bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Date of Harvest Maturity on Soybean Seed Quality and Phomopsis sp. Seed Information1
Authors: TeKrony D. M. , Egli D. B. , Balles J. , Tomes L. , Stuckey R. E.
Published: July 2010

Wide variation in soybean [Glycine max (L.) Merrill] seed quality is often observed by seedsmen. This investigation was conducted to determine the effect of the date of harvest maturity (first time the seed moisture declined to less than 14%) on seed germination, seed vigor, and infection of seed by fungi. Cultivars varying in maturity from Group II to V were planted in a Maury silt loam soil (Typic Paleudalfs, fine, mixed, mesic) during three periods (mid‐May, mid‐June, and early July) for 4 years (1976 to 1979). Seed were hand harvested at harvest maturity and evaluated for germination, vigor, and seedborne fungi. A wide range in seed quality was observed across the 4 years, with approximately 25% of the 54 cultivar‐planting date combinations having unacceptable seed germination and vigor at harvest maturity. Seed infection by Phomopsis sp. was the major factor influencing seed quality and was negatively correlated (r = −0.88) with seed germination. Phomopsis sp. seed infection decreased and standard germination increased with later dates of harvest maturity. Seed vigor also increased as harvest maturity was delayed, but was not closely correlated with the incidence of Phomopsis sp. seed infection. Later maturing cultivars (‘Kent’ and ‘York’) produced seed of the highest quality regardless of planting date. Delaying the planting date of early and mid‐season cultivars (‘Beeson’, ‘Williams’, and ‘Cutler 71’) delayed harvest maturity which improved seed germination and vigor and reduced the levels of seed infection by Phomopsis sp. Differences in seed quality and seed infection by Phomopsis sp. between two genotypes of nearly identical maturity (OX‐303 and Beeson) grown in similar environmental conditions provided evidence of genetic variability for improving seed quality.
Cytoplasmic Effects on Plant Traits in Interpecific Matings of Avena1
Authors: Robertson L. D. , Frey K. J.
Published: July 2010

Sixty populations of 20 oat lines each, representing reciprocal crosses of the BCo, BC1, and BC2 of all possible matings among five Avena sterilis L. accessions and two A. saliva L. cultivars, were evaluated in a field experiment for grain yield, straw yield, harvest index, heading date, plant height, unit straw weight, and vegetative growth index. On average, A. sterilis cytoplasm delayed heading date by 1.1 days and increased grain yield by 250 kg/ha or 10%. The cytoplasmic effect on heading date was consistent over backcross generations. Average grain yield was significantly greater for lines having A. sterilis cytoplasm in all BC generations, but the differences were less consistent than those for heading date. Straw yield, plant height, unit straw weight, and vegetative growth index were increased significantly by A. sterilis cytoplasm in the BCo, but these advantages decreased by BC1 and disappeared by BC2. Avena sterilis cytoplasm had no effect on harvest index in BCo, but by BC2, it had elevated this trait by 1.1%. Avena sterilis cytoplasm showed no interactions with matings for heading date, which indicates that the effect of the cytoplasm on this trait was direct. Significant interactions of A. sterilis cytoplasm with matings indicate that the grain yield increases were due to specific favorable interactions between A. saliva nuclear genomes and cytoplasms. The interaction between level of backcrossing and cytoplasmic effect for straw yield, plant height, unit straw weight, vegetative growth index, and harvest index probably resulted because of interactions between A. sterilis cytoplasms and A. sterilis nuclear genes, solely, or particular combinations of A. sterilis and A. sativa nuclear genes. These results suggest that breeders may be able to improve the potential for productivity of oats by using diverse cytoplasms. Additionally, cytoplasmic diversity might make oats more stable in production over diverse environments.
Effect of Stratification for Percent Protein in Two Soybean Populations1
Authors: Sebern N. A. , Lambert J. W.
Published: July 2010

Two populations of soybeans, Glycine max (L.) Merr., each having at least one parent with high percent seed protein, were studied to determine the effects of selection for percent protein in an early generation (F2 or F3) upon percent seed protein, percent seed oil, and seed yield in later generations (F4 and F6). The populations were stratified as follows: from 60 F2 plants in one population the 10 highest, the 10 lowest, and 10 intermediate in percent protein were selected; similarly, from 60 F3 lines of the other population the 10 highest, 10 lowest, and 10 intermediate in protein were selected. Resulting F4 lines of both populations were grown in replicated yield tests at two locations. On the basis of mean percent protein in these tests, the five highest lines of the high group, the five lowest of the low, and five intermediate from the intermediate group of each population were identified. Two plant progenies of each selected line were advanced to the F6 generation and grown in replicated yield tests at two locations. There was a significant correlation between early generations and subsequent generations for percent protein indicating that early classification of plants or lines is useful. Although there was a negative correlation between percent protein and seed yield and between percent protein and percent oil, F6 lines with desirable combinations of percent protein, percent oil, and seed yield were identified. The majority of these lines traced to the intermediate protein stratum established in the early generation.
Root Diversity among Peanut Genotypes1,2
Authors: Ketring D. L.
Published: July 2010

Improved drought tolerance of some crops has been associated with extensive root systems. Since peanut (Arachis hypogaea L.) is grown in many arid and semiarid regions, this study was done to determine if peanut genotypes differed in extent of root growth (volume and dry weight). A method to estimate root growth potential of peanut by measuring root volumes was developed and used to make comparisons among peanut genotypes. Plants were grown in the greenhouse for 46 to 49 days in PVC tubes (10.2 cm i.d, and 76.2 cm in length) containing fritted clay. Plants were fertilized twice weekly with 200 ml of modified Hoagland solution and watered twice daily. Comparisons of growth were made among and within virginia, spanish, and valencia botanical type peanut. Genotypes differed in both root (volume and dry weight) and shoot (height, dry weight, leaf area, and leaf number) characteristics. Root volume and dry weight were highly correlated among the entries tested. Shoot dry weight, leaf area, and number of leaves were significantly correlated in most tests. Root dry weight and volume were positively correlated with shoot dry weight, leaf area, and number of leaves, but not necessarily with all of these parameters in every test. The data indicate strong coordination between aerial and subterranean growth and considerable diversity in root volume. The differences among entries in this limited sample of peanut germplasm suggest selections for more extensive rooting traits is feasible for this crop and may prove useful for developing more drought tolerant peanut cultivars.
Genetic Shifts in Mixed Bean Populations. I. Storage Effects1
Authors: Roos Eric E.
Published: July 2010

A mixture containing equal numbers of seed of eight snap bean (Phaseolus vulgaris L.) cultivars was prepared to determine the effects of seed aging on genetic shifts in the population. The mixture was artificially aged to simulate long‐term storage using elevated storage temperatures and relative humidities/seed moisture contents. After seed aging, germination of each cultivar was regressed on the germination of the mixture to develop a series of equations which could be used to predict relative germination of the eight cultivars at any given level of germination for the mixture. Relative germination is defined as the ratio of the germination percentage of any cultivar to that of the highest germinating cultivar. At 50% mixture germination, the relative germination of the eight cultivars ranged from 1.00 (Cherokee Wax) to 0.49 (White Seeded Tendercrop). Computer simulation of the effects of repeated cycles of aging to reduce viability of the mixture to 50% predicted that four of the eight cultivars would be eliminated after eleven cycles, assuming a population size of 64 seeds for each cycle. The results of this experiment demonstrate the potential for loss in genetic variability within heterogeneous germplasm accessions during long‐term storage.
Effect of Genotype ✕ Environment Interactions on Selection for Low Linolenic Acid Soybeans1
Authors: Cramer M. M. , Beversdorf W. D.
Published: July 2010

Five soybean [Glycine max (L.) Merr.] lines of Maturity Groups 00‐0 were grown at two locations over 2 years in the 2600 (earliest) Ontario Soybean Variety Trials (OSVT) and 10 lines of Maturity Groups O‐I were grown at three locations over 2 years in the 2800 (next to earliest) OSVT. The effect of genotype ✕ environment (G ✕ E) interactions on selection for low linolenic acid was evaluated. In both trials G ✕ E interactions were significant. In the 2600 OSVT the genotype ✕ location ✕ year interaction was most important whereas two‐way interactions predominated in the 2800 OSVT. Genotype ✕ location interactions were minimized, however, by selecting a subset of genotypes in the 2800 OSVT with a narrow range of maturities. In both trials, few changes in ranking of genotypes with wide differences in linolenic acid percentage were observed across environments. The ranking of lines, however, varied for genotypes with a narrow range of linolenic acid content. In the latter case testing in more than one environment should be considered. The precision with which differences among genotypes could be detected was estimated by calculating the LSD of genotype means for various year‐location combinations. In both experiments an increase in testing from 1 to 2 years increased precision by about 25%. Increasing the number of locations was also effective but was less important. Increasing the number of replications had the smallest response. This research showed that G ✕ E interactions should be considered when breeding for low linolenic acid soybeans. Such interactions affected both the ranking of genotypes and the precision of detecting differences among genotypes.
A Method of Identifying Lines for Use in Improving Parents of a Single Cross1
Authors: Dudley J. W.
Published: July 2010

A method for identifying inbred lines containing dominant alleles affecting a quantitative trait, which are not already present in an elite single cross, was developed. If the elite single cross is designated P1 ✕ P2 and the lines to be tested Pw, the expression μG = [(P1 ✕ Pw) + (P2 ✕ Pw) − P1 − P2 − Pw − (P1 ✕ P2)]/4 is an estimate of the relative number of loci in Pw which contain favorable alleles not present in P1 or P2. Results from applying the method to a set of corn (Zea mays L.) grain yield data suggest the method may be useful in applied breeding programs.
Comparison of Field and Greenhouse Evaluations for Tolerance to Phytophthora Rot in Soybean1
Authors: Walker A. K. , Schmitthenner A. F.
Published: July 2010

Tolerance to phytophthora rot caused by Phytophthora megasperma Drechs. f. sp. glycinea Kuan and Erwin (Pmg) is an alternative control method to race.specific resistance. Simple, effective, and consistent methods of evaluating tolerance would improve the etficiency of screening genotypes for tolerance. Therefore, the effectiveness and reliability of a field, hill‐plot method and a greenhouse, mycelium‐inoculum‐layer method for evaluating soybean [Glycine max (L.) Merr.] for tolerance to phytophthora rot was studied. A visually rated hill‐plot evaluation and a yield test of 22 genotypes were conducted at Viekery, Ohio in 1977, 1978, and 1979 on soil infested with races 1, 3, 4, and 7 of Pmg. Hill plots were planted on 76‐cm centers with 12 seeds per hill. Hill plots were rated for root‐rot severity in late August by visually estimating the percentage of dead plants and amount of stunting. The yield test was conducted in an area adjacent to the hill plots. The greenhouse evaluations were conducted at Wooster, Ohio by placing 14‐day‐old, V‐8 juice agar cultures of Pmg 5 cm below the seed in composted, hardwood‐bark media. Sterile V‐8 juice agar was used in uninoculated controls. Ten seeds were planted in a 1‐L polystyrene cup. Genotypes grown with and without Pmg were compared for number of live plants and for average plant height at 28 days after planting. Both the hill‐plot and greenhouse disease evaluations were effective and reliable in identifying tolerant soybean genotypes. Field and greenhouse disease ratings were highly correlated with seed yield. Maturity of the genotypes significantly influenced seed yield but did not significantly influence field, hill‐plot ratings or greenhouse ratings.
Prediction of Tassel Initiation in Corn1
Authors: Russell W. K. , Stuber C. W.
Published: July 2010

A diallel of six corn (Zea mays L.) inbred lines was grown in five diverse environments to investigate the feasibility of using the relationship betwen total leaf number and leaf stage at tassel initiation to predict the occurence of tassel initiation. A single quadratic regression line accounted for 96% of the variation in leaf stage at tassel initiation; however, a better fit was obtained when individual linear regression lines were calculated for each entry. On the basis of individual regression lines, data from four of the environments were used to predict the leaf stage at tassel initiation in the fifth environment. The mean absolute value of the residuals from these gressions was less than one‐half a leaf stage.
Genetic Variability and Agronomic Performance of Soybean Populations Developed from Plant Introductions1
Authors: Vello N. A. , Fehr W. R. , Bahrenfus J. B.
Published: July 2010

Plant introductions (Pl's) of soybean [Glycine max (L.) Merr.] may enhance genetic improvement for yield beyond the level possible with the domestic gene pool of cultivars and experimental lines. The genetic variability and agronomic performance of soybean populations with five different percentages of PI germplasm were evaluated. Forty PI's and 40 domestic cultivars and experimental lines were intermated systematically during four generations to form the populations AP10 (100% PI), APII (75% PI), API2 (50% PI), AP13 (25% PI), and (0% PI). In 1980, 200 random lines from each population with a restricted range in maturity were evaluated for seed yield and time of maturity at two locations in Iowa. In 1981, 60 of the highest‐yielding lines from each population were evaluated for seed yield, time of maturity, plant height, and lodging at three Iowa locations. The genetic variability for seed yield among the 200 random lines was similar for API0 to API3 and about twice as large as the genetic variability for AP14. The mean yields of the random lines of 1980 and the selected lines of 1981 were greatest for AP14 and least for AP10. In the regression of mean yield of the populations in 1980 on percentage of PI germplasm in the populations, 73% of the variation was explained by the linear component. There was a similar decrease from API4 to API0 in the mean yields of the top 10 and 20 lines of each population that could be used as parents to form cycle 1 populations for recurrent selection. Lodging susceptibility of the populations decreased progressively from AP10 to AP14. The maximum difference in plant height among populations was only 8 cm. The use of PI germplasm for short‐term improvement of yield is not likely to be as productive as selection in populations developed from domestic cultivars or experimental lines. Longterm recurrent selection studies will be required to determine the ultimate value of PI germplasm for yield improvement of soybean.
Comparisons of Oat Population Developed by Intraspecific and interspecific Hybridization1
Authors: Murphy J. P. , Frey K. J.
Published: July 2010

Characteristics of four populations developed by interspecific (Avena sterilis ✕ A. sativa3) hybridization and two populations developed by intraspecific (A. sativa ✕ A. sativa) hybridization were studied to determine their potential utility in a spring oat breeding program. Six A. sativa cultivars and four randomly chosen A. sterilis introductions served as parents in the development of the six populations, each containing between 510 and 576 lines. The experiment was conducted over two years and three locations in Iowa. There were no significant differences among the six population grain yield means. Overall, intraspecific populations had a vegetative growth rate mean of 8% greater than the interspecific population mean, although individual interspecific populations had means equal to intraspecific populations. Interspecific populations did not display consistently larger genetic variances for either trait. Intraspecific populations had between 1.8 and 2.3% and interspecific populations between 0.0 and 1.8% high transgressive segregates for grain yield. Intraspecific populations had between 0.0 and 4.1% and interspecific populations had between 0.8 and 3.1% high transgressive segregates for vegetative growth rate. Differences between observed and expected population means suggest that non additive gene effects influenced grain yield and vegetative growth rate in both population groups. Subdivision of genetic variances in interspecific populations indicated that recombination between the genomes of the two species for loci controlling grain yield and vegetative growth rate was random. A population developed from a broad sample of A. sativa cultivars was a more efficient short‐term strategy for grain yield and vegetative growth rate improvement than was the introgression of limited samples of randomly chosen A. sterilis germplasm.
Selection for N Concentration and Forage Yield in Alfalfa1
Authors: Teuber Larry R. , Levin Renée P. , Sweeney T. Colleen , Phillips Donald A.
Published: July 2010

Alfalfa (Medicago sativa L.) germplasm pools developed by two cycles of phenotypic recurrent selection for forage dry matter production and forage reduced N concentration were evaluated under glasshouse conditions. Selections were based on previously described protocols that involved independent culling levels for dry matter and reduced‐N concentration in forage produced by each genotype grown sequentially on N2 and NH4NO2 as N sources. A single Rhizobium genotype (R. meliloti Dang, strain 102F28) was used in all selection and test procedures, and plants were evaluated at a single morphological stage during the two cycles of selection. In two nondormant germplasm sources, ‘Hairy Peruvian’ and ‘African,’ significant (P ≤ 0.01) increases were made in both forage dry matter production and reduced‐N concentration. Two cycles of selection for high dry matter production and high reduced N concentration increased dry matter 52% and reduced N concentration 5.2% averaged over both N sources in Hairy Peruvian. Results from African showed 17 and 5.2% increases, respectively, in the same parameters. Selection for average dry matter production and either high or low reduced N concentration resulted in significant (P ≤ 0.01) changes in reduced N concentration. Only selection for high dry matter production and high reduced N concentration, however, increased total forage N.
Effects of Plant Smoothness on Agronomic Traits of Upland Cotton—Lint Percentage1
Authors: Lee Joshua A.
Published: July 2010

In attempts to document agronomic deficits associated with plant smoothness in cotton (Gossypium hirsutum L.), two complete diallel sets involving various combinations of smoothness and pilosity alleles were grown in randomized, complete blocks at two locations in North Carolina in 1982. There were four replications per location. The first diallel was generated by intercrossing stocks homozygous for the allelic pairs Sms11 and sml, and Sm2 and sm2, and the second from intercrossing Sm2 and sm2, and Sm, and smh3. Increasing the number of Sm alleles increases plant smoothness, whereas the completely recessive genotype (all sm alleles) determines normally pubescent, the phenotype of ‘Coker 310’, the cultivar used as background. Within the two diallels, lint percentage varied from 38.1 to 43.3 with the lowest values associated with the Sm2 allele, and the highest involving a hybrid of Sms11 and sm1. Although the Sms11 allele was associated with a small deficit in lint percentage when homozygous, only the Sm2 allele was accompanied by significant deficits, and that related to relatively low lint index. Number of seeds per boll, seed index (weight of 100 seeds, g), lint index (lint per 100 seeds, g), and grams of seed cotton per boll varied significantly among some entries. There was no evidence that values for any of these traits tracked degree of plant smoothness. Mostly additive effects were associated with significant contrasts for most of the traits, although there were some significant interaction effects, particularly with the Sm2 and sm2 pairs of alleles. There was no evidence that increasing plant smoothness to the point of eliminating trichomes reduced lint percentage any lower than that associated with the Sm2 monomeric genotype.
Photoperiod Regulation of Floral Initiation for Soybean Plants at Different Ages1
Authors: Thomas Judith F. , Raper Davis C.
Published: July 2010

Soybean plants [Glycine max (L.) Merr.] of the determinate cultivar Ransom growing in controlled environments under 16‐h photoperiods were exposed to 10, 12, 14, 15, and 16‐h photoperiods upon expansion of either the two primaries or fifth trifoliolate leaf (V1 and V6 developmental stages, respectively) to determine the influence of plant size on sensitivity to photoperiod. Plants were sampled at 2 to 3‐day intervals over a 21‐day treatment period and examined microscopically for evidence of floral development. Time of floral initiation for plants exposed to photoperiod treatments at either V1 or V6 stage varied only by a few days among photoperiods, but the subsequent differentiation of floral primordia was much more rapid at shorter than at longer photoperiods. These results confirm previous observations for plants transferred upon expansion of the first trifoliolate leaf (V2 stage) and indicate that sensitivity of floral responsiveness to photoperiod changed little with plant size.
Oil Composition in Parental, F1, and F2 Populations of Two Oat Crosses1
Authors: Karow R. S. , Forsberg R. A.
Published: July 2010

The goal of this study was to determine the feasibility of maintaining or increasing the oil content of oats (Avena sativa L.) while decreasing polyunsaturated fatty acid concentration. The F1 and F2 populations from crosses between dissimilar parents were analyzed for groat oil percentage and for fatty acid composition. Inheritance patterns for linolenic acid suggested additive genetic control while oleic and linoleic acids were each controlled, in part, by a partially dominant gene or genes. Both additive and dominance gene action were observed for oil concentration. Cytoplasmic influence on fatty acid composition was not evident in reciprocal F1 populations but was suggested by F2 population analysis. Heritability estimates for the various fatty acids ranged from 49.3 to 79.8%. Oleic acid percentage was positively correlated with oil concentration while linoleic and linolenic acid correlations with oil level were negative. The breeding objective of lowering polyunsaturate concentration as a percentage of oil may be readily attained; however, if concentration as a percentage of grain is used, success seems less likely.
Alfalfa Yield Response to a Between‐Cutting Contact Herbicide1
Authors: Wolf D. D. , Foy C. L.
Published: July 2010

Alfalfa (Medicago sativa L.) fields sometimes develop weed infestation problems when conditions at harvest favor germination of weed seeds or when the stand begins to thin and lose vigor. A recently approved label for use of the contact herbicide paraquat (1,1′,dimethyl‐4, 4′‐bipyridinium ion) allows application between cuttings for weed control. Label directions require application of no more than 0.28 kg ha−1 within 5 days after cutting. The net result of this practice is increased yields of alfalfa if effective weed control is achieved. Our studies with weed‐free alfalfa stands indicated a 7.8% yield reduction caused by paraquat applied within 5 days after hay harvest. A greater reduction might have occurred if treatment was delayed beyond 5 days. This slight harmful effect was expressed only in the first cutting after treatment of weed‐free stands and always greatly offset by control of weeds in weedy alfalfa stands. The benefit from between‐cutting paraquat treatment was positively related to the degree of weed infestation. Alfalfa yields in two harvests following the between‐cutting paraquat treatment were increased by 2.40 Mg ha−1 as compared with nontreated weedy plots. In an old weedy alfalfa field, yields of alfalfa were increased three‐fold with a 70% decrease in weed composition for the first harvest following treatment. The weed control benefit was also observed in the second harvest after treatment. Stand longevity and sustained high yields should prove to be additional advantages to the practice of between‐cutting weed control using paraquat.
Characterization of Flowering Response to Photoperiod in Diverse Soybean Genotypes1
Authors: Cregan P. B. , Hartwig E. E.
Published: July 2010

Photoperiodic response of soybean [Glycine max (L.) Merr.] a major factor determining the latitude at which soybean cultivars are grown. Soybean cultivars adapted to temperate North America are often unproductive when grown under short‐day conditions because flowering and reproductive growth are initiated before adequate vegetative growth has occurred. To compare initiation of flowering in response to photoperiod in soybean, a total of 12 soybean genotypes were evaluated under constant photoperiodurations ranging from 11 to 20 h per 24 h. The soybean lines included PI 274454 and PI 159925 which, as a result of previous field tests, had been identified as having delayed flowering under short‐day conditions. In addition, a number of cultivars from a spectrum of maturity classifications were tested. In constant photoperiods of less than 14 h, PI 274454, PI 159925, and lines derived from crosses with PI 159925 flowered significantly later than any of the other genotypes tested including the normally late maturing cultivars ‘Biloxi’ and ‘Jupiter’. The regression of days to first flower on photoperiod duration was used to characterize the photoperiod response of each genotype. The soybean lines were placed in three response categories: those with no response, those with only linear response, and those with both significant linear and quadratic response. The genotypes characterized as late flowering under short‐day conditions showed only linear response. Cultivars such as ‘Maple Arrow’, ‘Williams’, ‘Hill’, ‘Tracy’, and ‘Forrest’, typical of soybeans grown in much of temperate North America, have both linear and quadratic response.
Effect of N Fertilization on Silk Synchrony, Ear Number, and Growth of Semiprolific Maize Genotypes1
Authors: Anderson E. L. , Kamprath E. J. , Moll R. H. , Jackson W. A.
Published: July 2010

Prolific (two‐eared) maize (Zea mays L.) genotypes usually yield more grain per plant than do comparable nonprolific (one‐eared) genotypes. Among semiprolific genotypes a larger proportion of two‐eared plants results when the top and second ear shoots emerge within 24 h of each other (silk synchrony). The present investigation was conducted to determine the influence of N fertilization on silk synchrony and the development of the second ear. A further objective was to determine the independent effects of silk synchrony and ear number on plant growth throughout the grain‐filling period at different levels of N. Nitrogen rates were 56 and 224 kg N/ha. A plant density of 22 600 plants per ha was used in order to provide an adequate number of both one‐ and two‐eared plants for sampling. Plants were classified as to silk synchrony and ear number. Leaves, stalks, and ear shoots were sampled four times during reproductive growth. Measurements were made of dry weight and N content. Increased rate of N fertilization resulted in a higher percentage of plants with synchronous silks and also increased the percentage of plants with synchronous silks that developed two ears. At a low N rate one‐eared plants with synchronous silks accumulated more dry matter and N than did plants with asynchronous silks. At high N rate silk synchrony per se had no effect. The higher grain yield at the high N rate was due to a higher percentage of two‐eared plants. Two‐eared plants accumulated more ear and total dry weight and total N than did one‐eared plants. Two‐eared plants also partitioned more of the dry weight and N to the ear than did one‐eared plants.
Diallel Analysis of Potato Leafhopper Resistance Among Selected Alfalfa Clones1
Authors: Soper J. F. , McIntosh M. S. , Elden T. C.
Published: July 2010

The quantitative genetics of potato leafhopper Empoasca fabae (Harris) resistance among selected alfalfa (Medicago sativa L.) clones from three different alfalfa populations (Arc‐PLH1, B16 Syn.I‐PLH1, and Indiana Syn. C) was studied. Resistance was measured using no‐choice laboratory screening techniques. Feeding damage after 1 and 2 weeks of exposure to leafhopper adults (FD‐1 and FD‐2, respectively) and subsequent nymphal populations were measured. A 10‐parent diallel analysis was performed to detect combining ability effects for the resistance characteristics. General combining ability effects were significant for FD‐1 and the number of nymphs. Specific combining ability effects were significant for the number of nymphs. Midparent‐offspring regression analyses were performed to obtain narrow sense heritability estimates for the resistance characteristics. The estimates obtained were 0.31, 0.31, and 0.56 for FD‐1, FD‐2, and the number of nymphs, respectively. A positive phenotypic correlation was found between FD‐1 and FD‐2 (r = ‒0.73**) (**significant at the 0.01 level.). The number of nymphs was negatively correlated with high levels of FD‐I (r = ‐0.49**), but was not correlated with FD‐1 at low or moderate levels. Results indicate that further improvements in potato leafhopper resistance as measured by these characteristics can be made in populations derived from the selected alfalfa clones
Peduncle Elongation in Dwarf and Normal Height Oats1
Authors: Kolb F. L. , Marshall H. G.
Published: July 2010

Dwarf oat (Avena sativa L.) lines with stiff straw are of interest because of their potential use as parents in the development of semidwarf cultivars. This study was conducted to obtain basic information about the relationship of peduncle cell length and cell number to the height of dwarfs. Two dwarf oat lines (NC 2469‐3 and OT 207) were studied and compared to the conventional height lines (NC 2469 and OT 184) from which the dwarfs were derived. Peduncles from primary culms of greenhouse grown plants were measured throughout peduncle elongation. The frequency of mitotic figures in the intercalary meristem was determined. The length of parenchyma cells was measured in longitudinal sections from three regions of fully elongated peduncles. The rate of peduncle elongation of OT 184 was faster than that of the dwarf OT 207. The percentage of dividing cells in the intercalary meristem in OT 207 (5.0%) was less than that of the parental line OT 184 (7.3%). NC 2469‐3 and NC 2469 did not differ in the frequency of mitotic figures in the intercalary meristem and differed only slightly in the rate of peduncle elongation. NC 2469‐3 had significantly shorter cells in the upper regions of fully elongated peduncles than NC 2469. The reduced peduncle length of NC 2469‐3 resulted largely from these shorter cells, but reduced cell number also may have contributed to reduction in peduncle length. In contrast, the parenchyma cells in the middle and upper regions of the dwarf OT 207 peduncle were not different in length from those of OT 184. The cells at the base of the peduncle of dwarf OT 207 were longer than those of OT 184. Therefore, the shorter peduncles of OT 207 were due primarily to fewer cells per peduncle file.
Carbon Metabolism in Alfalfa Root Nodules: Developmental Patterns of Host Plant Enzymes Before and After Shoot Removal1
Authors: Henson Cynthia A. , Collins Michael
Published: July 2010

Dinitrogen fixation in the nodules of perennial forage legumes usually decreases rapidly after the harvest of shoots and then increases as new shoots are produced. In this study the activities of enzymes of carbon metabolism which may indirectly support dinitrogen fixation and subsequent assimilation were measured in the plant fractions of alfalfa (Medicago sativa L.) nodules before and after shoot removal. Nodule enzymes of sucrose and glucose metabolism (invertase, glucose‐6‐phosphate dehydrogenase) and organic acid metabolism (malate dehydrogenase and NADP‐isocitrate dehydrogenase) decreased rapidly in activity (gram fresh weight basis) after shoot removal. Except for NADP‐isocitrate dehydrogenase, the decreases in specific activity of these enzymes after shoot removal were similar to that for soluble protein suggesting general proteolytic degradation. Amylase activity showed no clear response to shoot removal. These data suggest that when alfalfa shoots are removed, root nodule capacity to metabolize some hexoses and organic acids is reduced while the capacity to degrade nodule starch is not greatly influenced.
Digestion of Stem Tissues in Panicum Species1
Authors: Akin Danny E. , Brown R. Harold , Rigsby Luanne L.
Published: July 2010

Previous research on C4, C3, and intermediate species in the Panicum genus has shown variations in leaf blade anatomy and in digestibility. However, the stems have not been examined for such characteristics. The objective of this research was to determine cross‐sectional tissue percentages and histological reactions of tissues for lignin in upper and lower internodes of seven Panicum species differing in photosynthetic pathways and the reaction of tissues to rumen microbial degradation using microscopic techniques. The proportion of dry weight in stem averaged 31% for the seven species, ranging from 23 to 40%. About half (48 ± 10%) of the stem cross‐sectional area was parenchymand, in general, large differences in tissue types between upper and lower internodes did not occur. The epidermis, sclerenchyma ring, and vascular bundle (except phloem) contained lignin in most all species and were not degraded in stems of any species during 48 h incubation with rumen microorganisms. The parenchyma showed a variable reaction for lignin, with the lower internodes giving a positive reaction with chlorine sulfite in all but P. antidotale. Two species, P. maximum and P. virgatum, showed positive lignin reactions in the parenchyma with acid phloroglucinol. The parenchyma in lower internodes tended to be less digestible than that in upper ones and was significantly less digestible (P < 0.05) after 48 h digestion in P maximum, P. virgatum, and P. milioides. Variations occurred in the degree of degradation among species. No distinctive characteristics for stems in these species were related to photosynthetic type.
Patterns of Resistance in Sorghum to the Sorghum Midge1
Authors: Widstrom N. W. , Wiseman B. R. , McMillian W. W.
Published: July 2010

The sources of resistance to midge, Contarinia sorghicola (Coquillett), in sorghum [Sorghum bicolor (L.) Moench] have a need to be characterized so that different types may be consolidated and/or integrated into an effective selection program. Two separate sets of sorghum parents, F2, F3, and selfed backcross generations, (F1P1)S and (F1P2)S, were grown on a Tifton sandy (fine‐loamy, siliceous, thermic Plinthic Paleudult) in five‐replicate field experiments in 1971 and evaluated for resistance to sorghum midge. No simple inheritance pattern was evident, but the resistance of sorghum line SGIRL‐MR‐1 was determined to be inherited as primarily recessive. F2 progenies from nine crosses and their reciprocals were grown in replicated tests in two or more years during 1979–1981. Results revealed significant differences in resistance to the sorghum midge between progeny of reciprocal crosses. The resistance of the lines PI383856 and SGIRL‐MR‐1 seemed to be inherited differently. The resistance in PI383856 tended to diminish in crossbred progenies when the line was used as a female and resistance in all SGIRL‐MR‐1 crosses tended to be recessive. Therefore, PI383856 or SGIRL‐MR‐1 should have utility in breeding for resistance by alternate crossing or backcrossing and selfing during selection. Resistance in PI383856 and SGIRL‐MR‐1 should be combined into a common source that might be more stable and have a higher level of resistance to sorghum midge damage than either line alone.
Plot Type and Treatment Method for Assessment of Soybean Response to Defoliation1
Authors: Mesa Diane P. , Fehr Walter R.
Published: July 2010

Extensive labor is required to simulate soybean [Glycine max (L.) Merr.] defoliation in bordered row plots by removing a designated percentage from each leaf on all plants. We evaluated the use of unbordered hill plots and removal of all leaflets from a designated percentage of plants in a plot as a potential means of reducing the labor requirement. A determinate and an indeterminate cultivar were grown in an unbordered hill‐plot experiment that was adjacent to a bordered row‐plot experiment during 1981 and 1982. The leaf method of defoliation consisted of removing 0, 1, 2, or 3 of the leaflets from every leaf on all the plants in a plot, and the plant method consisted of removing all the leaflets from 0, 33, 66, or 100% of the plants in a plot. The treatments were imposed at the full‐bloom (R2) and beginning‐seed (R5) stages. The average yield loss from defoliation was 27.6% in the hill experiment and 17.7% in the row‐plot experiment. Although the main effect of plot type was not significant when tested with the plot type by year interaction, the greater loss in hill plots was consistent across cultivars, defoliation methods, and years. The plant method of defoliation had an average yield loss of 22.6%, which was significantly greater than the 16.2% loss obtained by the leaf method. Significant differences for 100‐seed weight were observed between defoliation methods, but not between plot types. Differences between plot types and defoliation methods for changes in maturity, height, and lodging were not significant. Hill plots should not be considered as substitutes for bordered row plots in estimating the yield response of a commercial soybean field to defoliation. The plant method of defoliation required less labor for imposing treatments than the leaf method, but the estimates may be biased by the effects of interplant competition in a mixture of defoliated and undefoliated individuals.
An EMS Induced Dominant Allele for Male‐Sterility Transferred to Euplasmic Wheat1
Authors: Maan S. S. , Williams N. D.
Published: July 2010

A dominant allele for male sterility was transferred to euplasmic Triticum aestivum L. from an alloplasmic T. aestivum line having cytoplasm of Aegilops squarrosa L. This was made possible when the expression of the dominant allele was altered in a few florets of an alloplasmic male‐sterile plant grown in a summer greenhouse where day‐temperature ranged from 21 to 35°C. The pollen from the exceptional fertile anthers of the alloplasmic male‐sterile plant was used to transfer male sterility to euplasmic T. aestivum. Transmission of the dominant allele in the progenies of euplasmic and alloplasmic T. aestivum lines was compared for several backcross generations. Male‐sterile plants with cytoplasm of either species had small, aborted, and nonextruding anthers under normal growing conditions. Expression of the dominant allele for male sterility apparently remained stable in the cytoplasmic background of alloplasmic as well as euplasmlc T. aestivum plants grown within the normal range of temperatures for wheat (16 to 25°C). Male‐sterile progeny of the euplasmic male‐sterile plant was used as a cytoplasmic source to attempt a transfer of the dominant allele to euploid T. durum Desf. Either the dominant allele for male sterility could not be transferred to euploid T. durum or the allele was not expressed in the nucleus of euploid T. durum under the conditions of this experiment.
Selection for Low Protein in Barley1
Authors: Piper Todd E. , Rasmusson Donald C.
Published: July 2010

Four populations were studied to determine effectiveness of selection for low grain protein content in spring barley, Hordeum vulgare L. From 46 to 60 unreplicated F5 lines were grown for each of the four populations at Crookston, MN in 1980. Selection blocks based on check cultivars were used to aid selection of 20% of the lines for low grain protein and 10% of the lines for high grain protein. The selected lines were grown in replicated trials at St. Paul and Crookston, MN in 1981. Realized heritabilities for grain protein content for the four populations ranged from 18 to 100% with a mean of 54%. Grain protein content was independent of grain yield, whereas protein content showed a variable relationship in the four populations with percent plump kernels. These findings encourage selection for grain protein content in early generation barley populations using one row plots.
Host Plant Nodule Enzymes Associated with Selection for Increased N2 Fixation in Alfalfa1
Authors: Groat R. G. , Vance C. P. , Barnes D. K.
Published: July 2010

In legumes symbiotically fixed N2 is assimilated into C skeletons to form amino acids as a prerequisite for enhancing plant growth. No attempts have been made to determine which nodule enzymes of ammonia and C assimilation are related to N2 fixation in alfalfa (Medicago sativa L.). The objective of this study was to assess if nodule enzymes of ammonia and C assimilation were associated with acetylene reduction acitivity in alfalfa genotypes previously selected for various traits associated with N2 fixation. Nodules from eight subpopulations derived by bi‐directional selection within each of two alfalfa germplasm sources, an intercross between the two germplasm sources and three alfalfa cultivars were used to measure nodule soluble protein, and in vitro specific activities of the plant enzymes glutamine synthetase (GS), glutamate synthase (GOGAT) glutamate dehydrogenase (GDH), and phosphoenolpyruvate carboxylase (PEPC). Acetylene reduction rate was measured as an indicator of nitrogenase activity. Significant genotypic differences were observed among subpopulations for all variables tested. The GOGAT and PEPC activities were correlated with acetylene reduction activity in one germplasm source but not the other. Phenotypic correlation coefficients among variables showed that GOGAT and PEPC activities were frequently coupled. Germplasm differences in nodule enzyme activity suggest that nodule carbon and N assimilation may be more closely associated with N2 fixation potential in one germplasm than the other. The GOGAT and PEPC activity may be useful traits to include in breeding programs to enhance N2 fixation in alfalfa.
Influence of Temperature on Leaf Dark Respiration of Diverse Tall Fescue Genotypes1
Authors: Volenec J. J. , Nelson C. J. , Sleper D. A.
Published: July 2010

Reduction of dark respiration (RD) of mature tissues could improve herbage yield of tall fescue (Festuca arundinacea Schreb.), especially during summer. Our objectives were to 1) examine the response of RD of collared leaf blades to temperature in seven genotypes of tall fescue, and 2) examine the interrelationships between RD, concentrations of water‐soluble carbohydrate (WSC) and N Of leaf blades, and sward yield components. Seven randomly selected genotypes were vegetatively propagated into pots. In Exp. I, established plants were allowed to regrow in controlled‐ environment chambers at leaf blade temperatures of 20, 27, or 34°C, while in Exp. II regrowth of genotypes was at 20, 25, and 30°C. A 14‐h photoperiod with photosynthetic photon flux density of 650 and 665 μmol m−2 s−1 was provided in Exp. I and II, respectively. After 6 weeks of regrowth at the specified temperatures, RD of center‐sections of recently‐collared leaf blades was measured manometrically and CO2 exchange rate (CER) was measured on similar leaves using an infrared gas analyzer. Within both experiments, RD at temperatures of 27°C or less were similar, averaging 10.8 and 6.8 μmol 02 kg−1 s−1 for the genotypes with the highest and lowest RD, respectively. At 30°C genotypes did not differ in RD but rates averaged 40% higher than those at 27°C or less. No plants survived at 34°C. The CER decreased as temperatures increased and was not related to RD or any other characteristic measured. At 27° C or less concentrations of WSC were lowest, while concentrations of N were highest in leaf blades of genotypes with high RD. As temperatures increased, concentrations of WSC decreased while N increased. Genotypes with high RD had significantly lower yield per tiller (YPT) and mass of WSC per stem base when compared with low‐RD plants. Genotypic variation for RD was apparent at temperatures between 20 and 27°C. Therefore, selection for altered RD would be more efficient at temperatures favorable for growth. Low N and high WSC concentrations of leaf blades may result from selection for low RD of collared leaf blades. Large stem bases with high concentration of WSC may also be selected indirectly with low RD, resulting in high YPT.
Response of Soybean Fruit Respiration to Changes in Whole Plant Light and CO2 Environment1
Authors: Satterlee L. D. , Koller H. R.
Published: July 2010

A nondestructive indicator of instantaneous seed growth rate in soybean [Glycine max (L.) Merr.] and other legumes would useful in studies of the physiology of seed growth. The responsiveness of soybean fruit respiration rate to whole plant environmental treatments known to affect photosynthate supply and seed growth was evaluated. Dark respiration (CO2 efflux) rates of individual, intact soybean fruits at the mid‐pod‐filling stage were measured while manipulating photosynthetically active radiation (PAR) or ambient CO2 concentration in growth chambers. The PAR levels employed were 450, 110, or 30 μmol m−2 s−1 and CO2 concentrations were 300 or 150 μL L−1. Fruit respiration rate.began to decline within 24 h after plants were subjected to either decreased PAR or CO2 concentration. After 2 to 3 days the response was complete and fruit respiration rate remained constant at a level determined by the treatment for an additional 4 days, the longest period evaluated. The respiratory response was rapidly reversible when either PAR or CO2 concentration were returned to control levels. As PAR was lowered from 450 to 110 or 30 μmol m−2 s−1, seed growth rate declined from 20.3 to 11.0 or 8.7 mg day−1 fruit−1, respectively. Fruit respiration and seed growth were apparently responding to changes in photosynthate supply. The results indicate that in situ fruit respiration rate is responsive to changes in the physiological status of the plant and may be useful as an indicator of instantaneous seed growth rate in some situations.