bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Field Production Techniques on Hybrid Wheat Seed Quality1
Authors: Miller J. F. , Rogers K. J. , Lucken K. A.
Published: July 2010

Seed quality characteristics of hybrid and male‐sterile wheat seed [Triticum aestivum L. em. Thell with T. timopheevi (Zhuk.) Zhuk. cytoplasm] were investigated in field‐scale production experiments that tested 1:1, 2:1, and 3:1 ratios of female to male parent. Drill‐strip widths ranged from 3.1 to 11.0 m. Test weight, seed protein percentage, kernel weight, and seed set percentage were evaluated. Seed harvested from the male‐sterile line was lower in test weight, higher in protein percentage and kernel weight, and had a faster rate of germination than seed of the normal line. The 1:1, 2:1, and 3:1 ratios had mean seed set percentages of 64, 51, and 45, respectively. Test weights of male‐sterile seed decreased from the 1:1 to the 3:1 ratio, and seed protein percentage increased.

Seed set and quality of sequential seed samples harvested within each of the three female drill‐strip widths also were determined. Seed set and test weight decreased, protein percentage increased, and kernel weight decreased toward the center of the male‐sterile drill strips within the 2:1 and 3:1 ratios. This decrease in seed quality adversely affected the emergence and subsequent yield of hybrid wheat.

These differences may be a factor determining field arrangements for commercial seed production. If conditions conducive to good production are not present, seed quality as well as seed set percentage may fall below acceptable levels.
Responses of Upland Cotton to Selection for Fiber Length and Fineness in a Nonirrigated Semiarid Environment1
Authors: Quisenberry J. E. , Ray L. L. , Jones D. L.
Published: July 2010

Fiber length and fineness were used as the selection criteria in the development of four groups of lines from a composite‐cross of upland cotton (Gossypium hirsutum L). These groups consisted of lines with long‐coarse, longfine, short‐coarse, and short‐fine fibers. These fiber groups were used to evaluate selection for fiber length and fineness on fiber strength and elongation, lint yield, earliness of crop maturity, stormproofness, lint percent, lint index, and seed index. All selections and evaluations were made in a semiarid environment without irrigation. Orthogonal comparisons, based on the fiber groups, were used to determine the response of these characters to selection for fiber length and fineness. Comparisons of linear regression coefficients from the parental and selected lines were used to estimate the changes in character relationships that occurred during selection.

Significant residual variation for most characters, existed among the selected lines within each group. This residual variation suggested that selection had not eliminated all genetic variance. The orthogonal comparisons showed that fiber length was associated with fiber fineness and elongation, lint yield, stormproofness, lint percent, and seed index and that fiber fineness was associated with fiber strength and elongation, earliness of crop maturity, stormproofness, lint percent, lint index, and seed index. Correlation coefficients from the parental and the selected lines suggested that the relationships between fiber length and both lint yield and lint percent did not change during the selection process, but that the associations between fiber length and earliness of crop maturity, stormproofness, lint index, and seed index did change. The relationships between fiber fineness and both fiber strength and lint index were the same in both the parental and selected lines, whereas fiber elongation, earliness of crop maturity, stormproofness, and seed index did not show the same degree of relationship with fineness in the parental and selected lines.
Determination of Yield, Yield Components, and Fiber Properties as Influenced by Selective and Nonselective Samplings1
Authors: Meredith William R. , Ramey H. H. , Bridge R. R.
Published: July 2010

We compared two methods of sampling cotton (Gossypium hirsutum L.) at Stoneville and Scott, Miss. We used 14 of the cultlvars from the 1971 regional high quality test. Each entry was replicated four times at each location, with two‐row plots, 16‐m long and l‐m wide. In the selective‐sampling method, individual samplers picked 75 bolls from throughout the plot. For nonselective samples, all bolls were counted and harvested from two random areas (about 0.8 m of row) in the plots. The samples from the first two replications and the last two replications were bulked to form two composite samples at each location.

Selective sampling resulted in the computation of higher yields (4.4%), lint percentage (4.4%), boll size (15.2%), seed index (2.5%), lint index (10.0%), and seeds/boll (9.5%), and a lower number of bolls/ha (12.8%). Interactions of sampling methods and locations were significant for yield, bolis/ha, lint percentage, boll size, lint index, and seeds/boll. Cultivar by sampling method interactions were significant for yield, bolls/ha, and boll size, and three factor interactions were detected for seed index, lint index, and seeds/boll. Although these interactions were small compared to that for cultivar, they do imply that selective sampling causes cultivar misevaluation.

As a result of selective sampling, yarn strength, 50% span length, 2.5% span length, length uniformity, reflectance, yellowness, and micronaire were 1.6, 2.8, 0.0, 3.3, 2.8, 0.1, and 8.0% higher, respectively, than that of the nonselective samples. Sampling by location interactions were detected for 2.5% span length, reflectance, and yellowness.

There are implications for genetic evaluations.
Swelling Response of Alfalfa Seedlings to Initial Stem‐nematode Infection1
Authors: Elgin J. H. , Evans D. W. , Faulkner L. R.
Published: July 2010

We tested seedlings of seven alfalfa (Medicago sativa L.) cultivars inoculated with stem nematodes [Ditylenchus dipsaci (Kűhn) Filipjev] to study relationships between initial nematode infection 3 days after inoculation, 3‐day symptoms, 24‐day symptoms, and nematode reproduction. Cultivars differed significantly for initial infection, 3 and 24‐day symptoms, 24‐day nematode populations, and rate of population growth. At 3 days, individual seedling symptoms varied with the initial numbers of nematodes infecting the cotyledonary node. Symptom ratings for individual plants did not change greatly between 3 and 24 days.

Because seedling symptoms at 3 and 24 days depended on the initial numbers of nematodes infecting the cotyledonary node, and because nematode infection is seldom uniform, the breeder may be able to select more effectively if he uses repeated inoculations and waits until differences in nematode reproduction make it possible to distinguish between resistant and susceptible plants.
Effects of Temperature and Light Intensity on the Expression of a Variegated Leaf Pattern in Bermudagrass1
Authors: Johnston Roy A. , Taliaferro Charles M.
Published: July 2010

In 1971 a variegated plant was found among an F1 bermudagrass [Cynodon dactylon (L.) Pers.,] population growing on the Agron. Res. Stn. at Stillwater, Okla. The variegated “Zebra” pattern consists of alternating green and chlorotic stripes that occur horizontally across the leaf blades. Occurrence of the Zebra pattern on the original plant and its progeny seemed to be environmentally dependent. Consequently, this study was designed to ascertain the effects of temperature and light intensity on the development and expression of the Zebra pattern. Two growth chamber tests, four temperature regimes (16, 21, 27, and 32 C), and two light intensities (16,150 and 32,300 lux) were used. A photoperiod of 14 hours at constant temperatures was used. Expression of the mutant character was primarily dependent on light intensity, with an increased amount and prominence of chlorotic stripping at the high intensity exposure (32,300 lux). Maximum expression of the character occurred on plants growing at 21 C and 32,300 lux of light. Plants growing at 27 C developed only slightly less chlorotic strippingthan those grown at 21 C, while those growing at 32 C developed no chlorotic strips at 16,150 lux and developed only slight stripping at 32,300 lux. Plants growing at 16 C and 16,500 lux had little stripping whereas those grown at 16 C and 32,300 lux had only a moderate reduction in stripping as compared to optimum temperature‐light regimes.
Monosomic Analysis of Photoperiod Response in Wheat1
Authors: Pirasteh B. , Welsh J. R.
Published: July 2010

Identification of specific chromosomes containing the genes for photoperiod response in common wheat (Tritlcure aestivum L. era. Thell.) was undertaken. F1 and F2 progenies from crosses of a photoperiod insensitive spring wheat (‘Sonora 64’) with 21 diferent monosomic lines of a sensitive winter wheat (‘Cheyenne’) were grown with the parental cultlvars under a 10‐hour photoperlod. A disomic F2 population was used to measure the standard segregation pattern.

The vernalized winter parent was still in the vegetative state after 152 days under a 10‐hour photoperiod. The spring parent headed, on an average, 54 days after planting. The F1 population headed, on an average, 66 days after planting. Disomlc F2 population segregation under a 10‐hour photoperiod indicated that three gene pairs, with dominant epistasis for earliness of one of the factors, controlled this character. Heading response of the F2 progenies of the monosomic line for chromosome 2D showed that this chromosome is the carrier of the Ppd 1 gene with the dominant epistatic effect. Two of the four chromosomes 2B, 4B, 3D, and 6D are possible carriers of the other two genes.
Comparisons of Lysine and Zein and Nonzein Protein Contents in Immature and Mature Maize Endosperm Mutants1
Authors: Dalby A. , Tsai C. Y.
Published: July 2010

Maize (Zea mays L.) endosperm mutant shrunken‐4 (sh4) was compared with nine other starch mutants and three “high‐lysine” mutants for lysine and zein and nonzein protein content at 22 days after pollination and at maturity. The sh4 mutant was unique in showing no zein at 22 days and only 10% of the normal value at maturity. Nonzein protein and lysine/kernel were extremely low at maturity in sh4, showing almost no increase after 22 years. The effects of sh4 on protein content appear to be an exaggerated form of those produced by the highlysine mutant opaque‐7.
Comparison of the Growth Responses of Spring and Summer Plants of Alfalfa Red Clover, and Birdsfoot Trefoil1
Authors: Smith Dale , Soberalske R. M.
Published: July 2010

Alfalfa (Medicago satlva L.), medium red clover (TriFolium prateuse L.), and birdsfoot trefoil (Lotus corniculatus L.) are important forage legumes in the northern United States. The current study was conducted to directly compare the growth of summer (second‐crop) plants with that of spring (first‐crop) plants. Soil cores spring plants were removed from the field before growth started and were stored at —2 C. When plants were at full bloom in the field, soil cores of plants again were removed and shoots were cut to leave 5‐cm (short) and 12‐cm (tall) stubbles. Spring and summer plants then were grown together under identical conditions. Spring and summer alfalfa plants produced essentially the same yields of herbage. In contrast, spring plants of trefoil and red clover produced significantly more herbage than summer plants. However, summer red clover plants yielded similarly at both stubble heights, while summer trefoil herbage yields were significantly higher with a tall than with a short stubble.

We conclude that the differential yield between spring and summer plants of trefoil was due to differences in carbohydrate reserves, while differential yield between spring and summer plants of red clover was due to differences in shoot initiation. The results explain in part why alfalfa is normally a higher yielding species than red clover or birdsfoot trefoil. They also reconfirm that a tall stubble is needed for trefoil to produce a satisfactory regrowth after cutting.
Application of Restricted Selection Indices for Grain Yield Improvement in Oats1
Authors: Rosielle A. A. , Frey K. J.
Published: July 2010

Genotypic correlations among grain yield, heading date, and height, calculated from a population of 1,200 F9‐ derived oat (Avena satlva L.) lines tested in six environments, showed that unrestricted selection for high grain yield would save undesirable lines with late heading dates and tall plant heights. We used restricted selection indices to examine the effect of restricting heading date and height on oat grain‐yield improvement. A restricted selection index for grain yield, with holding of heading date and height constant, was expected to be 57% as efficient for improving grain yield as unrestricted direct selection for grain yield; use of harvest index as a secondary trait in this restricted selection index increased the efficiency to 70%. More severe restrictions on heading date and height reduced the expected advance for grain yield, and very severe restrictions gave negative expected advance. Under some restrictions on heading date and height, indirect selection for grain yield through harvest index was expected to be almost as efficient as the use of a restricted selection index. With mild restrictions on heading date and height, much of the grain yield increase in oats may come from increased harvest index.
Effects of Male Cytoplasm on Inheritance in Hybrid Maize1
Authors: Fleming A. A.
Published: July 2010

It is generally thought the female and not the male gamete contributes the cytoplasm to the offspring. Suppose it is possible for the male parent to contribute some cytoplasm to the progeny. It would be advantageous to know if there is any measurable effect of the male cytoplasm on the progeny of a hybrid resulting from the union of female and male gametes in fertilization.

Seed of a double‐cross maize hybrid (Zea mays L.) was prepared to obtain all possible combinations of the male and female cytoplasms. The eight entries were tested in randomized, complete block field experiments in paired plots 2 years with 10 replications/year. All four inbreds in the double‐cross were uniform long‐time inbreds. Data were obtained on 11 and 13 agronomic characters in the two experiments.

This investigation indicates that the male cytoplasm can influence the hereditary expression of characters in the progeny. But, the expression of the male cytoplasm may be influenced by the female cytoplasm. One of the problems in the evaluation of cytoplasmic effects in breeding programs may be a cytoplasmic‐environmental interaction from year to year.
Resistance in Maize to Corn Rust, Controlled by a Single Dominant Gene1
Authors: Futrell M. C. , Hooker A. L. , Gene Scott E.
Published: July 2010

Southern corn rust (Puccinia polysora Underw.) has caused losses in late‐planted maize (Zea mays L.) in the southern United States in 1972, 1973, and 1974. Two susceptible × resistant crosses to this rust were made, and the parents, F1 F2, and BC1 populations were studied in the greenhouse for their response to this rust. A single dominant gene for resistance to corn rust was found in a recovered inbred line (B1138TRpp). The original source of resistance (B1138T) comes from South Africa and has resistance to Bipolaris turcicum (Pass.)Shoemaker.
Variation in Chlorophyll Content of Maize Lines and Hybrids1
Authors: Fleming A. A. , Palmer J. H.
Published: July 2010

Quantitative differences in chlorophyll, genetic implications, and the relationship of total chlorophyll to various agronomic characters were studied in 17 inbred lines and 24 single‐cross hybrids of maize (Zea mays L.). Differences occurred for total chlorophyll/g in fresh weight of leaf tissue, chlorophyll a;, chlorophyll b, visual chlorophyll ratings, Ca:Cb ratios, and yield/plant, both among inbreds and hybrids.

Relationships were found in both inbreds and hybrids,respectively, for total chlorophyll to visual rating (∗0.76* and ∗0.69*, *significant at P −0.01) and for total chlorophyll to Ca:Cb ratio (∗0.91* and ∗0.84*). No relationships were detected between total chlorophyll and yield in grams of ear corn/plant. Thus, chlorophyll levels in these experiments were not a limiting factor for yield.

Chlorophyll content of the hybrid was characteristically greater in all instances than the mean of the inbred parents. Results indicate that there can be heterosis for chlorophyll content and that the simplest explanation is the presence of more loci having a dominant or partially dominant gene in the hybrid than in either parent. There was a positive relationship between hybrids with high amounts of heterosis for yield and those with high amounts of heterosis for chlorophyll (r = 0.93*).

Significant reciprocal effects for total chlorophyll and yield were obtained in two pairs of single‐cross hybrids.
Quantitative Gene Action for Protein Content in Oats1
Authors: Sraon H. S. , Reeves D. L. , Rumbaugh M. D.
Published: July 2010

The objectives of this study were to determine gene action, heritability, and number of effective factors controlling protein content in oats (Avena spp.). One Avena sterilis L. and three A. sativa L. cultivars were crossed in a diallel, including reciprocals, with protein of 16.1 to 24.4%. The data showed additive gene action for groat protein percentage. Partial dominance for low protein percentage was observed. Narrow sense heritability was 41%. Protein percentage was inversely related to grain yield. The Avena sterilis L. parent exhibited recessiveness for high protein content.

Estimation of the number of effective factors controlling protein content varied from 1 to 25 depending upon the genetic diversity of the parents and direction of the cross.
Colombian Maize Germplasm as Sources of Modifier Genes for Opaque‐21
Authors: D'Croz N. E. , Crane P. L.
Published: July 2010

Despite its proven nutritional superiority, opaque‐2 maize (Zea mays L.) has not been generally accepted in tropical regions and for certain food uses because of its soft endosperm. Modified (more vitreous) opaque‐2 types would be more acceptable. Seven Colombian maize races and a population derived from ETO ✕ USA342 were outcrossed to the homozygous opaque‐2 lines L215 and L216, which have the soft endosperm expression. The crosses were self‐pollinated, and the F2 kernels were classified into three classes over a light. One sub‐family (single ear) of each family was reclassified into four classes on a black‐topped table with a lighted magnifying glass. Chi‐square tests indicated indirectly whether the intermediate classes II or II and III were modified opaque‐2 kernels or if the ratios deviated significantly from 3:1 due to an excess of normal kernels. In the latter case, some homozygous opaque‐2 kernels were so modified that they were phenotypically indistinguishable from normal. A high percentage of intermediates indicated that ETO ✕ USA342, Pira, Puya, and Comun were good sources of modifier genes for opaque‐2. Amagaceno was less promising and conflicting results within our smaller samples of Clavo, Chococeno, and Polio made it impossible to draw definite conclusions about their potential.
Heterosis, Inbreeding Depression, and Reciprocal Effects for Yield and Some Yield Components in a Cowpea Cross1
Authors: Kheradnam M. , Bassiri A. , Niknejad M.
Published: July 2010

Two pureline cowpea (Vigna sinensis L.) cultivars, differing in many agronomic characters, were crossed and carried to the F2 generation. The parental cultivars and F1 and F2 generations were grown in the field in a randomized block design, and notes were taken on individual plants for number of branches, clusters, seeds/ pod, pods and 100‐seed weight and yield. Analyses of variance were performed and heterosis, inbreeding depression and reciprocal effects were calculated, each by two different methods, and tested for significance.

The greatest heterosis with respect to the midparent was observed for seed yield and the lowest for number of branches. The mean values of F1 for number of clusters and pods and seed yield exceeded even the mean of the higher parent. For most characters studied, the mean values of F2 approached the values of the midparent, thus exhibiting inbreeding depression as a result of one generation of natural selfing. However, in general, the values obtained for heterosis were greater than those for inbreeding depression.

Both methods used for calculation and testing of each criterion yielded similar results. Significant heterosis and inbreeding depression were found for all characters except the number of branches. No reciprocal effects were present for any of the characters studied. It was concluded that the production of hybrid seed for cowpeas could be commercially advantageous, if large‐scale methods of emasculation and crossing were developed for this species.
Distribution of Specific Alkaloids in Reed Canarygrass Cultivars1
Authors: Hovin A. W. , Marten G. C.
Published: July 2010

Alkaloids in reed canarygrass (Phalaris arundinacea L.) are negatively associated with palatability and sometimes have undersirable effects on ruminant animals. Our objectives were to characterize several reed canarygrass cultivars with respect to alkaloid concentration and distribution patterns of specific alkaloids. Because current cultivars are difficult to describe morphologically, chemical characterization may aid in identifying or describing them.

We determined frequency distribution of three primary indole alkaloids: 3‐dimethylaminomethylindole (gramine); N,N‐dimethyltryptamine (DMT); and 5‐methoxy‐N,N‐dimethyltryptamine (5‐MeO‐DMT), among spaced plants of selected reed canarygrass cultivars and experimental strains grown in the field in 1973. Alkaloid composition and concentration were also determined from solid‐stand plots in 1973 and 1974.

‘Vantage’ was the only cultivar containing exclusively gramine. The presence of gramine was verified using forage from the six parent clones, plants from syn 1 generation and syn 2 generation seed, and from first growth and regrowth of solid‐stand plots. ‘Frontier,’ ‘Grove,’ ‘Rise,’ and three experimental strains contained both gramine and tryptamines. The experimental strain MN‐72 was differentiated from Grove, Rise, and two experimental strains by frequency distribution of gramine, DMT, and 5‐MeO‐DMT.

The 47 to 49 plants used for alkaloid typing of each entry were possibly too few to characterize other cultivars and strains. Grove, MN‐72, and Frontier had significantly lower total alkaloid concentration (% dry wt) than did RC‐2, Vantage, and Rise when determined on 4‐week‐old second regrowth in 1973 but not on 4‐week‐old first or second regrowth in 1974. Differences among entries were also smaller and seldom significant when based on 6‐week‐old first regrowth in 1973. The 2‐year mean alkaloid values over all sampling dates were significantly lower for Grove and MN‐72 compared to Vantage, Rise, and RC‐2. Concentration of total indole alkaloids appears to distinguish some reed canarygrass cultivars, but only at specific conditions of growth.
Growth of Cotton Plants on Nitrate and Ammonium Nitrogen1
Authors: Radin J. W. , Sell C. R.
Published: July 2010

Vegetative and reproductive growth of cotton (Gossypium hirsutum L.) were evaluated in the greenhouse on media containing nitrate or ammonium or both, to test for interactions between the two N sources on growth and yield. An inhibitor of nitrification was included in all treatments. Both N sources supported vegetative growth, although there was little response to increments of nitrate above meq/liter under the conditions of the test. Combinations of the two N sources did not support better growth than either one alone, except at low total N levels, perhaps because ammonium at ≥ 2 meq/liter inhibited in vivo nitrate reductase activity.

Reproductive growth of the plants was enhanced by N; however, 9 meq/liter nitrate was less effective than lower concentrations of either source, or their combination, in promoting fruitfulness and N accumulation relative to the vegetative parts. The failure to find a synergistic interaction in response to the two sources suggests that cotton responds to N source differently from some other crop species.
Straw‐protein Percentages in Avena sterilis L.1
Authors: Frey K. J. , McCarty T. , Rosielle A.
Published: July 2010

A group of 334 Avena sterilis L. strains was grown at Ames, Iowa, and measured for groat and straw‐protein percentages and heading date. F3 segregates from five crosses between A. sativa ✕ A. sterilis lines were measured for the same traits.

Straw protein for the A. sterilis strains ranged from 5.5 to 14.6%. Three A. sativa lines used as checks had mean percentages from 5.6 to 6.7. Collections from Libya generally had higher levels of straw and groat protein than those from other countries, even though the strain with the highest straw protein, PI 324721, was from Greece.

There was a positive correlation between heading date and straw‐protein percentage, but one A. sterilis strain, PI 324774, was early and had 12.1% straw protein. Groat protein and straw protein were uncorrelated for the A. sterilis strains.

The inheritance of straw‐protein content probably was due to a small number of segregating effective factor pairs.
Salt Tolerance in Cultivars of Grain Sorghum
Authors: Taylor R. M. , Young E. F. , Rivera R. L.
Published: July 2010

Forty‐eight cultivars of grain sorghum, Sorghum bicolor (L.) Moench, were germinated and grown for two weeks in a hydroponic salt system to screen for salt tolerance. Seedlings were grown at 3,000, 5,000, and 7,000 ppm salt. Fresh weight, as a percentage of the control, was used as a measure of growth. Growth decreased sharply with increased salt concentrations. Cultivars differed significantly at the 1% level. If these differences prove to be heritable, progress might be significant toward the development of salt‐tolerant lines through a judicious breeding program.
Identification of Cotton Haploids by Stomatal Chloroplast‐count Technique1
Authors: Chaudhari H. K. , Barrow J. R.
Published: July 2010

Chloroplast counts were made from the stomatal guard cells in haploid (n = 2x = 26) and in natural tetraploid (2n = 4x = 52) plants of Gossypium hirsutum L. and G. barbadense L. The mean chloroplast number was 10.46 ± 2.18 for haploids and 21.00 ± 3.31 for tetraploids. The means from haploid plants did not overlap with the means from tetraploid plants in 280 plants evaluated. Cotton plants can be classified much easier and quicker from the cotyledon stage to maturity as haploids or tetraploids and as accurately as by chromosome counts.
Genetic Variation in Enzyme Activity of Tall Fescue Leaf Blades1
Authors: Nelson C. J. , Treharne K. J. , Lloyd E. J.
Published: July 2010

Plants show genetic variation in several physiological responses that involve enzymes. Our objective was to determine if genetic variation existed in some representative metabolic enzymes of tall fescue (Festuca arundinacea Schreb.). Fully developed leaves from 12 genotypes selected from six diverse populations growing in the field were sampled for activity of eight enzymes. Genetic differences were found for activities of all enzymes studied and often between genotypes from the same population. Expressing enzyme activity on a fresh weight, dry weight, or leaf area basis gave better discrimination between genotypes than expressing on a Lowry protein basis.

Activities of ribulose 1, 5‐diphosphate carboxylase (RuDPc), phosphoenolpyruvate carboxylase (PEPc), and alanine aminotransferase (GPT) were positively correlated among genotypes. Phosphoglyceryl kinase (PGK) activity was correlated with RuDPc, GPT, and glyceraldehyde 3‐phosphate dehydrogenase (GAPDH). Also, activities of malate dehydrogenase (MDH) and GAPDH were positively correlated with those of RuDPc and PEPc. Isocitrate dehydrogenase had a lower relative activity, but was positively correlated with MDH and GAPDH, two other respiratory enzymes. Activity of glucose 6‐phosphate dehydrogenase, an enzyme of the oxidative pentosephosphate pathway, was not correlated with that of any other enzyme studied. It is apparent that genetic variation exists, and that genetic studies of enzyme activity will become increasingly more important as rate‐limiting steps in growth and metabolism of crop plants become clarified.
Effects of Pilose, Pubescent, and Smooth Cottons on the Cotton Leafperforator1
Authors: Wilson R. L. , Wilson F. D.
Published: July 2010

Strains of cotton (Gossypium hirsutum L.) deviating in both directions from the degree of pubescence typical of upland cotton, were more resistant than the latter to cotton leafperforator (Bucculatrix thurberlella Busck). Two densely hairy lines, TM‐I(H2) and SA 166, harbored significantly fewer insects than any of the other lines tested. Nonpreference for oviposition is probably the main mechanism of resistance involved. A no‐choice greenhouse feeding technique was devised that should be useful in screening cottons for resistance to cotton leaf perforator.
In Vitro Cultures of Maize Endosperm — A Model System for Studying In Vivo Starch Biosynthesis1
Authors: Chu Liu‐Jen C. , Shannon Jack C.
Published: July 2010

In vitro cultures of maize (Zea mays L.) endosperm derived from the dent inbred A636 have been maintained in culture for over three years. Tissue growing in liquid media containing 2% sucrose contained little starch, but the addition of 6 g of sucrose nine days after subculture stimulated considerable starch accumulation. Glucose and/or fructose supported growth and starch accumulation, but galactose did not. The addition of extra medium components accompanying sucrose supplementation had no beneficial effect on starch accumulation, but a second 6‐g sucrose supplementation 12 days after the first further stimulated starch deposition. The starch accumulation appeared to be directly related to the amount of metabolizable carbohydrates in the medium. Since a simple modification of the medium stimulates starch deposition, maize endosperm cultures should be a useful model system for studying in vivo starch biosynthesis.
A Design III Study of Linkage Disequilibrium for Percent Oil in Maize1
Authors: Moreno‐Gonzalez J. , Dudley J. W. , Lambert R. J.
Published: July 2010

The objectives of this study were 1) to estimate additive and dominance genetic variance and the average degree of dominance for percent oil in the F2 and F8 randommated generations of a cross between Illinois High Oil (IHO) and Illinois Low Oil (ILO) maize (Zea mays L.) strains using Design III and 2) to measure the effect of linkage bias on such estimates.

The following results were obtained: 1) The estimate of additive genetic variance was about eight ✕ larger than that of dominance genetic variance in the F2 and about four ✕ larger in the F6; 2) The estimate of additive variance in the F8 was half that in the F2 suggesting that many loci controlling percent oil were linked in the coupling phase in the parents; 3) The estimate of dominance variance in the F6 did not differ from the F2 indicating a lack of effect of linkage on dominance variance which could be interpreted as indicating that genes with dominant action are distributed throughout the genome with map distances approximating independent inheritance or that some genes are dominant for low oil while others are dominant for high oil; 4) Estimates of the average degree of dominance were 0.508 for the F2 generation and 0.681 for the F8. Both estimates are significantly different from zero and from one, but not from each other.
Contents of Chlorophylls a and b in Chlorophyll‐Deficient Mutants of Sweetclover1
Authors: Specht J. E. , Haskins F. A. , Gorz H. J.
Published: July 2010

Leaf extracts from twelve chlorophyll‐deficient mutants of sweetclover (Melilotus alba Desr.) were compared spectrophotometrically and chromatographically with extracts from normal plants to determine contents of chlorophylls a and b. Total chlorophyll contents in cotyledons and leaves of all mutants were significantly lower than those in corresponding tissues of normal plants. Chlorophyll contents were generally higher in later emerging leaves of both normal and mutant plants. Chlorophyll a/b ratios in first trifoliolate leaves were similar to normal in mutants ch7 and ch8, higher in mutants ch6, ch9, ch10, and ch1l, and extremely high in mutant ch4. A lower than normal a/b ratio was observed in mutant ch12. The four allelic ch5 mutants were unique in that chlorophyll b was not detected in any of the tissue extracts. The mutants appear to be only the third reported instance in higher plants of a viable mutant lacking chlorophyll b, the previously reported cases being in barley (Hordeum vulgare) and Arabldopsis thaliana.
Modification of a Self‐Propelled Plot Combine for Harvesting Hill Plots of Soybeans1
Authors: Carlson B. E. , Bandstra T. J. , Fehr W. R. , Clark R. C.
Published: July 2010

A self‐propelled plot combine was modified to facilitate the harvest of hill plots of soybeans (Glycine max (L.) Merr.). The modified combine reduces the amount of labor required by about 50% when compared with a stationary plot thresher.

A conveyor was mounted on the side of the combine to transport the identification tag for each hill from the header to the person bagging the seed. The person bagging sits on a carnage mounted near the seed delivery spout. The seed bag and identification tag are tied together by an air‐powered tying machine. A hydrostatic transmission provides the combine with a variable‐speed cylinder.
Effects of R1, a Gene for Red Plant Color, on American Pima Cotton1
Authors: Turcotte E. L. , Feaster Carl V.
Published: July 2010

A dominant gene conditioning red plant color, R1 was transferred to Gossypium barbadense L. from G. hirsutum L. The R1 gene had no significant effects on seed index, or fiber length, strength and elongation after eight backcrosses to G. barbadense. Homozygous red, R1R1, and heterozygous red, R1rl, significantly reduced lint yield, boll size, lint percentage, and Micronaire. Dosage effects were noted for yield, boll size, and Micronaire. Green BC8F3 plants were not significantly different from the recurrent parent, ‘Pima S‐4,’ for any of the 10 properties measured.
Genetic Changes in Oat Bulk Populations under Winter Survival Stress1
Authors: Marshall H. G.
Published: July 2010

Convergent crossing was used to produce 58 different winter oat (Avena by zantina K. Koch and A. sativa L.) bulk populations, and these populations were subjected to 4 years of winter survival stress in Pennsylvania. Two types of observations were subsequently made to determine the effect of natural selection on these populations. First, all populations were compared in the F8 and F7 generations to determine performance for juvenile growth habit, freezing resistance in a laboratory test, and winter survival in the field. Second, F8 and F7 individual plants were isolated from 12 populations and classified for juvenile growth habit, maturity, and plant height. Derived F1 and F8 lines from six of these populations were compared for freezing resistance.

Thirty‐four of the 58 populations increased significantly in freezing resistance and changed similarly for winter survival in the field. The majority of the populations that changed greatly for these chadracteristics were low performers in the F3. Initially elite populations made small, nonsignificant changes under natural selection. Nonresponsiveness to natural selection in the latter populations did not reflect low genetic variability, since a wide range in freezing resistance was observed among derived lines, regardless of generation or population.

In every population, the F3 growth habit ranged from intermediate to very erect. By the F7 generation, 28 populations were significantly more decumbent in juvenile growth habit. Plants from 10 out of 12 populations were significantly more decumbent by the F7 generation; and all populations were later in maturity. Plants with decumbent juvenile growth were latest in maturity, and these two characteristics were correlated within each generation of all populations. Five of 12 populations were taller by the F7 generation, and the others did not change in average plant height under natural selection. Changes in maturity and plant height were independent of natural selection on winterhardiness.

If the bulk population approach is to be used for natural selection for winterhardiness, controlled selection pressure during one or more early generations may have to be applied so that the tendency to increase gone frequencies for lateness and tallness can be offset.
Ontogenetic Model of Cotton Yield1
Authors: Worley Smith , Ramey Harmon H. , Harrell D. C. , Culp T. W.
Published: July 2010

A model of cotton (Góssypium sp) lint yield that equated yield to the volume of a parallelepiped with three dimensions was developed by Kerr. The model is extended to basic units by dividing the axes of the parallelepiped and the seed is recognized as the basic unit of yield. Yield per seed, per boll, and per unit area of land can be stated in equation form by using the divisions of the axes. The relative contributions of the primary lint yield components decrease as the complexity of the model increases from yield/seed to yield/unit area of land. The summation of each model has an upper R3 limit of 1.0. Therefore by the inclusion of additional components, the relative contribution of yield components from the previous models must decrease. Data are presented that illustrate a use of the model to define the component of yield more susceptible to alteration to increase yield.
Effects of Physical and Chemical Mutagens on Survival, Growth, and Seed Yield of Soybeans1
Authors: Constantin M. J. , Klobe W. D. , Skold L. N.
Published: July 2010

To acquire dose‐response data, seeds of ‘D68‐127’ soybeans (Glycine max L. Merr., a sib‐line of the recently released ‘Forrest’ cultivar) were treated with fission neutrons, gamma radiation, ethylmethane sulfonate, and diethyl sulfate. Treated and nontreated populations were grown in the greenhouse and in the field. In greenhousegrown populations, survival was unaffected by the neutron doses and by gamma radiation doses less than 70 krads but decreased with an increase in dose of chemical mutagens. Seedling height and shoot dry weight decreased as the dose of each mutagen increased. In fieldgrown populations, survival, height, and seed yield decreased as the dose of each mutagen increased. Seed treatments that reduced seedling height to ≤ 10% of control in the greenhouse also reduced seed yield to ≥ 10% of control. Based on seed yield of M1 plants, recommended seed treatments are 1.5 to 2.5 krads fission neutrons, 20 to 30 krads gamma radiation, 8‐hour soaking in 0.025 to 0.050 M ethylmethane sulfonate, and 90 to 150‐min soaking in 0.15% by volume diethyl sulfate.
Root Temperature and Soil Water Potential Effects on Growth and Soluble Carbohydrate Concentration of Corn Seedlings1
Authors: Barlow E. W. R. , Boersma L. , Young J. L.
Published: July 2010

Nine‐day‐old corn (Zea mays L.) plants were grown at soil water potentials of −035 and −2.50 bars for 6 days using an osmotic‐solution semipenneable‐membrane technique. Leaf elongation, total dry matter accumulation, transpiration, soluble carbohydrate concentrations, and leaf water potentials were measured daily. When the soil water potential was decreased from −035 to −2.50 bars, leaf elongation rates decreased 44% and soluble carbohydrate concentrations increased 42%, while rates of total dry matter accumulation and transpiration decreased 26 and 24%, respectively. The increase in the soluble carbohydrate concentration was inversely related to both the rates of leaf elongation and total dry matter accumulation. The plant maintains a positive carbon balance in the leaves partly in the form of an abundant supply of soluble carbohydrates during periods of mild water stress. The sensitivity of leaf elongation rate to mild water stress appears to be an important growth determining factor.
Altered Development of Ribonuclease Activity and Formation of Polyribosomes in Chilled Cotton Cotyledons1
Authors: Leffler H. R.
Published: July 2010

Sensitivity of cotton (Gossypium hirsutum L.) seedlings to 6 C chilling was measured by following the development of ribonuclease (RNase) activity in cotyledons during the first week of germination. Increases in RNase activity observed in control tissues were delayed during chilling. Development of RNase activity was most sensitive to chilling during the second day of germination.

Both total and specific activities of RNase preparations were similarly affected by chilling. Alterations of protein synthesis were suggested by comparisons of free polyribosome profiles from control and chilled tissues.

Chilled seedlings partially recovered RNase activity following return to warm temperature. Recovery was slowest in seedlings that were chilled during both the second and third days of germination.
Rice Seedling Vigor at Sub‐optimal Temperatures1
Authors: Jones David B. , Peterson Maurice L.
Published: July 2010

A laboratory method was devised for evaluating seedling vigor of rice (Oryza sativa L.) cultivars, hybrids, and segregating populations at sub‐optimal temperatures. Seeds of 20 cultivars of diverse origin were soaked in distilled water for 24 hours at 30 C and then germinated in the dark on moist blotters at 15, 18, 20, 25, and 30 C. Seedling height was used as the primary criterion for evaluation. Growth differences among cultivars, temperatures, and their interaction were highly significant. The same cultivars were evaluated in a field trial where mean days to emergence ranged from 9.4 to 17.7 with a mean of 12.9, and percentage emergence ranged from 22.0 to 87.5 with a mean of 57.4. The above two traits were components of an emergence index which ranged from 12.9 to 76.0 with a mean of 44.4. Correlation coefficients of laboratory seedling heights at five temperatures with days to emergence in the field ranged from ‐0.74 to ‐0.89, at the 1% level, with percentage emergence — from 0.56 to 0.69, at the 5% level, and with emergence index — from 0.75 to 0.81, at the 1% level. Results indicated that performance hi laboratory tests was a satisfactory indicator of field performance.
Differences in Alfalfa Flower Volatiles Among Parent and F1 Plants1
Authors: Loper Gerald M.
Published: July 2010

Nonrandom pollination of alfalfa (Medicago sativa L.) by honey bees (Apis mellifera L.) may be based on the ability of honey bees to detect differences in flower aroma among the plants in the field. When the bees associate these aroma differences with nectar or pollen availability a strong basis for ethological isolation exists. The purpose of this work was to gather quantitative data on flower volatile emanation from seven alfalfa clones and on F1 plants from these clones using one male sterile clone as a common parent. This information would assist alfalfa breeders as they consider factors involved in seed yield potential of new varieties. A gas liquid chromatography technique was used to measure the quantity of flower volatiles emanating from cut flowers from greenhouse plants. There was a six‐fold difference in total volatiles and a 19‐fold difference in ocimene (the major terpene of alfalfa flower volatiles) between the extremes of the parent clones. Among the F1 plants tested, there was only a 2.5‐fold difference in total volatiles and a 6‐fold difference in ocimene between the extremes. The F1 of one cross averaged nearly twice the ocimene level of either parent, which also raised total volatiles above that of either parent. Increased emanation of individual aroma compounds from flowers of some F1 plants suggests that total flower aroma and floral aroma character can be genetically influenced. Thus it may be possible to alter the floral character of alfalfa to increase its attractiveness to honey bees for pollination.
Growth of Kentucky Bluegrass Leaves and Tillers With and Without Defoliation1
Authors: Youngner V. B. , Nudge F. , Ackerson R
Published: July 2010

Tillering rates, leaf emergence rates, and responses to defoliation are important to productivity, density, and ersistence of grasses. Breeding programs might benefit a more precise understanding of these responses. Studies were conducted in the greenhouse on individual plants of Kentucky bluegrass (Poa pratensis L.) ‘Merion’, ‘Newport,’ and ‘Windsor’ to precisely describe leaf and tiller growth and the effects of defoliation on growth of these structures.

In the first of three studies, six plants of each cultivar, grown under uniform controlled conditions, were examined daily and leaf, tiller, and rhizome emergence recorded for 60 days. The second study differed from the first in that five plants of each cultivar were defoliated and five plants left intact. To provide uniform defoliation for all cultivars, entire leaf blades were removed at the time they reached full expansion. In the third study CO2 exchange as a measure of net photosynthesis was determined for all leaf surfaces and for leaf blade surfaces only by coating leaf sheaths with grease.

Under these fairly constant conditions, leaf and tiller emergence on the main shoot proceeded at constant rates characteristic for each cultivar. On all cultivars the first leaf of the main shoot was dead before the sixth leaf had emerged. Thereafter leaf senescence and leaf emergence proceeded at the same rate so each shoot had a maximum of five functioning leaves. The same growth patterns were observed on primary and secondary tillers until affected by intertiller competition.

Defoliation did not affect leaf emergence rates on any cultivar while reducing the rate of tiller emergence on Newport and Windsor but not on Merion.

The cultivar Merion had a higher rate of net photosynthesis than Newport. Leaf blade photosynthesis rate did not differ significantly between the two cultivars. The higher rate for Merion was thus attributed to a higher rate for leaf sheaths. The greater tolerance to defoliation displayed by Merion could be due to the greater photosynthetic activity of its leaf sheaths.

These results show that it may be possible to develop Kentucky bluegrass cultivars with higher rates of leaf and tiller emergence and greater tolerance to mowing. The potential for breeding strains more tolerant of mowing by selection of genotypes with higher leaf sheath photosynthesis should be explored.
Derivation of a New Forage Grass from Agropyron repens ✕ Agropyron spicatum Hybrids1
Authors: Dewey Douglas R.
Published: July 2010

Pentaplold hybrids (2n=35) of Agropyron repens (L.) Beauv. (2n=42) ✕ Agropyron spicatum (Pursh) Scribn. & Smith (2n=28) were intercrossed, backcrossed to both parent species, and open‐pollinated. The hybrid derivatives differed widely in vigor, rhizome development, spike characteristics, and fertility. Vigor, meiotic regularity, and fertility improved rapidly in advanced generations. By the F5 generation, the hybrid population was largely hexaploid (2n=42), and some plants had achieved complete meiotic stability and full fertility. Almost one‐fourth of the F5's were nonrhizomatous, and about half had only short rhizomes. Chromosome pairing in the various hybrid populations indicated that A. repens and A. spicatum have considerable genomic homologies. Genome formulas for A. repens and A. spicatum were written as S1S1S2S2XX and SSSS, respectively. Introgression via genetic exchange between the S genomes of A. repens and A. spicatum made possible the derivation of fertile hybrid progenies with morphological characteristics of both species. The advanced‐generation hybrids appear to have potential as economically important forage grasses.