bluuebunny/crossref_metadata_2025 huggingface dataset:
Selection Criteria for Combining High Grain Yield and High Grain Protein Concentration in Bread Wheat
Authors: McKendry Anne L. , McVetty P. B. E. , Evans L. E.
Published: July 2010

This study was designed to identify selection criteria for the simultaneous improvement of grain yield and grain protein concentration in spring wheat (Triticum aestivum L.). Eight cultivars were selected. Six expressed contrasting levels of grain protein concentration and grain yield. Two, the cultivars ‘UM632’ and ‘UM684’, expressed high levels of both traits concurrently. Plants in replicated plots were sampled from anthesis to maturity over 2 yr and data were collected on traits related to nitrogen (N) and dry matter accumulation and remobilization. Grain protein concentration was not correlated with grain yield but was correlated with post‐anthesis N uptake (r = 0.66**), total plant N at maturity (r = 0.49**), and N harvest index (r = 0.87**), and was inversely correlated with vegetative N at maturity (r = −0.49**). Grain yield was correlated with both post‐anthesis N (r = 0.50**) and dry matter uptake (r = 0.58**), with total N (r = 0.78**) and dry matter (r = 0.77**) at maturity, and with harvest index (r = 0.83**). Grain protein yield was highly correlated with post‐anthesis N accumulation (r = 0.90**), total N at maturity (r = 0.98**) and the sum of N harvest index and harvest index (r = 0.93**). UM632 and UM684 coupled high post‐anthesis N uptake and total N at maturity with high remobilization efficiency and N harvest index, while maintaining harvest index. We concluded that grain protein concentration and grain yield could be improved simultaneously if selection was practiced for threshold levels of grain yield or protein concentration followed by selection for grain protein yield in populations constructed from crosses combining high total N at maturity, N harvest index and harvest index.
Agronomic Performance and End‐Use Quality of 1B vs. 1BL/1RS Genotypes Derived from Winter Wheat ‘Rawhide’
Authors: Moreno‐Sevilla B. , Baenziger P. S. , Shelton D. R. , Graybosch R. A. , Peterson C. J.
Published: July 2010

The winter wheat (Triticum aestivum L.) cultivar Rawhide is heterogenous for the 1BL/1RS translocation. The 1BL/1RS translocation has been proven to increase grain yield and decrease end‐use quality in bread wheat. The objective of this research was to investigate if the excellent yield performance of Rawhide was due to higher yielding 1BL/1RS lines compensating for lower yielding 1B lines and if the acceptable quality of Rawhide was produced by higher end‐use quality 1B lines compensating for lower end‐use quality 1BL/1RS lines. To do so, 19 homogeneous 1B genotypes and 18 homogeneous 1BL/1RS genotypes were selected from Rawhide. These genotypes, three composites (Composite 1B, Composite 1BL/1RS, and Composite Total), Raw‐hide, and three check cultivars, were evaluated in four Nebraska environments for grain yield, yield components, and end‐use quality traits. No significant differences were found between chromosome classes for grain yield. The 1BL/1RS genotypes had a higher kernel weight (4%) than IB genotypes; however, the 1B genotypes had a greater number of spikes per square meter (5%). Composites were no different from Rawhide and from each other for grain yield and yield components. For end‐use quality traits, the 1BL/1RS genotypes had a higher protein content (137 mg g−1)> similar mixing time (4.8 min), and lower mixing tolerance (3.5) than 1B genotypes (132 mg g−1, 5.0 min, and 4.9, respectively). However, a mixing tolerance value of 3.5 is acceptable. In general, no differences were found among the composites and between the composites and Rawhide for quality traits. Hence, the 1BL/1RS translocation was not beneficial for yield nor was it detrimental for end‐use quality in this genetic background.
RAPD Characterization of Poa annua L. Populations in Golf Course Greens and Fairways
Authors: Sweeney Patricia M. , Danneberger T. Karl
Published: July 2010

Although identical populations of Poa annua L. may colonize golf course greens and fairways, management practices may cause strong selection pressure and cause genetic shifts in adjacent populations. The objective of our research was to assess genetic differences in adjacent P. annua populations with RAPD markers. Cores were collected from greens and fairways of three golf course holes and RAPD markers used to evaluate genetic differences between the two environments. Eighty‐six primers were screened to evaluate differences between bulk samples of greens and fairways. Nine primers produced 12 RAPD markers. Five of these were used to evaluate 54 individual plant samples from each environment. Statistical evaluation indicated significant differences (P = 0.01) between the green and fairway populations for four of the RAPD markers and among holes within fairways for three markers. These differences may indicate limited gene flow between adjacent populations of P. annua.
Molecular Marker‐Facilitated Analysis of Introgression in Winter Wheat × Triticum tauschii Populations
Authors: Fritz A. K. , Cox T. S. , Gill B. S. , Sears R. G.
Published: July 2010

Triticum tauschii (Coss.) Schmal., a wild, diploid ancestor of common wheat (Triticum aestivum L.) has become an important genetic resource for wheat improvement. As this trend continues, a detailed understanding of the introgression process becomes increasingly important. This study utilized molecular markers to track introgression of T. tauschii DNA into common wheat. Genotypes of 147 BC2F1 lines derived from crosses between wheat and T. tauschii were determined for one protein, 25 restriction fragment length polymorphisms, and eight random amplified polymorphic DNA markers. MAPMAKER and GMENDEL computer programs were used to determine linkage groups and genetic distances. Map orders and recombination distances of linked probes compared favorably with the existing T. tauschii map except for chromosome 4D, which was inherited as a unit. Certain chromosomal segments from either T. aestivum or T. tauschii were transferred more frequently than expected, and choice of recurrent parent played a role in the level of introgression that occurred. Recombination between the D genomes of T. aestivum and T. tauschii occurs at a level similar to that in an intraspecific cross; any abnormalities that exist should not hinder the ability to transfer genes of interest while eliminating flanking chromatin that may be responsible for deleterious effects.
Marker‐Based Analysis of Quantitative Traits in Winter Wheat × Triticum tauschii Populations
Authors: Fritz A. K. , Cox T. S. , Gill B. S. , Sears R. G.
Published: July 2010

Triticum tauschii (Coss.) Schmal. has become a commonly used genetic resource for wheat improvement. Although genes controlling qualitative traits such as disease and insect resistances are generally targeted in germplasm development programs, genes for quantitative traits may be introgressed along with the target genes. This study was designed to identify genomic regions associated with quantitative traits from hexaploid/diploid wheat crosses. One hundred forty‐seven BC2F1‐derived families from crosses between elite common wheat (Triticum aestivum L.) lines and T. tauschii were evaluated for yield, kernel weight, protein concentration, and kernel hardness in field experiments at two locations during 2 yr. Genotypes of these families were determined by testing with one protein, 25 restriction fragment length polymorphism probes, and eight random amplified polymorphic DNA (RAPD) markers. Two RAPD markers were associated with consistent effects on grain yield. Three markers were associated with kernel weight, accounting for 16% of the variance among families. In addition, two loci associated with protein concentration and one locus associated with kernel hardness were identified, accounting for 29 and 9% of the variance among families for the respective traits. In most instances, quantitative trait loci had relatively small effects, and regression analysis of agronomic performance on proportion of marker alleles from T. tauschii showed that the majority of linked chromatin from the diploid species had no detectable effect on any trait. Based on these results and previous studies, T. tauschii can be considered a primary source of resistance genes for wheat improvement.
Sainfoin Regrowth Declines as Metabolic Rate Increases with Temperature
Authors: Kallenbach R. L. , Matches A. G. , Mahan J. R.
Published: July 2010

Sainfoin (Onobrychis viciifolia Scop.) often exhibits poor growth following periods of high ambient temperatures. Our objective was to investigate the influence of air and soil temperature on regrowth and persistence of sainfoin. At 99 d post planting, ‘Renumex’ sainfoin grown in 5‐ by 40‐cm tubes were placed into growth chambers. Treatments were chamber air temperatures of 15, 25, or 35°C with soil temperatures of 10, 20, or 30°C. After a 21‐d adjustment period, all plants were clipped to 2 cm (Harvest 1). Plants regrew for 35 before the final harvest (Harvest 2). Measurements were number of leaves, leaf area, shoot mass, taproot mass, fine root mass, crown mass, taproot carbohydrates, tarch degrading enzyme activity, whole plant metabolism, and plant survival. Leaves per plant decreased with increasing air temperature and this caused a decrease in sainfoin leaf area per plant and shoot yield per plant. Increasing air temperature from 15 to 35°C or soil temperature from 10 to 30°C decreased crown, taproot, and fine root mass by as much as 98%. Concentration of taproot carbohydrates showed a negative correlation (P < 0.05) with increasing air temperature. Metabolic rates of leaves and roots were two and five times higher, respectively, when the air or soil temperature increased by 20°C. Increasing air temperature showed a positive correlation (P < 0.05) with the number of dead plants per treatment (R2 = 0.90). Few plants grown at 35°C survived. Severe defoliation during periods of high temperatures may cause plant death because high metabolic rates cannot be supported by existing leaf area or taproot carbohydrate
Genotypic and Environmental Modification of Wheat Flour Protein Composition in Relation to End‐Use Quality
Authors: Graybosch Robert A. , Peterson C. James , Shelton David R. , Baenziger P. Stephen
Published: July 2010

Identification of the biochemical factors responsible for end‐use quality variation of wheat (Triticum aestivum L.) would have important consequences for breeders, producers, grain handlers, millers, and bakers. Flour protein composition, or the distribution of flour protein in classes based on molecular size and solubility, has been reported to be a major variable influencing wheat processing quality. The proportions of five major protein fractions in flour samples of 30 wheat genotypes, obtained from 17 Nebraska environments, were measured by size‐exclusion high‐performance liquid chromatography (SE‐HPLC). Total flour protein content and sodium dodecylsulfate (SDS) sedimentation volume (SDSS), the latter a measure of flour protein aggregative ability, also were measured. The extent to which each character was modified by genotypic, environmental, and genotype × environment interaction sources of variation was determined. Phenotypic correlations were used to relate biochemical variation to wheat end‐use quality characteristics. Flour protein concentration and SDSS were more consistently correlated with quality variables than any of the protein fractions measured by SE‐HPLC. Interdependence of flour protein concentration and SE‐HPLC protein fractions prevented the identification of specific effects of the latter on wheat processing quality. The proportion of glutenin, however, was found to be significantly related to loaf grain properties, a parameter of critical concern to the milling and baking industry. Genotypes with both elevated and depressed proportions of glutenin, independent of flour protein concentration, were identified.
Persistance and Single‐Plant Productivity in Nondormant Alfalfa
Authors: Hotchkiss J. R. , Smith S. E. , Miller W. B.
Published: July 2010

Plant mortality is generally substantial in alfalfa (Medicago sativa L.) fields both at establishment and during the productive life of the stand. Most research has examined the effects of mortality on alfalfa yield per unit area. Consequences of mortality within a population on single*plant productivity have received relatively little attention. Understanding the basis for this mortality could affect management practices and the breeding and testing of alfalfa cultivars. The objective of this study was to describe agronomic, morphological, and physiological traits associated with persistence in nondormant alfalfa. This was accomplished by comparing two populations of S1 progenies derived from 60 surviving 6‐yr‐old plants from a commercial field of ‘CUF‐101’ (=field‐derived [FD] population) and 60 greenhouse‐grown CUF‐101 plants (=greenhouse‐derived [GHD] population) in field and greenhouse trials at Tucson, AZ. In a field trial, crown mortality, as measured by the percent live stems, did not differ significantly between the populations. Total forage yield, yield in winter and spring, and stem elongation rates were significantly greater in the GHD population. Root weight, total plant weight, root/shoot weight ratio, and concentration of total nonstructural carbohydrates in the root were significantly greater in the FD population in a greenhouse trial. Differences observed between the two populations are consistent with the elimination of presumably less competitive plants with smaller root systems and plants intolerant of grazing in the winter and early spring. This research suggests that mortality within stands of nondormant alfalfa is less likely for plants with larger roots and generally slower growth patterns that are typically associated with increased fall dormancy.
Effect of Temperature and Phosphorus Fertilization on Phosphorus and Nitrogen Uptake by Sorhgum
Authors: Ercoli Laura , Mariotti Marco , Masoni Alessandro , Massantini Franco
Published: July 2010

Temperature (T) and phosphorus (P) supply affect each of the mechanisms involved in P and nitrogen (N) uptake by grain sorghum [Sorghum bicolor (L.) Moench]. This study was conducted to assess the extent to which air temperature and P fertilizer influenced P and N uptake and partitioning in sorghum plant parts. Research was conducted in a climatic chamber, where plants (Venturoli Aralba hybrid sorghum) were grown in pots under a 14‐h day/night photoperiod regime. Temperature regimes were kept constant for the entire life cycle at 21, 24, 27, and 30°C. The P fertilization rate was 0 and 150 mg P pot−1 as triple mineral perphosphate. Temperature and P supply controlled P and N concentration and content in all sorghum plant parts during the biological cycle. Whole plant, leaf, stem, and root P and N contents were highest at 27°C in growth Stages 3, 6, and 9 for both P‐fertilized and unfertilized plants. Increased P supply resulted in greater P and N content in leaves and stems in all three stages and at all temperatures, while root P and N contents were unaffected. Panicle P and N contents were highest at 21 to 27°C in Stage 6 and at 24°C in Stage 9. The effect of T on increasing plant P and N contents was attributable primarily to higher P and N uptake rate per unit of root rather than to higher rate of root growth. Results do not support the view that poor growth at suboptimal temperatures is caused primarily by restricted P uptake, but that T and P supply limit growth independently, with additive responses.
Low Seed Manganesse Concentration and Decreased Emergence of Lupinus angustifolius
Authors: Longnecker Nancy , Crosbie Julie , Davies Fleur , Robson Alan
Published: July 2010

Seed of narrow‐leafed lupin (Lupinus angustifolius L.) produced in Western Australia can have a low manganese concentration and exhibit poor seedling emergence. We determined effects of internal seed manganese concentration, exogenously applied manganese, and soil temperature on lupin emergence and seedling growth. Uniformsized seed (cv. Gungurru) containing different manganese concentrations was collected from a manganese fertilizer experiment. Two greenhouse experiments were conducted with complete randomized block designs and two‐way factorial treatments: (i) three internal seed manganese concentrations (7, 15, or 35 mg Mn kg−1 DW) and four manganese treatments (no manganese fertilizer, MnSO4 banded below the seed or seed coatings of MnSO4 or MnO2 ; and (ii) four seed manganese concentrations (7, 11, 15 or 35 mg Mn kg−1 DW) and four temperature regimes (12, 12/20, 20/12, and 20°C). Emergence was 35 to 52% all pots sown with 7 mg Mn kg−1 seed compared with 88 to 100% in pots sown with other seed. Plants that emerged from 7 mg Mn kg−1 seed generally had lower shoot dry weight than plants from other seeds. There were more abnormal seedlings in pots sown with 7 or 11 mg Mn kg−1 seed than with other seeds. Although manganese fertilizer and higher soil temperature increased the manganese concentration of plants that emerged, they had no effect on final emergence or percentage of abnormal seedlings. Increased manganese availability did not overcome detrimental effects of sowing lupin seed with manganese concentrations of 11 mg kg−1 or less.
Identification of Cross‐Pollinated and Self‐Pollinated Progeny in Alfalfa through RAPD Nulliplex Loci Analysis
Authors: Gjuric R. , Smith S. R.
Published: July 2010

Alfalfa (Medicago saliva L.) is the most important forage crop in the world, but with current breeding practices improvements in yield potential have been limited during the last 40 yr. The development of hybrid alfalfa cultivars would likely improve forage yield potential, but an efficient method to estimate outcrossing rates would be needed to confirm percentage hybrid seed. The objective of this research was to demonstrate the applicability of a RAPD nulliplex analysis to estimate outcrossing/selfing rates in autotetraploid alfalfa. Marker selection is based on polymorphism between a seed parent and its bulk open‐pollination progeny. Polymorphic markers identify the seed parent as nulliplex (aaaa) for those particular loci, which allows the individual open‐pollinated progeny from that seed parent to be classified as F1 or S1 progeny based on the presence/absence of these markers. Two alfalfa genotypes served as seed parents in crossing studies which differed in pollination control and number of pollen parents. Random amplified polymorphic DNA (RAPD) nulliplex analysis was conducted on these two seed parents and their progeny. Controlled crossing and selfing provided independent control over S1s and F1s. Five polymorphic markers were identified for both seed parents and these markers were sufficient to identify S1 and F1 progeny. The percentage S1 seed was 7, 27, and 100% for crossing with emasculation, crossing without emasculation and self‐pollination, respectively. In conclusion, RAPD nulliplex loci analysis can provide accurate identification of F1 and S1 progeny and an estimation of outcrossing rates in autotetraploid alfalfa.
Association of T Gene with Chilling Tolerance in Soybean
Authors: Takahashi Ryoji , Asanuma Shuichi
Published: July 2010

Soybean [Glycine max (L.) Merr.] is sensitive to chilling temperatures (≈ 15°C) at flowering resulting in reduced seed yield and physical quality (brown pigmentation near the hilum region). In Japan, soybean cultivars with yellow hilum color are preferred to those with brown hilum color. However, of the two, the genotypes with yellow hilum are more sensitive to chilling temperatures. Because a combination between brown pubescence and yellow hilum cause a discoloration of the seed coats, in northern Japan, all genotypes with yellow hilum have gray pubescence. This study was conducted to determine if pubescence color, controlled by gene T/t, was related to chilling tolerance in a pair of soybean lines near‐isogenic for gene T/t and if the near‐isogenic lines differed for N2‐fixing ability under chilling conditions. Two determinate near‐isogenic lines for gene T/t, To7B with allele T (brown pubescence and brown hilum) and To7G with allele t (gray pubescence and buff hilum), were exposed to 15°C (day/night) in a phytotron at flowering. Seed coat pigmentation was scored by exposing plants to 15°C for 2 wk beginning at 8 d after anthesis. Plant height, acetylene‐reducing activity (nitrogenase activity), maturity date, and seed yield were compared by exposing plants to ]15°C for 4 wk beginning at anthesis. Under control conditions, only plant height was different between the lines. By exposing plants to 15°C, seed coat pigmentation near the hilum region increased with the age of flowers at the time of chilling treatment in To7G. No pigmentation was observed in the seeds of To7B. Nitrogenase activity and seed yield were less and maturity date was later in To7G than To7B only under chilling treatment. These results suggest that allele T is associated with chilling tolerance due to either pleiotropy or close linkage.
Genetic Base of Upland Cotton Cultivars Released between 1970 and 1990
Authors: Bowman Daryl T. , May O. Lloyd , Calhoun D. Steve
Published: July 2010

Most cotton (Gossypium spp.) breeders today, without recourse to critical data, assume that the genetic base in modern New World cotton cultivars is narrow. The objectives of this study were to: (i) determine the average coefficient of parentage for 260 upland cotton (G. hirsutum L.) cultivars released between 1970 and 1990; and (ii) determine the contributions of a number of public and private breeding programs and of various ancestral lines to the genetic diversity of those cultivars. Coefficients of parentage among 260 cultivars showed an average value of 0.07. This estimate suggests substantial remaining diversity. This conclusion must take into account possible bias from widespread reselection of cotton cultivars and the accompanying assumption of a genetic correlation of 0.75 between generations. The most influential breeding programs, in terms of genetic contributions to cultivar development, were Stoneville Pedigreed Seed Company, Coker's Pedigreed Seed Company, and New Mexico Agricultural Experiment Station. Historically, the most influential cultivar is Stoneville 2. The genetic contribution of 54 ancestral lines, including nine introductions, accounted for less than 25% of the total genetic variation among the 260 cultivars. This low value is thought to result from the loss of genetic information through the process of reselection. The genetic base in modern cotton cultivars is not particularly narrow and continue to offer opportunities for cultivar improvement.
Cotton Response to Seasonal Patterns of Flower Removal: II. Growth and Dry Matter Allocation
Authors: Jones M. A. , Wells R. , Guthrie D. S.
Published: July 2010

Development of a cotton (Gossypium hirsutum L.) crop is a full‐season process involving a complex balance between vegetative and reproductive allocation. Despite this fact, fruit removal studies have seldom examined the effects of flower removal during late anthesis. Flower removal treatments were imposed on two cotton cultivars to assess effects on vegetative and reproductive dry weights (DW) and boll maturation patterns. Flower removal treatments were imposed during early‐, mid‐, and late‐anthesis. Removal of 1st and 2nd and 1st through 3rd week flowers caused a decrease in the reproductive/vegetative ratio (RVR) at 105 d after planting (DAP) or 93 DAP 1991 and 1992, respectively. However, no difference in RVR was found between these treatments and the control (no removal) at either 133 or 131 DAP (1991 and 1992). Early removals (3rd week and earlier) increased number of bolls developing above Node 10 and decreased the number of bolls developing at first positions on sympodial branches. Flower removal during the 4th week and later decreased the RVR at 133 and 131 DAP (1991 and 1992) by at least 23% as compared with the controls. Late‐season removal treatments decreased the final number of total bolls and significantly reduced the number of bolls residing at main stem Nodes 11 and higher. Although fruit retention early in reproductive growth is often important for early maturity and maximal yield, this study found that subsequent development of distal and more apical flowers adequately replaced fruit lost durin early anthesis. In contrast, later developing bolls, often thought to be unimportant, were needed to achieve maximal yield.
Drought Resistance Aspects of Turfgrasses in the Southeast: Root‐Shoot Responses
Authors: Carrow Robert N.
Published: July 2010

Knowledge of relative drought resistance is important for selecting turfgrasses that persist during drought stress. Seven of the most commonly used turfgrasses in the Piedmont region of the humid Southeastern USA were evaluated in a field study under edaphic stresses common to the region for drought resistance and spatial rooting responses as a component of drought avoidance. Grasses were ‘Tifway’ bermudagrass (Cynodon dactylon × C. transvaalensis); common bermudagrass [C. dactylon (L.) Pers.]; ‘Meyer’ zoysiagrass (Zoysia japonica Steud.); common centipedegrass [Eremochloa ophiuroides (Munro.) Hack.]; ‘Raleigh’ St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze]; and ‘Rebel II’ and ‘Kentucky‐31’ tall fescue (Festuca arundinacea Schreb.). Grasses varied in drought resistance, as determined by wilt and leaf firing during dry‐down periods, from very high (Tifway and common bermuda), high (Raleigh St. Augustine, common centipede), medium‐high (Rebel II tall fescue), medium (K‐31 tall fescue), and medium‐low (Meyer zoysiagrass). High soil strength and acid soil complex stresses were present on the site. Under these stresses, deep rooting (20‐ to 60‐cm zone) in late summer ranged from Tifway bermuda (best) > Rebel II tall fescue = common bermuda > K‐31 tall rescue > Raleigh St. Augustine > common centipedegrass > Meyer zoysiagrass. Meyer produced only 4% of the root length density that Tifway did within this zone due to low genetic tolerance to the edaphic stresses. These results illustrate that genetic tolerance to edaphic stresses can markedly affect turfgrass rooting and drought resistance rankings. Plant breeders must give attention to edaphic stress tolerances if drought avoidance via roots is to be improved.
Genetic Diversity in Durum Wheat Based on RFLPs, Morphophysiological Traits, and Coefficient of Parentage
Authors: Autrique Enrique , Nachit Miloudi M. , Monneveux Philippe , Tanksley Steven D. , Sorrells Mark E.
Published: July 2010

Estimation of genetic diversity present in gene pools is an important determination for breeding programs. This study was conducted to determine the level of variation in durum wheat cultivars (Triticum turgidum L. var durum) based on different measures. Genetic diversity in durum wheat was measured in a collection of 113 improved cultivars and landraces of diverse ecogeographical origin by means of restriction fragment length polymorphism (RFLP), morphophysiological traits, and coefficient of parentage (COP). Thirty‐nine clones and a single restriction enzyme were used to measure the RFLP‐based genetic distance. Average taxonomic distances were calculated for the morphophysiological traits evaluated in four location‐years. Lower genetic distances were observed for both RFLP and morphophysiological traits for the improved cultivars and for some landraces from Morocco and Jordan, while genetic distances were larger for the rest of the landraces. Patterns of variation for morphophysiological traits were associated with days to heading, plant height, and harvest index. Landraces contained 99% of the total fragments observed in the pool of improved varieties and showed 13% unique fragments. Coefficient of parentage analysis revealed 15 ancestral lines that contributed 72% of the genetic make up of improved cultivars. Thirty‐nine different ancestors contributed to the remaining 28%. Correlation of distances based on different measures was higher for average taxonomic distance and Nei's genetic distance (r = 0.47) while COP relationship with the other two measures was lower. Narrower genetic diversity in breeding lines based on the measures used, suggests the utilization of other sources of variation.
Genetic Diversity Patterns in North American Public Soybean Cultivars based on Coefficient of Parentage
Authors: Gizlice Ziya , Carter Thomas E. , Gerig T. M. , Burton J. W.
Published: July 2010

The genetic relatedness of North American soybean [Glycine max (L.) (Merr.)] may threaten long‐term breeding progress. To alleviate this problem, we propose that breeders diversify applied programs by capitalizing upon genetic patterns that may exist in cultivated germplasm. To date, only one diversity pattern, the well‐known North‐South distinction, is explained in applied breeding. Our objective was to identify and quantify additional factors influencing diversity in 258 cultivars released by public agencies during 1945 to 1988. We theorized that maturity group effects (MG, as a hybridization restriction factor), location of breeding programs (BP, as a selection factor), and breeder intuition and success factors beyond MG and BP may all influence the soybean cultivar diversity patterns. The patterns of diversity associated with the first two factors, MG and BP, were examined by quantifying average coefficient of parentage (r) within and between MG and BP. Multidimensional scaling (MDS) was applied to the r matrix to produce coordinates for pictorial depiction of MG and BP. To examine the third factor, breeder intuition and success, the MDS coordinates were also subjected to a nonhierarchical cluster analysis that revealed nine major clusters of soybean cultivars. A regression analysis was employed to determine the relative importance of North‐South, MG, BP, and cluster patterns in explaining variation in the r matrix. The South‐North distinction accounted for only 21% of variability in cultivar relations indicating the presence of other major patterns of diversity. The MG, BP, and clusters independently explained 32, 42, and 57% of the total variation in the cultivar pedigrees. Clusters most efficiently revealed patterns of diversity, and we propose the use of these clusters in the further study and management of soybean diversity. Multidimensional scaling coupled with nonhierarchical cluster analysis was a highly promising approach to the study of diversity.
Additional Sources of Resistance to Tan Spot of Wheat
Authors: Riede C. R. , Francl L. J. , Anderson J. A. , Jordahl J. G. , Meinhardt S. W.
Published: July 2010

Tan spot, a foliar disease of wheat (Triticum aestivum L. em Thell) and durum (T. turgidum var. durum L.) caused by Pyrenophora triticirepentis (Died.) Drechs., reduces yield in susceptible cultivars by 3 to 50%. Additional sources for resistance to tan spot were sought in germplasm consisting of a collection of spring wheats previously screened for reaction to spot blotch [Cochliobolus sativus (Ito & Kurib.) Drech. ex Dastur] in Brazil, wheat cultivars recommended for cultivation in the state of Paraná, Brazil, and a collection of synthetic hexaploid wheats. Plants from each of the three groups were inoculated at the seedling stage with a composite of four fungal isolates and at the adult stage with one of the four isolates. A subset of germplasm was treated at the seedling stage with necrosis toxin, crude extract, and conidia produced by P. tritici‐repentis isolate 86‐124. Adult disease reactions did not always agree with seedling evaluations and some of the variation could be explained by sensitivity or a mixed reaction to necrosis toxin. Assay with purified necrosis toxin was a reliable way to detect a major factor involved in resistance. This work identifies diverse germplasm available for incorporation of tan spot resistance into cultivated wheats.
Selection for and Heritability of Stolon Characteristics in Two Cultivars of White Clover
Authors: Caradus J. R. , Chapman D. F.
Published: July 2010

White clover (Trifolium repens L.) herbage production in intensively grazed pasture is related to clover stolon growing point density. High stolon density is associated with small leaf size. The objective of this study was to examine the probability of breaking the genetically controlled link between leaf size and stolon density by manipulating internode length and branching propensity. Two white clover cultivars, Grasslands Tahora and Grasslands Kopu, were grown in two New Zealand environments, full sunlight or 50% sunlight (shade), during 1991 and 1992. Selections were made for high or low frequency of stolon branching, long or short stolon internodes, and large or small leaves. These selections were polycrossed within groups to give 24 lines. Lines were evaluated in pots grown outside to determine the effect of selection on these and other shoot characters. Selection of populations with high or low frequency of branching gave progeny with different frequency of branching for all cultivar‐environment combinations except for selection within Tahora grown in shade. Selection of populations with long or short internode length gave progeny with different internode length in all cultivar‐environment combinations. Selection for large and small leaflet width gave progeny with different leaflet width in all cultivar‐environment combinations except for selection within Kopu grown in sun. Two estimates were made of narrow sense heritabilities. Estimates from mid‐parent versus progeny regression heritabilities were higher for internode length and leaflet width than for frequency of branching. Realized heritabilities were again generally higher for internode length and leaflet width than for frequency of branching although there were some exceptions. Selection for high frequency of branching in Tahora grown in full sunlight had a high realized heritability. Stolon characters, such as internode length and frequency of branching, can be effectively manipulated by selection. The degree of selection success can be affected by environment and cultivar. Selection for variation in internode length is likely to be more successful than for frequency of branching.
Assessing User Perceptions of Genetic Resource Collections in Crucifer Crops
Authors: McFerson James R. , Lamboy Warren F. , Kresovich Stephen
Published: July 2010

Germplasm collections worldwide are increasing in both size and quality, but quantitative data on user needs and their perceptions of collection management are limited. Such information would enable more effective planning and management by collection curators. In 1991, we surveyed and analyzed the opinions of 47 scientists working with crucifer crops, including oilseed Brassica napus L. and B. rapa L., vegetable coles [B. oleracea subsp. italica (broccoli), B. oleracea subsp. capitata L. (cabbage), B. rapa subsp. pekinensis Lour. (Chinese cabbage), etc.], and wild and weedy relatives. Survey respondents were located in 19 countries and represented a broad range of institutional affiliations, professional interests, educational backgrounds, and research programs. Significant differences occurred among respondents’ opinions on various activities (acquisition, preservation and distribution, documentation, and research). Respondents utilized genetic resources from all gene pool categories, obtained them from an array of sources, and expected to increase their use about 30% by 1994. Nearly 80% of respondents maintained a germplasm collection for their own use. They estimated ex situ genebanks held <50% of total genetic diversity of crucifers and were dissatisfied with collection documentation. About 80% used biotechnological techniques and projected an increased use of gene pools comprising F1 fertile relatives, F1 semi‐sterile and sterile related species, and genetic stocks. Respondents felt that research that focused on identification and transfer of new and useful traits would enhance crucifer germplasm collections. Our survey results provided a current, systematic assessment of germplasm users’ expectations, but curators must have the scientific and managerial skills to reconcile those expectations with limited resources.
Growth Analysis of Alfalfa Subjected to Harvest Traffic
Authors: Rechel E. A. , Novotny T. J.
Published: July 2010

Harvesting practices currently used in alfalfa (Medicago saliva L.) reduce yields by damaging regrowth. Understanding the extent these practices change the plant's physiology and its subsequent growth rate would aid in evaluating current management strategies and developing new ones. Our objective was to compare the growth characteristics of alfalfa trafficked during harvest with those of non‐trafficked alfalfa. Growth analyses were conducted during two growth cycles in the second and third seasons of alfalfa production. Alfalfa subjected to several passes of a tractor at each harvest had a significantly higher leaf/stem ratio at the end of the growth cycle than non‐trafficked alfalfa. A single linear equation was used to describe the positive relationship between relative growth rate and unit leaf rate for all treatments from three of the four harvest cycles examined. Trafficked alfalfa had a higher relative growth rate and unit leaf rate (P ≤ 0.05) during the middle of the growth cycle than non‐trafficked alfalfa. This compensatory growth reflects a change in photosynthate partitioning between roots and shoots in plants subjected to traffic.
Screening Ethiopian Mustard for Erucic Acid By Near Infrared Reflectance Spectroscopy
Authors: Velasco L. , Fernández‐Martínez J. , De Haro A.
Published: July 2010

Near infrared reflectance spectroscopy (NIRS) has not been tested sufficiently for its capacity to estimate erucic acid in Brassica species. Our objective was to evaluate the potential of NIRS for screening whole‐seed samples of Ethiopian mustard (Brassica carinata A. Braun) for erucic acid concentration. A total of 1440 samples previously analyzed by gas‐liquid chromatography (GLC) were scanned by NIRS. Samples for calibration and validation were selected according to their erucic acid concentration. A calibration equation was developed and its validation gave a coefficient of multiple determination (r2) of 0.96. A comparison between GLC values and NIRS estimation was performed with the remaining samples not included in the calibration and validation sets. We found that 90% of samples were classified by NIRS in the same or an adjacent class as those determined by GLC. It demonstrates that screening for erucic acid in this species can be performed with high reliability by means of NIRS.
Effect of 1BL.1RS on Milling and Baking Quality of Soft Red Winter Wheat
Authors: McKendry A. L. , Tague D. N. , Finney P. L. , Miskin K. E.
Published: July 2010

Wheat (Triticum aestivum L.) breeders worldwide have used the 1BL.1RS translocation as a source of genes for disease resistance, broad adaptation, and enhanced yield potential. Although it appears to have detrimental effects on hard wheat baking quality, there are no known reports of its impact on soft wheat quality. This study was designed to investigate the effects of 1BL.1RS on milling and baking quality in soft red winter wheat and to evaluate the interaction of these effects with environment and genetic background. Grain from 1BL.1RS and nonrye sister lines, derived in the F9 from two experimental lines, SW85*294 and SW85*5626, was evaluated in five Missouri environments. In both genetic backgrounds, 1BL.1RS was associated with significant reductions in adjusted flour yield and overall milling quality and a significant increase in alkaline water retention capacity, which may be detrimental to soft wheat baking quality. Test weight in 1BL.1RS lines was reduced by 11.6 kg m−3 in SW85*294 but was not affected in SW85*5626. In the SW85*5626 background, 1BL.1RS increased softness equivalent 1.3 percentage units but had no affect in SW85*294. Neither flour protein content nor overall baking quality was affected by the presence of 1BL.1RS. For all traits, the effect of the genetic background was large compared with the effect of 1BL.1RS. Variation among the 1BL.1RS lines was significant in both genetic backgrounds and led to the conclusion that in these lines, the negative effects of 1BL.1RS could be overcome by selection.
Genetic and Environmental Variation in β‐Glucan Content and Quality Parameters of Barley for Food
Authors: Fastnaught C. E. , Berglund P. T. , Holm E. T. , Fox G. J.
Published: July 2010

High β‐glucan content is desirable in barley (Hordeum vulgare L.) for many food uses. The effects of environment, head type, and starch‐hull type on total β‐glucan and protein content, extract viscosity, and seed color in barley were tested. Barley cultivars varying in head (two row and six row), starch (normal, waxy, high‐amylose, and fractured), and hull (covered and hull‐less) phenotypes were grown in single‐row plots at one location front 1989 to 1991. Higher mean β‐glucan content and extract viscosity occurred in 1989, a low‐moisture, hot year. Cultivars with the two‐row and six‐row head type did not differ for any of the traits analyzed. Waxy hull‐less cultivars had the highest mean β‐glucan content (69.3 g/kg) and extract viscosity (29.1 cP) compared with the normal covered cultivars (38.0 g/kg and 4.6 cP, respectively). Single degree‐of‐freedom contrasts found differences between normal starch and waxy starch isotypes consistent among the background genotypes (‘Azhul’, ‘Betzes’, ‘Bowman’, ‘Robust’). Dietary fiber analysis of selected samples grown in 1990 found the highest soluble fiber content in cultivars having waxy or high amylose starch and hull‐less seed. In a separate experiment, ‘Wanubet’, a waxy hull‐less cultivar, was grown in 42 commercial fields from 1989 to 1991. β‐Glucan content varied from 45.5 to 94.6 g/kg, extract viscosity from 8.9 to 108.2 cP, and protein content from 98.0 to 186.0 g/kg. Seed color varied but was unrelated to these components. The significant effect of environment on all of the characteristics indicates the need for food barley quality standards and tests.
Regions of the Genome that Affect Agronomic Performance in Two‐Row Barley
Authors: Tinker N. A. , Mather D. E. , Rossnagel B. G. , Kasha K. J. , Kleinhofs A. , Hayes P. M. , Falk D. E. , Ferguson T. , Shugar L. P. , Legge W. G. , Irvine R. B. , Choo T. M. , Briggs K. G. , Ullrich S. E , Franckowiak J. D. , Blake T. K. , Graf R. J. , Dofing S. M. , Saghai Maroof M. A. , Scoles G. J. , Hoffman D. , Dahleen L. S. , Kilian A. , Chen F. , Biyashev R. M. , Kudrna D. A. , Steffenson B. J.
Published: July 2010

Quantitative trait locus (QTL) main effects and QTL by environment (QTL × E) interactions for seven agronomic traits (grain yield, days to heading, days to maturity, plant height, lodging severity, kernel weight, and test weight) were investigated in a two‐row barley (Hordeum vulgare L.) cross, Harrington/TR306. A 127‐point base map was constructed from markers (mostly RFLP) scored in 146 random double‐haploid (DH) lines from the Harrington/TR306 cross. Field experiments involving the two parents and 145 random DH lines were grown in 1992 and/or 1993 at 17 locations in North America. Analysis of QTL was based on simple and composite interval mapping. Primary QTL were declared at positions where both methods gave evidence for QTL. The number of primary QTL ranged from three to six per trait, collectively explaining 34 to 52% of the genetic variance. None of these primary QTL showed major effects, but many showed effects that were consistent across environments. The addition of secondary QTL gave models that explained 39 to 80% of the genetic variance. The QTL were dispersed throughout the barley genome and some were detected in regions where QTL have been found in previous studies. Eight chromosome regions contained pleiotropic loci and/or linked clusters of loci that affected multiple traits. One region on chromosome 7 affected all traits except days to heading. This study was an intensive effort to evaluate QTL in a narrow‐base population grown in a large set of environments. The results reveal the types and distributions of QTL effects manipulated by plant breeders and provide opportunities for future testing of marker‐assisted selection.
A Diallel Analysis of Ear Moisture Loss Rate in Maize
Authors: Zhang Yudong , Kang Manjit S. , Magari Robert
Published: July 2010

Maize (Zea mays L.) growers need hybrids with fast ear moisture loss rate (EMLR) to reduce grain drying cost. A 10‐parent diallel experiment with reciprocals (Griffing's Method 3) was conducted for 2 yr to study the genetic nature of EMLR in maize. Field ear moisture was measured with an electronic probe device at 30 and 51 d after midsilk. Analysis of covariance (ANCOVA) was used to increase precision of treatment comparisons and parameter estimation since F1 crosses differed in midsilk dates and in growing degree days (GDD) between the first (Moisture1) and the second probe moisture readings (Moisture2). Adjusted plot means were used to compute combining abilities. General combining ability fixed variance component (GCA, Vg) and reciprocal component were significant, whereas specific combining ability fixed variance component (SCA, Vg) was not significant for EMLR. The 2Vg/(2Vg + Vg) ratio was 0.81, indicating that GCA effects were more important than SCA effects for EMLR. Significant, positive GCA effects for EMLR were detected in L108, L605, and L654 inbred lines and negative GCA effects in Mo17 inbred line. Non‐maternal component was significant for EMLR. Moisture1 and Moisture2 also were genetically controlled. A relatively low Moisture1, high EMLR, and positive GCA and reciprocal effects for EMLR were important in lowering Moisture2. Specific interaction between nuclear genetic component(s) and non‐nuclear genetic factors can be exploited for enhancing EMLR. Inbred lines L668, B73, and H111 had relatively low Moisture2 due to either relatively low Moisture1 or high EMLR or both. In general, Louisiana (L) lines had higher Moisture1, Moisture2, and EMLR than B73, H111, and Mo17.
Dollar Spot on Bentgrass Influenced by Displacement of Leaf Surface Moisture, Nitrogen, and Clipping Removal
Authors: Williams D. W. , Powell A. J. , Vincelli P. , Dougherty C. T.
Published: July 2010

Dollar spot (Sclerotinia homoeocarpa F.T. Bennett) is a common fungal disease of creeping bentgrass (Agrostis palustris Hudson). Field experiments were conducted to quantify the effects of leaf surface moisture displacement, N fertilization, and collecting or leaving clippings on severity of dollar spot. Tests were conducted on A. palustris cv. Penncross maintained at 0.6 cm (putting green height) and on turf containing A. palustris cv. Penncross and annual bluegrass (Poa annua L.) maintained at 1.1 cm (fairway height). Six mowing treatments, four of which displaced morning leaf surface moisture and three of which collected clippings, were imposed on turf fertilized with 0, 36.6, and 73.2 kg N ha−1 in 1992 and 1993. Significant reductions of dollar spot after morning mowing or poling treatments, or both, were recorded on turf at both heights of cut and in both years. Maximum reductions of disease due to mowing treatments across all N levels were 81% on fairway turf in 1992 and 53% on putting green turf in 1992. Collecting or leaving clippings did not consistently affect the severity of dollar spot. The effects of N fertilization were significant at various levels in both tests and in both years. Maximum disease reductions comparing 0 and 73.2 kg N ha−1 were 57% on putting green turf in 1992 and 44% on fairway turf in 1993. There were no consistent interactions in the severity of dollar spot among mowing treatments and N levels.