.25**</td><td>0.84**</td><td>0.37**</td><td>0.90**</td><td>1.00</td><td></td><td></td><td></td><td></td></tr><tr><td>13</td><td>0.53**</td><td>0.89**</td><td>-0.80**</td><td>0.14</td><td>-0.81**</td><td>0.89</td><td>-0.82</td><td>0.87</td><td>0.80**</td><td>0.41**</td><td>0.66**</td><td>0.46**</td><td>1.00</td><td></td><td></td><td></td></tr><tr><td>14</td><td>0.43**</td><td>0.27**</td><td>0.81*</td><td>0.85</td><td>-0.21**</td><td>0.83</td><td>-0.99</td><td>-0.82</td><td>0.33**</td><td>0.23**</td><td>0.83**</td><td>0.53**</td><td>0.80**</td><td>1.00</td><td></td><td></td></tr><tr><td>15</td><td>0.67</td><td>0.25**</td><td>0.84</td><td>-0.84</td><td>0.81</td><td>-0.80**</td><td>-0.80</td><td>-0.17</td><td>0.17**</td><td>-0.00</td><td>0.12</td><td>0.25**</td><td>0.86</td><td>-0.02</td><td>1.00</td><td></td></tr><tr><td>16</td><td>0.40**</td><td>0.15*</td><td>-0.81</td><td>-0.25**</td><td>-0.83</td><td>-0.80</td><td>-0.93</td><td>0.11</td><td>0.80**</td><td>0.44**</td><td>0.56**</td><td>0.52**</td><td>0.81**</td><td>0.41**</td><td>0.87</td><td>1.00</td></tr><tr><td>17</td><td>0.81</td><td>0.88</td><td>-0.84</td><td>0.80</td><td>-0.18</td><td>0.86</td><td>-0.11</td><td>-0.06</td><td>0.26**</td><td>0.21**</td><td>0.17*</td><td>0.19*</td><td>0.11</td><td>0.80</td><td>-0.81</td><td>1.00</td></tr><tr><td>18</td><td>0.84**</td><td>0.24**</td><td>-0.81**</td><td>0.86</td><td>-0.23**</td><td>0.81</td><td>-0.88</td><td>-0.25</td><td>0.81**</td><td>0.46**</td><td>0.89**</td><td>0.88**</td><td>0.83**</td><td>0.76**</td><td>0.11</td><td>0.82**</td><td>1.00</td></tr></tbody></table>

* * significance at the 95% and 90% per cent level respectively

<table><thead><tr><th>Trait</th><th>Description</th><th>Trait</th><th>Description</th></tr></thead><tbody><tr><td>1</td><td>Harvested ears</td><td>10</td><td>silk height</td></tr><tr><td>2</td><td>No insect damage</td><td>11</td><td>Ear weight</td></tr><tr><td>3</td><td>Tip insect damage</td><td>12</td><td>Grain weight</td></tr><tr><td>4</td><td>Body insect damage</td><td>13</td><td>Husk weight</td></tr><tr><td>5</td><td>Total insect damage</td><td>14</td><td>Cob weight</td></tr><tr><td>6</td><td>N Parent's seed</td><td>15</td><td>Shelling</td></tr><tr><td>7</td><td>N FS family leaf</td><td>16</td><td>Stalk weight</td></tr><tr><td>8</td><td>N FS family seed</td><td>17</td><td>Lodging</td></tr><tr><td>9</td><td>Tassel height</td><td>18</td><td>Whole plant DM</td></tr></tbody></table>
<table><caption>Table 3 Heritability and expected gain of traits in population 1.</caption><thead><tr><th>Trait</th><th>Unit</th><th>σ<sup>2</sup><sub>t</sub></th><th>h<sup>2</sup></th><th>Gg</th><th>G%</th></tr><tr><td></td><td></td><td>%</td><td></td><td></td><td>%</td></tr></thead><tbody><tr><td colspan="6"><strong>Insect damage traits:</strong></td></tr><tr><td>1- Harvested ears</td><td>#</td><td>3.40</td><td>48</td><td>1.40</td><td>5.40</td></tr><tr><td>2- No damage</td><td>%</td><td>11.15</td><td><strong>40</strong></td><td></td><td></td></tr><tr><td>3- Tip damage</td><td>%</td><td>28.40</td><td>44</td><td></td><td></td></tr><tr><td>4- Body damage</td><td>%</td><td>12.20</td><td>32</td><td></td><td></td></tr><tr><td>5- Total damage</td><td>%</td><td>13.30</td><td>48</td><td>-3.00</td><td>-0.03</td></tr><tr><td colspan="6"><strong>Nitrogen conc. traits:</strong></td></tr><tr><td>6- Parent's seed</td><td>dag kg<sup>-1</sup></td><td>0.10</td><td>99</td><td></td><td></td></tr><tr><td>7- FS family leaf</td><td>dag kg<sup>-1</sup></td><td>0.20</td><td><strong>98</strong></td><td>0.60</td><td>20.90</td></tr><tr><td>8- FS family seed</td><td>dag kg<sup>-1</sup></td><td>0.01</td><td>60</td><td></td><td></td></tr><tr><td colspan="6"><strong>Plant height traits:</strong></td></tr><tr><td>9- Tassel</td><td>m</td><td>0.01</td><td>52</td><td>0.00</td><td>0.00</td></tr><tr><td>10- Silk</td><td>m</td><td>0.01</td><td>52</td><td>0.01</td><td>0.80</td></tr><tr><td colspan="6"><strong>Yield component traits:</strong></td></tr><tr><td>11- Ear weight</td><td>9 m<sup>-2</sup></td><td>2,482.10</td><td>41</td><td><strong>37.90</strong></td><td>6.10</td></tr><tr><td>12- Grain weight</td><td>9 m<sup>-2</sup></td><td>419.20</td><td>29</td><td>13.40</td><td>4.70</td></tr><tr><td>13- Husk weight</td><td>9 m<sup>-2</sup></td><td>194.70</td><td>54</td><td></td><td></td></tr><tr><td>14- Cob weight</td><td>9 m<sup>-2</sup></td><td>672.50</td><td>47</td><td></td><td></td></tr><tr><td>15- Shelling</td><td>%</td><td>38.90</td><td>46</td><td></td><td></td></tr><tr><td>16- Stalk weight</td><td>9 m<sup>-2</sup></td><td><strong>1,367.10</strong></td><td>53</td><td>33.20</td><td>11.40</td></tr><tr><td>17- Lodging</td><td>%</td><td><strong>3.40</strong></td><td>34</td><td></td><td></td></tr><tr><td>18- Whole plant DM</td><td>g m<sup>-2</sup></td><td>5,323.80</td><td>41</td><td>55.90</td><td>6.20</td></tr></tbody></table>

$\sigma^2_t$ = Genetic variance component. $h^2$ = Heritability.

Gg = Expected gain in the corresponding unit over the population mean. See table 7 for unit of measurement for each trait.

G% = Expected gain in percent over the population mean.
<figure><img src="image_36.png" /><figcaption>Figure 1. Frequency distribution for ear weight in Population 1.</figcaption></figure>

<figure><img src="image_37.png" /></figure>

Top 27% FS families selected based on ear weight.

The frequency classes where the mean of the population ($P_1$), parents ($F^{'}86$, $F^{'}87$ and $C-12$) and the control ($X-304C$) fell, are included.
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# INVESTIGATIONS ON THE EFFECTS OF REDUCED INTRA-ROW SPACING, FERTILIZER RATES AND CULTIVATION SYSTEMS ON EDDOES (*Colocasia antiquorum* L.) PRODUCTION<fnref n="1" />

By Azim Hosein<fnref n="2" />

## ABSTRACT

The effects of reduced tillage, spacing and rates of fertilizer on yield and yield components of Eddoes (*Colocasia antiquorum*) were investigated in two Experiments. In Experiment 1 the response of yield and yield components to fertilizer rates and systems of cultivation were studied. Marketable yield increased significantly with reduced tillage and high rates of fertilizer applications compared to the traditional method of ploughing and banking. The reduced tillage operations, in addition to conserving the soil, was less labour intensive and reduced the cost of production. In Experiment 2 the effects of closer intra-row spacing and system of cultivation on marketable yield and yield components were evaluated. The results showed that reduced intra-row spacing from 90cm to 15cm significantly increased marketable yields in eddoe without affecting cormel size or quality. Validation of the results on larger plots with economic analysis showed that closer intra-row spacing of 30cm established with minimum tillage and using fertilizer rates of 1.6 t ha⁻<fnref n="1" /> improved productivity (32t ha⁻<fnref n="1" />) compared to traditional production systems (17t ha⁻<fnref n="1" />). Cost of production was reduced by E.C. $0.25 kg⁻<fnref n="1" />

## Introduction

During the period 1984 to 1990 the total export of eddoes (*Colocasia antiquorum*) from St. Vincent and the Grenadines declined from 23 thousand to under 3 thousand tonnes. Further, the data from the

<footnote n="1">¹ Paper presented at the 28th Caribbean Food Crop Society meeting in Santo Domingo during the period August 9-14, 1992.</footnote>

<footnote n="2">² Technology Adaptation Specialist with The Caribbean Agricultural Research and Development Institute (CARDI) based in St Vincent and The Grenadines.</footnote>
Central Statistical Office in St Vincent showed that the commodity is still the second largest earner of foreign exchange among non-banana agricultural exports (Figure 1). Most of the product is exported to Trinidad and Tobago (Figure 2). Farmers produce the eddoe on small holdings on sloping hill-sides. The soils are of relatively recent volcanic origin and are characterized by good fertility but low water holding capacity (Watson et al., 1958).

Farmers prepare the land for eddoe production by 'Banking'. This involves ploughing the land with a hoe, pulverizing the soil and drawing it into rows of mounds. The mounds are 1 to 1.5m between rows and 0.75 to 1 metre along the row. Planting holes are then opened using a hoe in the top of the banks for planting. Over the years, this system has resulted in a progressive downward movement of soil from the top to the base of the hillsides.

As an alternative to this practice, a system known as 'Ranging' was introduced. It involves removing just sufficient weeds to enable planting holes to be prepared in rows along the contour. The weed debris is laid along the contour and the planting holes are then made in front of the debris. Spacing is 30 cm along the rows and 75cm between rows which means that the plant population can be two to three times that achieved with Banking.

As far as productivity is concerned, yields have been increased from 3.2 to 10.1 t ha⁻¹ during the period 1972 to 1983 (Gunsam, 1985). However, the potential yield is in excess of 20 t ha⁻¹ (O'Hair and Asokam, 1961). Therefore, this gap represents an opportunity for increasing productivity and exports.

In the light of the above, studies were carried out in St. Vincent and the Grenadines during 1989 to 1992 to investigate and validate technologies to increase yield, productivity, reduce the cost of production and prevent soil loss through modifying the existing system of cultivation.

## Materials and Methods.

The rainy season in St. Vincent and the Grenadines begins in June and is the main planting season for eddoes. The rainfall and
temperature data are presented in Figure 3 from the E.T. Joshua airport, the closest station to the experimental site. It should be noted that eddoes can be grown all year in Ecological Zones where the annual rainfall distribution is relatively uniform and in excess of 1800 mm. The experiments were carried out on a soil series known as Greggs Loam (Watson et al., 1958).

## Experiment 1

In this Experiment the response of yield and yield components to two land preparation systems (ranging and banking) and four rates (0.4, 0.8, 1.2 and 1.6 t ha⁻¹) of NPK fertilizer (15-08-24) were applied in three split applications (at planting, six and twelve weeks after planting) were examined. Farmers cultivated eddoes by using the banking system and applied fertilizer rates between 1.2 to 1.6 t ha⁻¹ and hereafter refers to as "the existing System". The experiment was laid down at Fenton on May 1990 and harvested on November 1990. The split plot design was utilized to facilitate land preparation. The main plot consisted of two land preparation systems, Ranging and Banking with the four fertilizer rates of 0.4 to 1.6 t ha⁻¹ with increments of 0.4 as the sub plot. There were two blocks and the main plots were replicated twice in each block. Data measured were marketable, unmarketable and main corm (head) weight and numbers. Data were subjected to Analysis of Variance using the Genstat V package.

## Experiment 2

In experiment 2 four methods of land preparation six intra-row spacings were evaluated for yield and its components in eddoes. The methods of cultivation were (1) banking, (2) ranging (3) cutlassing and making a hole using a fork and (4) spraying with paraquat and making a hole with a fork. The six intrarow spacings were 15, 30, 45, 60, 75 and 90 cm, with a spacing of 75 cm between the rows. The experiment was laid down in a split-plot design in two replicates. The main plot was land preparation with spacing being the subplot. Data collection and analysis were similar to Experiment 1. The Experiment was established on May 22, 1990 on a Greggs Loam soil at Queen's Drive close to Fenton and harvested on January 1, 1991.
## Technology validation

From the results of Experiments 1 and 2, validation plots were established to determine the economics of closer spacing, system of land preparation and fertilizer rates to be used on farmers holdings. This is referred to as the Alternative System or Technology II. The alternate technology consisted of a combination of the fertilizer rate of 1.6 t ha⁻¹, ranging as the method of land preparation and spacing of 30 cm intra-row and 75 cm inter-row spacing. This was compared to the existing system or Technology 1 is as previously described. The plots showing the recommended and the existing practices were established in the major eddoe producing areas of St. Vincent at Spring Village on 25/04/91, Vermont on 08/07/91 and Fenton on 14/12/90. Marketable tuber yield was used to compare the two systems. The cost of inputs used and labour requirements were monitored and used for economic analyses.

## Results and Discussion

### Experiment 1

There was a significant linear effect (p= 0.01) for the interaction of land preparation and fertilizer rates for both marketable and unmarketable yields. These effects are presented in Table 1. The fertilizer rate of 1.6 t ha⁻¹ on ranged lands gave the best results (30.72 t ha⁻¹). However, poor results of 12.40 t ha⁻¹ were obtained at the rate of 0.4 t ha⁻¹ on ranged lands. Banking showed no significant response to increased fertilizer rates. Plucknett and De La Pena (1977) showed that Nitrogen, Phosphorus and Potassium at 560 kg ha⁻¹ respectively, were beneficial to growth and development of *C. esculenta*.

The significantly high yield observed for marketable cormels from 'ranging' and 1.6 t ha⁻¹ fertilizer might be attributed to the conservation of nutrients coupled with improved plant water relations in this system. The increased yield of marketable cormels were due to the high number of cormels per unit area and not mean cormel weight. In addition, the zone where the plants are grown when ranged is less porous than when the area is banked, and therefore could retain fertilizer and moisture for longer periods thus improving growth. The
banking process loosens the soil that made the soil prone to the loss of nutrients and moisture (Watson, 1958). The results indicate that farmers should prepare their land by ranging. This system requires less labour for land preparation, more 'soil friendly' and seems to use fertilizer more efficiently. If farmers anticipate that funds may not be available for fertilizers and continues to bank, then the lower fertilizer rate should be used to prevent leaching into the water ways. It is important to note that ranging with low fertilizer rates resulted in poor yields.

<table><caption>Table 1. The effect of System of Cultivation and fertilizer rates on yield and yield components at Fenton.</caption><thead><tr><th rowspan="2"></th><th colspan="2">Marketable</th><th colspan="2">Unmarketable</th><th colspan="2">Heads</th></tr><tr><th>Weight<br>t ha<sup>-1</sup></th><th>Mean<br>weiht<br>/cormel(g)</th><th>Weight<br>t ha<sup>-1</sup></th><th>Mean<br>weiht<br>/cormel(g)</th><th>Weight<br>t ha<sup>-1</sup></th><th>Mean<br>weiht<br>/cormel(g)</th></tr></thead><tbody><tr><td colspan="7" style="text-align: center;">Ranging</td></tr><tr><th colspan="7" style="text-align: left;">Fertilizer rates</th></tr><tr><td>0.4 t/ha</td><td>18.78<br>(2.93)</td><td>95.27<br>(4.56)</td><td>4.24</td><td>44.19</td><td>6.88</td><td>227.1</td></tr><tr><td>0.8 t/ha</td><td>21.36<br>(3.06)</td><td>105.36<br>(4.66)</td><td>4.80</td><td>48.48</td><td>8.48</td><td>221.4</td></tr><tr><td>1.2 t/ha</td><td>21.80<br>(3.08)</td><td>101.70<br>(4.62)</td><td>4.78</td><td>57.79</td><td>9.23</td><td>256.3</td></tr><tr><td>1.6 t/ha</td><td>24.58<br>(3.20)</td><td>99.90<br>(4.60)</td><td>4.78</td><td>43.19</td><td>8.66</td><td>221.4</td></tr><tr><td colspan="7" style="text-align: center;">Ranging</td></tr><tr><th colspan="7" style="text-align: left;">Fertilizer rates</th></tr><tr><td>0.4 t/ha</td><td>12.40<br>(2.52)</td><td>86.40<br>(4.46)</td><td>5.16</td><td>47.11</td><td>7.90</td><td>227.2</td></tr><tr><td>0.8 t/ha</td><td>15.40<br>(2.73)</td><td>94.97<br>(4.55)</td><td>7.10</td><td>55.29</td><td>7.47</td><td>244.7</td></tr><tr><td>1.2 t/ha</td><td>24.10<br>(3.18)</td><td>103.43<br>(4.64)</td><td>5.22</td><td>48.70</td><td>8.71</td><td>233.0</td></tr><tr><td>1.6 t/ha</td><td>30.72<br>(3.42)</td><td>105.81<br>(4.66)</td><td>5.30</td><td>50.00</td><td>10.03</td><td>279.6</td></tr><tr><td>S.E.D.</td><td>0.52</td><td>0.39</td><td>N.S.</td><td>N.S.</td><td>N.S.</td><td>N.S.</td></tr></tbody></table>

Transformed data by logarithms are in parentheses.
## Experiment 2

A significant linear effect (p=0.01) of intra-row spacing to marketable yield was observed. The yields increased from 15 t ha⁻<fnref n="1" /> to 27 t ha⁻<fnref n="1" /> as intra-row was reduced from 90 to 15cm. There were no significant differences among systems of cultivation or for the interaction of systems by spacing. These effects are presented in Table 2. The increase in yield with closer spacing was due to the increase in number of cormels and not to mean cormel weight. Unmarketable yields followed a similar trend to marketable yields, increasing with closer intra-row spacing.

<table><caption>Table 2. The effect of systems of cultivation and intra-row spacing on yields and yield components of Eddoe.</caption><thead><tr><th rowspan="2"></th><th colspan="2">Marketable</th><th colspan="2">Unmarketable</th></tr><tr><th>Weight<br>t ha<sup>-1</sup></th><th>Mean Weight<br>/cormel</th><th>Weight<br>t ha<sup>-1</sup></th><th>Mean Weight<br>/cormel</th></tr></thead><tbody><tr><td>15</td><td>27.07 (5.20)</td><td>95.56</td><td>5.74 (2.40)<sup>1</sup></td><td>33.44</td></tr><tr><td>30</td><td>24.57 (4.96)</td><td>98.80</td><td>4.52 (2.13)</td><td>34.00</td></tr><tr><td>45</td><td>19.31 (4.39)</td><td>99.96</td><td>4.16 (2.04)</td><td>38.40</td></tr><tr><td>60</td><td>16.51 (4.06)</td><td>95.64</td><td>3.91 (1.98)</td><td>32.04</td></tr><tr><td>75</td><td>17.02 (4.13)</td><td>88.72</td><td>3.56 (1.89)</td><td>32.48</td></tr><tr><td>90</td><td>15.48 (3.93)</td><td>99.72</td><td>2.25 (1.50)</td><td>28.08</td></tr><tr><td>S.E.D.</td><td>0.24</td><td>NS</td><td>0.34</td><td>NS</td></tr></tbody></table>

Gooding and Campbell (1961) reported increased yields for dasheen with high density. Yields of 60 t ha⁻<fnref n="1" /> for wetland production of *Colocasia esculenta* and with high density cultivation, 123 t ha⁻<fnref n="1" /> has been recorded under experimental conditions. Since there were no significant differences in yields from the present experiment among the systems of cultivation at constant fertilization rates of 0.8 t ha⁻<fnref n="1" />, farmers should use the most convenient and cheapest method such as ranging or forkhole to conserve soil and water.

## Technology Validation

The proposed technology (Technology II) showed higher marketable yields of 31.8 t ha⁻<fnref n="1" /> than the existing technology (Technology I) which

<footnote n="1">¹ The data transformed using square root are in parentheses.</footnote>
gave 17.4 t ha⁻¹. Table 4 shows a partial budget of the cost of production for one hectare of eddoes grown under the two systems. The agency in St. Vincent (The Caribbean Agricultural Trading Company CATCO through the Organization for Rural Development, ORD) responsible for extra regional export graded and sorted the produce into marketable and unmarketable grades.

<table><caption>Table 4. Partial budget for eddoe production comparing existing (l) and an improved technology operating costs of labour, materials and fertilizer.</caption><thead><tr><th rowspan="2">Activity/<br>Description</th><th rowspan="2">Units</th><th rowspan="2">Unit Price<br>($EC)</th><th colspan="2">Technological alternatives</th></tr><tr><th>1</th><th>11</th></tr></thead><tbody><tr><td>Marketable yield<br>(A) Gross benefit</td><td>Tonnes (t)</td><td></td><td>17.4</td><td>31.8</td></tr><tr><td>Operating cost<br>Field preparation<br>(Man day)</td><td>$600 t-1</td><td></td><td>10.440</td><td>19.080</td></tr><tr><td>Land clearing</td><td>@20.00</td><td></td><td>2,740</td><td>1,200</td></tr><tr><td>Pest/Weed control</td><td></td><td></td><td>320</td><td>320</td></tr><tr><td>Fertilizing</td><td></td><td></td><td>280</td><td>840</td></tr><tr><td>Weeding (Moulding)</td><td></td><td></td><td>920</td><td>920</td></tr><tr><td>Planting</td><td></td><td></td><td>460</td><td>860</td></tr><tr><td>Fertilizer</td><td>kg</td><td></td><td>600</td><td>1,800</td></tr><tr><td>Herbicide</td><td>l</td><td></td><td></td><td></td></tr><tr><td>Planting Material</td><td>kg<br>(saved from<br>previous crop)</td><td>(Free)</td><td>(400)</td><td>(1,200)</td></tr><tr><td>Contingency</td><td></td><td></td><td>200</td><td>200</td></tr><tr><td>Transport<br>Interest</td><td></td><td></td><td>400</td><td>400</td></tr><tr><td>Other</td><td></td><td></td><td>60</td><td>60</td></tr><tr><td>Harvesting Operations</td><td></td><td></td><td>1.500</td><td>2,400</td></tr><tr><td>Harvest,<br>wash&grade</td><td></td><td></td><td>200</td><td>400</td></tr><tr><td>Transport to market</td><td></td><td></td><td>120</td><td>480</td></tr><tr><td>Total cost</td><td></td><td></td><td>7,800</td><td>9,980</td></tr><tr><td>Net benefit</td><td></td><td></td><td>2,640</td><td>9,100</td></tr></tbody></table>

All costs are in East Caribbean Dollar US $1.00 = $2.70
The Alternate Technology gave a higher net return per dollar invested for operating cost of labour, materials and for fertilizer of E.C. $1.10 compared to E.C.$0.34 for the existing system of cultivation. Productivity of the farm was increased giving higher profits for the farmer of E.C.$6,500.00. The alternate technology could increase production, farm incomes and save foreign exchange in fertilizer purchase by optimising usage. In addition, it might have implications for soil and water conservation.

## Acknowledgements

The Author gratefully acknowledges the support and collaboration provided by the Caribbean Agricultural Research and Development Institute professional and support staff from St Vincent and other member states; the Ministry of Agriculture, Industry and Labour, Extension Services, St. Vincent and the Grenadines; The University of the West Indies, Extension department, St Augustine; The Organization for Rural Development; The National Farmers Union. Special gratitude is extended to cooperation of the farmers Nola Miller, Ivy Edwards and Elise Jessop for volunteering their lands for this work. Special thanks are due to The United States Agency for International Development for funding this project.

## Literature Cited

Gunsam, C.G., 1985. Present status on production, storage and conservation of root and other tuber crops in St Vincent and the Grenadines. Paper delivered at the Round Table on Storage and Conservation of Root and Tuber Crops, October 29, 1985, Mayagüez Campus, University of Puerto Rico.

Gooding, H.J. and J.S. Campbell, 1961. The improvement of cultivation methods in dasheen and eddoe growing in Trinidad. Proceeding of the American Horticultural Society, Horticultural Science, Caribbean Region 5:6-20.
O'Hair, S.K. and M. P. Asokam, 1986. Edible Aroid Botany and Horticulture. Horticultural review 8:43-99.

Plucknett, D L. et al., 1971. Taro C. *Esculenta*, a review. Field Crop Abstracts, 23: 413-426.

Watson, J.P., 1958, Soil and Land Use Surveys. No 3. St Vincent. Soil Science Department, University of The West Indies, St Augustine, Trinidad and Tobago.
<figure><img src="image_38.png" /><figcaption>Figure 1 Earnings from eddoe compared to non-banana agricultural exports for 1990</figcaption></figure>

Statistical Office, St Vincent, 1992.

<figure><img src="image_39.png" /><figcaption>Figure 2 EDDOE EXPORT FROM ST VINCENT 1991 TARGET COUNTRIES (thousand tonnes)</figcaption></figure>

SOURCE: STATISTICAL OFFICE ST VINCENT 1992
CONDITIONED YIELD RESPONSE OF CORN
HYBRIDS TO TILLAGE AND THE INSECTICIDES
USED IN BREEDING PROGRAMS

J.R. Espaillat, and R.N. Gallaher

University of Florida, IFAS

Agronomy Department

304 Newell Hall

Gainesville, Florida, 32611

ABSTRACT

Researchers have reported differential and conflicting responses of corn (Zea mays L.) to insecticides. Our research was conducted to determine if tillage and corn genotypes cause the variation in response. Two experiments were conducted. In one 3-yr study no-tillage (NT) and conventional tillage (CT) were main plots and four insecticide treatments were split plots (2.2 kg a.i. Carbofuran ha⁻¹ (CF 2.2), 1.1 kg a.i. Carbofuran ha⁻¹ (CF 1.1), 2.2 kg a.i. Terbufos ha⁻¹ (TF 2.2), and a untreated control (C). In the other study six hybrids were main plots with the same insecticides as split plots. Grain yield was measured at harvest. Treatments with CF 2.2 gave higher grain yield in NT, but TF 2.2 gave equal grain response in CT. When "Asgrow RX777" (developed using TF) was treated with TF 2.2, it averaged 32 q ha⁻¹ more grain than the C. Also, "Dekalb XL71" (developed using CF) yield 28 q ha⁻¹ more grain with CF 2.2 than with the C. These results suggested that a hybrid will respond better to the insecticide used during its breeding development.

INTRODUCTION

The Entomological Society of America (1987) have reported differential and conflicting responses of corn (Zea mays L.) to insecticides. There is evidence that environmental factors influence both the magnitude and expression of genetic resistance. Tingey and Singh (1980) claim cultural factors such as soil fertility, soil moisture, pesticides, and plant growth regulators affect yield and nutritional quality of host plant tissue appearing to be particularly important in
the induction of resistance. Furthermore, Burton (1979) and Henson et al (1984) emphasize that genotypes may react differently in different environments resulting in populations that were relatively stable in their original environment, being unstable and fluctuating greatly in the stress of a new environment.

The advantages and disadvantages of no-tillage (NT) on crop production have been reviewed by Phillips et al (1980). No-tillage induces major modifications in ecological conditions in fields, especially the conditions affecting soil fauna. These alterations may enhance, have no affect, or deter the biopotential of soil arthropods including agricultural pests. Musick (1975) anticipated insect infestations are more severe in NT systems and their control will be more difficult than in conventional tillage (CT) corn. However, All and Gallaher (1977) found infestations of lesser cornstalk borer (Elasmopalpus lignosellus) to be deterred in NT corn cropping systems. Pathogens affect the absorption of soil applied pesticides. Kunstman and Lichtenstein (1983) concluded that both root rot (Giberella zeae S.) and Leaf rust (Puccinia sorghi S.) affected the translocation of carbofuran from soils into the plant.

The method and timing of pesticide application determine the efficiency of application. Depew and Hooker (1987) claim Terbufos gave excellent season-long control of greenbugs (Schizaphis graminum R.) and increased grain yield when injected into soil. Equivalent rates applied in a band on the soil surface gave poor control. Felsot (1981) and Garder (1982) established that Carbofuran degradation in some soils is rapid, occasionally failing to provide adequate pest control. In a tillage-corn genotypes study 60 commercial hybrids were grown under NT and CT, no differential response of these hybrids to tillage system was found by Newhouse and Crosbie (1986).

Since high grain yield is likely the overriding objective of the corn breeder, and since emphasis is directed to higher grain yields for grain farmers to maintain an existence in farming, hybrid development is likely carried out under ideal conditions such as; fertility and pest control. These genotypes (cultivars) would be developed under relatively specifically altered environments. Furthermore, it is proposed that a hybrid developed for high grain yield under high fertility
and ideal irrigation may not perform well in other environments of low fertility and/or non irrigation. Abbott (1925) hypothesized that if hybrids are developed using a specific pesticide (insecticide and/or nematicide) they may not perform the same if grown using another pesticide.

The objective of this research was to determine if tillage and corn genotype are the reasons why scientist, industry, and farmers disagree on yield response among pesticides.

## MATERIALS AND METHODS

This research was conducted in north-central Florida from 1981 to 1983. Two sets of experiments were carried out on Hernando LFS (Typic Hapludalf) soil. In both cases, a randomized complete block design was used. The two sets of experiments were the following: tillage/pesticide, and genotype/pesticide.

### Tillage/Pesticide Experiments

In this 3-year study (1981, 1982, 1983) the response of "Dekalb XL71" corn hybrid to insecticides under two tillage management conditions was evaluated. No-tillage plus in-row subsoil versus CT plus in-row subsoil were whole plots with four replications and three insecticide treatments and a control were split plots (1.1 Kg a.i. Carbofuran $ha^{-1}$ (CF 1.1) 2.2 Kg a.i. Carbofuran $ha^{-1}$ (CF 2.2), 2.2 Kg a.i. Terbufos $ha^{-1}$ (TF 2.2) and a untreated control (C)). Split plots were 10 feet (3.07 m) wide, and 30 feet (9.20 m) long. There were four rows 30 inches (0.75 m) apart.

Plots were kept under monocrop corn for 6-yr, 3-yr prior to the implementation of the pesticide treatments, and during the 3-yr experiment. The corn hybrid Dekalb XL71 at 90,000 seed per hectare was planted from 27 February to 10 March each year. A Brown Harden in-row subsoil NT planter was used either where no prior land preparation had occurred or where the soil had been prepared conventionally with an off-set Harrow and Rototiller. The pesticide treatments were applied in 6 inch (0.15 m) bands over the row at planting.
Complete fertilizer including N, P, K, S, Mg, Fe, Cu, B, Zn and Mn was broadcast prior to planting based on soil test and plant need. Preplant broadcast fertilization include 200 Kg ammonium nitrate (NO3), and 225 Kg KMAG ha⁻¹. Also, Ammonium nitrate was sidedressed at a rate of 168 Kg ha⁻¹ when plants were 10 inches (0.25 m) tall. Weed control was done 10 days prior to planting with Paraquat plus X77 surfactant. When corn was about six inches (0.15 m) tall a post-broadcast application over the top was done with Atrazine. Atrazine at 2.2 Kg a.i. ha⁻¹ and 2 L crop oil ha⁻¹ was used in all experiments.

Collected data consisted of grain yield (GY) at the soft dough stage of grain formation. Statistical analyses were performed using split plot ANOVA on a TRS-80 model III microcomputer. Means were tested using Duncan's new multiple range test at the 0.05 probability level.

## Genotype/Pesticide Experiments

In this three-location study six commercial hybrids were evaluated for yield as affected by pesticide treatment. This genotype/pesticide experiment was conducted during 1982 and 1983, having different locations. The 1982 experiment was in Alachua county, FL and the two 1983 experiments (1983A, 1983B) were in Levy county, FL. The three locations had similar cropping histories, of continuous double cropped NT corn followed by soybean (*Glycine max* L.) for 1 yr in the case of the 1982 location, and for the last 4 yr in both 1983 locations.

The hybrids evaluated were the following; Asgrow RX777(A), De-kalb XL 71(D), Funks G4507A(F), Coker 19(C), Pioneer Brand 3320(P), and Gold Kist 748(G). Hybrids were whole plots with 4 replications. The same insecticides and rates used in the tillage/pesticide study were split plots. The same plot size and cultural practices used in the tillage/pesticide experiment were used in this experiment, such as planting technique, weed control, and fertilization rate. Data collection, and statistical analysis were handled in the same manner.
# RESULTS AND DISCUSSION

## Tillage/Pesticide Experiments

The average of 3-yr data showed interactions between tillage and pesticide treatments for grain yield (Table 1). The highest GY was given under NT conditions by CF 2.2 which was different from the others at the 0.05 probability level. It was followed by the other two pesticide treatments, which did not differ in yield response to pesticides. All pesticide treatments gave higher GY than the Control (Table 1).

Under CT conditions there was no difference (0.05 prob. level) among pesticide treatments. However, both pesticides and rates were better than the Control (Table 1). Among the pesticide treatments, CF 2.2 gave the highest grain yield under NT conditions. The opposite occurred with CF 1.1, having greater grain yield under CT conditions. But TF 2.2 did not show any differences between tillage treatments. For the C, NT grain yield was higher than CT.

## Genotype/Pesticide Experiments

Interactions were shown between genotype and pesticide treatments under NT conditions for grain yield (Table 2). Asgrow RX777 attained the highest grain yield (105 qq ha⁻¹) using TF 2.0. All hybrids obtained highest grain yield with CF 2.0. Coker 19 responded equally to the two CF rates (Table 2). Grain yields were compared across hybrids within an individual pesticide treatment (Table 2) and for CF 2.0 Dekalb XL 71 and Gold Kist 748 gave the highest grain yield. However when CF 1.0 was used Pioneer 3320 and Gold Kist 748 gave the highest grain yield.

## CONCLUSIONS

Tillage treatments were different for the hybrid Dekalb XL71 only when the highest CF rate (2.2 Kg a.i. ha⁻¹) was used, being in favor of NT. This may have been due to the Growth regulator effects attributed to CF. The three insecticide treatments gave equal grain yield in CT. The results showed that it is not appropriate to use
recommendations from research conducted in one type of tillage and expect the same response in another tillage environment. Research is needed in both NT and CT in order to make proper recommendations to growers.

These data indicate that hybrids do not respond equally to pesticides and this genotype/pesticide relationship is likely the major reason why scientists disagree from one location to another. Strong evidence was found that commercial corn breeders are selecting for a pesticide when it is used during the development of the hybrid. This appears to be the case of Asgrow 777 which gave the highest yield when TF 2.2 was used. Terbufos was used throughout its breeding program. All other hybrids were developed using CF in their breeding program. In order to make valid recommendations on pesticide use by growers, recommended pesticides may need to be tested on all recommended hybrids in order to match up the proper pesticide, rate of pesticide, and hybrid for maximum response of each hybrid and maximum benefits from the use of pesticides.

<table><caption>Table 1. Corn grain yield response to tillage and pesticides (three year average)</caption><thead><tr><th rowspan="3">Pesticide</th><th rowspan="3">Rate</th><th colspan="4">Tillage</th></tr><tr><th>No</th><th>Yes</th><th colspan="2">Average</th></tr><tr><th colspan="2">Kg a.i. ha<sup>-1</sup></th><th colspan="2">q ha<sup>-1</sup></th></tr></thead><tbody><tr><td>Carbofuran</td><td>2.2</td><td>118 a</td><td>109 a</td><td>*</td><td>114</td></tr><tr><td>Carbofuran</td><td>1.1</td><td>100 b</td><td>108 a</td><td>*</td><td>104</td></tr><tr><td>Terbufos</td><td>2.2</td><td>102 b</td><td>104 a</td><td>NS</td><td>103</td></tr><tr><td>Control</td><td>0.0</td><td>92 c</td><td>81 b</td><td>*</td><td>87</td></tr><tr><td>Average</td><td></td><td>103</td><td>100</td><td></td><td></td></tr></tbody></table>

a, b, c, = within columns among pesticides, values not followed by the same letter are significantly different at the .05 level of probability. * = different at the .05 P in rows between tillage. NS = nonsignificant
<table><caption>Table 2 Corn hybrid grain yield response to pesticides in notillage management (three location average)</caption><thead><tr><th rowspan="3">Hybrid</th><th colspan="5">Insecticide Treatment</th></tr><tr><th colspan="2">Carbofuran (CF)</th><th colspan="2">Terbufos(TF)</th><th rowspan="2">Control</th><th rowspan="2">Average</th></tr><tr><th colspan="4">q ha<sup>-1</sup></th></tr></thead><tbody><tr><td>A</td><td>97 v</td><td>92 w</td><td>105 u</td><td>73 vw</td><td>92</td></tr><tr><td></td><td>b</td><td>c</td><td>a</td><td>d</td><td></td></tr><tr><td>D</td><td>103 u</td><td>92 w</td><td>90 v</td><td>75 vw</td><td>90</td></tr><tr><td></td><td>a</td><td>b</td><td>b</td><td>c</td><td></td></tr><tr><td>C</td><td>92 w</td><td>95 vw</td><td>93 v</td><td>75 vw</td><td>89</td></tr><tr><td></td><td>a</td><td>a</td><td>a</td><td>b</td><td></td></tr><tr><td>G</td><td>104 u</td><td>98 uv</td><td>84 w</td><td>77 v</td><td>91</td></tr><tr><td></td><td>a</td><td>b</td><td>c</td><td>d</td><td></td></tr><tr><td>F</td><td>90 w</td><td>83 x</td><td>79 w</td><td>69 w</td><td>80</td></tr><tr><td></td><td>a</td><td>b</td><td>c</td><td>d</td><td></td></tr><tr><td>P</td><td>98 v</td><td>101 u</td><td>89 v</td><td>91 u</td><td>77</td></tr><tr><td></td><td>a</td><td>a</td><td>b</td><td>b</td><td></td></tr><tr><td>Average</td><td>97</td><td>94</td><td>90</td><td>77</td><td></td></tr></tbody></table>

Insecticide rates expressed as Kg a.i. ha⁻¹. A= Asgrow RX777,

D = Dekalb XL71, C = Coker 19, G = Gold kist GK748, F = Funks G4507, P = Pioneer brand 3320.

a,b,c= within rows of pesticides, values not followed by the same letter are significantly different at the 0.05 level of probability;

u,v,w,x = within columns, values not followed by the same letter are significantly different at the 0.05 level of probability.

REFERENCES

Abbott, W. S. 1925. A method of computing the effectiveness of an insecticide. J. Econ. Entomol. 18:265-267.

All, J. N., and R. N. Gallaher. 1977. Detrimental impact of notillage corn cropping systems involving insecticides, hybrids, and irrigation on lesser cornstalk borer infestations. J. Econ. Entomol. 70(3):361-365.

Burton, G. W. 1979. Handling cross-pollinated germplasm efficiently. Crop Sci. 19:685-690.
Depew L. J., and M. L. Hooker. 1987. Effect of Insecticide placement at planting for control of Greenbug (Homoptera; Aphididae) on grain Sorghum. J. Econ. Entomol. 80:490-493.

Entomological Society of America. 1987. Insecticide and Acaricide test. p. 182-224. Volume 12.

Felsot, A., J. V. Maddox, and W. Bruce. 1981. Enhanced microbial degradation of Carbofuran in soils with histories of furadan use. Bull. Environ. Contam. Toxicol. 26:781-788.

Garder, G. W., P. A. Dahm, and J. J. Tollefson. 1982. Carbofuran persistence in Corn field soils. J. Econ. Entomol. 75:637-642.

Henson, A. R., M. S. Zuber, L. L. Darrah, D. Barry, L. B. Robin, and A. C. Waiss. 1984. Evaluation of an antibiotic factor in Maize Silks as a means of corn Earworm (Lepidoptera: Noctuidae) Suppression. J. Econ. Entomol. 77:487-490.

Musick, G. J. 1975. Insect problems associated with no-tillage corn production. Proc. N. E. No-tillage Conf. 1:44-59.

Newhouse, K. E., T. M. Crosbie. 1986. Interactions of Maize Hybrids with Tillage Systems. Agron. J. 78:951-954.

Phillips, R. E., R. L. Blevins, G. W. Thomas, W. W. Frye, and S. H. Phillips. 1980. No-tillage agriculture. Science (Washington, D.C.) 208:1108-1113.

Kunstman, J. L., and E. P. Lichtenstein. 1983. Effects of plant pathogens on the fate of soil-applied Carbofuran in Corn plants. J. Econ. Entomol. 76:1014-1021.

Tingey, W. M., and S. R. Singh. 1980. Environmental factors influencing the magnitude and expression of resistance. pp.87-114. in Breeding Plant Resistant to Insects. F. C. Waxwell, and P.R. Jennings ed. Wiley (New York). 683p.
## GERMPLASMA/GERMPLASM/GERMOPLASMÉ
Horticultural Problems in the Tropics: Breeding for less Favoured Environments

By Olimpia Gómez, T. Depestre and A. Casanova. "Liliana Dimitrova" Horticultural Research Institute Carretera, Quivican Km. 33 1/2, La Salud, Havana, Cuba

Tomato and pepper are originated from South America and had a certain advanced domestication degree in Central America before being carried to Europe. Both species had been bred intensively and now modern varieties are the result of a long work made by man. Weather factors such as temperature, humidity and light have a great influence in tomato and pepper reproductive processes. Tropical conditions are so related to tomato and pepper biological tolerance borders that little climatic variations may have great influence in plant development. Therefore, horticultural breeding is very important in the tropics. In Cuba, a breeding program has been carried out since 1975. Some tomato varieties are the result of this program such as: "HC 38/80" (fresh market); "HC 28/80" (fresh market and processing); "HC 78/80" (processing; mechanical harvesting); "Criollo Quivican" and "L 10/3" (from placero); as well as pepper varieties; "Español Liliana" (PVY; X) and "SC 81" (heat resistant, TMV, PVY, TEV, CMV, X).

## PROBLEMATICA HORTICOLA EN CONDICIONES TROPICALES: MEJORAMIENTO PARA AMBIENTES MENOS FAVORABLES

By Olimpia Gómez, T. Depestre and A. Casanova. "Liliana Dimitrova" Horticultural Research Institute Carretera, Quivican Km. 33 1/2, La Salud, Havana, Cuba

El tomate (*Lycopersicum esculentum*) y el pimiento (*Capsicum annum*) son originarios de América y habían alcanzado un avanzado estado de domesticación en el área de México y en el norte de Centro América antes de ser llevados a Europa.
Ambas especies, de amplia distribución mundial, han sido seleccionadas intensamente y puede decirse que son el resultado de largo trabajo hecho por el hombre. Los cultivares de frutos grandes en su mayor parte han sido obtenidos en los últimos 50 años en Europa y EEUU. Se establece por tanto que ambas especies han logrado su mayor importancia y desarrollo fuera de su lugar de origen, es decir lejos del trópico.

La cebolla (*Allium cepa*) es originaria de Asia Central y fue domesticada en varios lugares a la vez, pero al igual que las especies anteriores su mejoramiento genético ha tenido lugar fundamentalmente en Europa y EEUU. Como consecuencia, actualmente los agricultores en el trópico a menudo sólo disponen de semillas hortícolas de variedades modernas importadas de países templados, las cuales han perdido su adaptación de origen; por lo que no siempre resultan exitosas en la región tropical; igualmente las prácticas de manejo agrotécnico no se han desarrollado acorde a la problemática específica, de ahí que la productividad de estos cultivos sea baja en el trópico comparadas con países de clima templado.

Los factores ambientales tales como temperatura, humedad y luz afectan grandemente la reproducción en el tomate y el pimiento, por tanto el porcentaje de fructificación y el rendimiento. En estas especies termosensibles, los estados meióticos de las células madres, macro y micro esporas tienen lugar ocho o nueve días antes de la antesis, esta es la fase más sensible al calor. Por tratarse de factores dinámicos, en definitiva la fructificación y el desarrollo final del fruto quedan condicionados por el ambiente reinante en las fases en que dichos procesos tienen lugar.

En el tomate, temperaturas de 23 ± 3°C durante el día y 17 ± 3°C durante la noche son deseadas para el normal crecimiento, floración y fructificación. En el pimiento la temperatura más apropiada está entre 20-27°C durante el día y 15-17°C durante la noche, en este rango se obtiene la mayor producción; los extremos de humedad y luz son desfavorable a ambas especies. La cebolla exige temperaturas de 16-23°C en el inicio de su desarrollo vegetativo pero en la fase de formación de bulbo las temperaturas moderadamente altas promueven una buena maduración, esta especie es muy sensible al fotoperíodo y
la interacción fotoperíodo X temperatura define el proceso productivo.

Como puede observarse las exigencias ecológicas de estos cultivos distan mucho de las condiciones climáticas que a menudo prevalecen en el trópico. Estas condiciones se encuentran tan cerca de los límites biológicos de tolerancia para la especies hortícolas que las pequeñas diferencias en el clima pueden tener gran influencia en el comportamiento de las plantas. Esto es válido en Cuba, sujeta durante la campaña de producción hortícola a la influencia variable de los frentes fríos, donde de manera discontinua cambian los elementos meteorológicos.

De todo lo anteriormente expuesto se deduce la importancia del mejoramiento genético que en general en el trópico se encamina hacia tres objetivos: adaptación climática, resistencia a enfermedades y calidad del fruto.

La mala adaptación se traduce a nivel de la planta por una serie de desórdenes fisiológicos que llevan a una producción más débil y a una mala calidad del fruto. Esto se manifiesta en los diferentes estados de la planta y con una intensidad variable según la ecología. Los mecanismos principales de resistencia a estos efectos en las plantas son de defensa y tolerancia. Efectos de este tipo han sido reportados, la aplicación de métodos genéticos y la ayuda de la biotecnología han facilitado el progreso.

En Cuba se han obtenido variedades de tomate adaptadas al clima, estables y resistentes a enfermedades tales como: HC 38/80, HC 25/80, HC 78/80, Criollo Quivicán y L 10/3. Así como Cuba C 27-81, Tropical T 60, FL 5, Tropical C 28 V y Tropical M 10.

La tolerancia al calor en el tomate sin embargo es considerada como un carácter complejo desde el punto de vista genético, los genotipos tolerantes no responden a las altas temperaturas según un patrón sencillo, por otra parte los valores de su heredabilidad son general-
mente bajos lo cual indica que la mayor proporción de la variabilidad observada es debida al ambiente. Por ello el objetivo actual es el de combinar el vigor de un gran número de genotipos tolerantes en un solo cultivar. En este sentido, en el Instituto de Investigaciones Hortícolas "Liliana Dimitrova" se trabaja en la prueba de líneas provenientes de una población nasal "Lignon" obtenida por la técnica de mezcla de polen híbrido y selección por el método de descendencia de una sola semilla modificada (SSDM). Estas líneas han mostrado su eficiencia en diversos países tropicales como Martinica, Cabo Verde, Senegal y Mali, en todos dos últimos al igual que en Cuba, una de ellas se destaca por su resistencia parcial a geminivirus transmitido por mosca blanca(*Bemisia tabaci*).

En pimiento a través de selección se han obtenido las variedades "Español Liliana", con adaptación al calor; resistencia a *Xanthomonas, Fusarium*, y virus (TMV) y la variedad SC 81, para condimento en fresco, muy adaptada al calor, con resistencia a *Xanthomonas, Fusarium* multivirus (TMV, PVY, TEV Y CMV).

Igualmente se cuenta con las variedades Tropical CW 3, True Heart 28, True Heart 27, Chay L3 y Verano 1.

En cebolla a través de la selección de germoplasma introducido y adaptado se obtuvieron las variedades de bulbo rojo: Jagua 9-27 y Caribe 71 con adaptación climática y tolerancia a enfermedades.

Más recientemente a través de la androgénesis in vitro, se han obtenido líneas haploides dobladas (HD) de pimiento que sobresalen por su precocidad, tolerancia a enfermedades y productividad.

En el plano nacional conjuntamente con la utilización de variedades hortícolas resistentes a factores bióticos y abióticos obtenidos por métodos tradicionales y con el apoyo de la biotecnología y el estudio fisiológico y ecológico de dichos cultivos, se están desarrollando prácticas de manejo agrotécnico y de agricultura protegida en función de la problemática tropical (efecto de sombrilla), que coadyuven a la
máxima expresión del potencial de los nuevos genotipos. A su vez
hay un enfoque de integrar los siguientes aspectos:

* Producción controlada de posturas.

* Preparación adecuada y oportuna del suelo para incorporar material orgánico, almacenar agua, reducir la incidencia de plagas y enfermedades.

* Uso de técnicas de laboreo mínimo; asociación de cultivos; abonos verdes; estiércol; humus; biofertilizantes y desechos orgánicos para disminuir la necesidad de fertilizantes y uso de arropes como control de maleza y aumento de la disponibilidad de nutrientes y de la humedad del suelo.

* Control integrado de plagas y enfermedades.

* Pronóstico de riego.

* Rotación de cultivos.

* Manejo adecuado de la cosecha y poscosecha.

* Procesamiento y conservación de productos hortícolas.

Todo lo cual conlleva a un sistema de producción sustentable caracterizado por un exitoso manejo de los recursos con vistas a la satisfacción de las necesidades de la población, pero manteniendo o aumentando la calidad del ambiente y conservando los recursos naturales.
## COMPORTAMIENTO DE HIBRIDOS DE SORGO
GRANIFERO Y SUS LINEAS PROGENITORAS

Félix Navarro, José R. Ortiz, Ramón Celado y Rodolfo Pierre

Programa Maíz y Sorgo SEA-DIA-CESDA, Apdo. #24, San Cristóbal, República Dominicana.

### RESUMEN

En el período agosto-noviembre de 1991 se instalaron en San Juan de la Maguana dos ensayos de sorgo granífero. Uno evaluaba el comportamiento de 14 híbridos de color blanco y rojo y tres 'testigos incluyendo el DK-64 y SG-922, vendidos comercialmente. El otro experimento estudiaba características agronómicas de las líneas progenitoras de los híbridos experimentales. Se observaron varios híbridos blancos y rojos con características agronómicas y de rendimiento semejantes al DK-64. Según el comportamiento de las líneas, los híbridos rojos más factibles de ser producidos fueron ATx623 x RTx434 e ICSA-12 x (SC599-6xTx430)-2-6-2-BK-1-1-1 y entre los blancos el ICSA-4 x ICSR-LM88516 y ATx623 x ICSR-LM86557. Esto, por ser de alto rendimiento, estadísticamente iguales a DK-64, tener líneas rendidoras y buena coincidencia floral de los progenitores masculinos y femeninos. Los materiales experimentales evaluados son originarios del ICRISAT, Comisión Latinoamericana de Investigadores de Sorgo y Universidad de Texas A&M. Esos híbridos pueden ser producidos en la República Dominicana, pues tenemos los progenitores. Se recomendó hacer pruebas en un número mayor de localidades, validar los mejores híbridos y poner a disposición de las casas semilleras nacionales las líneas que originan los mejores híbridos. Reconocimiento al Dr. César Paniagua y Semillas Sureñas, S. A. por su entusiasmo con estos trabajos, poniendo a disposición tierra y recursos para la ejecución de los mismos.

La búsqueda de alternativas de producción agrícola que hagan esta actividad más estable, segura y menos afectada por factores fuera del control del escenario en que las explotaciones se realizan, constituye una de las tareas básicas de la investigación agrícola.
El aporte del estudio de híbridos de sorgo cuyas líneas progenitoras A, B y R están disponibles en instituciones locales, es importante pórque así se evita depender de materiales de padres importados. De este modo, las empresas productoras de semillas podrán producir las cantidades necesarias de acuerdo a la demanda esperada en el mercado con progenitores que se encuentran en sus cuartos fríos. Podrán tener, además, un absoluto control sobre la calidad genética de sus semillas.

El fortalecimiento planteado de la producción de semillas de sorgo en la República Dominicana es importante por el rol de este cultivo ante la demanda de cereales-registrada en los últimos años. Por ejemplo, el consumo aparente de maíz en 1990 (10,048,000 qqs.) fue aproximadamente 2.55 veces mayor a la registrada para 1981. Para 1990 se produjeron 1,294,000 qqs de maíz y 462,000 qqs de sorgo (SEA, 1990).

Los cultivares evaluados aquí han sido producidos con líneas del Instituto Internacional de Investigaciones en Cultivos para los Trópicos Semi-Aridos (ICRISAT), el programa de Mejoramiento de Sorgo para América Latina (LASIP), la Universidad de Texas A&M, Programas Nacionales de Investigación en Sorgo de Centro América, con el esfuerzo de la Comisión Latinoamericana de Investigadores de Sorgo (CLAIS). Varios trabajos han sido llevados a cabo con híbridos estudiados en esta prueba.

Pérez (1984), reportó resultados comparativos de ensayos regionales de sorgo conducidos en Barahona, Azua y San Juan de la Maguana. En estos, los híbridos ATx623 x RTx430, ATx623 x RTx430, ATx623 x 76CS490, AT x 623 x 77CS256, AT x 625 x SC0599, y AT x 623 x 76CS478 compitieron con los híbridos DK-64 y P-8454 dando rendimientos iguales y mayores a los dos últimos híbridos.

Hash et al (1991), reportó resultados comparativos de ensayos instalados en doce localidades de Centroamérica, en donde el híbrido AT x 623 x RT x 433 demostró ser estable en rendimiento, de productividad sobre la media general y de altura de planta aceptable para la cosecha mecanizada. Este híbrido se comportó igual al híbrido comercial DK-64 en estas pruebas.
Otros materiales de buen comportamiento en Hash et al (1991) fueron el Experimental 89-1 del ICTA-Guatemala, M-90362 del MIDINRA-Nicaragua, ES-726 del CENTA-E1 Salvador, el Experimental 89-2 del ICTA, el ISIAP-Dorado, ESHG-71 e ICSH-LM 89506 (ICSA 4/VG 233). Con excepción de la variedad ISIAP-Dorado, estos cultivares fueron de igual o mejor rendimiento que el NK-288, el cual ha sido distribuido en la República Dominicana.

A partir de 1985 se planificaron los ensayos de híbridos de sorgo producidos por los programas nacionales de Centroamérica, quedando en ese año como superiores los híbridos de ATx623 x VG-24, 2219 x VG-44, BJ-84 y 1399 x VG-28 (Guiragossian y Ramírez, 1986). En 1986 se repitió este mismo ensayo y los mejores híbridos fueron el 2219A x VG-44, ES-7A x LU-467, SCP-83A, 296A x VG-233, BJ-84, ATx623 x VG-22, 1391A x VG-24 y Var A x VG-79. A través de 1985-86, los mejores fueron ATx623 x VG-22 y BJ-84 (Paul, C. 1988).

En 1987, el híbrido 1696A x [(SC-110 x SC-120 x (CN5718 x P721)] fue superior a los demás e igual al VAR A x VG-2 ATx623 x ICSV-LM 86541(F3A-1067) y ATx623 x ES-87R (Clará, et al., 1989).

En 1988, los híbridos superiores en rendimiento fueron ATx623 x CS-3541 Crosses-31 e ICSA-1 x ES87R, seguidos por ATx623 x RTx434 y ATx623 x RTx433 (Clará et al, 1990).

En 1989 (Hash et al), los ensayos de híbridos mostraron que los híbridos de mayor rendimiento a través de siete localidades de Centroamérica fueron ATx625 x R6956, A155 x SC 1207-2, e ICSH 89504. Todos ellos con altura de planta entre 183-200 cm., lo cual puede ser una limitante para su cosecha mecanizada. El primero y el tercero eran de grano rojo y ciclo tardío y el segundo, de grano blanco y cliclo intermedio. En cuanto a la producción de semillas solo se pudo evaluar en el ICSH-LM 89504 y era factible su producción puesto que las diferencias de floración de hembras y machos son dos días en promedio. La hembra de éste híbrido también presentó buen potencial de rendimiento a través de las localidades en evaluación.
Los híbridos de mayor rendimiento en grano con altura de planta baja fueron: ICSH-LM 89502, A155 x Tx2817, ICSA-4 x VG-233 y ATx625 x VG-28 con altura de 146-153 cm. y rendimiento de 5.4-6.2 ton/ha. Todos ellos rindieron alrededor de 1/ha más que el DK-64. El primero es de grano color café y los otros tres de color blanco. Los cuatro son de ciclo tardío (64-70 días a la floración). La producción de semilla más factible, por la coincidencia de floración son para ICSA-4 x VG-233 y ATx625 x VG-28, pues su diferencia de floración en los progenitores masculinos y femeninos es solamente cuatro días. No se pudo evaluar la factibilidad de producir ICSH-LM 89502. Las hembras de los otros híbridos, a través de sus líneas mostraron buen potencial de rendimiento.

Los objetivos de este trabajo son estudiar las características agronómicas de 14 híbridos élites del Programa de Sorgo del CESDA, así como 21 líneas endogámicas que incluyen la mayoría de las líneas progenitoras de ellos. Se observará si existen materiales de los estudiados que puedan competir con el híbrido DK-64 de la casa Dekalb-Pfizer, el cual se distribuye en la República Dominicana y la factibilidad de su producción en el país.

# MATERIALES Y METODOS

## Materiales Genéticos

En estos ensayos se incluyen híbridos triple-enanos, precoces-intermedios, de factible producción de semillas para ser probados a alta densidad de población. Se involucran híbridos con líneas de ICRI-SAT/LASIP e INTSORMIL las cuales están disponibles para producir los híbridos de interés.
<table><caption>Tabla 1. Relación de Híbridos Evaluados, San Juan de la Maguana, 1991</caption><thead><tr><th>ENTRADA<br>No.</th><th>PEDIGRI</th><th>NOMENCLATURA<br>ICRISAT</th></tr></thead><tbody><tr><td>1.</td><td>ATx629 x ICSV-LM86557 (CS 3541<br>Crosses-31)</td><td>= ICSH-LM88501</td></tr><tr><td>2.</td><td>ICSA-4 x ICSR-LM88516 (VG-233)</td><td>= ICSH-LM89506</td></tr><tr><td>3.</td><td>ICSA-12 x (SC 599-6 x Tx430)<br>-2-6-2-Bk-1-1</td><td>= ICSH-LM87602</td></tr><tr><td>4.</td><td>ICSA-34 x (Tx430 x 77CS1)-1-1-5-1-1</td><td>= ICSH-LM91501</td></tr><tr><td>5.</td><td>1696A x ICSV-LM86543</td><td>= ICSH-LM91502</td></tr><tr><td>6.</td><td>1696A x (Tx430 x 77CS1)-1-1-5-1-1</td><td>= ICSH-LM91503</td></tr><tr><td>7.</td><td>ATx623 x ICSR-LM885007 (VG31)</td><td>= ICSH-LM88518</td></tr><tr><td>8.</td><td>ATx623 x ICSV-LM86541</td><td>= ICSH-LM91504</td></tr><tr><td>9.</td><td>ATx623 x ICSV-LM86557 (CS3541<br>Crosses 31)</td><td>= ICSH-LM88503</td></tr><tr><td>10.</td><td>ATx623 x RTx434</td><td>= ICSH-LM88509</td></tr><tr><td>11.</td><td>ATx625 x ES-87R</td><td>= ICSH-LM87608</td></tr><tr><td>12.</td><td>ATx625 x ICSR-LM88505 (VG-28)</td><td>= ICSH-LM89509</td></tr><tr><td>13.</td><td>ATx625 x ICSR-LM88506 (VG-30)</td><td>= ICSH-LM91505</td></tr><tr><td>14.</td><td>ICSA-LM87505 x (SC599-6 x tx430)<br>-2-6-2-Bk-1-1</td><td>= ICSH-LM90501</td></tr><tr><td>15.</td><td>ISIAP DORADO (TESTIGO)</td><td></td></tr><tr><td>16.</td><td>Dk-64 (Testigo)</td><td></td></tr><tr><td>17.</td><td>SG-922</td><td></td></tr></tbody></table>
## Metodología

El experimento de híbridos se condujo en San Juan de la Maguana, en los terrenos de la empresa Semillas Sureñas localizados 3 kms al norte del pueblo de San Juan en la carretera hacia Juan de Herrera. La localización geográfica de San Juan de la Maguana es de 18° 49' latitud Norte 70° 17' longitud Oeste; a unos 419 msnm. El diseño experimental utilizado fue el de bloques completos al azar con 3 repeticiones. La unidad experimental constaba de tres surcos de 5 m de largo cada uno y a 60 cm. entre surcos (0.6 X 3 X 5 = 9m²). La parcela útil era el surco central de la parcela, eliminándole 0.5 m de la cabecera a ambos extremos (0.6 X 1 X 4 = 2.4 m²). El distanciamiento de siembra fue 60 cm. entre surcos. Se sembró la semilla a chorro seguido y se raleó dejando 15 plantas por metro lineal.

El experimento se fertilizó 15 días después de la siembra con fertilizantes nitrogenados a razón de 100 kg/ha de N. Se realizaron dos aplicaciones de insecticida, la primera a base de Decis 2.5 EC (20cc/Bomba 20 lts), y la segunda a base de Furadan 3G (3 lbs/629 m²). Un control eficiente de las malezas se logró aplicando 3.5 lts/ha de Herbadox 330EC más un desyerbo manual. Se aplicaron tres riegos al cultivo durante su ciclo.

Para la comparación de líneas progenitoras de los híbridos estudiados se utilizó una metodología idéntica a la descrita y su ubicación era contigua al ensayo de híbridos. Las líneas endogámicas evaluadas se refieren a continuación:
<table><caption>Tabla 2. Relación de Líneas Endogámicas Progenitoras de Líbridos, SJM, 1991</caption><thead><tr><td>Entrada No.</td><td>Pedigrí</td><td>Origen</td></tr></thead><tbody><tr><td>1.</td><td>BTx623</td><td>Texas A&M University</td></tr><tr><td>2.</td><td>BTx625</td><td>Texas A&M University</td></tr><tr><td>3.</td><td>BTx629</td><td>LASIP</td></tr><tr><td>4.</td><td>ICSB-LM 87505</td><td>LASIP/ICRISAT</td></tr><tr><td>5.</td><td>1696B</td><td>ICRISAT</td></tr><tr><td>6.</td><td>ICSB-4</td><td>ICRISAT</td></tr><tr><td>7.</td><td>ICSB-12</td><td>ICRISAT</td></tr><tr><td>8.</td><td>ICSB-34</td><td>ICRISAT</td></tr><tr><td>9.</td><td>ICSB-LM86557</td><td>LASIP</td></tr><tr><td>10.</td><td>ICSR-LM86516</td><td>LASIP</td></tr><tr><td>11.</td><td>(SC599-6 x Tx430)-2-6-2-Bk-1-1-1</td><td>LASIP/Texas A&M</td></tr><tr><td>12.</td><td>(Tx430 x 77CS1)-1-1-5-1</td><td>LASIP/Texas A&M</td></tr><tr><td>13.</td><td>ICSV-LM86543</td><td>LASIP</td></tr><tr><td>14.</td><td>ICSV-LM86507</td><td>LASIP</td></tr><tr><td>15.</td><td>ICSV-LM86541</td><td>LASIP</td></tr><tr><td>16.</td><td>ICSR-LM88505</td><td>LASIP</td></tr><tr><td>17.</td><td>ICSR-LM88506</td><td>LASIP</td></tr><tr><td>18.</td><td>RTx434</td><td>Texas A&M University</td></tr><tr><td>19.</td><td>ES-87 R</td><td>CENTA</td></tr><tr><td>20.</td><td>ISIAP DORADO (Testigo)</td><td>LASIP/CENTA</td></tr><tr><td>21.</td><td>ICSB-LM87502</td><td>LASIP</td></tr><tr><td>22.</td><td>B-155 (Testigo)</td><td>Texas A&M University</td></tr><tr><td>23.</td><td>SG-922 (Testigo Local)</td><td>Garrison Seed Co.</td></tr></tbody></table>
## RESULTADOS Y DISCUIONES

### Híbridos Rojos:

La tabla 3 presenta el comportamiento de los cultivares, 16 híbridos y una variedad (ISIAP-DORADO) para la localidad de San Juan de la Maguana. Entre los híbridos de color rojo se destacaron con respecto al rendimiento cuatro materiales: DK-64, ATx623 x RTx434, ATx625 x ES-87R e ICSA-12 x (SC599-6 x Tx430)-2-6-2-Bk-1-1, sin diferencias estadísticas entre ellos según la prueba de Duncan. El SG-922 y el ICSA-LM87505 x (SC-599-6 x Tx430)-2-6-2-Bk-1-1 no mostraron buen comportamiento en esta prueba con respecto a rendimiento. Es notable que el Atx623 x RTx434 muestra características excepcionales de excerción (20.6 cm), lo cual es otra razón que lo hace atractivo. Su altura de planta de 160.7 cm. aún lo coloca en el rango aceptable para sorgos enanos (menor a 170 cm). El buen comportamiento de ATx623 x RTx434 está en consonancia con los resultados de Clará et al. 1990. El valor como progenitor de la línea ATx623 había sido puesto de manifiesto en Pérez (1984), Guiragossian y Ramírez (1986), Paul (1988), Clará et al (1989) y Hash et al. (1991).
<table><caption>Tabla 3. Característica Agronómica de 17 Cultivares de Sorgo Probados en San Juan de la Maguana, 1991.</caption><thead><tr><th>Estraña No.</th><th>Híbrido</th><th>Rendimiento (Ton/ha)</th><th>Altura Plantas (ctna)</th><th>Excerción (ctna)</th><th>Aspecto (1-5)</th><th>Color Grano</th></tr></thead><tbody><tr><td>16</td><td>DK-64</td><td>6.80 a</td><td>134.7</td><td>13.1</td><td>1.67</td><td>Rojo</td></tr><tr><td>10</td><td>ATx623 x RTx434</td><td>6.48 a</td><td>160.7</td><td>20.6</td><td>1.67</td><td>Rojo</td></tr><tr><td>11</td><td>ATx625 x ES-87R</td><td>6.36 a</td><td>130.0</td><td>9.5</td><td>1.67</td><td>Rojo</td></tr><tr><td>3</td><td>ICSA-12 x (SC599-6xTx430)-2..</td><td>5.89 a</td><td>143.3</td><td>14.7</td><td>2.17</td><td>Rojo</td></tr><tr><td>17</td><td>SG-922 (Testigo Local)</td><td>3.25 bc</td><td>130.0</td><td>18.1</td><td>3.00</td><td>Rojo</td></tr><tr><td>14</td><td>ICSA-LM87505 x (SC599-6xTx430)</td><td>2.83 c</td><td>137.0</td><td>14.4</td><td>2.83</td><td>Rojo</td></tr><tr><td>13</td><td>ATx625 x ICSR-LM88506-</td><td>7.44 a</td><td>143.0</td><td>10.2</td><td>1.50</td><td>Blanco</td></tr><tr><td>8</td><td>ATx623 x ICSV-LM86541</td><td>6.97 a</td><td>194.0</td><td>14.7</td><td>1.67</td><td>Blanco</td></tr><tr><td>2</td><td>ICSA-4 x ICSR-LM88516</td><td>6.22 a</td><td>155.7</td><td>18.5</td><td>2.00</td><td>Blanco</td></tr><tr><td>5</td><td>1696A x ICSV-LM86543</td><td>6.15 a</td><td>168.7</td><td>10.7</td><td>2.00</td><td>Blanco</td></tr><tr><td>7</td><td>ATx623 x ICSR-LM88507</td><td>6.04 a</td><td>154.3</td><td>16.8</td><td>2.33</td><td>Blanco</td></tr><tr><td>1</td><td>ATx629 x ICSV-LM86557</td><td>5.94 a</td><td>150.7</td><td>14.6</td><td>2.33</td><td>Blanco</td></tr><tr><td>9</td><td>ATx623 x ICSV-LM86557</td><td>5.84 a</td><td>150.0</td><td>11.9</td><td>2.17</td><td>Blanco</td></tr><tr><td>15</td><td>ISIAP DORADO</td><td>5.66 a</td><td>135.0</td><td>5.0</td><td>2.83</td><td>Blanco</td></tr><tr><td>6</td><td>1696A x (Tx430 x 77CS1)-1-1..</td><td>5.58 a</td><td>135.7</td><td>12.2</td><td>2.50</td><td>Blanco</td></tr><tr><td>4</td><td>ICSA-34 x (Tx430x77CS1)-1-1..</td><td>5.36 a</td><td>135.0</td><td>15.4</td><td>2.67</td><td>Blanco</td></tr><tr><td>12</td><td>ATx625 x ICSR-LM88505</td><td>5.14 ab</td><td>145.00</td><td>12.2</td><td>2.00</td><td>Blanco</td></tr><tr><td>Media</td><td></td><td>5.75</td><td>147.2</td><td>13.7</td><td>2.18</td><td></td></tr><tr><td>C.V.</td><td></td><td>20.2</td><td>4.4</td><td>24.9</td><td>15.6</td><td></td></tr><tr><td>DMS(5%)</td><td></td><td>2.72</td><td>10.7</td><td>5.7</td><td>0.57</td><td></td></tr></tbody></table>

Nota: Separación de medias para rendimiento por Duncan (5%). Letras iguales implican no diferencia estadística significativa.

Los híbridos ATx625 x ES-87R e ICSA-12 x (SC-599-6 x Tx430)-2-6-2- BK-1-1, muestran alturas de planta de 130 y 143.3 cms bastante cercana a la del híbrido comercial DK-64 (134.7 cms). El ICSA-12 x (SC-599-6 x Tx430)-2-6-2-BK-1-1 muestra mejor excerción que el ATx625 x ES-87R. La línea ATx625 había tenido buen comportamiento como progenitor en Hash et al. (1989).

## Materiales Blanco

Los materiales blancos mostraron en general muy buen comportamiento. El híbrido ATx625 x ICSR-LM88506 tuvo mayor rendimiento que el DK-64, aunque sus medias fueron estadísticamente iguales según la Prueba de Duncan (5%). El ATx625 x ISCR-LM88506 tuvo
muy buenas características de altura de plantas (143.0 cm) y su
exerción de panojas (10.2 cms) fue aceptable.

El híbrido ATx625 x ICSV-LM86541 mostró una altura de planta mayor de 170 cms. que lo hace indeseable para la producción de granos (194.0 cms). Sin embargo puede ser bastante deseable para un sorgo de doble propósito granífero-forrajero.

La variedad ISIAP-Dorado presenta bajo nivel de excerción de las
panojas (5 cms) lo cual es un carácter endeble en la producción de
granos.

Entre los materiales blancos, los de mejor aspecto general fueron: ATx625 x ICSR-LM88506, ATx623 x ICSV-LM-86541, ICSR-LM-88516, 1696A x ICSV-LM-86543 y ATx625 x ICSR-LM88505.

Análisis de Varianza para Rendimiento

Para el análisis de varianza para rendimiento en la prueba de híbridos
se decidió basarlo en dos repeticiones y no en tres como en todos los
demás casos, puesto que la inclusión de la repetición 1 en el análisis
traía como consecuencia estimados de las medias de los tratamientos
(cultivares) menos confiables. Esto fue notado al hacer análisis de
aditividad en el modelo de bloques al azar utilizado y notar que el
valor F para no aditividad era mucho mayor cuando se usaban tres
repeticiones que cuando se usaban dos (Tabla 4 y 5). A medida que
el valor de F. para no aditividad se hace más grande esto implica una
menor precisión en las medias estimadas y que el modelo estadístico
asumido Yijr =μ + Bj + Ti +Eij, es menos eficiente para resolver
el problema. En algunos casos se sugeriría hacer transformaciones,
pero no así para rendimiento.