bluuebunny/crossref_metadata_2025_split huggingface dataset:
Combining Ability in Durum Wheat: I. Agronomic Characteristics1
Authors: Widner J. N. , Lebsock K. L. 
Published: July 2010

The parents and 45 F1 and F2 populations from a diallel cross among 10 genetically diverse varieties or lines of durum wheat (Triticum durum Desf.) were evaluated at two locations in North Dakota in 1965. Parental, Fu and F2 populations of 17 of the 45 crosses were evaluated again in 1966 at one location. The traits studied were grain yield, number of tillers per unit area, kernels per spike, kernel weight, test weight, seedling vigor, maturity, height, and lodging.Heterosis percentages for grain yield in 1965, based on means of the higher parent of each cross, ranged from —19 to 84% for the F1's and from —23 to 26% for the F2's. Seventeen hybrids displayed significant heterosis for yield, but none was significantly higher than the check variety, ‘Wells.’ The best hybrid yielded 16 and 9% more than Wells when Wells was sown at 33 and 67 kg/ha, respectively. Heterosis also occurred for the other character studied. Twenty‐seven F2 populations yielded significantly less than their respective F1's.An estimate of genotype ✕ environment interaction was calculated for grain yield on the means of the 17 F1's, F2's, and parents for the crosses grown in 1965 and 1966. The analyses were based on mean values from three environments, Fargo 1965, Langdon 1965, and Fargo 1966. Genotype ✕ environment mean squares were significant for the F1 hybrids and parents, but nonsignificant for the F2 populations.General and specific combining ability mean squares were obtained from F1 and F2 populations grown in 1965. General combining ability mean squares were highly significant among F1's and among F2's for all nine characteristics.Specific combining ability mean squares among F1's were significant for kernel weight, test weight, and seedling vigor, and were significant among F2's for kernel weight, test weight, and lodging score. Maximum yields of durum wheat may be attainable only with a system that can exploit both additive and nonadditive genetic effects.
Insolation and Temperature Effects on Maize Growth and Yield1
Authors: Duncan W. G. , Shaver D. L. , Williams W. A. 
Published: July 2010

Five hybrid varieties of maize (Zea mays L.) were planted at three rates and two dates for 2 years at Lexington, Ky.; Greenfield, Calif.; and Davis, Calif.; locations with nearly the same latitude and elevation but having climates differing widely in insolation and average daily temperature. Plots were managed to minimize differences other than climate.Grain yields per hectare were highest at Davis, which had the highest daily insolation, highest daylight temperatures, and second‐lowest night temperatures. Grain yields were lowest at Lexington, which had the lowest daily insolation, moderately high daylight temperatures, and the highest night temperatures. Grain yields and environmental factors at Greenfield presented a more complex picture, which is discussed. Grain yields at each location were positively, and kernel weights, negatively correlated with planting rate.
Epistasis in Maize (Zea mays L.): III. Significance in Predictions of Hybrid Performances1
Authors: Stuber C. W. , Williams W. P. , Moll R. H. 
Published: July 2010

The relative significance of epistatic effects and genotype ✕ environmental interaction effects in predictions of hybrid performances was evaluated in 28 sets of single, three‐way, and double crosses. Parental inbred lines originated from two unselected maize (Zea mays L.) varieties and from these two varieties after three cycles of reciprocal recurrent selection. Comparisons between unselected (UNS) and selected (RRS) population means indicate that selection has influenced both the additive and nonadditive genetic contributions to the observed differences.Comparisons among means over sets show significant epistatic effects, which, on the average, cause underestimates of three‐way and double‐cross performances from predictions based on nonparental single cross means. However, these underestimates appear to be inconsequential except for a few unique combinations of lines. Correlations between predicted and observed performances indicate that both the effects of epistatic deviations and the effects of genotype ✕ environmental interactions cause significant biases in hybrid predictions. Predictions of yield and ear number based on data from a single environment show somewhat greater biases from genotype ✕ environmental interactions than from epistatic effects. However, when predictions are based on data from three environments, biases from the two types of effects differ little in magnitudes.Except for those unique, apparently infrequent combinations of lines very strongly influenced by epistatic effects, the results indicate that standard single‐cross procedures for predicting three.way and double crosses need not be replaced by more complex procedures. Data from a single environment provide poor discrimination among three‐way or double crosses and somewhat better discrimination among single crosses. It is suggested that preliminary selections for three‐way and double‐cross hybrids are most efficiently performed by utilizing predictions based on nonparental single‐cross means from a few environments. Final testing of reduced numbers of selected hybrids requires several environments for adequate evaluation. Likewise, ascertainment of commercially acceptable unique single‐cross combinations requires several environments.
Performance and Within‐Hybrid Variability of Three‐Way and Single Crosses of Grain Sorghum1
Authors: Walsh E. J. , Atkins R. E. 
Published: July 2010

Mean performance and within‐plot variability of parents and hybrids of grain sorghums [Sorghum bicolor (L.) Moench] were evaluated from the results of experiments conducted during 2 years in Iowa. Analyses of the data combined over years indicated that fertile single crosses and three‐way hybrids did not differ significantly for mean grain yield, 100‐seed weight, seeds/head, heads/plant, plant height, and days to midbloom. Mean within‐plot standard deviations for plant height and days to midbloom of the three‐way hybrids were significantly greater (P < 0.01) than those of single‐crosses, but the differences do not seem large enough to be important agronomically.Mean grain yields of single and three‐way crosses and within‐plot standard deviations for the other characters were not highly correlated. Neither the differences between parents of male‐sterile single crosses nor heterogeneity within parental lines was closely associated with level of variability within three‐way hybrids. Male‐sterile single crosses yielded significantly more (19%) than sterile lines as parents for the production of hybrid seed. Superiority of the single crosses resulted primarily from larger numbers of seeds/head.
Development of a Set of Upland Cotton Lines for Comparisons of Fusarium Wilt‐Root‐Knot Nematode data from Several Tests1
Authors: Kappelman A. J. , Sappenfield W. P. 
Published: July 2010

Ten cotton (Gossypium hirsutum L.) cultivars were evaluated under five environments to determine their reaction to Fusarium wilt (Fusarium oxysporum f. vasinfectum (Atk.) Snyd & Hans.) and root‐knot nematodes (Meloidogyne spp.). These tests were conducted in an effort to determine a set of entries with known differential susceptibility to the Fusarium wilt‐root‐knot nematode complex. ‘Auburn 56’ and ‘Auburn M’ were highly resistant, while ‘Rowden’ and ‘Stardel’ were highly susceptible under all environments. The other six cultivars differed over environments but usually were intermediate in resistance.Although a complete set of differentials was not determined, two distinctively different groupings were observed. Using a cultivar from both the resistant group and the susceptible group as check materials hi Fusarium wilt screening tests will enable investigators to compare results from different areas on a relative basis.
Performance of Crosses Within and Between Two Diverse Sources of Birdsfoot Trefoil, Lotus corniculatus L.1
Authors: Conje A. M. , Carlson I. T. 
Published: July 2010

Nine clones derived from the cultivar ‘Empire’ and nine clones derived from two Russian introductions of birdsfoot trefoil (Lotus eorniculatus L.) were crossed in a partial diallel fashion, both within and between sources, to evaluate the influence of genetic diversity on expression of heterosis, to study combining ability of the parent clones, and to study interrelationships among characters that affect forage yield, seed size, and seed production. Sibmating was practiced in 16 F1 progenies to study breeding behavior in the second generation.In a space‐planted test, intersource F1 progenies yielded 14% more forage than intrasource progenies; however, they did not outyield crosses within the Russian source. General combining ability mean squares usually were considerably larger than specific combining ability mean squares. Full‐sib progenies derived from intersource crosses were superior to those from intrasource crosses in forage yield, winterhardiness, spring vigor, and pod production.High forage yield was closely associated with spring vigor and winterhardiness in F1 and full‐sib progenies and tended to be associated with a more prostrate growth habit and good pod production. Large seed size showed a low but significant association with low forage yield. Seed size was independent of pod production.
Meiotic Irregularities in Hybrids Between Diverse Genotypes of Tall Fescue (Festuca arundinacea, Schreb.)1
Authors: Evans G. M. , Asay K. H. , Jenkins R. G. 
Published: July 2010

Hybrids between American and North African Festuca arundinacea genotypes were characterized by numerous multivalents and univalents at first metaphase of meiosis and, consequently, were sterile. This was most likely due to differences in the arrangement of genetic material in the two parental groups. On the other hand, meiosis in progeny of crosses between American and European (French and Dutch) genotypes was much more regular with only one translocation evident.The sterility barrier imposed by the karyotypic divergence of American and North African genotypes seriously limits breeding efforts to combine desirable attributes of each. However, the relatively minor difference between European and American stocks should not impose any limitation on their inclusion in new synthetic varieties.
Effects of Deheading on Stalk Yield and Juice Quality of Rio Sweet Sorghum1
Authors: Broadhead Dempsey M. 
Published: July 2010

The carbohydrates in the grain normally produced by sweet sorghum [Sorghum bicolor (L.) Moench.] would more valuable to a sugar producer as sugar in the juice of the plant. April 1, May 1, and June 1 plantings of ‘Rio’ were deheaded in the boot and flower stages of head development. Deheaded and normal plants were compared when the normal plants were in the milk, dough, and rip stages of grain development to determine the effect of deheading on stalk yield and juice quality.Deheaded plants were higher in Brix, sucrose, and starch, but they contained less juice than normal plants. The effects of deheading on juice extraction, Brix, sucrose, and starch were similar for the milk, dough, and ripe stages of grain development. Deheading in the boot stage resulted in a slightly greater increase in sucrose than deheading in the flower stage. Plants deheaded in the boot and flower stages were similar in yield of stalks, juice extraction, Brix, starch, and juice purity. Deheading did not affect stalk and sugar yield or juice purity. Deheaded plants lodged less and had more side branches than normal plants.
The Inheritance of Several Agronomic and Fiber Properties Among Selected Lines of Upland Cotton, Gossypium hirsutum L.1
Authors: Baker Jerry L. , Verhalen Laval M. 
Published: July 2010

A quantitative genetic study of lint yield, earliness, lint percent, 2.5 and 50% span length, uniformity index, fiber fineness, and fiber strength was conducted in upland cotton, Gossypium hirsutum L., utilizing the Jinks‐Hayman diallel analysis. Ten selected lines and their 45 possible F1 combinations in 1969 and 1970, plus the 45 corresponding F2's in the second year, were included in randomized, replicated experiments at a single location.Analyses of variance indicated highly significant differences among entries for all traits in both years. Partial failures of the diallel assumptions were noted for each trait, although some traits did more nearly comply with those assumptions than did others. Epistasis was not detected as a significant factor for any of the traits. A genotype by environment interaction for the additive components of variation was observed for lint yield, lint percent, and 2.5% span length. The dominance relationships among parents were not constant over years for earliness, lint percent, 2.5% span length, fiber fineness, or fiber strength. Multiple allelism was shown by all traits except fiber fineness; however, gene correlations and parental heterozygosity were not (or could not be) detected for any trait.Overdominance governed lint yield, earliness, lint percent, 50% span length, and uniformity index. Partial dominance was operative for fiber fineness, and complete dominance was indicated for 2.5% span length and fiber strength. Narrow‐sense heritabilities indicated that mass selection should be effective for improving 2.5% span length, fiber fineness, and fiber strength among lines in this material and somewhat less effective for improving earliness, lint percent, 50% span length, and uniformity index. Alternatives, such as pedigrees, sib tests, and progeny tests, must be considered to achieve genetic progress for lint yield in this material.
Intra‐Plant Variation for Pollen Production in Male‐sterile and Fertile Alfalfa1
Authors: Barnes D. K. , Garboucheva Rada A. 
Published: July 2010

In Medicago saliva L. intra‐plant variation in pollen production occurred in partially male‐sterile clones, but it was not associated with either flower position on the plant or sampling date. The variation occurred at random throughout the plant. Anthers within the same flower varied for both number of pollen grains and percentage of normal pollen grains.The average number of pollen grains per anther varied among clones from about 440 to 850. The free anther had only about two‐thirds as many pollen grains as each of the remaining nine anthers. The number of normal pollen grains correlated with visual estimates of the amount of dehisced pollen, r = .854**, 11 d.f. Pollen abortion in male‐sterile plants apparently reduced internal pressure sufficiently to prevent rupture of the anther wall and extrusion of pollen.
Plant Measurements as Indicators of Crop Water Deficit1
Authors: Clark R. N. , Hiler E. A. 
Published: July 2010

An irrigation experiment was conducted with southern peas [Vigna sinensis L. (Endl.) var. ‘Burgundy’] utilizing lysimeters in which the soil water balance could be controlled. The purpose of the experiment was to compare certain plant measurements as indicators of crop water deficit. Plant measurements made on stressed and non‐stressed plants throughout the growing season were leaf‐water potential, leaf‐air temperature differential, and leaf‐diffusion resistance.Leaf‐water potentials were measured by the pressure chamber method on well‐exposed leaves. Leaf temperatures were measured by infrared radiometry and a diffusion porometer was used to measure leaf‐diffusion resistance. Tensiometers were used to determine the soilwater potential and to time the irrigations.The plant response data taken throughout a day were sensitive to water deficits during the late vegetative stage; however, the measurements were less responsive when the leaves aged, indicated by plants in the pod development stage. The change was particularly evident in the leaf‐water potential measurements. All three plant measurements did indicate water deficit to some degree. Leaf‐diffusion resistance was the least responsive, and leaf‐water potential was the most responsive. Results relating leaf‐water potential to leaf‐diffusion resistance and soilwater potential are also given.
Comparison of Three Methods of Recurrent Selection in Maize1
Authors: Horner E. S. , Lundy H. W. , Lutrick M. C. , Chapman W. H. 
Published: July 2010

Concurrent recurrent selection experiments were conducted for five cycles to compare three methods of selection for grain yield in maize (Zea mays L.): (1) combining ability with an inbred line (Inbred Tester Method), (2) combining ability with the broad‐base parental population (Parental Tester Method), and (3) yield S2 lines per se (S2 Progeny Method). The 15 selected populations were then crossed with the parental population and with another broad‐base synthetic to evaluate changes in general combining ability, and also were tested as randommated and selfed populations per se.A significant linear increase in general combining ability over cycles was obtained for all methods, but the Inbred Tester Method was significantly more effective than the other two methods (4.4% gain per cycle, compared with 2.4 and 2.0% for the Parental Tester and S2 Progeny Methods, respectively). There was no significant difference among methods for yield of random‐mated selected populations when adjustments were made for differences in rate of inbreeding.The results indicate that the inbred tester used was homozygous recessive at many important loci. This would result in larger testcross variances and more successful selection of dominant favorable alleles than is possible with a broad‐base tester, which probably has intermediate gene frequencies at most loci. The slow progress in combining ability improvement with the S2 Progeny Method suggests that this method also was not effective in fixing dominant favorable alleles.
Characterization of Freezing Inhibitors from Winter Wheat Cultivars1
Authors: Shearman Linda L. , Olien C. R. , Marchetti B. L. , Everson E. H. 
Published: July 2010

The activity of freezing kinetics inhibitors was characterized by a visual rating technique for several wheat (Triticum aestivum L.) cultivars. The procedure allowed a single test of a cultivar with a minimum of 13 g of seed, and 10 tests per day with the equipment available. Comparisons between several replications of kinetic inhibitor ratings and cultivar survival of high‐intensity freezing showed expected relationships. The activity of kinetic inhibitors from some cultivars was commensurate with survival ability. However, other cultivars exhibited better kinetic inhibitor activity than indicated by their survival rating. The ability to identify cultivars with high activity with no confounding effect by plant weaknesses in other areas that can affect survival, is a distinct advantage of this test. All wheat cultivars tested had lower ratings than ‘Rosen’ rye, the standard for the maximum rating. A large number of cultivars with varied genetic backgrounds are now being screened for improved kinetic inhibitor activity using this technique.As an initial inquiry leading to the screening technique, the validity of using seed as the polysaccharide source in the kinetic inhibitor tests was substantiated by hydrolysis and chromatography. Monosaccharide components were similar for polysaccharides extracted from crown tissues, the important area of freezing resistance, and from seed tissue. Purifying the polysaccharide extracts has proved difficult. In the best preparations, no compositional differences were seen between those polysaccharides exhibiting activity as kinetic inhibitors and those showing inactivity.
Growth of Alsike Clover Pollen In Vitro1
Authors: Benner L. R. , Townsend C. E. 
Published: July 2010

Pollen germination and pollen tube elongation in vitro and their relationship to self‐incompatibility were investigated in diploid alsike clover (Trifolium hybridum L.). Of four culture media evaluated, the most suitable one contained 25% (w/v) sucrose, 100 ppm of CaCO3 and 50 ppm of H3BO3 in deionized distilled water. Pollen germination was 82% and average pollen tube length was 0.43 mm after 24 hours at room temperature. Pollen tube elongation was approximately 10% of that necessary to effect fertilization. In a subsequent study, sucrose concentration of the selected medium was varied as follows: 10, 25, and 35% (w/v). Pollen germination was best (92%) in the solution containing 35% sucrose, but pollen elongation was best (0.41 mm) in the 25% sucrose solution. Pollen germination and pollen tube elongation were the poorest at the 10% sucrose concentration. Germination and tube elongation appeared to be two separate processes with different nutritional requirements.Pollen from 25 plants representing 11 S‐allele genotypes was evaluated in vitro for percentage germination and tube elongation. Although there were differences among genotypes and among plants within genotypes for these characters, no relationship was established between pollen grain nutrition and S‐allele genotype. Tube elongation sufficient to effect fertilization was not obtained.
Evaluation of Intergenotypic Competition with a Paired‐Row Technique1
Authors: Fehr W. R. 
Published: July 2010

A paired‐row technique was developed to measure intergenotypic competition between soybean (Glycine max (L.) Merr.) cultivars. A paired‐row plot consisted of two rows spaced 8 cm apart, the closest that we were able to grow soybeans in Iowa and still distinguish the individual rows at harvest. Different paired‐row plots were grown 1 m apart. To evaluate the competitive interaction of two soybean cultivars, three paired‐rows are needed per replication, one where the cultivars compete and one for each of the two cultivars in pure stand.Intergenotypic competition in paired‐rows was compared with that in a 1:1 blend grown in a single‐row plot for nine cultivar pairs. A cultivar with tawny pubescence and a cultivar with gray pubescence were selected for each blend to permit separation of the cultivars at maturity. The individual cultivars were harvested separately in both the paired‐rows and the 1:1 blend, and their yield performance was compared with that in a pure stand.The paired‐row technique was effective for determining the good and poor competitors in a blend for every cultivar pair tested. The percentage yield increase or decrease of each cultivar in competition generally was similar in the blend and the paired‐rows. The data suggested, however, that growing cultivars in rows only 8 cm apart did not perfectly simulate the competitive interactions that occur in a 1:1 blend.
Effect of Temperature on Self‐ and Cross‐Compatibility and In Vitro Pollen Growth Characteristics in Alfalfa1
Authors: Dane Fenny , Melton Bill 
Published: July 2010

Five selected alfalfa (Medicago sativa L.) clones were evaluated for self‐compatibility, cross‐compatibility, and pollen growth characteristics under four temperature treatments. Crosses were made with and without emasculation. An increase in temperature resulted in a decrease in self‐ or cross‐compatibility estimates. Field results were similar to those obtained at 32C in the growth chamber.Clonal differences existed, but a highly significant clone ✕ temperature interaction for all characteristics measured showed that these clones would not be expected to perform the same in all environments. Cross‐ and self‐compatibility or male and female cross‐compatibility estimates were generally not correlated. Some plants performed differently as male and female parents. Female cross‐compatibility was correlated between 21 and 27C and between 27C and the field study temperatures. Higher correlations were found for male cross‐compatibility values from the different temperature regimes. The cross‐compatibility estimates from the crosses produced with and without alcohol emasculation were not correlated. Pollen germination was affected by the temperatures at which the plants were grown, whereas pollen tube elongation was affected more by incubation temperatures. Male cross‐compatibility was correlated with pollen germination.