bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Variation and Relationship of Quality Traits between Herbage and Seed of Tall Fescue
Authors: Pavetti Daniel R. , Sleper David A. , Roberts Craig A. , Krause Gary F.
Published: July 2010

Information is lacking on inheritance of in vitro dry matter digestibility (IVDMD), neutral detergent fiber (NDF), acid detergent fiber (ADF), and hemicellulose (HEM) of tall fescue (Festuca arundinacea Schreb.) seed and their relationship to these quality traits in herbage. if a close relationship were found between seed and herbage quality, indirect selection for improved herbage quality would be effective. Objectives of this study were to evaluate genetic variation for these quality traits and yield of herbage and seed and to examine association of these quality parameters between seed and herbage. Twenty‐three endophyte‐free parents were randomly chosen from a genetically broad‐based population, and their respective half‐sib families were generated. Herbage and seed samples were analyzed for quality parameters using near infrared reflectance spectroscopy. Significant (P < 0.01) variation was observed in herbage for all traits in the summer (immediately after seed harvest) and the fall for parents. There was no significant variation for IVDMD of herbage in summer or fall or for NDF and ADF in the summer for half‐sib families. For seed, all traits had highly significant variation. Narrow‐sense heritabilities for herbage ranged from 0% for IVDMD, NDF, and yield in the summer to 71% for HEM in the summer. Narrow‐sense heritability of IVDMD for seed was 78%. Heritabilities from herbage estimated by genotypic regressions were higher, ranging from 26% for IVDMD in the summer to 80% for NDF. Seed traits had a similar relationship, with genotypic regression heritabilities ranging from 62% for IVDMD to 86% for NDF. Correlation coefficients of quality traits between herbage and seed were low. Data indicated that indirect selection for improved forage quality via the seed is not useful. Selection for herbage quality directly would also be difficult because gains from selection were low.
Enzymatic Control of Nonstructural Carbohydrate Concentrations in Stems and Panicles of Sorghum
Authors: Tarpley Lee , Lingle Sarah E. , Vietor Donald M. , Andrews David L. , Miller Frederick R.
Published: July 2010

Sorghum [Sorghum bicolor (L.) Moench] stores starch as the principal nonstructural carbohydrate in grain, but primarily stores sucrose in stem. The extent of sucrose accumulation in stem varies among cultivars, and has been previously related to decline in activities of soluble sucrose‐degrading enzymes in sweet sorghum stem. The hypothesis that soluble sucrose‐degrading activity would vary inversely with patterns of sucrose accumulation was tested in panicles and stems of five diverse sorghum genotypes grown and sampled in the field from boot to post‐black layer. Activities were greater in panicle than stem during inflorescence development, and invertase activities remained relatively greater in panicle during grain filling than in stem during sucrose accumulation. Panicle invertases were speculated to hydrolyze sucrose prior to endosperm import. In contrast, invertase and sucrose synthase activities were already low by the period of sucrose accumulation in stem regardless of the stem sucrose‐accumulating abilities of the studied genotypes. A follow‐up greenhouse study tested for parallel changes in levels of activity and mRNA for sucrose synthase, and provided evidence that activity was regulated by pretranslational control. In this study also, sucrose accumulated after sucrose synthase activity and mRNA levels were already low. A decline in soluble sucrose‐degrading activities appears to be a prerequisite for, but cannot explain the extent of, accumulation of sucrose in stem.
Maize Topmost Axillary Shoot Interference with Lower Ear Development In Vitro
Authors: Pinthus M. J. , Belcher A. R.
Published: July 2010

Interference by the topmost axillary shoot of maize (Zea mays L.) with the development of lower axillary shoots is well known. However, investigations with intact plants have not clarified whether this involves exertion of a growth retarding effect per se or is due, primarily, to the advantage that the topmost shoot has in competing for nutrients. These possibilities have now been examined by means of in vitro cultures. Topmost, second, and third axillary shoots of maize were excised between the stages of tassel emergence and silking and cultured separately for 11 to 15 d. In such cultures, relative elongation rates of the second and third ears were considerably faster than those of ears in corresponding axillary shoots on intact control plants. In joint cultures of topmost and second axillary shoots taken from the same plants, the topmost shoot grew similarly to shoots cultured separately. However, the elongation of the second shoot (husks, ear, and silk) was conspicuously less than that of equivalent shoots cultured separately. These results suggest exertion of a growth restricting effect of the topmost axillary shoot on lower shoots, that is mediated by the release of a growth inhibitor.
Oat Grain β‐Glucan Content as Affected by Nitrogen Level, Location, and Year
Authors: Brunner B. R. , Freed R. D.
Published: July 2010

β‐Glucan is a hypocholesterolemic water‐soluble fiber component of oat (Avena sativa L.) grain. Despite beneficial physiological effects associated with β‐glucan, few data are available on the effects of environment on β‐glucan content. The objective of this study was to examine the effect of N fertilizer, location, and year on oat grain β‐glucan concentration. Plantings were made at East Lansing and Caro, MI, in 1987,1988, and 1989. The experimental design was a split plot with three replications. Whole plots consisted of each of three N levels (0, 37, and 74 kg ha−1), and subplots consisted of five oat cultivars (Heritage, Korwood, Ogle, Pacer, and Porter). Increased levels of applied N tended to increase groat β‐glucan content. No significant differences in mean β‐glucan concentration were found between locations or among cultivars used in the study. β‐Glucan concentration was affected by year, with lowest mean values in 1988, intermediate concentrations in 1987, and highest values in 1989. Cultivar × year and cultivar × location interactions were significant. Correlations between β‐glucan content and test weight, hull percentage, grain yield, or groat weight were mostly small or nonsignificant. Correlations between groat protein and groat β‐glucan were significant, relatively large and positive in 1987 and 1989, but were non‐significant in 1988. The results of this research indicate that environment, especially soil N and year‐to‐year climatic variability, is important in determining oat grain β‐glucan concentration.
Detection of Ergoline Alkaloids in Endophyte‐Infected Tall Fescue by Immunoassay
Authors: Hill N. S. , Agee C. S.
Published: July 2010

Previously, a monoclonal antibody was developed to the lysergic ring common to ergoline alkaloids (EA). The objectives were to develop an immunoassay for EA in tall fescue by determining (i) time requirement; (ii) tissue mass, and (iii) optimum volume of extraction solution necessary for detection protocols with repeatable results; and (iv) the acceptability of oven‐ versus freeze‐dried samples. A competitive enzyme‐linked immunosorbent assay (ELISA) was conducted on plant extracts (0‐548 μg kg−1 ergovaline). Regressions of ELISA and high performance liquid chromatography (HPLC) data gave good fits (R2 ≥ 0.87, MSE ≤ 0.03). Using 0.10 g (±0.01 g) of oven‐dried tissue, and extraction for 15 min in a 1:40 dilution, we analyze 200 samples daily.
Choosing Evaluation Environments to Increase Wheat Grain Yield under Drought Conditions
Authors: Calhoun D. S. , Gebeyehu G. , Miranda A. , Rajaram S. , van Ginkel M.
Published: July 2010

A key question in genetic improvement of yield under drought stress is how to choose environments to evaluate and identify genotypes that yield well under drought. The objective of this study was to compare various moisture regimes as evaluation environments for wheat (Triticum aestivum L. emend. Thell.) germplasm, based on performance of specific genotypes and on expected genetic advance from direct and indirect selection. The test included 12 new, experimental spring bread wheat genotypes selected for high yield under both full and reduced irrigation in Mexico and four cultivars selected in and adapted to each of the following moisture regimes: (i) full irrigation (FI), (ii) late season drought (LD), (iii) early season drought (ED), (iv) residual moisture (RM), and (v) sporadic drought. All genotypes were yield tested for 2 yr under four moisture regimes: (i) FI (five irrigations), (ii) LD (two early season irrigations), (iii) ED (one early and two late season irrigations), and (iv) RM (one early season irrigation). Estimates of expected selection response indicated that indirect selection under FI would result in greater yield gains under drought than would direct selection in any of the drought environments. However, under all drought conditions, certain of the new, experimental genotypes produced yields that were numerically, though not always statistically, higher than genotypes selected only Under FI. Evaluation under both optimum and drought conditions appears to be an effective method to take advantage of the increased selection response under FI while preserving alleles for high yield under drought.
Genetic Variation for Fiber Properties in Elite Pee Dee Cotton Populations
Authors: May O. Lloyd , Green Cynthia C.
Published: July 2010

Knowledge of heritability and type of genetic variation involved in the expression of fiber traits would facilitate further improvement of cotton fiber properties. A 4 × 4 Design II mating was employed to estimate magnitude and type of genetic variation controlling fiber traits in populations derived from crossing elite Pee Dee cotton (Gossypium hirsutum L.) parents. Significant genetic variation was found for 2.5 and 50% span length (SL), fiber length uniformity ratio (UR), fiber strength (T1), fiber elongation, and micronaire (MIC). Mating design variances from the F2, F3, and F4 generations of the Design II were resolved into estimates of additive, dominance, and additive epistatic variance for the fiber properties. Dominance genetic variance was greater than additive genetic variance for all of the fiber traits. Additive epistatic variance was detected for 2.5% SL, UR, and MIC. Low single‐plant heritability for all fiber traits suggested that alternatives to a pedigree generation advance beginning with F2 plant selection be considered. Evaluation of F2 bulk populations with a low selection intensity was adequate to identify populations with superior fiber traits. Less than half of the offspring of the top 10% of F3 lines with highest T1 were in the 10% of F4 lines with highest yarn strength (YS). Additionally, the correlation between T1 and YS among 283 unselected F4 lines was only 0.25 (p < 0.05). Maximum progress in improving YS may require selection for traits in addition to T1 or for components of YS not measured by the standard fiber properties.
Nitrogen Use Efficiency among Diverse Sorghum Cultivars
Authors: Gardner J. C. , Maranville J. W. , Paparozzi E. T.
Published: July 2010

Genetic diversity for N use efficiency (NUE) has been demonstrated in sorghum [Sorghum bicolor (L.) Moench] with some of the most efficient types being cultivars that evolved from low‐fertility environments. The objectives of this study were to compare diverse sorghum cultivars for their ability to cope with limited supplies of N. A Nigerian landrace (SC566), an Indian improved line (M35‐1), two U.S. pure lines (CK60 and Martin), and a commercial sorghum hybrid (Dekaib E59 4‐) were compared in solution culture and under two levels of limited N availability in a Nebraska field environment. Dry matter production and NUE (grants of dry matter per gram of N) were determined among all environments. In the field environments, the vertical canopy profile was divided into three layers and repeated observations were made of leaf morphology, internal leaf anatomy, N content, and CO2 gas exchange rates under light saturating and dark conditions. As the nature of N stress changed and increased among environments, SC566 and M35‐1 becmne superior to all U.S. cultivars in NUE. Conversely, U.S. cultivars were among the most responsive in total dry matter production and grain yield as N supply increased. In general, traits related to high NUE included larger canopies comprised of fewer but larger leaves with low N concentration, thicker leaves, larger leaf phloem transsectional area, rapid solubilization and remobilization of N from older to younger leaves, and lower dark respiration rates. These cluwacteristics did not necessarily seem related to the level of domestication or origin of a cultivar, though M35‐1 was found superior in NUE among all environments. Unique and possibly useful traits were found among both landrace and domesticated cultivars.
Timing and Level of Nitrogen Fertility Effects on Spring Wheat Yield in Eastern Canada
Authors: Ayoub M. , Guertin S. , Lussier S. , Smith D. L.
Published: July 2010

Bread wheat (Triticum aestivum L.) produced in areas of higher rainfall, such as eastern Canada, are often low in protein. Our objective was to determine if N management could be used as a way to produce bread quality wheat in eastern Canada. An experiment was conducted for 2 yr at two Quebec sites. The effects of N fertilizer level and timing on grain yield, yield components, and lodging level of four hard red spring wheat cultivars with breadmaking potential were investigated. The soil type was Ste‐Rosalie clay (fine, non‐acid, frigid, typic Humaquept). The experiment was a four (cultivars) × four (N level) × two (N timing) factorial. Cultivars were Columbus, Katepwa, Max, and Hege 155‐85. In both years, 0, 60, 120, and 180 kg N ha‐1 were applied at seeding or 60% at seeding and 40% at anthesis. Hege 155‐85 had the highest gram yield, responded most to N fertilizer addition, and was the most resistant to lodging. Differences in N management effects and cultivar responses were observed among the four site‐years. Grain yield, plant height, lodging, tillers per square meter, spikes per square meter and kernels per spike increased with increasing N fertility. When compared with application of all the fertilizer N at seeding, split application of N fertilizer (60% at seeding, 40% at heading) had little effect on yield (no effect at three site‐years, small reduction at the fourth), reduced the risk of lodging at one site, caused a reduction in the number of tillers per square meter and spikes per square meter at one site‐year, caused an increase in 1000‐kernel weight at two site‐years, and caused an increase in test weight at three site‐years. Gram yield increases due to greater N application were largely due to increases in kernels per spike and tillers per square meter. The correct combination of N application level and timing of N application can increase yields and reduce the risk of lodging. However, under these experimental conditions, the most important management decision is the choice of cultivar.
Molecular Marker Diversity and Yield of Isogenic 2x and 4x Single‐Crosses of Alfalfa
Authors: Kidwell K. K. , Woodfield D. R. , Bingham E. T. , Osborn T. C.
Published: July 2010

The positive correlation between level of heterozygosity and yield in autotetraploid alfalfa (Medicago sativa L.) suggests that genetic diversity between parents may be related to yield of their hybrid progeny. This was tested by comparing the levels of polymorphism among parental genotypes for restriction fragments homologous to 61 recombinant DNAc lones with the yield of their single‐cross progenies. Diploid (2x) genotypes were chromosomed oubled to produce autotetraploids (4x), and these isogenic 2x and 4x genotypes were used parents to generate progenies in 4 × 4 diallels. Seeds from reciprocal crosses were bulked to produce six single‐cross families for field evaluation at each ploidy levd. Yield data of single‐crosses were collected in spaced‐plant and microplot field trials over two and three years, respectively. Genetic dissimilarities (GDs) were estimated for all pairs of the four parents by the complement the Dice coefficient calculated from 244 restriction fragments. At the diploid level, no significant associations between GD and yield of single‐cross progenies were detected; however, high correlations were detected for tetraploid progenies in microplots and spaced‐plant field trials (r = 0.69, p < 0.16 and r = 0.82, p < 0.05, respectively). Inconsistencies in correlations detected between GD and yields of isogenic 2x and 4x families may be related to the level of heterozygosity expected among progenies derived from heterozygous parents at different ploidy levels. Autotetrapioids have more heterozygous loci due to tetrasomic segregation than equivalent diploids, and can benefit from greater complementargye ne interactions. Although RFLP‐based GD measurements do not appear to accurately predict yield of diploid single‐cross progenies, results from this preliminary investigation suggest that molecular marker evaluation may be useful for predicting yield of tetraploid alfalfa hybrids.
Genetics of Resistance to Peanut Stunt, Clover Yellow Vein, and Alfalfa Mosaic Viruses in White Clover
Authors: Pederson G. A. , McLaughlin M. R.
Published: July 2010

Peanut stunt virus (PSV), clover yellow vein virus (CYW), and alfalfa mosaic virus (AMV) reduce white clover (Trifolium repens L.) yield and persistence in the southeastern U.S. Southern regional virus resistant (SRVR) germplasm is the only white clover with resistance to these viruses, but little is known about the genetics of this resistance. Our objective was to determine the relative importance of general combining ability (GCA), specific combining ability (SCA), maternal effects, and nonmaternal reciprocal effects in the inheritance of resistance to PSV, CYW, and AMV in a diallel cross of one Tillman' and seven SRVR plants with differing virus susceptibilities. Progeny were grown in the greenhouse in three separate experiments and were inoculated with PSV, CYW, or AMV. Plants were evaluated for resistance by visual symptoms and either inoculation of ‘California Blackeye’ cowpeas, Vigna unguiculata (L.) Walp. subsp. unguiculata (for PSV and AMV) or enzyme‐linked immunosorbent assay (ELISA; for CYW). Differences among crosses for PSV, CYW, and AMV resistance were due to GCA, SCA, and nonmaternal reciprocal effects. For PSV and CYW resistance, additive genetic effects were more important than any other effects. For AMV resistance, nonadditive genetic effects and nonmaternal reciprocal effects were also important. Direction in which a cross is made is not important, because there were no consistent male or female effects of parents involved in more than one significant reciprocal effect. For this group of parents, breeding procedures utilizing additive genetic effects should be the most effective in improving the PSV, CYW, and possibly AMV resistance of white clover.
Recurrent Selection for Microgametophytic Vigor in Alfalfa and Correlated Responses at the Sporophytic Level
Authors: Rosellini D. , Veronesi F. , Falcinelli M.
Published: July 2010

In alfalfa (Medicago sativa L.), ovules closest to the stigma (apical) were more likely to be fertilized than the ones closest to the pedicellar end of the ovary (basal). Based on the hypothesis that basal ovules are fertilized by more vigorous microgametophytes, differential selective pressures for microgametophytic vigor were applied by selecting the basal seed and the apical seed in alfalfa pods. Ten pods containing at least eight seeds from each of 100 plants were used for each of three cycles. Plants from apical and basal seed were separately intercrossed. Pollen tube lengths of apical and basal plants from the second and third cycle of selection differed. The tubes of plants from apical seed were shorter than the tubes of plants from basal seed after 2, 5, and 22 h of in vitro growth. Divergence increased from the second to the third selection cycle, indicating that additive genetic effects are involved in the expression of microgametophytic vigor. Pollen germination percentage was not affected by selection. Sporophytic traits of second‐cycle plants from the selected populations were evaluated for 2 yr. Plant height, dry matter yield at the first harvest, and seed yield were significantly lower for plants from apical seed, showing genetic overlap between the gametophytic and the sporophytic phases for vigor‐related traits. Also, coefficients of variation of plants from basal seed were lower than those from apical seed for seed of yield. The absence of an unselected control prevented us from concluding whether or not selection of basal seed can increase sporophytic vigor, but our results encourage further study to assess the practical interest of this type of selection in alfalfa breeding.
Early Generation Selection for Grain‐Filling Period in Wheat
Authors: Sharma R. C.
Published: July 2010

Grain‐filling period (GFP) may be a useful physiological selection trait that could influence grain yield of cereals. This study was conducted to estimate heritability of GFP and to determine the response to selection for long and short GFP in six genetically diverse populations of spring wheat (Triticum aestivum L. emend. Thell.). Selections were made in the F2 generation and selected progenies were evaluated in replicated field tests in the F3 generation. The tests were seeded under normal and late conditions at Rampur, Nepal, in 1990. Date of seeding had a significant effect on GFP, grain and biomass yield, harvest index, and hundred kernel weight. Selection in the F2 for long and short GFP was effective in identifying F3 lines with long and short GFP, respectively. Also, selection for long GFP usually resulted in higher grain and biomass yield. Average harvest index and hundred kernel weight of the long GFP lines were higher than those of the short GFP fines. Realized heritability estimates for GFP were intermediate to high in magnitude (0.52–0.86). Duration of GFP had a high positive genotypic correlation with grain yield (0.52–0.79), harvest index (0.50–0.80), and hundred kernel weight (0.53–0.72). Results indicated that selection for long GFP in early segregating generations should bring about positive improvements in these yield components.
Inheritance of the Stay Green Trait in Sorghum
Authors: Walulu Richard S. , Rosenow Darrell T. , Wester David B. , Nguyen Henry T.
Published: July 2010

Stay green is an important trait associated with drought resistance in sorghum [Sorghum bicolor (L.) Moench]. This study was conducted to obtain preliminary information on the mode of gene action for the stay green trait in sorghum. Stay green inbred line (B35), nonstay green inbred line (TxT7000), and their F1, F2, and backcrosses were grown in the field and under a rainout shelter in Lubbock, TX. Moisture stress was allowed to develop in both trials during the grain filling period by witholding irrigation 2 wk prior to flowering. Stay green was evaluated on an individual plant basis at or soon after physiological maturity by using a visual leaf and plant death rating score. The results suggest that the stay green traits in B35 is influenced by a major gene that exhibits varied levels of dominant gene action depending on the environment in which evaluations are made.
Mycorrhizae Alter Protein and Lipid Contents and Yield of Pea Seeds
Authors: Bethlenfalvay G. J. , Mihara K. L. , Schreiner R. P.
Published: July 2010

Root colonization by arbuscular‐mycorrhizal (AM) fungi may affect seed protein and lipid composition by altering P nutrition or by eliciting metabolic responses by the host plant. These fungi may therefore play a role in plant breeding programs. This study was conducted to determine the effects of an AM fungus and different levels of P availability on seed protein and lipid composition and yield. Pea (Pisum sativum L.) plants were grown in a greenhouse under different P regimes (0, 1, 2, or 4 g hydroxyapatite kg−1 soil) with or without the AM fungus Glomus mosseae (Nicol − Gerd.) Gerd. and Trappe. At the lowest level of P availability, protein concentration was significantly lower and lipid concentration and seed dry mass were higher in AM than in non‐AM plants. Protein/lipid concentration ratios were invariant in non‐AM plants at all soil P levels. Those of the AM plants varied, were highest at an intermediate P level, and coincided with the highest intensity of root colonization and the greatest reduction of seed yield relative to the non‐AM plants at the same level of P availability. Lipid and protein contents were highly correlated (second order) with P content in all plants. In non‐AM plants, however, lipid and protein contents were very low at the lowest soil P level, but statistically not different at the other soil P levels. The data show different patterns of seed P accumulation and different relationships between seed P content and protein and lipid composition in AM and non‐AM plants. This suggests that both the presence and the intensity of AM‐fungal colonization altered the response of seed lipid metabolism to increasing P availability, which affected the protein and lipid ratios.
Sowing Date and Maize Productivity: I. Crop Growth and Dry Matter Partitioning
Authors: Cirilo A. G. , Andrade F. H.
Published: July 2010

Changes in the environment that are associated with different sowing dates can be expected to alter maize (Zea mays L.) growth and development in temperate regions. The objective of this work was to study the effect of sowing date on growth and dry matter partitioning of maize crops grown without water and nutrients limitations. A commercial hybrid (DK636) was grown in the field at four sowing dates (mid‐September through mid‐December) for 3 yr. Delays in sowing date hastened development between seedling emergence and silking, decreasing cumulative incident radiation on the crop during the vegetative period. However, late sowings increased crop growth rate during the vegetative period because of high radiation use efficiency and higher percent radiation interception. Conversely, late sowings decreased crop growth rate during grain filling because of low radiation use efficiency and low incident radiation. Late sowings affected grain yield by decreasing kernel weight and kernel number per unit area. Moreover, maize subject to these treatments accumulated more dry matter before silking than from silking to physiological maturity, while the inverse was true for early sowings. Thus, delaying the sowing date strongly decreased dry matter partitioning to grain.
Sowing Date and Maize Productivity: II. Kernel Number Determination
Authors: Cirilo A. G. , Andrade F. H.
Published: July 2010

Kernel number in maize (Zea mays L.) depends on the physiological conditions of the crop at flowering. Our objective was to study the effect of sowing date on the relationship between crop growth rates in the 4‐wk‐period bracketing silking and the components of final kernel number. A commercial hybrid (DK636) was grown in the field at four sowing dates (mid‐September, mid‐October, mid‐November, and mid‐December) for 3 yr at INTA Balcarce Experimental Station, Argentina, at a density of 8.6 plants m−2, without water and nutrients limitations. Significant reductions in final kernel number per unit area of crop were observed when sowing date was delayed. Final number of kernels per unit area was associated with the number of kernels per ear and with the number of ears at harvest. No significant differences were found among sowing dates for maximal number of spikelets per ear at flowering, indicating that kernel abortion was the main factor determining the differences in final kernel number per ear. Reductions in crop growth rate after silking determined decreases in the number of kernels set per ear, whereas reductions in number of ears were not associated with crop growth rate in the presilking period, in which an important allocation of assimilates to structural vegetative growth and maintenance respiration in late sowings would be associated with high ear barrenness.
Internodal Compartmentation of Stem‐Infused [14C]Sucrose in Sweet and Grain Sorghum
Authors: Tarpley Lee , Vietor Donald M. , Miller Frederick R.
Published: July 2010

Stem infusion was evaluated for quantifying downward movement, intracellular allocation, and interorgan partitioning of assimilate in sweet and grain sorghum [Sorghum bicolor (L.) Moench] stems during mid‐grain fill and post‐black layer. Sucrose concentration did not vary below the site of infusion with [14C]sucrose, although gradients of intracellular 80%‐ethanol soluble and insoluble 14C‐components were established in the stem. Variation in gradient steepness between cultivars resulted from aspects of parenchymal uptake or phloem uptake of sucrose and appears related to sucrose‐concentrating ability. The introduced [14C]sucrose concentration gradient in stem tissue is useful for studying stem mechanisms that controls ink strength.
Inheritance of Anther Culture Traits in Barley
Authors: Hou Liming , Ullrich Steven E. , Kleinhofs Andris
Published: July 2010

Doubled haploid (DH) plants represent valuable tools for plant breeding and genetic study. While DH plant production efficiency via anther culture has improved, genotypic effects are still considerable. The objective of this study was to investigate the inheritance of anther culture response to facilitate the application of anther culture to breeding programs. Two donor plant environments (field vs. growth chamber) were compared for anther culture performance of four barley (Hordeum vulgare L.) parents [WA10217‐83 and ‘Hazen’ with high green plant regeneration (GPR), WA9035‐84 and WA7773‐83 with low GPR] and their 12 F1 hybrids ( 4 × 4 complete diallel). The traits evaluated were number of embryoids, total number of plants regenerated, and number of GPR per 100 anthers cultured. Genetic effects were significant while the effects of the two donor plant environments were not. There were additive and dominance effects for all three traits evaluated, and reciprocal effects for GPR. Intermediate responses generally resulted from high × low parent crosses in the F1 for the three traits. The performance of F2 populations from reciprocal crosses between Hazen and WA9035‐84, and WA9035‐84 and WA7773‐83, confirmed the F1 additive and dominance effects. The reciprocal effect in F1 from crosses between WA9035‐84 and WA7773‐83 for GPR per 100 anthers was probably maternal. The GPR of two selected F3 families verified transgressive segregation observed in the F2. F3 performance indicated that selection of recombinant genotypes for higher GPR ability was effective. In conclusion, specific but complex genetic effects for anther culturability were demonstrated and this information has application to barley breeding strategy.
Relationships among North American Oat Cultivars Based on Restriction Fragment Length Polymorphisms
Authors: O'Donoughue L. S. , Souza E. , Tanksley S. D. , Sorrells M. E.
Published: July 2010

Knowledge of genetic variability within a crop species is essential to its improvement. The objectives of this study were to assess restriction fragment length polymorphism (RFLP) patterns for oat (Arena sativa L. and A. Byzantina K. Koch) cultivar characterization, to estimate genetic relationships among oat cultivars based on RFLP patterns, and to contrast these estimates with genetic relationships obtained from pedigree information. Eighty‐three North American oat cultivars were subjected to RFLP analyses using 48 oat and barley (Hordeum vulgare L.) cDNA clones selected to represent a large portion of the genome. The 46 polymorphic clones detected a total of 278 fragments, 205 (73.7%) of which were polymorphic. The number of fragments detected per polymorphic clone varied from 2 to 11 with an average of 6.0 fragments per clone (4.5 polymorphic fragments per clone). The average number of phenotypes produced per clone was 8 (range of 1–25). All cultivars could be distinguished with a minimum of 11 clones. The RFLP banding patterns were used to generate a genetic distance matrix, which was used in both cluster and principal coordinate analyses. Both analyses clearly separated the spring and fall sown groups of cultivars, and further subgroupings were consistent with available pedigree information. The RFLP‐based genetic distance matrix was compared with a matrix of coefficients of parentage for a subset of 55 cuitivars. The Mantel statistic was highly significant (P < 0.01) but low (r = − 0.32) indicating moderate relationship between genetic distance derived from RFLP patterns and the pedigree‐based coefficient‐of‐parentage. The RFLP patterns could be used to predict genetic relationships between germplasm of unknown or ambiguous pedigrees as well as for the fingerprinting of North American oat cultivars.
Management Effects on Yield and Yield Components of Late‐Planted Wheat
Authors: Shah S. A. , Harrison S. A. , Boquet D. J. , Colyer P. D. , Moore S. H.
Published: July 2010

Intensive cereal management can increase the yield and performance of winter wheat (Triticum aestivum L. emend. Thell.), but wet soils often delay planting along the Gulf Coast. Field experiments were conducted at four locations in 1991 and two locations in 1992 to evaluate the effects of two seeding rates (84 or 168 kg ha−1) and two. topdress N rates (90 or 90 + 45 kg ha−1) for an early and late‐maturing cultivar planted at a recommended date or 35 d later. Main effects were generally more significant than interactions except for those involving environment (year‐location). Late planting resulted in significant reduction in grain yield even though more spikes per square meter were produced. Wheat kernels from the recommended planting date were heavier and each spike contained more kernels, which resulted in higher grain yield. Additional N significantly increased yield when the crop was planted at the recommended date by increasing kernels per spike and spikes per square meter, but did not increase yield of the late‐planted crop. Grain yield was not affected by seeding rate for the early planted wheat. Seeding rate effects were influenced by the environment for late planting; however, there was evidence that the higher seeding rate increased yield of the late‐planted crop. Delayed planting reduced yields due to a decrease in kernel weight and kernel number per spike, but the magnitude of yield loss was reduced by using an early‐maturing cultivar and a higher seeding rate.
Digestion Kinetics and Composition of Normal and Brown Midrib Sorghum Morphological Components
Authors: Gerhardt R. L. , Fritz J. O. , Moore K. J. , Jaster E. H.
Published: July 2010

The brown midrib (bmr) mutation has shown the potential to improve the nutritive quality of forage sorghum [Sorghum bicolor (L.) Moench]; however, no study has been conducted to directly compare the effect of the bmr gene in a sudangrass (sorghum × drummondii (Steudel) Millsp. & Chase) and its hybrid with a grain sorghum. Research was conducted to evaluate the relationship between cell wall composition and digestibility within the morphological components of normal and bmr sorghum cultivars. Cell wall constituents, structural carbohydrates, alkali‐labile phenolic monomers, and in vitro digestion kinetics were determined for ‘Piper’ (normal sudangrass), ‘S407’ (Piper. bmr‐6 sudangrass), and ‘F1006‐8 × S407’ (male sterile grain type bmr‐6 sorghum × Piper bmr‐6 sudangrass). Whole plants were harvested at the boot and hard dough growth stages and separated in to leaf blade, leaf sheath, inflorescence, and stem components. Significant differences were found between cultivars in concentrations of cell wall constituents. Neutral detergent fiber (NDF) concentration was lower (P < 0.05) in the bmr cultivars than in Piper due to lower concentrations of cellulose and acid detergent lignin (ADL). Concentrations of ADL averaged g kg−1 dry matter for Piper, 28 g kg−1 for S407, and 25 g kg−1 for F1006‐8 × S407. The bmr cultivars had lower (P<0.05) concentrations of p‐coumaric acid and higher (P < 0.05) concentrations of vanillin than Piper. There were no differences (P > 0.05) among cultivars ferulic acid concentration. p‐Coumaric acid concentrations averaged 25 g kg−1 of NDF for Piper, 16 g kg−1 NDF for S407, and 14 g kg−1 NDF for F1006‐8 − S407. Rate constants for in vitro digestion of NDF were similar (P > 0.05) among cultivars. The bmr sudangrass (S407) had a greater (P < 0.05) extent of NDF digestion than either Piper of F1006‐8 × S407. Extent of NDF digestion averaged 0.596 for Piper, 0.623 for S407, and 0.597 for F1006‐8 × S407. Results of this study indicate that the bmr mutation can effectively be expressed in both sudangrass and sorghum × sudangrass hybrid backgrounds
Somatic Embryogenesis and Plant Regeneration from Callus Cultures of ‘Tifton 9’ Bahiagrass
Authors: Shatters Robert G. , Wheeler Richard A. , West S. H.
Published: July 2010

Identifying appropriate tissue culture and plant regeneration systems for agronomically important cultivars is often an important step in developing gene introduction techniques. Culture conditions for somatic embryogenesis and plant regeneration of ‘Tifton 9’ bahiagrass (Paspalum notatum Fluegge L.) from leaf‐stem cross sections are described. Cultures were initiated and maintained in the dark on Schenk and Hildebrandt medium containing 3% sucrose and 6.6 mg L−1 dicamba. Plant regeneration was initiated by transfer of callus tissue to medium lacking dicamba and incubating in continuous light. Scanning electron microscopy demonstrated, somatic embryogenesis as the process leading to plantlet formation. More than 96% of 4‐mm‐diam. callus segments produced plants, many with multiple germinating embryos. Approximately 300 plantlets were produced per gram of calli. Plants could be grown to maturity by transferring to greenhouse flats 3 wk after placing on regeneration medium. Nonspecific subculturing of primary calli resulted in a decline in regenerability and an increase in the number of albino regenerated plants after 4 to 5 mo from the initiation of callus growth on the explants. However, subculturing of specific callus cells identified as embryogenic extended the efficiency of regeneration and reduced the frequency of albino regenerates. Efficiency of regenerating green plants remained essentially unchanged for 10 mo. We have therefore identified a tissue culture and plant regeneration system suitable for use in genetic engineering.
Moving Mean and Least Squares Smoothing for Analysis of Grain Yield Data
Authors: Clarke F. R. , Baker R. J. , DePauw R. M.
Published: July 2010

Soil heterogeneity often decreases precision in large yield trials. Estimation of, and adjustment for, fertility trends within a trial may increase precision. Two methods of estimating fertility trends were evaluated in 12 experiments with hexaploid wheat (Triticum aestivum L.) and 11 experiments with tetraploid wheat (T. turgidum L. var durum). Each experiment consisted of a trial with two replications of 114 to 282 entries repeated at each of two locations in south‐western Saskatchewan, Canada. With moving mean, the fertility trend for each plot was calculated as the average of the unadjusted yields of six neighbor plots. With least squares smoothing, the fertility trend was calculated as a weighted average of plot yields adjusted for differences among treatments. Weights were inversely proportional to the distance from the adjusted plot and depended upon the observed fertility trend. Compared with unadjusted yields, adjustments by moving means increased the correlation between the two trials within an experiment from an average of 0.41 to 0.48, whereas least squares smoothing increased the average correlation from 0.41 to 0.49. These increases indicate an average increase of within‐trial precision of 20% for moving mean analysis and 24% for least squares smoothing. Either method is useful for removing fertility trends in large yield trials.
Inheritance of Apospory in Buffelgrass
Authors: Sherwood R. T. , Berg C. C. , Young B. A.
Published: July 2010

Previous studies on inheritance of monopolar (Panicum type) apospory in the Panicoideae resulted in three widely different genetic models and mutually incompatible data sets. We report additional data for tetraploid buffelgrass [Pennisetum ciliate (L.) Link = Cenchrus ciliaris L.] and attempt to reconcile earlier studies. Sexual buffelgrass plant B‐2s and five sexual progeny from open pollination of B‐2s were self pollinated and intercrossed. Three obligately aposporous half‐siblings from open pollination of B‐2s and two other aposporous plants were used as male parents in hybridizations with the sexual plants. Selling and crossing among sexual plants gave only sexual progeny. Crosses of sexual × aposporous plants gave progeny segregating for sexual (Polygonum type) and aposporous (Panicum type) embryo sacs at ratios near 15:13 or 3:8 depending upon the aposporous parent. Two earlier models postulating that Panicum type apaspary was regulated by two disomic genes could not account for all types of segregation observed. Assuming random assortment of chromatids, the data fit a model earlier proposed for Panicum maximum Jacq. that postulates expression of apospory requires the dominant allele (A) of a single tetrasomieally inherited locus. Published and present data could be accommodated by a two‐locus model for tetrasomic transmission in which the dominant allele (A) of one locus is required for apaspory but is hypastatic to the dominant allele (B) of the second locus which confers sexuality. Alternatively, it is suggested that tetraploid parents thought to be purely sexual in earlier studies actually were highly sexual, facultative apamicts that yielded segregating progenies after self pollination.
Comparison of Related Wheat Stocks Possessing 1B or 1RS.1BL Chromosomes: Agronomic Performance
Authors: Carver Brett F. , Rayburn A. Lane
Published: July 2010

The 1RS.1BL translocation is widely used by wheat (Triticum aestivum L.) breeders to enhance agronomic performance and particularly grain yield. Research is lacking that compares agronomic trait expression in closely related stocks with or without the translocated chromosome arm. Our objective was to determine the effects of 1RS.1BL on means and genetic variances for grain yield and other agronomic traits in two hard red winter wheat populations segregating for the ‘Aurora’ translocation. Two field experiments were conducted using different genetic materials derived from two crosses, OK83398 × ‘Chisholm’ and OK83398 × ‘Arkan’. In Experiment 1, 25 pairs of F5‐derived near‐isolines homozygons for either 1B or 1RS.1BL were evaluated in three environments. In Experiment 2, plants homozygons for either 1B or 1RS.1BL were selected in the F2, and further subsampled in the F3; forty F3(F2) lines per chromosome type in each cross were evaluated in four environments. The average effect of 1RS.1BL in Experiment 1 was to increase grain yield by 9 to 10%, increase aerial biomass by 11 to 12%, and increase kernel weight by 4 to 6%, depending on the cross. Differences in kernels per spike, harvest index, and test weight were not detected, whereas differences in plant height and the number of spikes per meter squared were inconsistent between crosses or among environments. The magnitude of the effect of 1RS.1BL varied considerably among the paired near‐isolines, presumably by the effects of genes present on other wheat chromosomes. Heterogeneity of genetic variance in Experiment 2 was usually caused by larger variance among 1RS.1BL genotypes than 1B genotypes. These results encourage further use of 1RS.IBL to improve agronomic traits of wheat.
Genetics of Tolerance to Soil Acidity in Tropical Maize
Authors: Pandey S. , Ceballos H. , Magnavaca R. , Bahía Filho A. F. C. , Duque‐Vargas J. , Vinasco L. E.
Published: July 2010

Maize (Zea mays L.) is grown on approximately eight million hectares of acidic soils, where yields are low because of the toxicity of AI and Mn and deficiency in Ca, Mg, and P. Maize cultivars tolerant to soil acidity would increase yields on such soils. A diailel study was conducted involving six soil‐acidity tolerant and two susceptible segregating populations to identify superior germplasm to develop cultivars for acidic soils. The eight populations and their 28 crosses were evaluated in seven acidic soil environments. Tolerant populations averaged higher in yield (2.19 vs. 1.58 Mg ha−1; P < 0.01), ears per plant (0.79 vs. 0.64; P < 0.05), and ear height (61.6 vs. 51.4 cm; P < 0.01), and fewer in days to silk (68.8 vs. 69.7 d; P < 0.05) than the susceptible populations. Mean squares of parents vs. crosses were highly significant for yield, ear height, and ears per plant, and significant for days to silk, indicating beterosis for these traits. Crosses between tolerant populations tended to yield higher (3.00 Mg ha−1) than those between tolerant and susceptible populations (2.40 Mg ha−1) and between susceptible populations (2.01 Mg ha−1). General combining ability (GCA) was highly significant for all traits, but specific combining ability (SCA) was significant only for ears per plant. Reciprocal recurrent selection would be effective in developing superior cultivars for acidic soils and should include populations 90SA‐3 and 90SA‐4 or CMS‐36 for yellow endosperm cultivars and 90SA‐6 and 90SA‐7 for white endosperm cultivars.
Salinity Affects the Timing of Phasic Development in Spring Wheat
Authors: Grieve C. M. , Francois L. E. , Maas E. V.
Published: July 2010

Understanding effects of environmental factors on crop phenological development is useful for predicting crop growth stages and scheduling management practices. We evaluated the effect of salinity on the rate of leaf appearance and the duration of critical stages of growth in wheat (Triticum aestivum L.) in terms of both thermal unit (TU; °C day) and phyllochron intervals. Two hard red spring wheat cultivars, Yecora Rojo and Anza, were grown two cropping years in greenhouse sand cultures and outdoor field lysimeters. In each case, two saline treatments were compared with a nonsaline control. The sand cultures were irrigated with complete nutrient solutions to which NaCl and Cad; were added. The electrical conductivities, Kiw, were 2.0, 14.3, and 18.1 dS m−1 in 1989 and 1.7, 12.2, and 15.1 dS m−1 in 1990. The Kiw for the field lysimeters were 0.9, 10.7, and 17.2 dS m−1 in 1989 and 0.8, 11.4, and 17.1 dS m−1 in 1990. Leaf appearance rate was determined by regressing the number of mainstem leaves against cumulative TU. In all treatments, the cultivars differed in both rate and duration of leaf appearance. The phyllochron increased with salinity. Leaves emerged more slowly in the greenhouse than in the field. Durations of the vegetative stages (°C day) from sowing to the initiation of the flag leaf and its subsequent appearance were relatively insensitive to salinity inasmuch as increases in leaf plastochron (TU between the initiation of successive leaves on a culm) and leaf phyllochron were balanced by decreases in leaf number. However, for both cultivars, salinity significantly reduced the thermal time between sowing and the reproductive phenological stages.