bluuebunny/crossref_metadata_2025 huggingface dataset:
Heterosis and Combining Ability in a Diallel Cross Peas1
Authors: Gritton E. T.
Published: July 2010

Eight cultivars of peas (Pisum sativum L.) were crossed in diallel, and the parents, Fl's, and F2's, evaluated for 2 years at two locations in Wisconsin. All traits studied except days to bloom showed heterosis and inbreeding depression. Yield heterosis of Fl's based on the midparent averaged 55%, and on the high parent 28%, over locations and years. Both general and specific combining ability were important for days to bloom, plant height, pods/plant, peas/pod, peas/plant, weight/seed, and seed yield. Pods/plant showed some maternal influence, which in turn led to maternal or reciprocal effects for seeds/plant and yield. Days to bloom showed a significant maternal influence in one experiment.
Growth and Development of Fiber and Seed in Upland Cotton1
Authors: Quisenberry J. E. , Kohel R. J.
Published: July 2010

Three environments and four cultlvars of upland cotton (Gossypium hirsutum L.) were used to evaluate the affect of environment on the growth and development of cotton fiber and seed. The environments were a College Station planting, an early Lubbock planting, and a late Lubbock planting. These environments were quantified by conversion of the daily average temperatures from each environment into heat units. The College Station planting had the most and the late Lubbock planting the least number of available heat units. ‘TM‐I,’ ‘CA 491,’ ‘Acala 1517 Br‐2,’ and ‘Western Stormproof,’ were planted in replicated tests in each environment. Tagged bolls were harvested weekly to give estimates of the rates of fiber elongation and fiber dry‐weight accumulation. After boll maturity, fiber length, fiber elongation periods, fiber/seed, fiber fineness, seed size, and number of seeds/boll, were determined. Linear correlation and regression analyses between heat units and the characters measured after boll maturity were used to evaluate the relationships between environments and cultivars.

Environment influenced the rate of fiber elongation and fiber dry weight accumulation. Fiber elongated and accumulated dry weight faster in the College Station environment than in the two Lubbock environments. Correlation and regression coefficients from the simple linear regressions of heat units on the characters measured after boll maturity revealed that all of the cultivars responded to a reduction in the number of available heat units. However, CA 491 and Acala 1517 Br‐2 appeared to be somewhat better adapted to growth and development of fiber and seed in a cooler environment than were TM‐1 and Western Stormproof.
Inheritance of Maize Weevil Resistance in Maize1
Authors: Widstrom N. W. , Hanson W. D. , Redlinger L. M.
Published: July 2010

Ten, eight‐line sets of dent maize inbreds (Zea mays L.) were tested for seed resistance to maize weevil (Sitophilus zeamais Motschulsky) in a design II experiment. The genetic variability was evaluated for maternal, cytoplasmic, and endosperm genotype sources. Dominance effects were important for seed resistance among sources segregating for maternal and endosperm genotypes. Most of the additive variation originated from maternal tissues, while cytoplasmic effects were unimportant. A procedure of recurrent selection within two breeding populations, with concomitant attention to crossbred performance, is suggested.
Heritability of Purple Seed Stain Resistance in Soybeans1
Authors: Wilcox J. R. , Laviolette F. A. , Martin R. J.
Published: July 2010

Soybean [Glycine max (L.) Merr.] plants in the F2, F3, and F4 generations from the cross ‘Amsoy’ x PI 80837 were inoculated with Cercospora kikuchii (Matsumoto and Tomoyasu) Gardner, the causal organism of purple seed stain. Incidence of purple seed stain averaged 84.3, 28.4, and 85.7% on Amsoy and 2.8, 0.2, and 2.3% on PI 80837 during the 3 years of the test. Heritabilities for disease incidence were 0.91 in the F2 and 0.51 in the F3 generations. Predicted response to selection closely approximated observed gains, when the most resistant 10% of the plants in each generation were evaluated in the next generation. Since the disease has not been shown to adversely affect agronomic characteristics, selection against extreme susceptibility seems more appropriate than intensive selection for a high level of resistance to the disease.
Agronomic and Genetic Analysis of Tarnished Plant Bug Tolerance in Cotton1
Authors: Meredith William R. , Laster M. L.
Published: July 2010

We investigated at Stoneville, Miss., in 1973, the effects of heavy and light infestations of tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois), on six genetic populations of cotton, Gossypium hirsutum L. Mustard Brassica juncea (L.) Czern, planted in rows adjacent to cotton, was used to attract and accumulate large numbers of plant bugs. The light infestations of plant bugs were maintained by six early‐season insecticide applications. The genetic populations used were ‘Stoneville 213,’ ‘Coker 201,’ their reciprocal F1 and F2 hybrids, and the reciprocal F1 backcrosses to the recurrent parents. Lint yield, six yield components, and five fiber properties were determined for plants harvested on four dates: September 12 and 21, October 4, and November 9.

The presence of plant bugs resulted in more terminal damage on small plants, and higher lint percentage and decreased boll size and seed/boll on mature ones. Plant bugs had no effect on seed index, lint index, and fiber properties. The reduced number of bolls/plot caused by plant bugs resulted in decreased lint yields. Lint yield and bolls/plot of the more tolerant cultivar (Stoneville 213) were not appreciably reduced by plant bugs until the last harvest. However, in the less tolerant cultivar (Coker 201) yield and number of bolls/plot were reduced most in the first two harvests.

No reciprocal genetic effects were detected for any characteristic in this study. An analysis of generation means indicated that additive gene action and additive Χ additional epistasis, were both significant in accounting for terminal damage. Analyses of generation means for lint yield and bolls/plot indicated that additive gene action was responsible for conferring tolerance to plant bugs. No dominance or epistatic effects involved in tolerance to plant bugs were detected. Once the plants had recovered from the early‐season plant bug damage, significant dominance for late‐season production was detected.
Genotypic Response to Potassium in Soybeans1
Authors: Walker A. K. , Schillinger J. A.
Published: July 2010

Soybean [Glycine max (L.) Merr.] genotypes usually yield about the same under high K fertility as under moderate K fertility. The objective of this study was to verify the results of a preliminary screening test, which revealed that the FC31702 and ‘Lincoln’ genotypes were responsive and nonresponsive, respectively, to high K fertility.

FC31702 and Lincoln soybeans were grown under moderate (approximately 130 kg K/ha) and high (approximately 193 kg K/ha) K fertility on a Beltsville silt loam soil for 3 years. ‘Cutler,’ a recommended cultivar for Maryland, also was included the last 2 test years. Seed yield and percent K in the leaves during the growing season were determined.

FC31702 had a significant increase in seed yield when grown under high K fertility as compared to moderate K fertility. Lincoln and Cutler had no yield increase. The response in yield of FC31702 to high K fertility was associated with higher K percentages in the leaves during the growing season.
Yield Potential in a Dwarf Spring Wheat and the Effect of Shading1
Authors: Fischer R. A.
Published: July 2010

A dwarf spring wheat (Triticum aestivum ‘Yecora 70’) was grown under irrigation and optimal agronomy in northwest Mexico during four winter seasons. Single shading treatments of approximately four (1971, 1972), three (1973), and two (1974) weeks duration and various intensities were used to elucidate the importance for grain yield of radiation and crop photosynthesis at different stages of development.

Shading always reduced crop growth, approximately in direct proportion to the reduction in radiation. Grain yield reduction was however curvilinearly related to radiation such that small reductions had little effect on yield at any developmental stage. Yield reductions with heavier shading only occurred with shading after about 60 days after seeding and were greater before anthesis (90 days) than after anthesis, especially in 1973.

The shorter shading treatments indicated that the period of rapid spike growth, approximately 35 to 5 days before anthesis, was that showing greatest sensitivity to shading. Shading then led to fewer spikes/m2 (lower tiller survival) and fewer grains/splkelet (fewer florets produced), hence reduced grains/m2

Responses to post‐anthesis shading suggest that the degree of yield limitation by post‐anthesis photosynthesis is not constant for a given genotype, varying substantially from year to year. Thus in 1973 immediate pre‐anthesis conditions were unfavorable due to cloudiness, grains/m2 was low, and yield was entirely limited by this factor. In other years, yield was more sensitive to post‐anthesis shading. However it is concluded that grains/m2, hence crop photosynthesis in the immediate pre‐anthesis period, is the key to higher yield in this cultivar.
Photosynthetic Responses of Tall Fescue to Selection for Longevity below the CO2 Compensation Point1
Authors: Nelson C. J. , Asay K. H. , Patton L. D.
Published: July 2010

There have been many attempts to identify efficient C3 plants by survival in CO2 environments below their normal CO2 compensation point (Γ). Thus far there have been no reports on characteristics of final survivors from such a treatment. Our objective was to determine relationships between CO2 exchange parameters in tall fescue (Festuca arundinacea, Schreb.) and to determine if selection for longevity under sub‐Γ conditions would be feasible for decreasing photorespiration or increasing net carbon exchange (NCE).

About 4,400 seedlings of ‘Alta’ and 2,200 of ‘Kentucky 31’ were exposed to sub‐Γ conditions for seven to eight days and 36 and 22 final survivors, respectively, were selected. In both cultivars, the selected population was not different from the base in rate of NCE in 21% O2, NCE in 0% O2, or photorespiration estimated as NCE enhancement in 0% O2 over 21% O2. Rate of dark respiration was significantly increased in both Alta (P < 0.01) and Kentucky 31 (P < 0.10).

Rate of dark respiration was not correlated with rates of other CO2 exchange parameters except in the base population of Kentucky 31, where it was positively correlated (P < 0.05) with photorespiration, NCE in 21% O2, and NCE in 0% O2. Rate of photorespiration was positively correlated (P < 0.01) with NCE in 21% O2 in all four populations and regression coefficients were similar. Combining all populations gave an overall correlation coefficient of 0.649 (P < 0.001) and a regression coefficient of 0.54.

This suggests that in plant breeding programs selection for increased NCE will probably also increase photorespiration, unless genetic control is independent and selection pressure is placed on both characters.
Estimation and Utilization of Inter‐cultivar Competition in Peanuts1
Authors: Beg Akhtar , Emery D. A. , Wynne J. C.
Published: July 2010

Competition among three peanut (Arachis hypogaea L.) cultivars: ‘NC 5,’ ‘NC 17,’ and ‘Florigiant,’ was measured in replicated hill and row‐plot field designs for purposes of predicting optimum proportions of the components in seed blends. The three cultivars are adapted to the Virginia‐North Carolina peanut belt, but differ in maturity and growth habit. Competition was determined by calculating the coefficients of regression for mean plant, fruit, and seed characters on numbers of competing plants or rows.

Three‐year trials provided evidence of inter‐cultivar competition. Fruit yield, fruit number, and plant weight of NC 17 were found to increase (overcompensate) significantly over that of pure stands when grown in competition with Florigiant. Coefficients tended to be negative, small in magnitude, and nonsignificant when Florigiant was in competition with NC 17. NC 5 and NC 17 frequently had reduced numbers, sizes, and weights of fruit when grown in competition with each other. Overcompensation was not found when the coefficients for the regression of NC 17 performance on number of competing plants or rows of Florigiant were summed with coefficients based on reciprocal arrangements of the cultivars.

Yields of cultivar blends could not be predicted using data from competition tests.
Some Factors Limiting Nitrate Reduction in Developing Ovules of Cotton1
Authors: Radin J. W. , Sell C. R.
Published: July 2010

Ovules of developing cotton (Gossypium hirsutum L.) bolls had significant nitrate reductase activity, although considerably less than in leaves. The capability of the ovules to reduce nitrate (total nitrate reductase activity) increased during development, whereas the absolute rate of nitrate assimilation in situ reached a maximum at about 16 days after anthesis and then declined. Nitrate was present only in extremely small quantities in ovules, severely limiting their rate of nitrate reduction in situ. Transpiration from bolls was extremely slow, suggesting that ovules lack a mechanism for rapid replenishment of consumed nitrate. Estimated rates of ovular nitrate reduction could account for < 5% of the accumulation of reduced nitrogen.
Results of Breeding for Tolerance to 2,4‐D in Birdsfoot Trefoil1
Authors: Devine T. E. , Seaney R. R. , Linscott D. L. , Hagin R. D. , Brace N.
Published: July 2010

To develop a weed control system for birdsfoot trefoil (Lotus corniculatus L.) utilizing an effective, inexpensive, and relatively safe herbicide, 2,4‐D, a recurrent selection program was undertaken to breed a strain of trefoil tolerant to this herbicide. We believe that this is the first report of the successful use of recurrent selection to develop herbicide tolerance.

A series of tests established that five cycles of field selection had been effective in developing a strain substantially more tolerant to 2,4‐D than commonly used trefoil cultivars. After 2,4‐D treatment, green weight of the lowest yielding progeny line of the tolerant strain was five times that of ‘Viking.’ Survival percentage of the resistant strain was significantly higher than Viking, ‘Empire,’ ‘Mansfield,’ ‘Granger,’ and ‘Tana.’ Fresh and dry weight, plant N composition, and surface wax accumulation were significantly less affected by 2,4‐D in the tolerant strain. Evidence is presented that the 2,4‐D tolerant strain is resistant to the 2,4‐D homologs as well as the parent compound. It was suggested that evaluation of early seedling growth during exposure to herbicides in petri dish culture may prove to be both an effective and efficient screening device in breeding programs to develop tolerance to specific herbicides.
Fertility Restoration of Male‐Sterile Cytoplasm in Wild Sunflowers1
Authors: Gimenez Juan Dominguez , Fick Gerhardt N.
Published: July 2010

Wild sunflower (Helianthus spp.) populations, collected from the northern Great Plains, were evaluated in crosses with a cytoplasmic male‐sterile inbred line to determine the frequency of fertility restorer genes in wild annual species and obtain information on the inheritance of fertility restoration. All of 52 H. annuus L. and six of seven H. petiolaris Nutt. populations were found to possess dominant genes for fertility restoration. Segregation ratios of male‐fertile to male‐sterile plants in the BC1 and F2 generations of seven crosses suggested that four genes were involved, and that fertility was restored when at least two dominant alleles were present at any of the four loci. Segregation occurred for one gene in four crosses, three genes in two crosses, and possibly four genes in one cross. Although the wild sunflower populations used in this study cannot be used directly as restorers in commercial production of hybrids, lines with acceptable agronomic characteristics were identified after one and two backcrosses to cultivated types.
Quality Factors Affecting the Nutritive Value of Bean Seed Protein1
Authors: Kelly J. D. , Bliss F. A.
Published: July 2010

Seeds of four bean (Phaseolus vulgaris L.) strains with a range in protein content from 21.5 to 31.9% were selected and analyzed for their constituent amino acids. Differences in the levels of certain essential amino acids were detected. Total methionine and microbiologically available methionine, each as percent of protein, were similar in three of the four strains, but one strain had a lower level of available methionine, suggesting that part of the total methionine was unavailable.

Correlation between protein efficiency ratio (PER) for rats and available methionine as percent of protein in the four strains was positive and significant, while similar correlations between PER and total methionine as percent of protein with or without cystine were not significant.

The microbial assay used in determination of available methionine levels is outlined and its value in a breeding program for improving nutritive quality of beans is discussed.
Linkage Tests Among Genes for Six Qualitative Characters in Sunflowers1
Authors: Fick G. N. , Zimmer D. E.
Published: July 2010

Inheritance and linkage relationships among genes for fertility restoration (Rf1), resistance to rust, Puccinia helianthi Schw. (R1), resistance to downy mildew, Plasmopara halstedii (Farl.) Berl. et de Toni (Pl2), resistance to Verticillium wilt, Verticillium dahliae Kleb. (V), recessive branching (b1), and genetic male‐sterility (ms) were studied in sunflowers, Helianthus annuus L. The monogenic inheritance of each of these traits was confirmed. A close repulsion linkage, or allelic relationship, of R1 with Pl2 was identified on the basis of inoculations with races 1, 2, and 3 of rust and the Red River race of downy mildew, respectively. No recombinant types were recovered from among 543 F3 lines and 105 F4 lines tracing to two crosses. Independent inheritance was shown for Rf1 with R1, b1, Pl2, and V; R1 with V; Pl2 with b1 and V; V with b1,; and ms with b1.
Characteristics and Performance of Interspecific Hybrids Between Kentucky Bluegrass and Canada Bluegras1
Authors: Dale M. R. , Ahmed M. K. , Jelenkovic G. , Funk C. R.
Published: July 2010

Interspecific hybridization involving four Poa pratensis L. selections as female parents in crosses with P. compressa L. produced 2,104 hybrids. Crosses using the highly sexual Kentucky bluegrass cultivar, ‘Warren's A‐20,’ and selections, Warren's A‐25 and Warren's A‐26, produced a very high frequency of hybrids.

Many of these hybrids showed considerable first year vigor with more abundant panicle production than generally found in Kentucky bluegrass. However, these particular plants produced a very few or no viable seeds. Cytological studies indicated that these mostly sterile hybrids originated from the fertilization of reduced female gametes by reduced male gametes.

The 54 interspecific hybrids produced using highly apomictic ‘Belturf’ Kentucky bluegrass as the female parent showed moderate to good floret fertility, acceptable seedling vigor, and some produced rather attractive turf. Cytological studies indicated that these fertile hybrids originated from the fertilization of unreduced eggs by reduced male gametes. These “triploid” F1 hybrids are moderately to highly apomictic.
Effect of Recurrent Selection for Combining Ability with a Single‐Cross Tester in Maize1
Authors: Horner E. S. , Lutrick M. C. , Chapman W. H. , Martin F. G.
Published: July 2010

To obtain additional information on the effectiveness of recurrent selection for specific combining ability in maize (Zea mays L.), we evaluated seven cycles of selection for combining ability with the single‐cross tester F44 ✕ F6. Grain yield, lodging resistance, and low ear height were the main selection criteria.

Seed of the selected population from each cycle was stored and later evaluated for combining ability with the original tester, F44 ✕ F6, and with an unrelated synthetic. The evaluation with F44 ✕ F6 indicated that the seven cycles of selection resulted in 18% more grain yield, 9% lower ear height, and 35% less lodging. Performance was similar when the same selected populations were crossed with an unrelated synthetic. This suggests that gains for all traits resulted from increasing the frequency of genes with additive effects.

These results and others previously reported for inbred testers suggest that narrow‐base testers are effective for improving general as well as specific combining ability, and that it is possible to change such testers in a recurrent selection program with little loss in accumulated improvement.
Harvest Index in Spaced Populations and Grain Weight in Microplots as Indicators of Yielding Ability in Spring Wheat1
Authors: Fischer R. A. , Kertesz Z.
Published: July 2010

A set of 40 adapted homozygous spring wheat (Triticum aestivum L.) genotypes were grown under similar conditions of irrigation and high fertility utilizing large plots and microplots seeded at normal densities, and spaced plants (60 × 60 cm grid). The objective was to see how well spaced plant traits, especially grain weight and harvest index, and microplot yields predicted true yielding ability as measured with the large plots. Phenotypic correlation coefficients were calculated using genotype means.

Microplot yield was highly correlated (r = 0.67 at the 1% level) with large plot yield but explained less than half of the variation between the genotypes. Much of the residual was probably related to the highly significant genotype Χ plot type interaction. With spaced planting, yield/plant was correlated (r = 033 at the 5% level) with crop yield. Better correlations with crop yield were obtained with plant and shoot harvest indices (r = 0.56 and 0.66, respectively, at the 1% level). No numerical components of yield measured on spaced plants gave better correlations with crop yield than yield per plant itself.

These results emphasize the major effect that the degree of interplant competition, probably primarily for light in this case, has on the performance of a genotype. As the degree of competition declined going from crop plots to spaced plants, genotypes which can more fully occupy the increased space available were favored; thus, the performance of non‐erect genotypes improved noticeably relative to erect ones. We conclude that harvest index measurement offers promise as a predictor of yielding ability where the seed available is limited.
Selection Among and Within Full‐sib Families to Develop Single‐crosses of Maize1
Authors: Hoegemeyer T. C. , Hallauer Arnel R.
Published: July 2010

Systematic genetic advance in maize (Zea mays L.) hybrid yields depends on the improvement of breeding populations and the efficient extraction of inbred lines. We evaluated the efficacy of selection among and within fullsib families produced in two 2‐eared populations for the extraction of lines and for the identification of superior yielding hybrids. Intra‐ and interpopulation crosses were made among selected and unselected lines developed from ‘Iowa Two‐ear Synthetic’ (BSI0) and ‘Pioneer Prolific Composite’ (BSll). The selected lines were superior paired‐plant interpopulation crosses tested from the S0 ✕ S0 through S4 ✕ S4 generations. Six sets, each containing 28 crosses, produced from selected and unselected lines, were grown in three locations for 3 years.

Interpopulation crosses averaged 5.8 quintals/ha (7.4%)greater yields than intrapopulation crosses, and the crosses of selected lines yielded 8.7 quintals/ha (11.2%) more than crosses of unselected lines. On the average, the tested paired‐plant crosses yielded 3.7 quintals/ha (4.2%) more than the untested crosses among selected lines and the specific combining ability (SCA) effects tended to be strongly positive for the tested line pairs. The yields of the previously untested crosses among the selected lines also showed that the selected lines expressed high general combining ability (GCA) with other selected lines.

If the five best single‐crosses from each set were selected (9% selection intensity), 28 of 30 were from interpopulation crosses, 23 of 28 from selected lines, and II of 23 from the tested‐line pairs. If only the selected interpopulation crosses were grown (96 entries), 23 of the best 30 hybrids were identified from 336 entries. The method of selection, therefore, does develop an elite group of lines having high SCA with its tested mate and also high GCA with other elite lines with a minimum of testing. Thus selection among and within full‐sib families seems to be an efficient method of developing superior parental lines for hybrids.
Photosynthesis of, and 14CO2‐Photosynthate Translocation from, Calcium‐deficient Leaves of Crops1
Authors: Gallaher R. N. , Brown R. H. , Ashley D. A. , Jones J. B.
Published: July 2010

Limited information is available on the role of Ca in net photosynthesis (Pn) and 14C translocation. This research was done to determine the influence of the removal of Ca supply from 2‐month old soybean (Glycine max (L) Merr. ‘Hampton 266A’), peanut (Arachis hypogaea L. ‘Florunner’), and cotton (Gossypium hirsutum L. ‘Goker 310’) plants on Pn, 14C translocation, and Ca concentration. Removal of Ca from the nutrient solution did not influence Pn of any of the species until Ca dificiency was visible in the measured leaf. Critical levels of total Ca on Pn were near 0.3% but acetic acid extractable Ca was 0.09 to 0.23% indicating that Ca requirements for Pn may be in micronutrient amounts. Short‐term translocation of 14C from Ca‐deficient leaves was 36% higher for peanut and 56 and 31% lower for soybean and cotton, respectively, compared to plants of the same species supplied with Ca.
Genetic Resources in Wild Relatives of Crops1
Authors: Harlan Jack. R.
Published: July 2010

Currently, the extent of use of wild relatives in breeding programs depends on 1) how wild the crop is, 2) how desperate the situation is, 3) the pressures to turn out new cultivars, 4) the availability of materials, 5) the difficulty of use, and 6) the character of the plant breeder and of the institution in which he works. Wild rdatives have been used as sources of disease, insect, and nematode resistance, to widen adaptation, to provide alternate cytoplasms and develop cytoplasmic sterility systems, to improve quality, alter modes of reproduction, induce short stature, increase crossability between species, improve resistance to stress, and increase yield. Some crops could not mainain commercial status without genetic support of their wild relatives. The principal bottleneck to the use of wild relatives at present is the paucity of materials in our collections. In the future, the need for genetic variability and sources of resistance shall drive us to a much fuller exploitation of all the genetic resources we can assemble.
Chlorogenic Acid Content of Meal from Cultivated and Wild Sunflowers1
Authors: Dorrell D. G.
Published: July 2010

The chlorogenic acid (CA) content of dehulled and defatted sunflower (Helianthus annuus L.) seeds was determined on a portion of the germplasm maintained at the Modern Research Station. This material represented 167 inbred accessions, 387 highly inbred Morden lines, and 42 North American wild H. annuus collections.

Cultivated sunflower seeds contained from 1.1 to 4.5% CA with an overall mean of 2.8% and a normal distribution. Approximately 6% of the cultivated inbreds contained 2% or less CA. The wild sunflower lines averaged 2.1% CA with almost half containing less than 2% CA.

There was a highly significant correlation between CA content and oil content in all populations. Seed size was not related with CA content. In the wild population, low CA content was highly significantly correlated with high hull content. Although there was no association between country of origin and CA content for the cultivated inbreds, wild sunflowers collected in the southern USA contained lower levels of CA than those collected north of 40°N latitude.
Separation of Kentucky Bluegrass Cultivars using Peroxidase Isoenzyme Banding Patterns1
Authors: Wehner D. J. , Duich J. M. , Watschke T. L.
Published: July 2010

The peroxidase isoenzyme banding pattern of 15 Kentucky bluegrass (Poa pratensis L.) cultivars was investigated for use in identification. Isoenzymes were separated by polyacrylamide slab gel electrophoresis, stained with benzidine‐H202, and the relative intensities of the bands evaluated with a densitometer. Cultivar separations were made on single seedling samples at the 1% level of confidence using band number, mobility, and intensity ratios. Overall variability of the procedure was evaluated using a horeradish peroxidase standard and the effects of seedling age and seedlot determined. Of the 15 cultivars, 11 could be separated individually, whereas the remaining 4 were grouped into two pairs. Band mobilities for the standard and the cultivars varied 1 to 3%, whereas intensity ratios varied 9% for the standard, and 5 to 20% for most cultivars. Neither seedlot, seedling age, nor leaf position on the same seedling affected the peroxidase isoenzyme banding pattern.
Growth and Development of the Lint Fibers of Pima S‐4 Cotton1
Authors: Schubert A. M. , Benedict C. R. , Gates C. E. , Kohel R. J.
Published: July 2010

Lint fiber elongation, lint dry weight per seed, and lint dry weight per seed per unit length, was studied from anthesis to maturity in field‐grown ‘Pima S‐4’ cotton (Gossypium barbadense L.). These parameters of fiber growth and differentiation were plotted against boll age and fitted to best‐fit curves by curvilinear regression analysis. The curve fitting procedures yielded mathematical equations which were differentiated to give rate curves. Fiber growth stopped 39 days after anthesis. Splining analysis of fiber dry weight and fiber dry weight per unit length showed that the lint weight per unit length ratio was constant to 17.99 ± 2.35 days. This is the time that secondary wall thickening begins. This analysis also indicates that during the 48‐day boll development period, both fiber elongation and secondary wall thickening were occurring simultaneously for 21 days. During the 21‐day overlap period, 19.7% of the final fiber length was attained. At the end of fiber elongation, fiber dry weight and fiber dry weight per unit length had reached 90% of their final values. These data show that fiber elongation and secondary wall thickening are not separate phases and a substantial amount of secondary wall thickening occurred before fiber elongation stopped. This degree of overlap of fiber growth and differentiation phases is more striking than for upland cottons and may be related to the fact that the maximum rate of elongation continues for 12 days longer in ‘Pima S‐4’ compared to ‘Stoneville 213’ cotton (Gossypium hirsutum L.). The findings reported here show that deposition of almost pure cellulose in the secondary wall does not immediately stop all of fiber elongation.
Inheritance of Resistance to Race C2 of Cercospora beticola in Sugarbeet1
Authors: Lewellen R. T. , Whitney E. D.
Published: July 2010

Crosses between sugarbeet (Beta vulgaris L.) lines that differed in their reaction to race C2 of Cercospora beticola Sacc. were studied in F1, F2, testcross, and F2 resistant ✕ susceptible populations. Resistance to race C2 was shown to be conditioned by a single dominant gene (Cb = resistant, cbcb = susceptible). The Cb allele had no influence on reaction to race C1. Sugarbeet lines with quantitatively inherited resistance to Cercospora leaf spot but without the Cb allele displayed nearly equal reactions to isolates of both races. The resistant reaction in sugarbeet was manifested either by apparent immunity or by a highly resistant fleck reaction. Of the lines surveyed, the Cb allele was found in lines derived from ‘GW 359’ and in US 201.
Relationship of Yield, Seed Quality, and Fiber Properties in Upland Cotton1
Authors: Turner John H. , Ramey Harmon H. , Worley Smith
Published: July 2010

Seed and fiber samples of four Upland cotton (Cossypium hirsutum L.) cultivars, grown at 17 locations in the 1973 Regional Cotton Variety Test, were examined for yield, seed quality, and fiber quality. Correlation coefficients were calculated among eight agronomic and quality parameters.

No significant correlations were found between yield and oil content or yield and protein content. Three of the cultivars showed positive correlations between oil content and fiber maturity and negative correlations between oil content and percent immature seed. The strongest correlation for protein was a negative relationship with fiber maturity. ‘Lockett 4789A’ gave a high positive correlation between oil content and seed index. ‘Acala 1517–70’ showed a strong negative relationship between protein and fiber maturity. Both of these cultivars showed positive correlations between yield and fiber strength.

The feasibility of using Micronaire readings (fiber maturity) as indicators of oil content for cottonseed in the various production zones are discussed.
Photoperiodic Control of Seed Filling for Soybeans1
Authors: Thomas Judith F. , Raper C. David
Published: July 2010

Soybean plants [Glycine max (L.) Merr. ‘Ransom’] were grown in the controlled‐environment rooms of the phytotron at N.C. State Univ. to investigate the effects on floral and pod development of the morphological stage of plant development upon initial exposure to inductive short days, number of consecutive short days, and temperature. All plants were initially grown under long‐day photoperiods and at day/night temperatures of 18/14, 22/18, 26/92, and 30/26 C. In Experiment I, groups of plants were transferred to an inductive short‐day photoperiod at three stages of development: expansion of paired primary leaves, unfolding of third trifoliolate leaf, and unfolding of sixth trifoliolate leaf. Plants from each group were returned to the long‐day photoperiod upon appearance of the first open flower, when pods were becoming visible, or retained under the short‐day photoperiod until termination of the experiment. Measurements of vegetative and reproductive growth were made of all plants at 63 days after planting. In Experiment II, groups of plants were transferred to short‐day photoperiods either upon expansion of paired primary leaves or unfolding of sixth trifoliolate leaf. Plants from each group were returned to long‐day photoperiods after 0, 10, 15, 95, 30, and 50 consecutive short‐days. Measurements of vegetative and reproductive growth were made of all plants, regardless of when returned to long‐day photoperiod, at 50 days after initial exposure to short‐day photoperiod.

Pod production efficiency (number of pods set/total number of flowers initiated) was greater for plants initially exposed to short days upon expansion of paired primary leaves than for plants exposed at a later morphological stage. However, the numbers of both flowers and pods/plant were increased by delay of exposure to inductive photoperiods due to increased numbers of main stem and axillary branch nodes. As thermoperiod was decreased, maximum pod production efficiency was achieved with fewer consecutive short‐days. An increased number of short‐day photoperiods beyond that required for efficient pod set was disruptive to vegetative growth. Dry weight of vegetative tissues and area of leaves generally was decreased, and pod weight was increased correspondingly, by increased numbers of consecutive short‐days. These data support a conclusion that the rate of seed‐fill for soybeans is responsive to photoperiodic conditions.
Diallel Analysis of Maize for Leaf Angle, Leaf Area, Yield, and Yield Components1
Authors: Mason Lee , Zuber Marcus S.
Published: July 2010

The 15 possible single‐crosses among six maize inbred lines (Zea mays L.) were grown at three population densities and two leaf conditions (all leaves removed below the ear vs. no defoliation). Three of the six parental lines had relatively small leaf angles while the other three had relatively large leaf angles.

The interreationships among leaf angle, grain yield, leaf area, ear size, and prolificacy were examined, and a diallel analysis of combining ability was calculated based on the fixed model. Therefore, the findings reported apply only to the six parental inbred lines included in this study.

Defoliation resulted in yield reductions, ranging from 22 to 73%, and leaf area index (LAI) values were reduced by 53 to 68% among hybrids. Upright‐leaf by upright‐leaf (small leaf‐angle) hybrids averaged 42% reduction in yield associated with leaf removal, while upright‐leaf by horizontal‐leaf (large leaf angle) hybrids experienced an average reduction in yield of 39%.

For hybrids in this experiment, leaf angle, from vertical orientation, was negatively correlated with yield and with the yield components: grain weight/ear and number of ears/100 plants. LAI was positively correlated with yield, the two yield components, and population density. Plant density was negatively correlated with the two yield components.

General combining ability (GCA) and specific combining ability (SCA) effects appeared to be equally important in the expression of leaf angle. One parental line with the upright‐leaf habit exhibited a high GCA value for small leaf angle. There were significant differences in SCA estimates for small leaf angle among the three upright‐leaf inbreds. GCA effects were relatively more important than SCA effects for grain yield, leaf area, ear size, and prolificacy. Population density affected the magnitude of combining ability estimates for certain variables among some crosses.
Water Relations of Field Grown Cotton and Sorghum: Temporal and Diurnal Changes in Leaf Water, Osmotic, and Turgor Potentials1
Authors: Ackerson R. C. , Krieg D. R. , Miller T. D. , Zartman R. E.
Published: July 2010

Trends in leaf water, osmotic, and turgor potentials of cotton (Gossypium hirsutum L., cv. ‘Dunn 56C’) and sorghum (Sorghum bicolor L. Moench, cv. ‘RS671’) were monitored on both a seasonal and diurnal basis. The effects of differential soil water availability on leaf water potential components were examined in order to ascertain the differences in the water relations of these two species.

Decreasing availability of soil water was responsible for decreased morning and afternoon leaf water potentials in sorghum and cotton. The magnitude of degression in leaf water potential was greater in cotton than in sorghum at equivalent soil water potentials. Decreasesin osmotic potentials maintained positive turgor in both species when sufficient soil water was available. However, as water stress increased, turgor potentials became zero due to the failure of osmotic potentials to decrease more than water potentials.

Diurnal changes in water potential components were distinctly different for each species. Leaf water potentials of sorghum came into approximate equilibrium with soil water potential in the early morning, whereas leaf water potentials of cotton did not. Concomitant changes in leaf osmotic potentials on a diurnal basis resulted in specific trends of increasing turgor in sorghum, while anomalous fluctuations were evident in cotton leaf turgor potentials.

The relationship between leaf water potential and relative water content was determined for each species. The change in relative water content per unit change in leaf water potential was greater in cotton than in sorghum.

Drought tolerance of these two species appears to be dependent on species speciIic relationships in leat water potential components.
Accumulation of Ethanol in Ice‐encased Winter Cereals1
Authors: Andrews C. J.
Published: July 2010

Ice cover at the soil surface is frequently damaging to winter cereals in northern areas, even at mild subfreezing soil temperautres under snow. In controlled environments, winter cereal plants were rapidly damaged during ice encasement at −1 C, and exposure periods giving 50% kill ranked in accordance with cold hardiness of the cultivars. These exposure periods varied from 7.8 days for ‘Puma’ winter rye (Secale cereale L.) to 3.4 days for ‘Dover’ winter barley (Hordeum vulgare L. emend) with intermediate values for ‘Kharkov’, ‘Frederick’ and ‘Cappelle Desprez’ winter wheat (Triticum aestivum L. em Thell). Seedlings encased in ice accumulated ethanol, which increased to higher levels in cultivars more resistant to ice. Much of the ethanol produced in the plant leached into the surrounding water during thawing. The total production by the plant was about 0.5% of the fresh weight after 7 days encasement. This concentration was the same as that from isolated crowns. In the hardier cultivars, production of ethanol by isolated crowns was similar during supercooled immersion, or ice encasement at −1 C. Crowns of winter cereal cultivars differed in their tolerance to exogenous ethanol. At the interpolated LD50 concentration due to exogenous ethanol, the internal content of ethanol was at least three times its concentration at the LD50, duration due to ice, indicating that ethanol is not the only damaging factor in ice encasement.
Nitrogen Nutrition and Grain Protein in Two Spring Wheat Genotypes Differing in Nitrate Reductase Activity1
Authors: Rao K. P. , Rains D. W. , Qualset C. O. , Huffaker R. C.
Published: July 2010

Two spring wheat (Triticum aestivum L.) genotypes were studied to identify and isolate factors involved in grain protein production, with the aim of establishing physiological criteria for use in breeding and selecting wheat lines efficient in N utilization. ‘Anza’ and ‘UC44‐111’, which differed greatly from each other in tissue nitrate concentration in a field experiment, were tested in a growth chamber experiment to determine any differences in nitrate absorption and nitrate reduction capacities and their effects on straw and grain protein content. Anza, with higher tissue nitrate concentration than UC44‐111, had lower nitrate absorption capacity in short‐term experiments (up to 6 hours). UC44‐111 had a 70% higher in vitro nitrate reductase activity than Anza but differed little in in vivo nitrate reduction. This indicates that UC44‐111 has other factors limiting its potential for nitrate reduction.

This study reveals no single identifiable factor that can be used as a physiological criterion in selecting wheat genotypes for efficient N utilization. Selection must consider two or more factors simultaneously, including long‐term capacity for absorption and in vivo reduction of nitrate and efficiency of translocation of vegetative N to the developing grain.
Nitrate Reductase Activity, Nitrogen Distribution, Grain Yield, and Grain Protein of Tall and Semidwarf Near‐Isogenic Lines of Triticum aestivum and T. turgidum1
Authors: Deckard E. L. , Lucken K. A. , Joppa L. R. , Hammond J. J.
Published: July 2010

Standard height ‘Chris’ and six near‐isogenic semidwarf selections of hard red spring wheat (T. aestivum L. em Thell) and five pairs of durum lines (T. turgidum var. durum L.) near‐isogenic for plant height were grown under non‐lodging conditions. The objective was to determine if the semidwarf character affected nitrate reductase activity, distribution of reduced N, grain yield, or grain protein (percent and total). There were no significant differences among the hard red spring semidwarf selections for any of the measured characters. There were significant differences among pairs of durum lines for most of the measured characters. The gene or genes for semidwarfism did not significantly affect enzyme activity, distribution of reduced N, or any of the production parameters, with the exception that the semidwarf durum lines exhibited slightly higher percent grain protein values than their standard height counterparts. Significant correlations between nitrate reductase activity and grain yield or grain protein (percent or total) were noted. These data suggest that the effectiveness of nitrate reductase assays as a selection criterion should not be reduced in populations segregating for plant height.
Genetic Control of Spikelet Number in Hexaploid Wheat1
Authors: Rahman M. S. , Halloran G. M. , Wilson J. H.
Published: July 2010

Inheritance of spikelet number per ear was studied in wheat (Triticum aestivum L. em. Thell.) using the cultivar ‘Sunset’ and a land race cultivar ‘8–27’ under controlled temperature (20 C) and a photoperiod of (12 and 24 hours). Under the 24‐hour photoperiod, spikelet number per ear behaved as a quantitative trait in the F1 and F2 populations with indications of dominance for high spikelet number. However, the magnitude of environmental effects on the parents and F2 did not preclude the possibility of the F2 segregation being that of a single gene. The backcross F1 of the cross (Sunset ✕ 8–27) ✕ Sunset gave a 1:1 ratio for high:low spikelet number, indicating the likelihood of a single gene difference between these two wheats in the determination of spikelet number per ear. Under the 12‐hour photoperiod, however, low spikelet number was dominant and governed by a single gene which was most likely a gene governing a difference in photoperiodic sensitivity between the parents, and which masked the action of the gene governing differences in spikelet number. It is suggested that such studies be made under environmental conditions which minimize differences in the rate and/or duration of spike differentiation between the parents, revealing genetic differences in the expression. Alternatively, such studies may be conducted under any environments provided the parents have similar developmental patterns.
Callus and Suspension Cultures of Melilotus alba Tissues and Cells1
Authors: Taira Tomoaki , Haskins F. A. , Gorz H. J.
Published: July 2010

These studies were designed to define conditions for the satisfactory establishment and maintenance of sweetclover (Melilotus alba Desr.) callus and cell suspension cultures.

Callus was derived from cotyledons and hypocotyls of germinated sweetclover seeds of various genotypes. Under the conditions used, 2,4‐dichlorophenoxyacetic acid (2,4‐D) was effective (optimal concentration ca 1 mg/liter) for callus induction; other auxins and cytokinins were ineffective. Best callus growth occurred at a 2,4‐D concentration of about 2 mg/liter and a sucrose concentration of 2%. Callus growth was improved by casein hydrolysate (0.9 g/liter). Glutamic acid appeared to be the most important single amino acid in the hydrolysate.

Suspension cultures failed to survive in the absence of 2,4‐D. Highest cell numbers and final/initial cell‐count ratios were observed at a 2,4‐D concentration of 0.2 mg/liter. The callus type that yielded highest cell counts in suspension culture was friable, but friable growth type on agar was not always associated with highest cell numbers in suspension cultures. Inoculum size was important in determining the performance of suspension cultures, possibly because of the influence of “conditioned” medium.

Attempts to regenerate intact plants from the cultured callus tissues were not successful.