bluuebunny/crossref_metadata_2025 huggingface dataset:
Selection for Acetylene Reduction Rates in ‘Mesilla’ Alfalfa1
Authors: Duhigg Pat , Melton Bill , Baltensperger Arden
Published: July 2010

The rate of N fixation by leguminous plants depends on both the effectiveness of the Rhizobium strain and the genotype of the host plant. Most of the previous work has involved attempts to improve the bacterial strain. The objective of this study was to determine the variability in ‘Mesilla’ alfalfa (Medicago sativa L.) for plant characteristics considered to be indices of N fixation and to determine the response of these indices to selection based on acetylene reduction rate. Alfalfa seedlings were grown for a 10‐week period in a N‐free sand culture. Before planting, seeds were inoculated with a commercial peat base alfalfa inoculum. Data were obtained on nodulation score, nodule color score, root score, dry weight of the top growth, % N in the top growth, total N in the top growth, and acetylene reduction rate. Considerable variation existed for all traits measured among 278 plants of the cultivar Mesilla. Plants selected for high rates of acetylene reduction were higher in nodulation score, nodule color score, root score, dry weight of top growth and total N in the top growth than the original cultivar. Fifteen plants with high acetylene reduction rates and 15 with low acetylene reduction rates were selected. These plants were intercrossed within groups by hand pollination without emasculation. Progeny of the high selections showed an 82% increase in acetylene reduction, a 57% increase in dry weight of the top growth, and a 60% increase in total nitrogen in the top growth as compared to the original cultivar. These progeny also had a significant increase in nodulation. Nodule score and root score were highly correlated with each other and with dry weight of the top growth. Dry weight of the top growth was more closely correlated with total nitrogen in the top growth than percent nitrogen in the top growth. Dry weight of the top growth and total nitrogen in the top growth were highly correlated with acetylene reduction rates. A selection procedure for nilnitrate conditions was suggested involving 1) a 10‐week growth period, 2) initial selection on the basis of dry weight of the top growth, and 3) acetylene reduction assays of selected plants.
Interaction of Near‐isogenic Populations of Wheat in Infested and Uninfested Environments of Wheat Soilborne Mosaic Virus1
Authors: Kayastha B. N. , Heyne E. G.
Published: July 2010

Five resistant‐susceptible populations of winter wheats (Triticum aestivum L.) and the susceptible cultivar ‘Eagle’ were grown in Kansas in 13 environments (uninfested or infested with soilborne mosaic virus) to evaluate their performance in different environmental conditions and to examine the usefulness of the regression approach for environments differing in a major known factor. All the populations evaluated in the infested and uninfested environments exhibited a wide range of stability‐parameter estimates, and the individual mean yield was important for interpreting the regression coefficient and deviation from regression. At sites where environments differed in a major known factor, this approach seemed to describe satisfactorily and/or locate genotypes causing or contributing significantly to genotype ✕ environment interactions. Our data showed that cultivars with below unity regression coefficients would be preferable when selecting for disease resistance. The data also indicated that the ranking of environments may lead the breeder to an effective choice of environments to use for discriminating between genotypes with respect to particular sensitivities. The interaction of genotypes with wheat soilborne mosaic virus‐infested or uninfested environments showed that breeding lines should be studied in more than one environment.
Linkage Tests in Upland Cotton. III1
Authors: Kohel R. J.
Published: July 2010

A summary of tests of 255 linkage combinations are reported. Two new linkages were established as follows: Rd and v8 (14.22% recombination; Linkage Group XIV) and Li and v8 (10.12% recombination; Linkage Group XV). Eleven other suspected linkages are discussed, but they were either eliminated through monosomic analysis or were not adequately validated. In the latter case, current information is presented because these mutants are so difficult to manipulate that development of test populations will require several years of work.
Resistance of Corn to Leaf‐Feeding Damage by the Fall Armyworm1
Authors: William W. Paul , Davis Frank M. , Scott Gene F.
Published: July 2010

A diallel cross of nine inbred lines of corn (Zea mays L.) was planted late and evaluated for response to leaffeeding by the fall armyworm [Spodoptera frugiperda (J. E. Smith)] under natural infestation in 1976 and 1977. In 1976, plants were evaluated after anthesis on a rating scale of 0 (resistant) to 9 (susceptible). In 1977, plants were rated about 5 weeks after planting on a scale of 1 (resistant) to 3 (susceptible) because of an extremely heavy, early infestation. Mean squares for general and specific combining ability were highly significant in 1976. In 1977, the mean square for general combining ability was highly significant, but the mean square for specific combining ability was not significant. The mean leaffeeding damage ratings for the resistant ✕ resistant, resisant ✕ susceptible, and susceptible ✕ susceptible crosses were, respectively, 5.48, 6.16, and 7.22 in 1976 and 1.50, 2.02, and 2.83 in 1977.
Cytoplasmic‐Genic Male‐Sterility Systems in Sorghum1
Authors: Schertz K. F. , Ritchey J. M.
Published: July 2010

Essentially all sorghum, Sorghum bicolor (L.) Moench, hybrids are made with a single cytoplasmic‐genic sterility system. In an attempt to derive new cytoplasmic‐genic male‐sterility systems in sorghum, recently introduced lines of diverse types from widespread geographic locations were intercrossed and backcrossed. Three male sterile from this program were tested to determine their cytoplasmic diversity for induction of male sterility. Fertility of the F1 hybrids from crosses of each sterile line with a series of tester lines was compared with fertility of hybrids from crosses of a currently used sterile (‘A Tx3197’) with the same testers. Differential sterility responses indicated that each of these cytoplasms probably differ from milo cytoplasm of A Tx3197. Of these, the line with IS 12662C cytoplasm is the most desirable sterile and has been released as ‘A2 Tx2753’. Differential sterility responses among the three steriles also indicated possible cytoplasmic differences among them. Because each of these steriles was in an early generation and differed in nuclear genes, definitive conclusions must await the testing of more nearly isocytoplasmic lines developed by incorporating a common nuclear genotype into each cytoplasmic source.
Effects of Sucrose Concentration on Plant Production in Anther Culture of Rice1
Authors: Chen Chi‐Chang
Published: July 2010

Rice (Oryza sativa L.) anthers of various developmental stages were cultured on medium with 3%, 6%, and 9% sucrose to test the effects of sucrose concentration on plant production. It was found that high sucrose concentrations in the callus‐induction medium promoted callus formation and subsequent organogenesis. However, callus initiated on the 9% sucrose medium differentiated more albino plants than callus from the medium with lower sucrose concentrations.
A Proposed Barley Karyotype Revision Based on C‐Band Chromosome Identification1
Authors: Noda K. , Kasha K. J.
Published: July 2010

Individual chromosomes of barley (Hordeum vulgare L.) were identified by C‐banding the primary trisomics for chromosomes 1, 2, 3, and 4 of the cultivar ‘Betze’. Karyotype analysis of C‐banded chromosomes indicated that chromosome 2 was the longest chromosome while chromosome 1 had the most median centromere. Chromosomes associated with linkage groups 1, 2, 3, and 4 were similar to those described as 3, 2, 1, and 4, respectively, in the previous standard barley karyotype. A key to chromosome identification is presented and a revision of the barley karyotype is proposed so that the chromosomes described correspond to the numbering of the linkage groups as currently being used for barley. The reliability of C‐banding for barley chromosome identification is discussed.
Production Response and Stability Characteristics of Oat Cultivars Developed in Different Eras1
Authors: Langer I. , Frey K. J. , Bailey T. B.
Published: July 2010

Grain yield data for 66 oat cultivars, developed over the past 4 decades in the midwestern U.S., were used to determine whether genetic changes had occurred for mean grain yield, yield response to improving environments (measured via linear regression), and stability of yield (measured via coefficients of determination). The 4 decades were divided into seven periods of cultivar development, and the productivity indexes for the test environments were measured by the means of the yields of two cultivars, ‘Richland’ and ‘Cherokee’, that were grown as longtime checks in all environments. Mean productivity for all cultivars was 9.0% higher than the yield of the checks. This increase occurred in the earliest era (i.e., 1932 to 1942), and no additional increase was detected throughout the 4‐decade period. Three‐quarters of the new cultivars yielded significantly greater than the checks, and only one yielded significantly less. The mean regression response index ranged from 0.89 to 0.98 for the seven eras, and there was no evident trend for this parameter over time. It is suggested that the oat germplasm of Avena sativa L., originally introduced from northern Europe into the midwestern U.S., may have contained little genetic variability for grain yield. Seemingly, the only times when bursts of yield improvement have been made in cultivated oats have followed introgression of germplasm from other species or ecotypes.
Effect of Planting Date on Natural Selection in Soybean Populations1
Authors: Luedders V. D.
Published: July 2010

Early‐maturing segregates are frequently eliminated in soybean (Glycine max (L.) Merr.) bulk populations. Six simulated bulks were made of five cultivars in maturity groups I through V, the two cultivars in each bulk differed by at least two maturity groups. These bulks were planted at several dates in 4 years to determine whether late planting would increase the relative reproduction of the early cultivars in the bulks. Their relative reproductivity increased twice, decreased once, and did not change once. The early cultivars in all bulks were at a reproductive disadvantage compared to the relationship in pure stands. The reproductive disadvantage tended to increase with differences in the time of maturity in the simulated bulks, although plant size probably was more important than maturity per se. Even though the early cultivars in the bulks did not consistently gain in reproductive advantage with late planting, late planting should help maintain them in bulk populations because of improved seed quality.
Genetics of Seed Dormancy and its Association with Other Traits in Safflower1
Authors: Kotecha Ashok , Zimmerman L. H.
Published: July 2010

Two selections of wild safflower (Carthamns palaestinus Eig.) possessing short‐term seed dormancy and three cultivars of domestic safflower (C. tinctorius L.) were used in crosses to study the genetics of seed (achene) dormancy and its association with other traits.

Seeds from the parents of each cross differed significantly in all germination periods (24, 48, and 72 hours after 2 and 24 weeks of storage). Seed of all populations stored for 24 weeks had higher germination percentage than that stored for 2 weeks, which indicated that seed dormancy was lessened by long‐term storage. Variability of the F2 generation was of genetic origin, except in a few cases. Heritability in the broad sense ranged from 0 to 99% for 2 and 24 weeks of storage. Heritability estimates in the narrow sense were 55, 46, and 33% for 24, 48, and 72 hours of germination, respectively, for 2 weeks of storage. Except for one case, gene action was nonadditive. Seed germination characteristics were quantitatively inherited. The expectation of genetic advance for 48 hours of seed germination was higher than that of 24 and 72 hours of germination for 2 weeks of storage. Thus, selection for 48 hours of a 2 week storage period should be most desirable. Germination of seeds from plants with striped hulls and green midveins of cotyledons was higher than germination of those with nonstriped hulls and purple midveins. Correlation coefficients for all germination periods with seed weight and pappus were low. Correlation coefficients for seed weight with pappus were also low. Thus, these traits are not important in breeding for seed dormancy.
Lesion Nematode Resistance in Peanuts1
Authors: Smith O. D. , Boswell T. E. , Thames W. H.
Published: July 2010

Six peanut (Arachis hypogaea L.) introductions and two commercial cultivars (‘Starr’ and ‘Spancross’) were evaluated for lesion nematode (Pratylenchus brachyurus (Godfrey) Felip & Sch. Stek) resistance under field conditions. Multiple harvests were used to compensate for maturity differences among peanut lines. Nematicide treatments were included to aid in evaluating the level of resistance.

Shells of the peanut introductions PI 295233 and PI 290606 had significantly less pod discoloration and fewer nematodes from shell extractions than the commercial Spanish cultivars. Nematode extractions from root tissue supported the results from the shell samples. Three additional PI's showed lesser degrees of resistance.

Subsequent comparisons among Starr, ‘Florunner’, PI 295233 and PI 290606 verified the results. Significantly more (P = 0.00036) nematodes were extracted from shell tissue of Starr and Florunner than of the other two entries. More nematodes (P=0.00003) were extracted from root samples of Starr than of the other three entries. The possibility that resistance is controlled separately in shell and root tissue is suggested.
Inheritance of Resistance to Hessian Fly Derived From Triticum turgidum L.1
Authors: Carlson S. K. , Patterson F. L. , Gallun R. L.
Published: July 2010

A heterogeneous wheat line (Triticum turgidum L.) submitted to the USDA‐SEA world collection of wheats by J. C. Santiago, Portugal, was reselected at Purdue University on the basis of resistance to Hessian fly (Mayetiola destructor Say), biotype D. We designated our selection ELVA (CI 17714). From chromosome homologies and plant characters it was classified as a Triticum turgidum L. Resistance to Hessian fly from Elva was transferred to common wheat (Triticum aestivum L.) by backcrossing. Three of the resultant resistant lines were analyzed for number of genetic factors controlling resistance to biotype D at 20 C. Progenies from individual F2 plants and BC1 F1 plants from crosses between the resistant lines and the susceptible ‘Arthur’ were classified for reaction to Hessian fly. In two lines, resistance appeared to be controlled by two linked dominant genetic factors, either conferring resistance. The third line most likely contained a single dominant genetic factor.
Variation in Mobilization of Plant Nitrogen to the Grain in Nodulating and Non‐Nodulating Soybean Genotypes1
Authors: Jeppson R. G. , Johnson R. R. , Hadley H. H.
Published: July 2010

Due to the large nitrogen requirement by soybeans (Glycine max L. Merr.), efficient N utilization might conserve plant energy for other metabolic processes. One method of improving efficiency of N utilization would be to have a high total N content in the seeds vs. that in the above‐ground portion of the plant (i.e. a high N index). The objective of this field study was to evaluate a diverse group of 32 nonnodulating lines and nodulating and non‐nodulating near isogenic lines of ‘Clark’ and ‘Harosoy’ for genetic variability in harvest nitrogen index when grown at three N fertilizer rates. In a second year's experiments lines representing extremes in harvest N index were sampled throughout reproductive development and quantity of N in leaflets, petioles, stems and pods was determined. Harvest indices for grain yield and N varied among the genotypes tested. Harvest indices and harvest nitrogen indices were positively correlated with seed yield. A significant positive correlation between harvest and harvest nitrogen indices suggested that certain genotypes are efficient in mobilizing both N and dry matter to the developing seed. Differences in harvest nitrogen index at maturity resulted from differential N mobilization from leaflets, petioles and stems of efficient (high harvest N index) as compared to inefficient (low harvest N index) genotypes. In general stem N characteristics were most diagnostic of harvest N index. At maturity harvest N index was statistically correlated with grams of N in stems, percent N in stems, and percent of maximum N accumulated that was translocated from the stems. Averaged across genotypes adding N fertilizer increased the quantity of whole plant N, grain yield and percent protein in the seed. However harvest N indices were not significantly affected by N fertilization. The ranking of genotypes for harvest and harvest N indices were consistent in different environments, but the inclusion of abscised leaflets and petioles caused some differences in ranking. Of the genotypes evaluated noduating Harosoy had the greatest grain yield and was among the highest in N index.
Genetic Relationships Among Chemical Constituents in Seeds, Flower Buds, Terminals, and Mature Leaves of Cotton1
Authors: Hanny B. W. , Meredith W. R. , Bailey Jack C. , Harvey A. J.
Published: July 2010

This experiment was conducted to determine the genetic association among chemical constituents considered to be associated with pest resistance of cotton (Gossypium hitsuture L.). Three replications of 39 cotton genotypes were grown in field plots at Stoneville, Miss. in 1977. Flower buds, terminals, and mature leaves of the genotypes were assayed for terpenoid aldehydes (including gossypol) and condensed tannis; seed were assayed for terpenoid aldehydes (including gossypol), oil, and protein. Cabbage looper [Trichoplusia ni (Hubner)] damage and lint percentages for all genotypes were determined.

Seed and flower bud terpenoid contents were highly variable among genotypes. Although less variability was found for the remaining characteristics, all except leaf terpenoid content were significantly variable. Flower bud and terminal condensed tannins were significantly correlated (r = 0.67); each was moderately correlated with leaf condensed tannin (r = 0.41 and 0.45, respectively). Condensed tannin content of the plant parts was weakly correlated with terpenoid content.

Lint percentages appeared to be independent of all chemical constituents measured. Seed oil was negatively correlated with flower bul (r _ ‐‐0.39) terpenoid content. Cabbage looper damage correlations of ‐‐0.46, ‐‐0.60, and ‐‐0.31 for flowerbud, terminals, and leaf terpenoids, respectively, were obtained. No relationship was found between looper damage and tannin content.
Nectar Characteristics Associated With Sources of Alfalfa Germplasm1
Authors: Barnes D. K. , Furgala Basil
Published: July 2010

Alfalfa (Medicago sativa L.) is a major source of nectar for honey production in the USA. No cultivars have been developed especially for nectar productivity. The objective of the research reported here was to survey the nectar characteristics of alfalfa plants from various parental germplasms. Greenhouse‐grown plants from 82 cultivars were assayed for nectar volume per 100 florets, percent nectar solids (sugars), and ratios of sucrose, fructose, and sucrose. Highly significant differences occurred among alfalfa sources for all traits measured. An index developed with visual scores for flower size and nectar quantity was correlated (r = 0.80) with extracted nectar volume. It should be possible to breed alfalfa cultivars with wide ranges in nectar characteristics.
Lysine Estimation in Cereals by Near‐Infrared Reflectance1
Authors: Rubenthaler G. L. , Bruinsma B. L.
Published: July 2010

The determination of lysine in cereals has been limited by methods which are slow and relatively expensive. Experimental data obtained with a standard near‐infrared‐ reflectance (NIR) instrument — commercially available to determine protein, moisture, lipids, and other constituents of cereals and oil seeds — were highly correlated (r = 0.98) with lysine in some 77 samples of hard red (spring and winter) wheats (Triticum aestivum L.). Standard error (Sy•x) for the test was ±0.049 mg lysine/ 100 g protein. The method is rapid (1 min), relatively accurate, involves little sample preparation, and provides direct readout of lysine. The test is non‐destructive and, therefore, the sample can be used for other quality tests. Minimum sample required is approximately 2 g and optimum is 6 to 8 g. Care in sample selection, preparation (grinding and filling the sample cell), and monitoring with a reference method is necessary for consistent meaningful results.
Genetic Control of Nitrogen Uptake and Translocation in Maize1
Authors: Pollmer W. G. , Eberhard D. , Klein D. , Dhillon B. S.
Published: July 2010

Hybrid combinations of 10 flint with nine dent inbred lines of maize (Zea mays L.) along with 10 standard cultivars were evaluated in two environments. Four flint and four dent inbred lines were the result of a breeding program for high protein percentage in the grain and good combining ability for agronomic traits. The materials were harvested at two stages, i.e. at the beginning of the grain‐filling period and at grain maturity. Data based on stover, ear, and grain were collected to study N translocation from stover to ear during the grain‐filling period and N uptake in two phases of plant growth: the pre‐grain‐filling period (phase 1) and the grain‐filling period (phase 2).

Highly significant differences were observed due to general combining ability (GCA) and specific combining ability (SCA) for total N uptake, N uptake in phase I, N uptake in phase 2, and N translocation. Genotype ✕ environment interactions involving both GCA and SCA contributed significantly to the variation for these traits. A high N uptake in phase 1 accompanied by a low N uptake in phase 2 seemed to increase the N translocation, depending on the capacity of the sink. The experimental hybrids, with high protein percentage and protein yield of grain, generally silked later than the conventional hybrids, but were at least comparable for percent ear dry matter at maturity and grain yield. This indicated a high rate of ear dry matter production and drying of the high‐protein hybrids. It is hypothesized that a high protein percentage and protein yield of mature grain, may be due to an intensive N uptake, a prolongation of the N uptake phase, and a high N translocation. The relative importance of these factors may vary in different genotypes and environments.
Inbreeding Depression of Selected F3 Cotton Progenies1
Authors: Meredith William R.
Published: July 2010

The objective of this study was to investigate yield inbreeding depression of selected cottons (Gossypium hitsutum L.). In 1973, 360 F3 equivalent progeny rows from the cross and random intercross of ‘Deltapine 16’ ✕ ‘Mo 277‐396’ were grown at two Delta locations with two replications each. From 50 of the 72 highest lint‐producing progenies, F4 and F5 seed were produced in 1973 and 1974.

In 1975, the 50 families were grown in five sets of 10 families each at two locations. Families were grown as whole plots; F3, F4, and F5 progenies were grown as subplots. An additional whole plot of Deltapine 16, Mo 277‐396, F1 F2, and the unsefected bulk of F3, F4 and F5 plants was grown in each set. The average lint yields of these seven populations were 633, 899, 859, 751, 725, 709, and 713 kg/ha, respectively. The average yields of selected F3, F4, and F5 progeny were 759, 748, and 710 kg/ha, respectively. Significant inbreeding depression was detected in both selected and unselected populations. These results imply that inbreeding depression is a major factor in the poor yield performance of early generation selections for yield in cotton.
Seedling Photosynthetic Efficiency of a Grain Sorghum Hybrid and Its Parents1
Authors: Arkin G. F. , Monk R. L.
Published: July 2010

Seedlings of a hybrid and its parents of Sorghum bicolor (L.) Moench were examined from emergence through the four leaf stage for photosynthetic efficiency. Seedling root components were included in the analysis. Significant heterosis occurred for leaf area, total dry weight, and for rate of development, but significant heterosis was not exhibited for root/shoot ratios, net assimilation rate (NAR), or total dry matter/leaf area ratios. These results indicate that heterosis is not present for photosynthetic efficiency as measured by NAR in these hybrid sorghum seedlings.
Utilization of Plant Introductions in Soybean Breeding Populations1
Authors: Schoener C. S. , Fehr W. R.
Published: July 2010

The relationship between percentage of germplasm from plant introductions (PIs) in soybean [Glycine max (L.) Merr.] populations and their performance for seed yield, height, and lodging was evaluated. Five intermated populations were developed from four PIs selected for their good yield potential, PI 68600, PI 68704, PI 81029, and PI 91150, and four cultivars or experimental lines, ‘Chippewa 64’, C1426, L15, and ‘Calland’. The parents and their hybrid progeny were intermated up to five times to form population AP1 with 100% PI germplasm, AP2 with 75%, AP3 with 50%, AP4 with 25%, and AP5 with 0%. Performance of progeny from 96 random S3 plants from each population was evaluated in three environments in Iowa during 1975 and 1976.

Both the linear and quadratic mean squares were significant for differences in yield among the five populations. There was a linear increase in yield from AP1 to AP5; however, AP1 consistently was higher yielding than AP2. AP5 had the highest mean yield and greatest frequency of lines with high yield. AP3 had the greatest amount of genetic variability for yield, AP2 and AP4 were intermediate and AP1 and AP5 had the least. There was a significant linear increase in height from AP1 to AP5 and linear decrease in lodging score from AP1 to AP5.

The use of PIs with good yield potential and up to five intermatings before selection did not overcome the superiority of the population developed from high yielding cultivars and experimental lines. The superiority of AP5 was small enough, however, to suggest that evaluation of PIs for yield may permit selection of parents that do not cause a drastic yield reduction in genetically diverse populations. The acceptable mean yield and high genetic variability of AP3 suggested that up to 50% PI germplasm may be suitable for populations intended for long‐term improvement by recurrent selection.
Flowers with Abnormal Numbers of Involucral Bracts in Cotton1
Authors: Wilson F. D. , Stapp B. R.
Published: July 2010

A primitive race stock of cotton (Gossypium hlrsutum L.) Texas 703, had 26 to 59% flowers with more than the usual number of three involucral bracts in four seasons in the field at Phoenix, Ariz. The most common variant was a flower with a fourth, almost full‐sized bract, but other flowers had up to seven bract segments. Two cultivars, ‘Deltapine 16’ and ‘Stoneville 7A’, had lower frequencies of flowers with abnormal numbers of bracts. Plants of the race stock and cultivars had only three‐bract flowers in the winter greenhouse. We selected race stock ✕ cultivar F5 progenies that were almost true‐breeding for abnormal (98.9%) and normal (99.5%) numbers bracts. About one‐third of the F4 plants selected for all abnormals in the field had low frequencies of abnormals when cut back and moved into the greenhouse in the fall. The most common variant in the advanced‐generation selections, as in the race stock, was a flower with four bracts; one progeny had 95% four‐bract flowers. Others, however, had lower proportions of four‐bract flowers in relation to other abnormal numbers. Thus, it may be possible to select plants having flowers with more than four bracts. An inheritance study of selected F3 parents and four hybrid generations suggested that abnormal bract number is conditioned by three or four pairs of genes that show additive, intra‐allelic, and interallelic effects.
Processing Potential for Diallel Hybrids of High‐Sugar Corn1
Authors: Andrew R. H. , von Elbe J. H.
Published: July 2010

Numerous genes acting alone or in various combinations influence the endosperm composition of corn (Zea mays L.). Hybrids carrying the sh‐2 gene have found some acceptance by home gardeners because of their high level and slow rate of loss of moisture and sugars. This research was planned to determine the potential use for processing of su‐1 sh‐2 germplasm. To this end, su‐1 sh‐2 lines were combined in a diallel series of single hybrids and evaluated in field and canning trials. The su‐1 sh‐2 hybrids ranked above standard sweet corn (su‐1 sh‐2) for color and sweetness, approximately the same for flavor, and below for tenderness. Their wide range in color following processing emphasizes the need for specific cooking procedures on an individual hybrid basis. Highly significant GCA and SCA mean squares point to the importance of both additive and nonadditive gene action for the attributes studied. It is desirable to incorporate the su‐1 sh‐2 gene combination into a wide spectrum of adapted germplasm in a search for other modifiers which will increase their processing potential, provided the germination problems of the shrunken‐2 phenotype can be overcome.
Forage Sampling Factors Influencing the Variability of In Vitro Fermentation Results of Grass Selections1
Authors: Holt E. C. , Ellis W. C. , Engdahl G. R.
Published: July 2010

Variation in in vitro fermentation estimates of forage digestibility is a problem. Only a few studies have quantified the extent of laboratory variation, and even less information is available on variability associated with sample collection, processing, and storage prior to analysis. A study was designed to evaluate the effects of source of samples and maturation on genotype selection in a breeding program. Variance was partitioned into genotype effects; sampling procedures; effects of handling, drying, grinding, and storing samples; and laboratory analysis. The sampling procedure consisted of collecting bulk and tiller samples of 31‐day regrowth forage of five clones from each of five Panicum coloratum L. and seven Cenchrus ciliaris L. selections (genotypes). Tillers in the early inflorescence stage were selected while bulk samples consisted of the top growth from one‐half of each clone. Each sample was randomly divided in the field, and bulk samples were again subdivided following drying and grinding. Laboratory analyses were run on duplicate 0.5‐g samples.

Bulk samples exhibited a wider range of digestibility among selections, and approximately the same genotypic rankings as did tiller samples. Bulk samples collected at three ages (approximately 4, 6, and 8 weeks of regrowth) showed genotype ✕ age interactions, indicating the need to sample at more than one stage of maturation. The largest component of variance (3.01 to 8.1) was associated with selections (genotypes). The second largest component of variance (1.81 to 2.65) was associated with clones. Clones accounted for 14 to 25% of total variance. Relatively little variance was associated with handling, drying, grinding, and storage of samples. From 9 to 22% of total variance was associated with in vitro analysis (duplicate samples). The components of variance for laboratory analysis ranged from 1.18 to 2.38, which is similar to that reported in other studies.

The results indicate that for indeterminate plants, and others not varying widely in date of flowering, bulk sampling is acceptable. Improvement in precision of the in vitro procedure may be realized by sampling multiple clones of the same genotype and by multiple laboratory analysis. Grass breeders should sample plants at more than one stage of maturation to gain an improved assessment of forage digestibility potential.
Evaluation of Vigor in Soybean Seeds: Influences of Date of Planting and Soil Type on Emergence, Stand, and Yield1,2
Authors: Yaklich R. W. , Kulik M. M. , Garrison C. S.
Published: July 2010

Soybean [Glycine max (L.) Merr.] seed lots were evaluated for emergence, stand, and yield. Seven cultivars were analyzed in 1975 and eight in 1976. The seeds were planted 3.8 cm deep at a rate of 6 seeds/0.3 m of row in sandy and heavy type soils. Three planting dates — early, pre‐optimum, and optimum — and four replicates were used for the evaluations. Emergence counts (V2 to V3 growth stage) and stand counts (R6 growth stage) were recorded for the planting dates and sites. Yield was determined on 4.9 m of row for seeds planted on the optimum planting date in the heavy type soil.

Each year, seedling emergence and stand were better on a sandy type soil than on the heavy soil and were best for the optimum date of planting. Simple correlation coefficients of emergence and stand counts for both years were high and significant. However, analysis of variance showed seed lots did not perform similarity across sites and planting dates in 1975. A 10 to 15 percentage point difference in emergence was necessary for a significant difference between seed lots, depending on site and planting date. In 1975 and 1976 the correlations between stand and yield were low, rr= 0.361 and 0.311, respectively, but those between stand and yield/plant were high and negative, r = −0.862 and −0.830, respectively. Stand and yield for the cultivar ‘Wayne’ were significantly correlated each year.
Effect of Non‐Milo Cytoplasms on the Agronomic Performance of Sorghum1
Authors: Ross W. M. , Kofoid K. D.
Published: July 2010

Over 97% of the grain sorghum [Sorghum bicolor (L.) Moench] hybrids in the United States are ipade with male‐sterile (A) lines that have cytoplasm tracing to one sorghum type, milo. Six ‘Combine Kafir‐60’ (CK)‐type A lines, ‘KS34A’ through ‘KS39A’, have non‐milo cytoplasms which are maintained with the same CKB line that maintains CKA, which has milo cytoplasm; but apparently KS34 through KS39 are seldom used.

The six A lines and CKA were crossed to ‘Tx 414’ to make F1's, and the F1's were used to make six pairs of modified backcrosses as follows: (KS4‐CKB) ✕ (CKA‐Tx 414) vs. (CK4‐CKB) ✕ (KSA‐Tx 414) which are the same except for cytoplasms. The two sets of crosses, F1's and modified backcrosses, were grown at Mead, Nebr. in 1976 and 1977 in a replicated test to determine effects of the non‐milo cytoplasm on yield and other agronomic characters.

No significant differences among entries were found for flowering, plant height, grain yield, heads per plant, 1,000‐seed weight, or seed number per head in either the F1's or the backcross group. The non‐milo cytoplasms apparently had neither adverse nor beneficial effects on the agronomic performance of the crosses. In consideration of the possible hazards that exist with one cytoplasm, widely used females should be extended into KS34 through KS39 cytoplasm bases for potential use in hybrid seed production.
Potato Leafhopper Resistance in Glandular‐Haired Alfalfa Species1
Authors: Shade R. E. , Doskocil M. J. , Maxon N. P.
Published: July 2010

Five glandular‐haired alfalfa (Medicago) species were evaluated for resistance to the potato leafhopper (Empoasca fabae (Harris) in cages under greenhouse conditions. Preference was based on the percentage of time adults were observed on the plant rather than on the cage surface. Data showed that adults spent significantly less time on M. blancheana Boiss. and M. disciformis DC. than the adults did on the glabrous control (M. sativa L. ‘Vernal’). Adult mortality occurred at a higher rate on all five glandular‐haired species than on the control. Highest rate of mortality (100%) occurred on M. noeana Boiss. within 3 days, compared with 53% mortality on the control after 9 days.

Total nymphal production, which reflects the over‐all influence of the plant on the potato leafhopper, was significantly less on all five glandular‐haired species than on the control. Glandular‐haired species were nearly immune to the first instars, as all nymphs produced were found dead in the first stadium and trapped in glandular hair exudate.
Speed of Germination as a Criterion of Seed Vigor in Soybeans1
Authors: Pinthus M. J. , Kimel U.
Published: July 2010

The effect of germination speed on the development and seed yield of soybean [Glyclne max(L.) Merr.] plants was investigated. Seedlings from graded ‘Clark’ soybean seeds were geminated in individual turf pots and grouped according to speed of germination. The pots of each group were planted in separate lots in greenhouse and field experiments.

In both experiments, foliage development, dry matter accumulation, and seed yield of the rapidly germinating plants exceeded those of the slowly germinating plants. In the field experiment, the average seed yield of the plots planted with seedlings germinating 4 and 5 days after sowing exceeded the yield of the plots planted with seedlings germinating 6, 7, and 8 days after sowing by 22%. Through tests of the progenies of the different groups it was ascertained that the differences in the speed of germination were not heritable.
Inheritance of Prolificacy in Maize1
Authors: Sorrells M. E. , Lonnquist J. H. , Harris R. E.
Published: July 2010

The inheritance of prolificacy and the relationship of multiple ear development to time intervals between developmental stages of reproductive structures were studied in maize (Zea mays L.) in three different experiments using both quantitative and qualitative methods of genetic analysis.

A six‐line diallel involving unrelated parents, F1's, and F2's were grown at population densities of 17,200 and 34,400 plants/ha over 2 years. General (GCA) and specific (SCA) combining ability effects were significant for both ear number and multiple‐ear‐weight index (MEWI). This index is defined as the total grain weight minus first ear grain weight divided by total grain weight. The ratio of GCA to SCA fixed‐effects variance ranged from 3.7:1 to 7.4:1 for ear number and from 2.5:1 to 7.2:1 for MEWI. Higher ratios were usually associated with the low population density. Phenotypic correlations and the correlations of GCA effects were strongly positive for the time intervals, first‐to‐second ear shoot emergence, and first‐to‐second silk. Also, silking interval was negatively correlated with both ear number and MEWI.

In a second experiment, six unrelated parents and 15 F1's were dissected daily and the dates of initiation of tassel and ear shoot meristems recorded. General combining ability effects were highly significant for the time periods tassel‐to‐first ear shoot initiation and first‐to‐second ear shoot initiation. Only the time period between initiation of the first and second ear shoot was correlated with ear number (−0.57**) and MEWI (−0.63**).

In an experiment involving related inbred lines, their F1's, F2's, and backcrosses, additive gene effects were highly significant for ear number and MEWI, and dominance effects were significant (0.05 level) for MEWI. Negative correlations were observed between both ear number and MEWI and the time periods, ear shoot emergence‐to‐pollen‐shed, first‐to‐second ear shoot emergence, and first‐to‐second silk. For the F1 and segregating generations of one pair of related lines, a greater frequency of second ears occurred on plants having fewer nodes above the first ear. In both experiments prolificacy factors segregated in a manner predictable from the penetrance and genetic segregation inferred from parents and F1's. The genetic analysis on two pairs of related lines indicated that a single locus or group of linked loci account for the majority of the variation in ear number an their segregating generations.
Resistance to Mexican Bean Beetle and Corn Earworm in Soybean Genotypes Derived from PI 2276871
Authors: Smith C. M. , Brim C. A.
Published: July 2010

Progeny of three advanced soybean [Glycine max (L.) Merr.] backcross populations {‘Forrest’ ✕ [‘Bragg’ (2) PI 227687]). {Bragg ✕ [Bragg (3) ✕ PI 227687]} and {Bragg X [Bragg (3) ✕ PI 227687]) were sc reened for resistance to Mexican bean beetle (MBB) (Epilachna vorivestis Mulsant) and corn earworm (CEW) [Heliothis zea (Boddie)] defoliation in 1977 and 1978. Of the 258 progeny evaluated, 53% were similar to the resistant check PI 227687 in MBB resistance, but only 7% exhibited dual resistance to MBB and CEW. The level of MBB resistance differed significantly (P ≤ 0.05) among the 17 CEW‐resistant progenies from the three populations. Visual estimates of CEW feeding preference accurately indicated resistance in 73% of all observations, as compared to resistance ratings based on weight of leaf tissue consumed.

Results of the study indicated that levels of MBB and CEW resistance equal to or greater than that of PI 227687 exist in progeny from the three backcross populations tested, and that evaluation of CEW leaf feeding resistance by visual estimate appears to be a useful method of rapidly eliminating large amounts of susceptible germplasm. The low incidence of progeny with CEW resistance among those with high MBB resistance suggested that indirect selection for resistance to CEW leaf feeding by screening for MBB resistance may be ineffective, and that future breeding efforts should utilize direct selection for resistance to CEW defoliation.
A Comparative Analysis of Nuclear‐determined Resistance to Helminthosporium maydis Races T and O in Maize1
Authors: Caunter Ivor G. , Gracen V. E.
Published: July 2010

Nuclear gene resistance to Helminthosporium maydis races T and O was studied using diallel analysis. Plants were artificially inoculated in the field and ratings based on measurements of lesion length and lesion area were obtained. Resistance to both races was basically determined by the same set of nuclear genes. Deviations in the relative rankings of certain inbreds suggested that resistance genes functioned both additively and on a gene‐for‐gene basis with pathogenicity factors.

Gene action conditioning resistance was similar for both races. Additive gene action was primarily involved in determining resistance, but dominance effects were also significant. The results suggest that several, possibly the majority, of genes that condition resistance to race T of H. maydis in the resistant lines, Mol7 and C103, also contribute to resistance to race O.
Trisomic Transmission in Six Primary Trisomics of Sorghum1
Authors: Liang G. H.
Published: July 2010

Transmission rates of the extra chromosomes in six primary trisomics of sorghum (Sorghum bicolor (L.) Moench) were estimated by examining the progeny of selfed trisomics and the progeny when the trisomics were crossed to disomics. When the trisomics were selfed, ‘cone’ had the highest transmission rate (29.3%) and ‘small glume’ the lowest (5.0%). When the trisomics were used as females in crosses with disomics, cone also had the highest transmission rate and small glume the lowest; when the trisomics were used as males in crosses to disomics, transmission rate was greatly reduced in general. Variation in transmission rate was observed from plant to plant for the same trisomic type. Study of the transmission rate of the extra chromosome indicated that the following factors probably were contributing to the lower rate: small or light weight seeds tended to have a higher proportion of trisomics than heavier seeds; lighter seeds had a lower percentage germination; the extra chromosome was often eliminated during meiosis; trisomic plants were less vigorous than disomics and tended to die prematurely. Frequency of aborted pollen in trisomics did not seem to be related to the deviation from expected frequency.
Field Drying of Flint and Dent Endosperm Maize1
Authors: Hunter R. B. , Mortimore G. , Gerrish E. E. , Kannenberg L. W.
Published: July 2010

Flint and dent endosperm type versions of several hybrids were grown under field conditions to determine the effects of endosperm type on field drying rate following physiological maturity. The results indicated there was no inherent major difference in field drying rate between the flint and dent endosperm types. This does not suggest that all flint endosperm material has equivalent drydown rates to the dent germplasm so widely used in North America. However, the findings do suggest that the flint endosperm type per se is not responsible for slow drydown in the field. In this study the dent hybrids were found to have a higher moisture level at physiological maturity than the flint hybrids.
Nitrate‐N and Rhizobium Strain Roles in Alfalfa Seedling Nodulation and Growth1
Authors: Heichel G. H. , Vance C. P.
Published: July 2010

Alfalfa (Medicago sativa L.) seedlings grown for 14 day with initial levels of 0, 10, 25, and 50 µg N/ml as nitrate and inoculated with individual strains of Rhizobium meliloti or a mixture of these strains were investi. gated to learn how seedling growth and nodulation are mediated by nitrate N levels similar to those found in soils during alfalfa establishment. With a mixed Rhizobium culture, the proportion of the seedlings that nodulated declined from 84% at zero N to 53% at 50 µg N/ml. Significant (P = 0.05) differences in frequency of seedling nodulation occurred among individual Rhizobium strains at each N level, and significant (P = 0.05) strain × N interactions were observed.

At 0 and 10 µg N/ml, number of nodules per seedling elicited by inoculation with the mixture of strains was significantly (P = 0.05) higher than with any of the five constituent strains. At 25 and 50 µg N/ml, number of nodules per seedling was similar with the strain mix. ture and with individual strains. At all N levels, seedlings inoculated with a strain mixture consistently developed more leaves and longer roots than uninoculated controis. Individual strains significantly (P = 0.05) differed in stimulation of leaf and root development at 0, 10, and 25 µg N/ml, but not at 50 µg N/ml.

Variance analysis, leaf growth, and nodulation frequency experiments suggested that one of the five Rhizobium strains was less effective than the other four or than the mixture. The results suggest the possibility of improving alfalfa nodulation by selecting for increased nodule numbers in the presence of nitrate N, or by the identification of Rhizobium strains with maximum effectiveness at ambient N levels.