bluuebunny/crossref_metadata_2025 huggingface dataset:
Error Variation in Multienvironment Peanut Trials: Within‐Trial Spatial Correlation and Between‐Trial Heterogeneity
Authors: Casanoves F. , Macchiavelli R. , Balzarini M.
Published: August 2005

Multienvironment Trials (MET) are used to make cultivar recommendations about genotypes in plant breeding programs. Because of the presence of genotype × environment interaction, METs are usually conducted in multiple environments using designs that involve several replications per environment. Blocking of plots within each trial enables one to account for between plot variation. To improve the comparison of genotype means, taking into account within‐trial spatial correlation as well as between‐trial residual variance heterogeneity, alternative mixed models can be used. The objective of this study was to compare several spatial models, including or excluding heterogeneity of residual variances for cultivar evaluation in a set of independent peanut (Arachis hypogaeaL.) METs. The modeling impact was evaluated by comparing genotype means from each trial. A series of 18 METs from a peanut breeding program, as according to a randomized complete block design (RCBD) at each location, were simultaneously fitted by (i) a classic analysis of variance model for an RCBD with blocks random and (ii) mixed models incorporating spatial correlation through isotropic and anisotropic covariance structures for the error terms (power correlation function) and including homogenous and heterogeneous residual variances to take into account the different environments having different precision. Results suggest that the model with stationary anisotropic error structure AR1×AR1 within each environment and heterogeneous residual variances constitutes a good alternative analysis for METs, but it was not always better than the RCBD models for peanut. Differences were found between long‐ and short‐cycle peanut cultivars with respect to the best model.
Effect of Temperature and Soil Moisture Status during Seed Development on Soybean Seed Isoflavone Concentration and Composition
Authors: Lozovaya Vera V. , Lygin Anatoliy V. , Ulanov Alexander V. , Nelson Randall L. , Daydé Jean , Widholm Jack M.
Published: August 2005

Soybean [Glycine max (L.) Merr.] seed isoflavone concentration has been shown to be highly dependent on environmental conditions, but isoflavone concentrations have not been studied under controlled conditions to quantify the effects of specific factors. To determine the effect of air temperature and soil moisture status during soybean seed development on seed isoflavone concentration and composition, soybean plants were grown in the greenhouse under intermediate (18/28°C), 9.5 h night/14.5 h daytime temperatures with high soil moisture conditions. Beginning at the R6 growth stage plants were subjected to either intermediate (18/28°C), low (13/23°C), or high (23/33°C) 9.5 h night/14.5 h daytime temperatures with either low or high soil moisture conditions. Two French cultivars, Imari and Queen, and three U.S. cultivars, Dwight, Jack and Loda, all in maturity group II were studied. The overall results show that low temperatures and high soil moisture conditions produced the highest seed isoflavone concentrations with changes in temperature having the larger effect. The changes in daidzein and genistein concentrations were similar to changes in total isoflavones but the glycitein concentration was much less affected. The three U.S. cultivars were much less responsive to soil moisture than the two French cultivars. All five cultivars showed a two‐ to threefold increase in total isoflavone concentrations at the low temperature regime compared to the high temperature regime. Plant height was greatest under the intermediate temperatures; whereas, low temperatures and low soil moisture hastened maturity. Seed size was not significantly affected by any treatment. Soil moisture and air temperature have clear effects on the isoflavone concentrations in mature soybean seeds, but the ranking of all the cultivars based on average isoflavone concentration remained the same with all treatments. Environmental factors can have a large effect on isoflavone concentration, but the potential for isoflavone production is largely under genetic control.
Evaluation of Lupinus albus L. Germplasm for the Southeastern USA
Authors: Noffsinger Steven L. , van Santen Edzard
Published: August 2005

While white lupin (Lupinus albus L.) has potential as a new minor winter crop, adapted germplasm have to be discovered and considerations for cold tolerance, pest resistance, and other traits determined. We evaluated 100 accessions in 1990–1991 and 616 in 1991–1992 at two locations in central Alabama, USA. Twenty‐four seeds per accession were hand sown in an upland area on a Marvyn sandy loam (fine‐loamy, kaolinitic, thermic, Typic Kahapludults) and in a river bottom area on a Wickham fine sandy loam (clayey, kaolinitic, thermic, Typic Rhododults). Backward stepwise and canonical discriminate analysis (CDA) was used to determine which agronomic traits and groups of accessions were most important for adaptation. Accessions were selected for further evaluation and breeding on the basis of survival through physiological maturity in 1990–1991 and on grain yields ≥27.6 g plot−1 (2128 kg ha−1 equivalent) in 1991–1992. The first two canonical discriminate variates (CAN) had Eigenvalues ≥1 and accounted for ≥51% of the total variance for both years. Vernalization type ratings (winter, semiwinter, spring) were most highly correlated (≥0.87) with CAN 1 for both years, so CAN 1 was labeled vernalization type. The continuum for vernalization requirements was represented by CAN 1 in the 1990–1991 data. On the basis of correlations with CAN 2 for both years, earlier flowering of spring types was detrimental to survival. Selection of accessions with cold tolerance proved to be more important than extremely high vernalization requirements in severe winter types. Brown spot leafspot and root rot [caused by Pleiochaeta setosa (Kirchn.) Hughes] were the most prevalent diseases. East and West Mediterranean germplasm comprised >55% of the selections for further testing; these lines were better adapted to the Southeast, while Southwest Asian and North African severe spring types with little or no vernalization requirement were better suited for use in short season areas of the northern USA.
Grain Quality of Brazilian Maize Genotypes as Influenced by Nitrogen Level
Authors: Duarte Aildson P. , Mason Stephen C. , Jackson David S. , Kiehl Jorge de C.
Published: August 2005

Maize (Zea mays L.) is an important crop in Brazil, and concerns about grain quality are increasingly important with increasing exports and use of grain for specific end‐uses. A wide range of genotypes are grown and N application is required to produce high yields. The objectives of these studies were to: (i) determine N application effects on the kernel hardness and breakage susceptibility of a wide range of Brazilian genotypes ranging from dent to flint kernel types and (ii) determine relationships among kernel hardness and breakage susceptibility tests, yield and N and oil concentration. Three studies were conducted with a broad range of maize genotypes and N application rates of 0, 60, 120, and 180 kg ha−1 Grain was harvested and yields corrected for water content, and grain was evaluated through a series of chemical and physical quality tests. Application of 180 kg ha−1 N application increased grain yield by 747 to 1466 kg ha−1, increased grain N concentration by 0.9 to 2.4 g kg−1, and increased hardness to a lesser extent, while reducing breakage susceptibility by 1.9 to 6.9%. Genotype had a much larger influence on grain quality parameters than did N rate. The limited correlation between grain yield, grain N concentration, and grain oil concentration to kernel hardness suggests that development of further improved genotypes with high maize yields and excellent dry milling grain quality is feasible in Brazil. The large variation in grain yield and dry milling grain quality in intermediate kernel‐type (semident, semiflint) genotypes used in Brazil presents short‐term potential to select hybrids that produce both high yield and good dry milling grain quality.
Resource Allocation and Cultivar Stability in Breeding for Fusarium Head Blight Resistance in Spring Wheat
Authors: Fuentes R. G. , Mickelson H. R. , Busch R. H. , Dill-Macky R. , Evans C. K. , Thompson W. G. , Wiersma J. V. , Xie W. , Dong Y. , Anderson J. A.
Published: August 2005

The development of wheat (Triticum aestivum L.) cultivars resistant to Fusarium head blight (FHB) (caused by Fusarium graminearum Schwabe) requires screening methodologies that accurately characterize reaction to this disease. The objectives of this study were (i) to characterize the stability of cultivars for their FHB reaction and (ii) to define an optimum resource allocation for FHB evaluation. Fourteen cultivars were evaluated in FHB‐screening nurseries at two locations across a 4‐yr period. Field data were used to calculate disease incidence (INC) as the frequency of symptomatic spikes and disease index (DIS) as the mean disease score of all spikes. FHB reaction also was evaluated on harvested grain as percent visually scabby kernels (VSK) and deoxynivalenol (DON) concentration. Significant differences among cultivars for all FHB parameters were found in each environment. Pearson correlation coefficients among FHB parameters were positive and highly significant, ranging from 0.32 between INC and DON to 0.72 between INC and DIS. Spearman rank correlation coefficients for yearly cultivar rankings and Kendall's coefficient of concordance were high, indicating similarity of the rankings of the tested cultivars in different environments. Visually scabby kernels was the FHB parameter with highest similarity for cultivar ranking across environments. Most of the cultivars, including susceptible ones, expressed stability for FHB reaction. Optimum resource allocation for DIS was most affected by the number of environments with three being the minimum to accurately characterize a genotype's resistance level. Using more than three replications or scoring more than 10 spikes per plot had little practical value in characterizing FHB reaction.
Recovery of Recurrent Parent Traits when Backcrossing in Cotton
Authors: Bayles Melanie B. , Verhalen Laval M. , McCall Lloyd L. , Johnson William M. , Barnes Bradley R.
Published: August 2005

Six family groups of upland cotton (Gossypium hirsutum L.), derived by backcrossing, were compared over multiple environments. Each group consisted of a different nonrecurrent parent (NRP), a cultivar from Africa with resistance to bacterial blight [caused by Xanthomonas campestris pv. malvacearum (Smith) Dye]; the same recurrent parent (RP), ‘Westburn 70’, susceptible to that disease; the F4 of the cross between them; and the Bc1F4, Bc2F4, Bc3F4, and Bc4F4 generations. All entries were evaluated for lint yield, six fiber properties, and seven agronomic characters. Reactions to three diseases were also determined for the Bc4F4 and the RP in two environments per disease. The objectives of this study were to measure the degree and rate of recovery of RP traits through four backcross generations in upland cotton as well as to determine reactions to three diseases (including blight) in the Bc4F4 generation. Eighty‐four sets of comparisons (six family groups by 14 traits) were possible in the portions of the study not involving diseases. The NRPs differed significantly from the RP in 69 of the 84. Among those 69 combinations, the number (and percentage) of significant differences from the RP in the F4, Bc1F4, Bc2F4, Bc3F4, and Bc4F4 were 47 (68%), 35 (51%), 25 (36%), 25 (36%), and 14 (20%), respectively. No significant differences were detected in any family group between the Bc4F4 and the RP for lint yield, 2.5 and 50% span lengths, uniformity index, and pulled lint percentage. One or more such differences were found for micronaire, T0 and T1 fiber strengths, picked lint percentage, boll size, bur size, lint weight per boll, lint index, and seed index. Depending on the trait, three, four, and often more backcrosses were required to recover the RP traits. Several instances of transgressive segregation were noted mainly in the earlier backcross generations. The observed rate of recovery of RP traits was 96% of the theoretical rate. The only intentional selection in these materials was for bacterial blight resistance. As expected, the level of blight resistance in the Bc4F4 reflected that of its NRP. Also as expected, the level of tolerance to Verticillium wilt (caused by Verticillium dahliae Kleb.) and of resistance to the Fusarium wilt [caused by Fusarium oxysporum Schlect. f. sp. vasinfectum (Atk.) Snyd. & Hans.]–root‐knot nematode [Meloidogyne incognita (Kofoid & White) Chitwood] complex in the Bc4F4 reflected that of the RP with three possible exceptions.
Effect of Control Plot Density, Control Plot Arrangement, and Assumption of Random or Fixed Effects on Nonreplicated Experiments for Germplasm Screening Using Spatial Models
Authors: Sebolai Boi , Pedersen J. F. , Marx D. B. , Boykin D. L.
Published: August 2005

Early generation selection experiments typically involve several hundred to thousands of lines. Various systematic and statistical techniques have been developed to increase effectiveness and efficiencies in such experiments, including the development and application of spatial statistical models. In this study, mixed model equations were used to provide least squares means (LSMEANs) and best linear unbiased predictors (BLUPs) and compare selection effectiveness and efficiencies to observed (Y) and true values in simulated experiments varying in size (10 × 10, 20 × 20 and 30 × 30 grids), control plots densities (0, 5, 10, 20, and 50%), control plot arrangements (high, medium, and low A‐optimality), and spatial range of influence (short and long). Results were similar for all grid sizes. In experiments in which the simulated land areas were highly variable (short range), none of the predictors, Y, LSMEAN, or BLUP, were very effective in identifying the true superior genotypes. When the simulated land areas were less variable (long range), use of BLUPs consistently resulted in the highest proportion of true top ranking genotypes identified across all control plot densities, while using the observed values consistently resulted in identification of the lowest proportion of the true top ranking genotypes. Effectiveness of LSMEANs was dependent on control plot density and arrangements. Use of BLUPs for early generation germplasm screening experiments should result in a high effectiveness in selecting truly superior germplasm and high efficiency because of the ability to account for spatial variability with the use of few or no control plots.
The Maize lpa241 Mutation Causes a Remarkable Variability of Expression and Some Pleiotropic Effects
Authors: Pilu Roberto , Landoni Michela , Cassani Elena , Doria Enrico , Nielsen Erik
Published: August 2005

Phytic acid is a nearly ubiquitous component of plant seeds, supplying both phosphate (P) and cations during germination. However, during digestion, the phytic acid form of P is not bioavailable for monogastric animals. A possible solution to this problem is the isolation of cereal mutants accumulating less phytic P and more free P and cations in the seed (low phytic acid, lpa). In a previously published study, we described a single, recessive lpa mutation (named lpa241) in maize (Zea mays L) mapping on chromosome 1S in the same location of the lpa1‐1 mutant, showing a decrease in the expression of the first enzyme of phytic acid pathway, myo‐inositol‐3‐phosphate synthase (MIPS). The goal of this study was to gain further information about the nature of lpa241 mutation as well as its effects on seed physiology and plant growth. We present new results of genetic, molecular, and histological analyses demonstrating that lpa241 is indeed allelic to lpa1‐1, its MIPS1S coding region does not show a relevant molecular lesion, is accompanied by a strong reduction in globoid number and size, and shows highly variable expression causing some negative pleiotropic effects related to embryo development and size, germination rate, seedling growth rate, and ear size. The origin and the consequences of the lpa241 mutation led us to advance the hypothesis of an epigenetic nature of the mutation and to emphasize the role of myo‐inositol and its derivatives during seed maturation, germination, and seedling growth.
Phenotypic and Molecular Analysis of Oleate Content in the Mutant Soybean Line M23
Authors: Alt Jessie L. , Fehr Walter R. , Welke Grace A. , Sandhu Devinder
Published: August 2005

Soybean [Glycine max (L.) Merr.] oil with elevated oleate content would be useful for food and industrial applications that require increased oxidative stability. The first objective of this study was to determine if molecular selection for the Fad2‐1 deletion associated with the ol allele in the mid‐oleate mutant line M23 could be used to identify mid‐oleate individuals in a breeding program. The second objective was to determine if modifying genes affect phenotypic expression of oleate content in individuals homozygous for the deletion from a cross between M23 and Archer, a cultivar with normal oleate content. The segregation among 88 F2 plants from the cross satisfactorily fit a ratio of 1:2:1 homozygous normal (OlOl)/heterozygous (Olol)/homozygous (olol) for the Fad2‐1 deletion on the basis of Southern analysis. A PCR‐based marker Fad2‐1‐ol identified the same olol individuals as the Southern analysis. The PCR‐based marker would be a more rapid and less labor intensive method for molecular selection of olol individuals than Southern analysis. The olol individuals had the highest mean oleate content, the Olol individuals were intermediate, and the OlOl individuals had the lowest mean oleate content. There was significant variation among the olol individuals and their distribution overlapped that of the OlOl and Olol individuals, which indicated that modifying genes had an important influence on the trait. It would be necessary to test the fatty acid profile of olol individuals to select those with the highest oleate content.
Analysis of Genetic Factors Influencing the Developmental Rate of Globally Important CIMMYT Wheat Cultivars
Authors: van Beem Janny , Mohler Volker , Lukman Rudy , van Ginkel Maarten , William Manilal , Crossa José , Worland Anthony J.
Published: August 2005

The rate at which wheat (Triticum aestivum L.) reaches anthesis and other developmental stages depends largely on the variation of three major factors: vernalization (Vrn), photoperiod (Ppd), and earliness per se (Eps). The objectives of this study were to characterize a set of genotypes for the presence of developmental genes and their potential association to adaptability and to identify diagnostic molecular markers for the vernalization gene Vrn‐D1 Fifty‐one genotypes were crossed with testers containing known Vrn and Ppd genes. To determine earliness per se and its interaction with temperature, genotypes were vernalized for 8 wk and placed in a 24‐h photoperiod regime at two temperatures. To validate molecular markers for Vrn‐D1, the cultivars were genotyped with closely linked SSR markers Xgwm292‐5D and Xgwm212‐5D Segregation analysis on F2 populations of field‐grown plants showed that Vrn‐D1 was present in 66% of the cultivars, while Vrn‐A1, Vrn‐B1, and Vrn4 were found in 41, 39, and 8% of the lines, respectively, either solely or in combination with other Vrn genes. A low percentage of cultivars appeared to have a constitutive genetic character for early flowering (Eps), while most of the cultivars may have temperature‐sensitive genes that respond to local environmental changes. Vrn‐D1 was reliably detected in 76.5% of the genotypes using the 215‐bp allele of microsatellite marker Xgwm292‐5D, whereas Xgwm212‐5D did not reveal sufficient allelic variation within the tested wheats.
Aluminum Tolerance in Medicago truncatula Germplasm
Authors: Sledge M. K. , Pechter P. , Payton M. E.
Published: August 2005

Aluminum (Al) toxicity is a major limiting factor of crop production in acidic soils. Medicago truncatula Gaertn., a close relative of alfalfa (M. sativa L.), is negatively affected by Al toxicity. The objective of this study was to assess the variation for Al tolerance among M. truncatula accessions held in the USDA National Plant Germplasm System, with the long‐term goal of identifying Al tolerance genes to be used for alfalfa improvement. Three hundred twenty‐one accessions of M. truncatula, from 20 different countries, were screened for Al tolerance in a hydroponics approach. Seed from each M. truncatula accession were surface sterilized and germinated before being grown in hydroponics. Ten germinated seedlings were transferred to a hydroponics culture tank containing modified Blaydes medium without aluminum and ten were transferred to a second tank containing modified Blaydes medium with 50 μM Al. Seedlings were grown for 5 d and root length was measured. Relative root growth in Al medium was used as a measure of Al tolerance. Relative root growth varied from 0.35 to 1.09, indicating that sufficient variation exists within this collection of M. truncatula accessions to select sensitive and tolerant accessions, which could be used to identify QTL for Al tolerance, the first step in a map‐based cloning approach to discover Al tolerance genes.
Effects of Summer Grazing Strategies on Organic Reserves and Root Characteristics of Big Bluestem
Authors: Mousel E. M. , Schacht W. H. , Zanner C. W. , Moser L. E.
Published: August 2005

Quantifying root structure response to multiple defoliation events in a grazing situation is critical in developing management plans for warm‐season tallgrasses. A pasture experiment was conducted in 1999, 2000, and 2001 near Mead, NE. The objective of the experiment was to determine the effect of timing and frequency of grazing on big bluestem (Andropogon gerardii Vitman) etiolated tiller growth and root and rhizome structure. Paddocks were grazed at a stocking rate of 9.9 Animal Unit Month (AUM) ha−1 in two to four cycles from mid‐May to early‐September. In April 2002, five 6.6‐ × 132‐cm soil cores were extracted from each paddock. Soil cores were subsampled at 30‐cm depth increments for estimates of root mass, root surface area, and root volume. Etiolated tiller tents were used to estimate organic reserves of big bluestem in each paddock in spring 2002. Mean number and weight of etiolated tillers were reduced by up to 40% and 50%, respectively, in paddocks grazed in a sequence of June after internode elongation, early August, and early September. Root structure in the top 30 cm of the soil profile was affected most by multiple defoliation events with <40 d of recovery between grazing periods. Root mass decreased by 25%, while mean surface area and volume of roots declined 10 and 15%, respectively, in the upper 30 cm of the soil profile in paddocks grazed in the sequence of post‐internode elongation in June, early‐August, and early‐September. To maintain vigorous big bluestem pastures, grazing management should concentrate on the elongation and postelongation periods. Grazing at the elongation stage should be rotated among paddocks in successive years and the recovery period following grazing at internode elongation should be >40 d.
Quantitative Trait Loci for Seed Protein and Oil Concentration, and Seed Size in Soybean
Authors: Panthee D. R. , Pantalone V. R. , West D. R. , Saxton A. M. , Sams C. E.
Published: August 2005

Soybean [Glycine max (L.) Merr.] is an important crop because of its high oil and protein concentration. However, there is an inverse relationship between seed protein and oil concentration, making it difficult to improve both traits simultaneously. Molecular breeding may be helpful to facilitate a balanced accumulation of desirable alleles. The objective of this study was to identify quantitative trait loci (QTL) governing soybean protein, oil and seed size. To achieve this objective, 101 F6–derived recombinant inbred lines (RIL) from a population developed from a cross of N87‐984‐16 × TN93‐99 were used. Heritability estimates on an entry mean basis for protein and oil concentrations, and seed size were 0.66, 0.54, and 0.71, respectively. A total of 585 simple sequence repeat (SSR) molecular genetic markers were screened and 94 were polymorphic in the RIL. Single factor ANOVA was used to identify candidate QTL, which were then confirmed by composite interval mapping. One novel molecular marker (Satt570) on molecular linkage group (MLG) G associated with a protein QTL was detected. Novel molecular markers (Satt274, Satt420, and Satt479) located on MLG D1b, O, and O respectively and a previously reported marker (Satt317) located on MLG H were associated with oil QTL in this study. Molecular markers Satt002 (MLG D2) and Satt184 (MLG D1a) associated with seed size QTL were verified whereas Satt147 (MLG D1a) was novel. The individual QTL explained 20.2, 9.4‐15, and 10 to 16.5% of the phenotypic variation for protein and oil concentrations, and seed size, respectively. Thus, we identified major loci for improving soybean seed quality.
Oat Germination Characteristics Differ among Genotypes, Seed Sizes, and Osmotic Potentials
Authors: Willenborg Christian J. , Wildeman Jeffery C. , Miller Aaron K. , Rossnagel Brian G. , Shirtliffe Steven J.
Published: August 2005

Oat (Avena sativa L.) yield and quality on the northern Great Plains are consistently reduced by frequent drought and wild oat (Avena fatua L.) competition. Wild oat cannot be selectively removed from oat with herbicides. Identifying genotypes or seed size(s) with high germination potential under moisture stress may facilitate improved seedling vigor, stand establishment, and crop competitiveness. Therefore, a germination study was conducted to determine the effects of genotype and seed size on the germination of oat seed subjected to moisture stress. Large, medium, and small seeds of six common western Canadian oat genotypes were germinated in polyethylene glycol (PEG 8000) solutions with initial osmotic potentials ranging from 0 to −0.4 MPa at 5°C. Generalized linear mixed models fit to the data provided a statistically valid, appropriate, and convenient method to analyze germination data. In all genotypes examined, decreasing seed size and osmotic potential increased median germination time (MGT) and lowered final germination percentage (FGP). Among genotypes, CDC Bell had the fastest MGT while AC Mustang had the highest FGP. Delays in MGT and reductions in FGP resulting from increased moisture stress were similar to those observed in other cereals, suggesting that oat may be as capable of germinating under low spring soil moisture conditions as wheat and barley. The results of this study also indicate that large seed of genotypes such as AC Mustang and CDC Bell appear better suited to germinate under the range of osmotic potentials in this study. Although differences in MGT and FGP between seed sizes in this study were statistically significant, they were generally small and thus, oat germination characteristics may not be substantially improved by screening out small seed from farm‐saved seed.
Differences in Thermal Time Requirement for Germination of Three Turfgrass Species
Authors: Larsen Søren Ugilt , Bibby Bo Martin
Published: August 2005

Temperature is among the most influential environmental factors for germination and establishment of grass species. We compared germination response to suboptimal temperature for the turfgrass species slender creeping red fescue (Festuca rubra L. var. littoralis Vasey), perennial ryegrass (Lolium perenne L.), and Kentucky bluegrass (Poa pratensis L.). Two cultivars of each species were germinated at five constant temperatures (8, 12, 16, 20, and 24°C), and germination was recorded one to three times per day. Final germination percentage was little affected by temperature, indicating that the base temperature for germination (Tb) is relatively constant within seed populations. Consequently, germination response to temperature was analyzed by a nonlinear regression method, which combined the thermal time model and the four parameter Weibull function. The analysis provided biologically significant parameters for comparing the cultivars and species. Tb only varied slightly between species, from 2.6°C for red fescue and Kentucky bluegrass to 3.6°C for perennial ryegrass. Thermal time to 50% of final germination was 63.9 degree‐days for perennial ryegrass, 43.8 for red fescue, and 115.6 for Kentucky bluegrass, and thermal time from 25 to 75% of final germination was 14.9, 11.1, and 35.0 degree‐days. Thus, Kentucky bluegrass requires a longer thermal time to germinate and has a larger variation in thermal time requirement within a seed lot. Consequently, low soil temperature results in a relatively slower germination of Kentucky bluegrass, possibly resulting in a poorer competitive ability of this species. This suggests that poor establishment of Kentucky bluegrass may partly be due to a larger thermal time required for germination.
Grazing Management and Nitrogen Fertilization Effects on Vaseygrass Persistence in Limpograss Pastures
Authors: Newman Y. C. , Sollenberger L. E.
Published: August 2005

Vaseygrass (Paspalum urvillei Steud.) is a weed in environments where limpograss [Hemarthria altissima (Poir.) Stapf & Hubb.] is a productive pasture grass. The objective of this study was to determine grazing management and N fertilization effects on persistence of vaseygrass in limpograss pastures on a Pomona sand (sandy, siliceous, hyperthermic Ultic Alaquod). Treatments were arranged in a split‐plot experiment; combinations of grazing method (continuous vs. rotational) and stubble height (15 and 30 cm) were the main plots, and N fertilization (50 and 150 kg N ha−1) was assigned to subplots. Continuous stocking for two grazing seasons reduced vaseygrass cover by 15 percentage units (−3 units for rotational) and increased limpograss cover by 6 units (−8 units for rotational). A stubble height × N rate interaction occurred because at the shortest height and lowest N rate the decline in vaseygrass cover (15 units) and increase in limpograss cover (7 units) were most pronounced. After 2 yr of continuous stocking, vaseygrass stem‐base mass was lower than for rotational stocking (12 vs. 23 g plant−1), and stem‐base (0.40 vs. 0.78 g plant−1) and root (0.46 vs. 0.91 g plant−1) content of total nonstructural carbohydrate (TNC) were lower under continuous compared to rotational stocking, respectively. Grazing to a 15‐ vs. 30‐cm stubble height resulted in lower vaseygrass stem‐base mass (12 vs. 23 g plant−1) and TNC content (0.44 vs. 0.73 g plant−1). Continuous stocking reduced vaseygrass plant mass and density while limpograss cover increased, but careful management of stubble height is required to avoid subsequent invasion by other undesirable species.
QTL Mapping of Antibiosis Resistance to Common Cutworm (Spodoptera litura Fabricius) in Soybean
Authors: Komatsu Kunihiko , Okuda Shiori , Takahashi Masakazu , Matsunaga Ryoichi , Nakazawa Yoshinori
Published: August 2005

The common cutworm (CCW; Spodoptera litura Fabricius; Lepidoptera: Noctuidae) is a major pest of soybean [Glycine max (L.) Merr.] in Japan. Previously, we analyzed a soybean cultivar named Himeshirazu and found that it exhibits a heritable antibiosis resistance to CCW. In this study, we performed quantitative trait locus (QTL) analysis using composite interval mapping (CIM) method to locate the source of the antibiosis resistance of Himeshirazu. We used a previously reported F2 segregating population of susceptible ‘Fukuyutaka’ × resistant Himeshirazu. We constructed a linkage map spanning 2270.4 cM with 146 simple sequence repeat (SSR) markers and a phenotype marker (pubescence color). Two QTLs for antibiosis resistance were detected in linkage group (LG) M. One was located between SSR markers Satt220 and Satt175, with a maximum logarithm of odds (LOD) score of 12.7 and r2 = 0.283. The other was located between Satt567 and Satt463, with a maximum LOD score of 6.8 and r2 = 0.159. The resistant allele of both QTLs was derived from Himeshirazu. One‐way ANOVA of the F2 family classified by genotypes of SSR loci linked to each QTL suggested that a significant antibiosis effect was exhibited when both QTLs were homozygous for the resistant allele.
Managing Irrigation and Nitrogen Fertility of Hard Spring Wheats for Optimum Bread and Noodle Quality
Authors: Guttieri Mary J. , McLean Reuben , Stark Jeffrey C. , Souza Edward
Published: August 2005

End‐uses of hard wheat (Triticum aestivum L.) are increasingly diverse. However, limited understanding of crop management system interactions with genotype exists to tailor production systems for both bread and Asian noodle production. Therefore, we evaluated the bread quality and alkaline noodle color of four hard spring wheat genotypes differing in end‐use quality at four nitrogen fertilizer levels and three irrigation levels. The trials were grown for 2 yr at Aberdeen, ID, using the hard red cultivar ‘Westbred 936’, the hard white cultivars ‘Idaho 377s’ and ‘Lolo’, and the hard white breeding line ‘IDO523’. The main effects of genotype, nitrogen fertilizer, and irrigation affected grain protein concentration, which led to significant differences among treatments for mixograph characteristics and loaf volume. Genotypes differed significantly in their optimum nitrogen levels for grain yield, yet grain protein concentration of all four genotypes increased linearly with increasing nitrogen fertilizer application. Reducing the amount of irrigation elevated grain protein concentration; however, it also reduced milling yield. By contrast, increasing nitrogen fertility did not affect milling yield. Reducing the amount of irrigation also increased grain polyphenyl oxidase (PPO) activity, generally undesirable for Asian noodles. In this study, it was preferable to increase grain protein concentration by increasing fertilization rather than by reducing irrigation. Nitrogen fertilizer did not affect alkaline noodle brightness, except at the lowest irrigation level where increasing nitrogen fertilizer decreased initial brightness. Increased nitrogen fertilizer increased both peak flour pasting viscosity and final flour pasting viscosity. The increase in viscosity occurred at all irrigation levels but with different slopes among the genotypes. The flour pasting properties of Lolo were most affected by nitrogen fertilization.
Agronomic Evaluation of Sugarcane Lines Transformed for Resistance to Sugarcane mosaic virus Strain E
Authors: Gilbert R. A. , Gallo-Meagher M. , Comstock J. C. , Miller J. D. , Jain M. , Abouzid A.
Published: August 2005

Genetic transformation of sugarcane (Saccharum spp.) holds promise for increasing yields and disease resistance. However, the tissue culture and transformation process may produce undesirable field characteristics in transgenic sugarcane. The primary objective of this study was to evaluate variability in agronomic characteristics and field disease resistance of sugarcane transformed for resistance to Sugarcane mosaic virus (SCMV) strain E. One hundred plants derived from cultivars CP 84‐1198 (n = 82) and CP 80‐1827 (n = 18), consisting of independent virus resistant lines VR 1 (n = 14), VR 4 (n = 24), VR 14 (n = 4), and VR 18 (n = 58) were evaluated in Exp. 1. Transgenics derived from CP 84‐1198 had significantly greater tonnes of sucrose per hectare (TSH) and significantly lower SCMV disease incidence than those from CP 80‐1827 in the plant‐cane (PC), first‐ratoon (1R), and second‐ratoon (2R) crops. Plants from the VR 18 line had significantly greater economic indices and lower SCMV disease incidence than the VR 4 line in all three crops. Phenotypic variation was high in Exp. 1, with tonnes of cane per hectare (TCH) ranging from 26 to 211 and TSH from 3.2 to 28.9 in the PC crop. Agronomic trait variation decreased with increased selection pressure in Exp. 2, evaluating 30 VR 18 lines, with TCH ranging from 70 to 149 and TSH from 8.5 to 19.0 in PC. The large variability in yield characteristics and disease resistance encountered in this study demonstrates the necessity of thorough field evaluation of transgenic sugarcane while selecting genetically stable and agronomically acceptable material for commercial use.
Candidate Cool‐Season Legumes for Filling Forage Deficit Periods in the Southern Great Plains
Authors: Rao S. C. , Northup B. K. , Mayeux H. S.
Published: August 2005

This study was conducted to determine seasonal forage production and nutritive value of the cool‐season annual legumes grasspea (Lathyrus sativus L. cv. AC‐Greenfix) and lentil (Lens culinaris Med. cv. Indianhead) grown to fill the spring forage deficit period of the southern Great Plains. Data were collected from March to June in 2001 through 2003 at the USDA‐ARS Grazinglands Research Laboratory, El Reno, OK. Seeds of each species was inoculated and planted (60‐cm row spacing) annually on 15 March (75 kg ha−1 for grasspea; 25 kg ha−1 for lentil) in 60‐m−2 plots. Aboveground biomass was collected on five dates [45–95 d after seeding (DAS)], dried 60 h at 60 to 65°C, weighed, and used to calculate aboveground standing crop. Samples were ground (1.0 mm) and analyzed for nitrogen (N) and in vitro digestible dry matter (IVDDM) concentrations. Standing crop and N concentration showed significant (P = 0.05) interactions between DAS, cultivars and years. Differences were detected for DAS × cultivar and DAS × year interactions for IVDDM concentration (P = 0.05). Grasspea outperformed lentil and reached its maximum yield of 6415 vs. 2013 kg ha−1, respectively, on 75 DAS before declining. Nitrogen concentration (23–55 g kg−1) and IVDDM (786 ± 3 g kg−1) of the two cultivars were similar during the growing season. The higher level of production gives grasspea greater potential as a component of wheat‐based (Triticum aestivum L.) forage systems in the southern Great Plains, particularly for filling the deficit period during late spring.
Germination and Early Seedling Growth of Chaffy‐Seeded Grasses at Negative Water Potentials
Authors: Springer T. L.
Published: August 2005

Drought is the most frequent cause of stand establishment failure of native grasses. An experiment was conducted to determine the interactions of seed processing and simulated dry conditions on seed germination and seedling growth of five chaffy‐seeded, warm‐season grasses. Seed of big bluestem (Andropogon gerardii Vitman), sand bluestem (Andropogon hallii Hack.), little bluestem [Schizachyrium scoparium (Michx.) Nash], yellow bluestem [Bothriochloa ischaemum (L.) Keng. var. ischaemum (Hack.) Celarier and Harlan], and indiangrass [Sorghastrum nutans (L.) Nash] were processed into intact spikelets‐chaffy pure‐seeds, debearded spikelets‐chaffy pure‐seeds lightly trimmed of hair and awns, and caryopses. Fifty‐seed samples of each species and seed form were germinated at water potentials of –1.6, –0.8, –0.4–0.2, and 0 MPa for a 21‐d period. There were species × water potential and species × seed form interactions for 7‐d germination, 21‐d germination, and potential maximum germination, and for seedling root and shoot lengths. In general, seed germination and seedling growth were reduced as the water deficit potentials increased. Germination was slower and much lower from intact and debearded spikelets compared with caryopses. The slower germination of intact and debearded spikelets also resulted in shorter root and shoot lengths when compared with caryopses. Given the amount of genetic variation within most cross‐pollinated species, this procedure could be used as an effective selection tool for breeding cultivars with improved germination and seedling growth at low water potentials.
Genetic Diversity within and among Nordic Meadow Fescue (Festuca pratensis Huds.) Cultivars Determined on the Basis of AFLP Markers
Authors: Fjellheim Siri , Rognli Odd-Arne
Published: August 2005

Twelve Nordic cultivars and one Icelandic natural population of meadow fescue (Festuca pratensis Huds.) were assessed by AFLP (amplified fragment length polymorphism) marker technology to determine levels of genetic diversity within and genetic relationships between populations. Three cultivars were analyzed from each of the Nordic countries (Norway, Finland, Sweden, and Denmark), including germplasm of long, medium, and short antiquity. A total of 253 plants were analyzed by 89 AFLP markers. A substantial degree of genetic heterogeneity was uncovered, and all individuals were genetically distinct from one another. AMOVA revealed that most of the variation is distributed within rather than between cultivars. The genetic diversity within newly released cultivars was as large as within old cultivars, indicating that breeding has not eroded genetic diversity over time. PCO‐ and UPGMA‐analyses revealed no clear structure on the basis of country of origin of the cultivars. This can probably be explained by the fact that an extensive exchange of breeding material between the Nordic countries has occurred since the genetic improvement of meadow fescue started at the beginning of the 20th century. These exchanges of breeding materials have counteracted genetic erosion and genetic differentiation between countries. The applicability of AFLP markers in cultivar identification in meadow fescue is discussed.
Light‐Emitting Polythiophenes
Authors: Perepichka I. F. , Perepichka D. F. , Meng H. , Wudl F.
Published: August 2005

Polythiophenes are one of the most important classes of conjugated polymers, with a wide range of applications, such as conducting films, electrochromics, and field‐effect transistors, which have been the subject of a number of older and more recent reviews. Much less attention has been paid to the light‐emitting properties of this class of materials, although their unique properties present a number of opportunities unavailable from more popular polymeric light emitters such as polyfluorene or poly(p‐phenylene vinylene). This article reviews achievements to date in applications of thiophene‐based polymers and oligomers as electroluminescent materials. We demonstrate the basic principles of controlling the optical properties of polythiophenes through structural modifications and review the most important light‐emitting materials created from thiophene derivatives. Special attention is paid to consequences of structural variations on the performance of light‐emitting diodes fabricated with these materials.
Cover Picture: Multilayer Polymer Light‐Emitting Diodes: White‐Light Emission with High Efficiency (Adv. Mater. 17/2005)
Authors: Gong X. , Wang S. , Moses D. , Bazan G. C. , Heeger A. J.
Published: August 2005

White‐light‐emitting polymer diodes can be fabricated by solution processing using a blend of luminescent semiconducting polymers and organometallic complexes as the emission layer, and water‐soluble (or ethanol‐soluble) polymers and/or small molecules as the hole‐injection/transport layer (HIL/HTL) and the electron injection/transport layer (EIL/ETL), as reported on p. 2053 by Gong, Bazan, Heeger and co‐workers. Illumination‐quality light is obtained from these multilayer, high‐performance devices, with stable CIE coordinates, color temperatures, and high color‐rendering indices all close to those of “pure” white light. The cover illustration envisages the incorporation of the fabrication technique with low‐cost manufacturing technology in order to produce large areas of high‐quality white light.
Removal of 1,2‐dichloroethane from aqueous solutions with novel composite polydimethylsiloxane pervaporation membranes
Authors: Liang Liang , Dickson James M. , Zhu Zhen , Jiang Jianxiong , Brook Michael A.
Published: August 2005

Composite pervaporation membranes were prepared by the crosslinking of H‐terminated oligosilylstyrene (oligo‐SiH3) and vinyl‐terminated polydimethylsiloxane (vinyl‐PDMS) on the surface of polysulfone ultrafiltration membranes. The morphology of the composite pervaporation membranes were investigated through changes in the mass ratio of oligo‐SiH3 to vinyl‐PDMS. The pervaporation of crosslinked polydimethylsiloxane composite membranes was evaluated by the removal of 1,2‐dichloroethane (1,2‐DCE) from dilute aqueous solutions with different downstream pressures, feed temperatures, feed concentrations, and top layer thicknesses. A low feed flow rate, corresponding to a Reynolds number of 97, was maintained during the entire process. The separation factor of 1,2‐DCE was 600–4300, and the permeation rate of 1,2‐DCE was 0.4–15 g/m2 h; they depended on the operating conditions and the compositions of the membranes. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1477–1491, 2005
Study of metal poisoning in natural rubber–based tire‐tread compound
Authors: Chakraborty S. , Mandot S. K. , Agrawal S. L. , Ameta R. , Bandyopadhyay S. , Gupta S. Das , Mukhopadhyay R. , Deuri A. S.
Published: August 2005

In the present study the effect of metal poisoning was studied in a natural rubber (NR)–based tire‐tread compound. The experimental compound contained 1000 ppm copper metal as an additional ingredient. A detailed study was carried out and the results of the experimental compound were compared against a control compound having no metal ion. The effect of metal poisoning was not significant in the case of the green experimental compound, even after prolonged storage of 150 days. However, the cured experimental compound deteriorated substantially after ageing in aerobic‐, anaerobic‐, oil‐, and outdoor‐ageing conditions. The ozone resistance property of the experimental compound also proved to be inferior. The degradation kinetic of metal poisoning was found to be a first‐order reaction and the service life (as expressed by the half‐life period) was drastically reduced for the poisoned compound. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1492–1499, 2005
Novel reactive diluents for UV/moisture dual‐curable coatings
Authors: Qi Yusong , Yang Jianwen , Zeng Zhaohua , Liao Zhengfu , Chen Yonglie
Published: August 2005

The novel silicone‐modified polyacrylate reactive diluents for UV/moisture dual‐curable coatings were synthesized fromN,N‐bis[3‐(trimethoxysilyl)propyl]amine and multifunctional acrylates such as ethoxylated trimethylolpropane triacrylate and polyethyleneglycol diacrylate through Michael addition reaction. Their structures were characterized by NMR and FTIR and their average molecular weights were determined by vapor pressure osmometry. With FTIR, it was found that the obtained diluents could be cured both by UV radiation and moisture mode. The29Si‐NMR showed that dimer was the main condensation product at the initial stage of moisture curing. The rheological behavior of the diluents investigated by rotary viscometer indicated they were very close to Newtonian fluid, and the viscosity of coatings decreased evenly with increasing concentration of reactive diluents in the coatings. In particular, they were found to be highly efficient in diluency and reactivity for UV polymerization. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1500–1504, 2005