bluuebunny/crossref_metadata_2025 huggingface dataset:
Grazing Management Effects on Productivity, Nutritive Value, and Persistence of ‘Tifton 85’ Bermudagrass
Authors: Liu K. , Sollenberger L. E. , Newman Y. C. , Vendramini J. M. B. , Interrante S. M. , White‐Leech R.
Published: December 2010

‘Tifton 85’ bermudagrass (Cynodon spp.) is an important forage in the southern United States, but its responses to the interaction of grazing frequency and intensity have not been studied. Sward persistence, herbage accumulation, and nutritive value were measured during 3 yr. Treatments were all combinations of three postgraze stubble heights (SH; 8, 16, and 24 cm) and three regrowth intervals (RI; 14, 21, and 28 d). Short SH (8 cm) with long RI (28 d) or tall SH (24 cm) with short RI (14 d) produced greatest herbage accumulation (11–15 Mg ha−1 yr−1). Lowest or nearly lowest herbage accumulation occurred with 14‐d RI and 8‐cm SH or 28‐d RI with 24‐cm SH (7.4–12 Mg ha−1 yr−1). Intermediate levels of RI (21 d) or SH (16 cm) produced consistent herbage accumulation regardless of level of the other factor. Nutritive value was primarily affected by RI, and P (3.1 to 2.8 g kg−1), crude protein (CP; 150 to 108 g kg−1), and in vitro digestible organic matter (IVDOM; 602 to 582 g kg−1) concentrations decreased as RI increased. Organic matter and nutrient mass of storage organs increased with increasing SH, but the 24‐cm SH treatment exhibited greater reduction in percentage cover (∼43% units) than the other SH treatments (∼22% units) after 3 yr of grazing. These data indicate that intermediate levels of SH (16 cm) and RI (21 d) provided relatively high Tifton 85 herbage accumulation and nutritive value while minimizing negative impacts on persistence‐related responses.
Inositol Metabolism in Developing Seed of Low and Normal Phytic Acid Soybean Lines
Authors: Israel Daniel W. , Taliercio Earl , Kwanyuen Prachuab , Burton Joseph W. , Dean Lisa
Published: December 2010

While inositol has key roles in phytic acid and raffinosaccharide synthesis, its concentration in developing seed of low phytic acid soybean [Glycine max (L.) Merr.] lines derived from CX1834 (Wilcox et al., 2000) has not been compared to that of normal lines. Concentrations of metabolites in the phytic acid and raffinosaccharide biosynthesis have been measured in mature seed of CX1834‐derived lines but not throughout seed development. Our objective was to compare concentrations of inositol and metabolites associated with phytic acid and raffinosaccharide synthesis in developing seed of CX1834‐derived and normal lines. Plants were cultured with complete nutrient solutions in growth chambers with 650 to 700 μmol m−2 s−1 of photosynthetically active radiation and a 26/22°C day/night temperature. Seed inositol concentrations were high (60 to 90 mmol kg−1 seed dry wt.) at 20 d after flowering (DAF) and decreased 95% by maturity in both normal and low phytic acid lines. In two of three experiments, low phytic acid lines had significantly (p ≤ 0.05) greater seed inositol concentrations than normal lines at the first two sampling dates, but differences at maturity were not significant. Seeds of low phytic acid and normal lines had statistically similar concentrations (p > 0.05) of partially phosphorylated inositol intermediate (inositol triphosphate [IP3]), stachyose, raffinose, and phytase activity throughout development. These results corroborate previous studies that ruled out defects in genes coding myo‐inositol‐1‐P synthase, inositol kinases, and phytase as the basis for the low seed phytic acid trait in CX1834‐derived lines.
Effectiveness of Single‐Plant Selection at Low Density under Organic Environment: A Field Study with Lentil
Authors: Vlachostergios Dimitrios N. , Lithourgidis Anastasios S. , Roupakias Demetrios G.
Published: December 2010

Cultivation of well‐adapted varieties under organic environment requires effective breeding schemes. A field study was conducted to investigate the effectiveness of single‐plant selection at low density under organic environment. Single plants originating from 20 lentil (Lens culinaris Medik.) varieties along with their seed composite were grown in an R‐21 honeycomb design under two plant densities for two consecutive growing seasons at two sites. Sowing plant densities (PDs) were 12.8 plants m−2 (PD I) and 3.2 plants m−2 (PD II). Selection was applied in each environment (site per growing season) and each plant density and the top 50 plants were selected. Varieties were also evaluated in plot trials under farmer's conditions and the entry ranking across four environments was considered as the proven entry ranking. Effective selection (ES) was measured by the number of the 50 selected plants originating from the top five varieties, while non‐ES was measured by the number of the 50 selected plants originating from the five‐lowest yielders. It was observed that the experimental case that indicated higher ES and lower non‐ES was PD II. Under PD II, ES ranged from 34 to 74% from environment to environment and from 46 to 62% across two environments, while non‐ES ranged from 0 to 12% from environment to environment and from 3 to 12% across two environments. It was concluded that single‐plant selection at low plant density could be applied in breeding programs for organic agriculture with considerable effectiveness.
Does Modification of Tall Fescue Leaf Texture and Forage Nutritive Value for Improved Livestock Performance Increase Suitability for a Grass‐feeding Caterpillar?
Authors: Keathley Craig P. , Potter Daniel A.
Published: December 2010

Grass breeders are developing new forage‐type tall fescue [Schedonorus arundinaceus (Schreb.) Dumort = Lolium arundinaceum (Schreb.) Darbysh., formerly known as Festuca arundinacea Schreb.] cultivars with smoother texture, improved nutritive value, and reduced fiber for improved livestock performance. We tested if such grasses are also more susceptible to a grass‐feeding caterpillar. True armyworms, Pseudaletia unipuncta (Haworth), were reared from first instar to adult on grass clippings from thirteen fescue cultivars or accessions differing in texture (smooth vs. standard), ecotype (northern European vs. Mediterranean), use (pasture vs. turf‐type), or provenance to clarify how modifying the texture (edge spines, trichomes, or cellulose margin), thickness, tissue strength, and nutritive value (dry matter, fiber, ash, or N) of pasture grasses will affect their resistance. We also studied feeding site initiation and development of first instars on intact leaf blades when prevented from exploiting a cut leaf edge. Larvae performed equally well across all groups when reared with grass clippings, despite variation in leaf texture and nutritive value. On intact blades, however, leaf thickness and tissue strength were correlated with reduced feeding site initiation and larval development. Gregarious and window feeding may allow more efficient exploitation of common feeding sites on tougher leaves. True armyworm is adapted to feed on a range of structurally‐diverse grasses, so increased use of forage‐type tall fescue cultivars with smoother texture or reduced fiber is unlikely to worsen its damage to pastures.
Pollen‐Mediated Gene Flow in Commercial Fields of Spring Wheat in Western Canada
Authors: Beckie Hugh J. , Warwick Suzanne I. , Sauder Connie A. , Hall Linda M. , Harker K. Neil , Lozinski Chris
Published: December 2010

Crop intraspecific pollen‐mediated gene flow (PMGF) can be scale dependent. In 2004—the first year imidazolinone (IMI)‐resistant spring wheat (Triticum aestivum L.) was commercially available—a study was conducted in western Canada to examine PMGF in commercial fields. At each of two sites located 4 km apart in the semiarid grassland region of Saskatchewan, PMGF was measured from a 16‐ha (400 × 400 m) field of IMI‐resistant wheat (cultivar CDC Imagine) to an adjacent field of conventional (non‐IMI‐resistant) wheat (cultivar AC Barrie) with the same dimensions. Wheat grain samples of AC Barrie were collected at varying distances to 400 m along five equally‐spaced transects oriented perpendicular to the common border with CDC Imagine. A total of 2000 seedlings per sample were screened for resistance to imazamox at 200 μM in a 7‐d soilless bioassay. Putative resistant hybrids were confirmed by polymerase chain reaction (PCR) analysis. Averaged across transects and sites, PMGF was 0.2% at the common border and declined exponentially with increasing distance; the maximum distance that PMGF was detected was 80 m from the donor field. Higher levels of PMGF were generally observed in this study compared with that of previous studies in western Canada. Results of this study provide a more complete assessment of PMGF in this crop under western Canadian climatic conditions. Together with previous studies, frequency and distance of PMGF can guide grower stewardship practices for identify preservation in wheat cultivars possessing different traits.
The Genetic Architecture of Flowering Time and Related Traits in Two Early Flowering Maize Lines
Authors: Khanal Raja , Earl Hugh , Lee Elizabeth A. , Lukens Lewis
Published: December 2010

Flowering time is the major factor in determining maize (Zea mays L.) maturities. Genetic bases of flowering time and other agronomically important traits were examined in a set of interheterotic‐pattern recombinant inbred lines (RILs). The RILs were developed from crossing the short‐season Iodent inbred line CG60 with the short‐season Stiff Stalk inbred line CG102. Recombinant inbred lines were derived through single‐seed descent (S‐RILs) or intermated for three generations before inbreeding (I‐RILs), thereby increasing recombination. Genetic variation was high for all traits in both populations, and a large number of RILs had days to silking, days to anthesis, plant height, visual stay green, canopy reflectance, and leaf number trait values beyond the parental line ranges. Both the I‐RIL and S‐RIL populations had similar genetic variances and similar genetic and phenotypic correlations between traits. We conclude that although Northern Corn Belt Dents have been subjected to strong selection and drift and have diverged greatly from their source population, there is substantial cryptic variation for many traits. Our results also suggest that coupling and repulsion phase linkage blocks are not prevalent within parental genomes and that genetic correlations are caused by pleiotropic genes. Intermating may have little value in recovering extreme phenotypes for flowering time and other agronomically important traits.
Genetic Support for Phenotype‐based Racial Classification in Sorghum
Authors: Brown Patrick J. , Myles Sean , Kresovich Stephen
Published: December 2010

The classification of domesticated sorghum [Sorghum bicolor (L.) Moench] into five major races is based on phenotypic characteristics of the spikelet and panicle. Presumably, this classification also reflects genetic relatedness. In this study, we apply both model‐based (STRUCTURE) and model‐free (principal components analysis) approaches to a genetic data set of 434 single nucleotide polymorphisms and simple sequence repeat alleles in a panel of 216 exotic sorghum lines to study the congruence between genetic relatedness and phenotype‐based racial classification. Both model‐based and model‐free approaches clearly identify genetic groups that correspond closely to the caudatum, durra, kafir, and guinea races of sorghum. Genetic groups differ from racial groups in several significant ways, including the classification of the West African Kaura group with guineas rather than with caudatums, and the identification of a novel genetic group affiliated with both kafirs and guineas. These results highlight that high‐throughput genotyping now provides curators with an additional, critical tool to better characterize and quantify diversity found in collections. Because of technological advances and associated cost reductions of unit assays, high‐throughput genotyping is now applicable to all crop species.
Genetic Mapping of Quantitative Trait Loci Associated with Important Agronomic Traits in the Spring Wheat (Triticum aestivum L.) Cross ‘Louise’ × ‘Penawawa’
Authors: Carter A. H. , Garland‐Campbell K. , Kidwell K. K.
Published: December 2010

Understanding the genetic factors underlying agronomic traits in common wheat (Triticum aestivum L.) is essential to making gains from selection during the breeding process. A set of 188 recombinant inbred lines (RILs) from a ‘Louise’ × ‘Penawawa’ mapping population was grown for two crop years at two locations in the Pacific Northwest region of the United States to identify quantitative trait loci (QTL) associated with seedling growth habit, leaf color, plant height, flowering date, maturity date, grain volume weight, grain protein content, and grain yield. Quantitative trait loci for flowering date and maturity date were associated with the Ppd‐D1 gene for photoperiod insensitivity. Variation in the QTL for plant height was dependent on location and year and localized to chromosome 2D and 3B. A QTL for leaf color was identified on chromosome 2B. Seedling growth habit mapped to chromosome 2D, and a significant QTL for grain volume weight was detected on chromosome 1B. Quantitative trait loci were identified for grain yield; however, some of these QTL were associated with other known QTL for pest resistance, seedling growth habit, or photoperiod insensitivity. Flowering date, maturity date, and plant height were significantly correlated, which resulted from the pleiotropic effects of the Ppd‐D1 gene. The identification of agronomic QTL, and the correlations between and among them, is the first step toward making gains from selection using molecular marker‐assisted selection for these important agronomic traits.
Rumen‐Undegradable Protein Supplementation Effects on Early Weaned Calves Grazing Annual Ryegrass
Authors: Vendramini J.M.B. , Arthington J.D. , Sollenberger L.E. , Saraiva T.
Published: December 2010

Early weaned beef calves (Bos spp.) can be raised on cool‐season pastures in Florida but more information on protein supplementation is necessary to optimize the performance of those calves. The objective of this study was to evaluate the effects of three levels of rumen‐undegradable protein (RUP) supplementation on performance of early weaned calves grazing annual ryegrass (Lolium multiflorum Lam.) pastures. The study was conducted in Ona, FL in 2007 and 2008. Treatments were 1.5 g kg−1 body weight (BW) supplementation of three levels of supplemental RUP, soybean meal (SBM, 350 g kg−1 RUP), Soyplus (SP, 600 g kg−1 RUP, modified expeller soybean meal, West Central, Ralston, IA), or a 50:50 mixture of soybean meal‐Soyplus (SBMSP, 475 g kg−1 RUP). Pasture size was 0.3 ha and four early weaned calves were assigned to each pasture. There was a linear increase in herbage mass (HM, from 1.9–2.1 Mg ha−1) and herbage allowance (HA, from 1.1–1.4 kg dry matter [DM] kg−1 live weight, LW) with increasing levels of RUP. Increased RUP supplementation decreased forage dry matter intake (FDMI) and total dry matter intake (TDMI) in 2008 but there was no effect in 2007. There was no difference in average daily gain (ADG, 0.76 kg d−1) among treatments. Increasing the levels of RUP supplementation has potential to increase stocking rates of early weaned calves grazing annual ryegrass pastures.
Two New Strategies for Detecting and Understanding QTL × Environment Interactions
Authors: Gauch Hugh G. , Rodrigues Paulo C. , Munkvold Jesse D. , Heffner Elliot L. , Sorrells Mark
Published: December 2010

Two new strategies are proposed to improve the detection and understanding of quantitative trait loci (QTL), especially those exhibiting QTL × environment interactions (QEI), in the context of experiments conducted in multiple environments. First, a parsimonious Additive Main effects and Multiplicative Interaction (AMMI) model is applied to the phenotypic data to gain accuracy and thereby to increase the logarithm of odds (LOD) scores for QTL detections. Second, the environments are ordered by AMMI parameters that summarize genotype × environment interaction information to reveal consistent patterns and systematic trends that often have an evident ecological or biological interpretation. The combination of greater accuracy for the phenotypic data and systematic trends for the environments provides for more consistent and understandable QTL results. These new strategies are illustrated with two examples: preharvest sprouting scores of a biparental wheat (Triticum aestivum L.) population from 14 environments spread over 5 yr, and yield for a doubled‐haploid barley (Hordeum vulgare L.) population tested in 16 environments. AMMI parameters can also provide successful predictions of entire QTL scans for new environments. The statistical methods developed here are of great generality, applicable across microbial and plant populations grown in multiple environments, and may be adapted to animal and human genetic studies.
Genetic Contribution to Advanced Yield for Maize Hybrids Released from 1970 to 2000 in China
Authors: Ci Xiaoke , Li Mingshun , Liang Xiaoling , Xie Zhenjiang , Zhang Degui , Li Xinhai , Lu Zhenyu , Ru Gaolin , Bai Li , Xie Chuanxiao , Hao Zhuanfang , Zhang Shihuang
Published: December 2010

Four to five cycles of maize (Zea mays L.) hybrid replacement have occurred in China since the 1970s. Retrospective analyses of genetic yield may provide an understanding of unexploited genetic potential and indicate pathways for future yield improvement. The objective of this study was to assess genetic gains in grain yield, especially those due to increased tolerance to stress in China from the 1970s through the 2000s. Trials were conducted at two locations per year and three densities per location during the 2005–2006 (Exp. 1) and 2007–2008 (Exp. 2) growing seasons. Over a 40‐yr period, the genetic gain in yield averaged 94.7% kg ha−1 per year and 53% of this was attributable to breeding undertaken in China. The newer hybrids showed increased tolerance to compound stress. We estimated that the contribution of stress tolerance to genetic yield gain was equal to 46 or 74% at 60,000 or 75,000 plants ha−1, respectively. Yield improvement has occurred at a slow pace at densities of 60,000 and 75,000 plants ha−1 in China. Further increasing maize grain yield in China will be achieved through higher plant populations, and this will require breeding for greater stress tolerance.
Gene Flow between Gossypium hirsutum L. and Gossypium barbadense L. is Asymmetric
Authors: Van Deynze Allen E. , Hutmacher Robert B. , Bradford Kent J.
Published: December 2010

As both Pima cotton (Gossypium barbadense L.) and Acala (Upland; G. hirsutum L.) are grown in the southwestern United States, understanding gene flow within and among these species is important to maintain genetic purity. In small scale and commercial fields, gene flow decreased exponentially from 1.44% at 1 m to less than 0.50% at 10 m in Acala cotton. Corresponding values for Pima cotton were 0.19% at 3 m and 0% at 10 m or beyond. When interspecies outcrossing occurred, Pima cotton was preferentially pollinated by Acala cotton. Gene flow was nondetectable in 7.5 m borders. Asymmetric pollination between Acala and Pima cotton was also observed in samples collected in borders located 6 m from the pollen source with no detectable gene flow beyond 7.5 m. At a given distance, in commercial scale Pima fields, gene flow was tenfold less than reported in Acala fields with gene flow not exceeding 0.43% beyond 10 m. No gene flow was detected beyond 800 m (0.5 mile). This study indicates that isolation distances can be shorter in Pima cotton than in Acala cotton to maintain the same level of genetic purity. Comparison with historical evidence suggests that there has been a shift in the relative gene flow among species in modern cultivars of Pima cotton.
Nitrogen Source and Rate Effects on Velvet Bentgrass Putting Green Turf
Authors: Pease Benjamin W. , Koeritz Eric J. , Soldat Douglas J. , Stier John C.
Published: December 2010

Nitrogen source and rate effects on velvet bentgrass (Agrostis canina L.; VBG) putting greens are not well documented, particularly in the north central United States which has different conditions than areas where VBG is normally grown. Acidic soil pH is perceived as necessary for VBG; in nonacidic soils, acidifying fertilizers may provide better VBG quality than less or nonacidic fertilizers. We wanted to determine the effects of N sources representing a range of acidity and N rates (49, 146, 244 kg ha−1 yr−1) on VBG agronomic and playability characteristics when grown on alkaline soils. Fertilizer treatments were applied at 2‐wk intervals to ‘Vesper’ VBG putting greens using liquid forms of ammonium sulfate, urea, ammonium nitrate, and calcium nitrate. Separate trials were conducted on two root zones: an 80:20 sand/peat mixture (pH 7.8) and a Troxel silt loam (pH 7.0). Nitrogen source usually had negligible effects on turf characteristics, though occasionally calcium nitrate resulted in poorer quality or shoot density than other sources. Clipping yield, shoot density, and relative chlorophyll index increased, and ball roll distances decreased, as N rate increased. On sand, not even the 244 kg ha−1 yr−1 rate of N guaranteed acceptable turf quality. On silt loam, 146 kg ha−1 N yr−1 usually provided acceptable turf quality, though quality was occasionally improved at 244 kg ha−1 N yr−1 Velvet bentgrass suffered from mid‐summer stress alleviated by higher rather than lower quantities of N fertilizer.
Selecting Soft Wheat Genotypes for Whole Grain Cookies
Authors: Souza Edward J. , Guttieri Mary J. , Sneller Clay
Published: December 2010

Increased consumption of whole grain cereal products has broad health benefits. Using an experimental whole grain flour‐milling system, we evaluated soft wheat (Triticum aestivum L.) winter wheat genotypes in whole grain flour for use in cookies. Grain from 14 soft winter wheat cultivars grown in two locations within two crop years was milled using a short‐flow flour mill to produce white flour, and then the bran was ground and reconstituted with a white flour to produce a whole wheat flour for comparison baking. Flour samples were evaluated with the solvent retention capacity (SRC) test and the wire‐cut cookie method. Bran fractions were analyzed for water‐extractable nonstarch polysaccharides. Whole grain flour cookie diameter could be estimated from the diameter of cookies made with white flour. The best predictive models for whole grain wire‐cut cookie performance were based on milling softness equivalent and the whole grain sucrose SRC test. Greater softness equivalents and smaller whole grain sucrose SRC values were predictive of larger cookie diameters. Variation in whole grain cookie diameter and texture was due to total water extractable arabinoxylan and the arabinose:xylose ratio in the bran. Early generation selection for whole grain characteristics can use softness equivalent and cookie quality information from white flour. Yet identification of the lines with uniquely superior whole grain flour quality may require whole grain flour analysis.
Complex Ploidy Level Variation in Guayule Breeding Programs
Authors: Gore Michael A. , Coyle Gwen , Friebe Bernd , Coffelt Terry A. , Salvucci Michael E.
Published: December 2010

Guayule (Parthenium argentatum A. Gray) is a potential source of natural rubber, but attempts to domesticate and cultivate this perennial crop for large‐scale production in the southwestern United States have been intermittent over the past century. Genetic improvement through modern plant breeding is needed to increase its yield potential and suitability for commercialization. Natural variation for ploidy level is extensive among individuals in wild guayule populations, but less is known about the extent of ploidy level variation in guayule breeding germplasm. Because ploidy variation is among the factors that slow the rate of genetic gain in guayule breeding programs, determining the ploidy level of publicly available guayule accessions would help to accelerate the development of stable, high yielding cultivars. To that end, we adapted flow cytometry to examine the ploidy of 34 guayule accessions available from the National Plant Germplasm System. The data revealed a natural polyploid series ranging from diploid (2n = 2x = 36) to pentaploid (2n = 5x = 90), with 4x being the predominant ploidy. Interestingly, not all plants sampled from an accession had the same ploidy level (mixed ploidy). Notably, the integration of ploidy and pedigree data uncovered complex ploidy variation in guayule breeding programs. The frequency and range of ploidy variation observed in this germplasm will help to direct future breeding efforts as well as linkage analysis and genome‐wide association studies.
Differential Response of Wheat Cultivars to Components of the Freezing Process in Saturated Soil
Authors: Skinner Daniel Z. , Bellinger Brian S.
Published: December 2010

Winter wheat (Triticum aestivum L. em. Thell.) is sown in the autumn and harvested the following summer, and therefore must survive subfreezing temperatures for several months. Because of autumn rains and winter snows, the plants usually are subjected to these subfreezing temperatures while growing in saturated soil. As the plants freeze, they are subjected to freezing episodes that may vary in the cooling rate, the minimum temperature, the time at the minimum temperature, and the warming rate as the freezing episode ends. We investigated the impact of each of these freezing process components on the ability of 22 winter wheat cultivars to survive freezing in saturated soil using logistic regression and cluster analyses. The 22 cultivars formed three distinct groups when clustered on the odds ratios associated with the freezing process components. The distinctiveness of the three clusters indicated the cultivars within each cluster responded differently to the freezing process than cultivars in the other clusters. Some cultivars occurred in different clusters but had equal levels of freezing tolerance. We conclude the logistic regression/clustering analysis identified cultivars that differed in the mechanisms used to respond to freezing stress, and that equal levels of freezing tolerance can be attained through these different mechanisms. It may be possible to improve winterhardiness by genetically combining these disparate responses to the freezing process components.
Relationships between Normalized Difference Vegetation Index and Visual Quality in Turfgrasses: Effects of Mowing Height
Authors: Lee Hyeonju , Bremer Dale J. , Su Kemin , Keeley Steven J.
Published: December 2010

Canopy spectral reflectance may provide an objective means to evaluate visual quality of turfgrass, but evaluations of quality may be confounded by cultural practices that affect reflectance, such as mowing height. In this 2‐yr study near Manhattan, KS, we examined effects of mowing height on relationships between normalized difference vegetation index (NDVI) and visual quality ratings in Kentucky bluegrass (KBG; Poa pratensis L., ‘Apollo’) and in a KBG × Texas bluegrass (Poa arachnifera Torr.) hybrid (HBG; ‘Thermal Blue’). Mowing heights were 7.62 cm (high) and 3.81 cm (low). The NDVI averaged 4.5 to 7% greater in high‐ than in low‐mown plots. Distinct regression models of visual quality were found at each mowing height and in each species (r2 from 0.40 to 0.81); separate relationships between NDVI and visual quality were also found between years in the same plots. Correlations between NDVI and visual quality were stronger at high than at low mowing heights, possibly because of greater green biomass at high mowing heights. The 95% confidence intervals surrounding predictions of visual quality from NDVI ranged from ±1.34 to 2.75 (on a 1‐to‐9 scale). Thus, lack of precision is a concern when using these models for detection of differences between treatments. Results indicate that when using NDVI to evaluate turfgrass quality, evaluations should be limited to plots maintained at the same mowing height and with the same species to reduce variability in NDVI.
Genotypic Variation in Rice Cold Tolerance Responses during Reproductive Growth as a Function of Water Temperature during Vegetative Growth
Authors: Shimono Hiroyuki , Ishii Ayako , Kanda Eiji , Suto Mitsuru , Nagano Kuniaki
Published: December 2010

We examined genotypic variation in the effect of rice (Oryza sativa L.) responses to water temperature (Tw) during vegetative growth on cold tolerance during reproductive growth in pot and field experiments. Cold tolerance was evaluated based on the percentage spikelet sterility induced by a cool and deep irrigation treatment during the reproductive growth phases. In the pot experiment, rice plants from two cultivars with different cold tolerance were exposed to different levels of Tw during vegetative growth and their cold tolerance was tested. Spikelet sterility of both cultivars decreased with increasing Tw during the vegetative growth phase for temperatures ranging from 19 to 30°C, with parallel lines for the regression equations for sterility as a function of temperature (a slope of 4.0% per 1°C) for both cultivars, although the y‐intercepts differed by 38% points between the cultivars. In the field experiment, four rice cultivars were grown under two levels of Tw during vegetative growth, and their cold tolerance was tested during reproductive growth at two locations (Miyagi Prefecture and Aomori Prefecture in Japan). We found that spikelet sterility decreased at high Tw during vegetative growth for all cultivars and locations. Our results suggest that high Tw during vegetative growth can improve cold tolerance during reproductive growth for the tested cultivars without a significant cultivar × Tw interaction.
Transfer of Soft Kernel Texture from Triticum aestivum to Durum Wheat, Triticum turgidum ssp. durum
Authors: Morris Craig F. , Simeone Marco C. , King G. E. , Lafiandra Domenico
Published: December 2010

Durum wheat (Triticum turgidum ssp. durum) is a leading cereal grain whose primary use is the production of semolina and pasta. Its rich culinary relationship to humans is related, in part, to its very hard kernel texture. This very hard texture is due to the loss of the Puroindoline genes that were eliminated during the allopolyploid formation of T. turgidum approximately 0.5 million years ago. In the present report, we describe the transfer of the Puroindoline genes through ph1b‐mediated homoeologous recombination. Puroindoline a and Puroindoline b were successfully recombined (translocated) from chromosome 5D of the soft wheat (T. aestivum) variety Chinese Spring into cv. Langdon durum using a Langdon 5D(5B) disomic substitution line. Although initial recombination lines were highly unstable, recurrent backcrossing into Svevo durum cultivar produced stable lines that segregated in a normal 1:2:1 soft:heterozygous:very hard ratio. The final backcross (BC3) Svevo line produced uniformly soft grain (Single Kernel Characterization System hardness of 24 ±14). The transfer of this fundamental grain property to durum wheat will undoubtedly have an expansive and profound effect on the way that durum grain is milled and on the products that are made from it. As such, our interaction with this important food species will continue to evolve.
Development of Pearl Millet Minicore Collection for Enhanced Utilization of Germplasm
Authors: Upadhyaya Hari D. , Yadav Devvart , Reddy K. N. , Gowda C. L. L. , Singh Sube
Published: December 2010

Pearl millet [Pennisetum glaucum(L.) R. Br.] exhibits enormous genetic diversity in the global germplasm collection. The pearl millet core collection (∼10% of the entire collection), with 2094 accessions, is still large for precise evaluation to identify parents for a genetic improvement program. A minicore collection of pearl millet comprising 238 accessions was constituted by using data on 10 qualitative and 8 quantitative traits of 2094 core collection accessions. The hierarchical cluster analysis of data using a phenotypic distance matrix resulted in 136 clusters. A proportional sampling strategy with 10% or a minimum of one accession from each cluster was used to form the minicore collection. The comparison of data in the minicore and core collections using various statistical parameters, such as homogeneity of distribution for geographical origin and frequency classes of qualitative traits, means, median, within and between‐accession variances, diversity index, and phenotypic correlations, indicated that almost the entire genetic variation present in the core collection was captured in the minicore collection. The possible impact of high between‐ and within‐accession variability in pearl millet on maintenance of genebank accessions is discussed. With its greatly reduced size, the pearl millet minicore collection can be used for precise evaluation of traits of agronomic importance and biotic and abiotic stresses as well as mapping with molecular markers for identification of trait‐specific germplasm and discovery of new genes.
First 100 Years – Inheritance of Testa Color in Peanut (Arachis hypogaea L.)
Authors: Branch W. D.
Published: December 2010

Inheritance studies of testa color in the cultivated peanut (Arachis hypogaea L.) began in the Netherlands East Indies (Java), now Indonesia, by J. E. van der Stok in 1910. He was the first to report the results from crossing peanut plants with red‐brown seed coat (red testa) × plants with light red (pink testa). The first (F1) generation was red, and the second (F2) generation segregated in three times as many plants with red as with pink (3:1 ratio). Currently, there are five basic testa colors known in the peanut (white, tan, pink, red, and purple) with variegated testa having red and white, purple and white, purple stripes on tan, and white spots on red. Genetic inheritance studies over the past 100 yr have established at least 12 genes controlling basic testa color (F1, F2, D1, D2, R1, R2, R3, P, W1, W2, Wh1, and Wh2). These genes interact with at least five variegated genes (V, Vsp1, Vsp2, Wsp1, and Wsp2) to result in the phenotypic testa color expression found within the present‐day peanut germplasm collections.
Mapping Eight Male‐Sterile, Female‐Sterile Soybean Mutants
Authors: Slattery Rebecca A. , Pritzl Sarah , Reinwand Katie , Trautschold Brian , Palmer Reid G. , Sandhu Devinder
Published: December 2010

In soybean [Glycine max (L.) Merr.], mutations in genes involved in meiosis can lead to altered chromosome pairing and result in nonfunctional gametes. Mutability of the w4 flower color locus in soybean is due to an unstable allele designated w4–m (mutable). Several germinal revertant studies using the w4–m system resulted in generation of mutants for necrotic roots, chlorophyll‐deficiency, and sterility. In the present study, six male‐sterile, female‐sterile mutant lines were identified from an independent mutational event that involved T366H (female‐partial sterile mutant), which was a germinal revertant of w4–m In addition, two spontaneous mutations were identified that resulted in male‐sterile, female‐sterile mutants. The objectives of this study were to investigate if the newly identified six male‐sterile, female‐sterile germinal revertant mutants were allelic to previous germinal revertant steriles or are novel mutants and to molecularly map the locations of these six mutants along with two spontaneous male‐sterile, female‐sterile mutants. Three of the six mutants identified in the germinal revertant study mapped to the st8 region on chromosome Gm16 (molecular linkage group [MLG] J). The other three mutants mapped to a novel location on chromosome Gm14 (MLG B2). Of the two spontaneous mutants, one mapped to chromosome Gm02 (MLG D1b) and the second one mapped to Gm18 (MLG G).
Comparative QTL Map for White Mold Resistance in Common Bean, and Characterization of Partial Resistance in Dry Bean Lines VA19 and I9365‐3
Authors: Soule Marilyn , Porter Lyndon , Medina Juliana , Santana Gloria P. , Blair Matthew W. , Miklas Phillip N.
Published: December 2010

White mold caused by the necrotrophic fungusSclerotinia sclerotiorum(Lib.) de Bary limits common bean (Phaseolus vulgarisL.) production in temperate climates. Disease resistance has been identified, but breeding is hampered by a paucity of resistance sources and complex inheritance, as numerous quantitative trait loci (QTL) conditioning partial resistance have been found. Our objectives were to characterize the partial white mold resistance found in breeding lines I9365‐31 and VA19 and to construct a comparative linkage map for all the white mold resistance QTL identified to date. Recombinant inbred line (RIL) populations ‘Benton’/VA19 (BV) and ‘Raven’/I9365‐31 (R31) consisting of 79 F6and 105 F5RILs, respectively, were evaluated for white mold (WM) reaction in multiple greenhouse and field tests. Two QTL were found in BV, WM2.2 expressed in the greenhouse (R2= 33%) and the field (13%) and WM8.3 expressed in field (11%) only, and seven were found in R31 (WM2.2, WM4.2, WM5.3, WM5.4, WM6.1, WM7.3, WM8.4), three expressed in greenhouse tests and four in the field, ranging in phenotypic variance from 5 to 52%. These QTL were compared with 26 previously identified QTL, resulting in a comparative linkage map of 35 QTL, which coalesced into 21 distinct regions across nine linkage groups. Four QTL found in R31 were novel. Sequence characterized amplified region markers associated with WM2.2, WM8.3, and WM7.3 QTL were generated. The comparative linkage map provides a framework for integrating and interpreting future QTL studies concerning white mold resistance in common bean.
Membrane Fatty Acid Composition and Saturation Levels Associated with Leaf Dehydration Tolerance and Post‐Drought Rehydration in Kentucky Bluegrass
Authors: Xu Lixin , Han Liebao , Huang Bingru
Published: December 2010

Changes in fatty acid composition and saturation levels may be involved in leaf tolerance to dehydration during drought stress and recovery on rewatering. The objective of this study was to compare changes in compositional and saturation levels of leaf fatty acids between two cultivars of Kentucky bluegrass (Poa pratensis L.) contrasting in drought tolerance in response to drought stress and rewatering. Drought‐tolerant ‘Midnight’ and sensitive ‘Brilliant’ were maintained well‐watered (control) or subjected to drought for 15 d by withholding irrigation and then rewatered in a growth chamber. Compared to Brilliant, Midnight maintained higher turf quality, leaf photochemical efficiency, relative water content, and membrane stability expressed as electrolyte leakage during drought stress. Following rewatering, Midnight recovered more rapidly in each parameter than Brilliant. The degree of fatty acid unsaturation decreased in both cultivars during drought stress, and the decrease was less pronounced and occurred later in Midnight. Fatty acid unsaturation level resumed to the control level in Midnight leaves, but did not fully recover in Brilliant after rewatering. The alteration in fatty acid unsaturation level induced by drought and rewatering were mainly due to the changes in the composition of linolenic acids (18:3), linoleic acids (18:2), palmitic acids (16:0), and stearic acids (18:0). Our results suggest that leaf dehydration tolerance and postdrought recovery in Kentucky bluegrass was associated with their ability to maintain relative higher proportion and level of unsaturated fatty acids, particularly linolenic acids and linoleic acids.
Nature of the Genetic Variation in an Elite Maize Breeding Cross
Authors: Singh A. K. , Coleman T. K. , Tollenaar M. T. , Lee E. A.
Published: December 2010

Maize (Zea mays L.) breeders through selection have had profound impacts on the maize genome. In this study we examine one aspect of this intense selection pressure, the extent and nature of genetic variation present in an elite maize breeding cross. Specifically genetic variation is examined with regards to genotype × environment interactions (G × E), magnitude of the genetic variance (Vg) estimates, and the underlying grain yield quantitative trait loci (QTL). Using two elite Iodent sister‐lines that are 64% identical by descent, 128 recombinant inbred lines (RILs) were generated and testcrossed to a Stiff Stalk inbred line (CG102). Hybrid RILs were grown in 24 trials encompassing 4 yr, three locations, and three planting densities. Additive main effects and multiplicative interaction analysis resolved the trials into eight unique patterns of G × E. Smaller Vg estimates were associated with the more frequently observed patterns of G × E. Nine single‐effect QTL and four epistatic interactions were detected across seven of the G × E patterns; however, the single‐effect QTL and epistatic interactions were, in general, specific to a G × E pattern. In summary, we found extensive linkage disequilibrium (LD), reduced Vg in the more commonly occurring G × E patterns, and genetic variation due to larger effect epistatic interactions and smaller single effect QTL specific to the G × E pattern. Consequences of the genetic variation are discussed in relation to modern maize breeding programs.
Cloning and Characterization of a Gene, AsEXP1, Encoding Expansin Proteins Inducible by Heat Stress and Hormones in Creeping Bentgrass
Authors: Zhou Peng , Zhu Qi , Xu Jichen , Huang Bingru
Published: December 2010

Expansin proteins play a role in regulating cell growth and plant adaptation to various environmental stresses. The objectives of this study were to clone and characterize the expression and promoter activity of a gene in creeping bentgrass (Agrostis stolonifera L.) encoding an expansin protein, AsEXP1, in response to heat stress and plant hormones. The AsEXP1 cloned from the genome of heat‐tolerant genotype ‘Penn A‐4’ spans a 2659 bp DNA sequence and consists of three coding sequences, two introns, a 962 bp 5′‐noncoding region, and a 483 bp 3′‐noncoding region. Several putative abscisic acid (ABA)‐response cis‐elements and gibberellic acid (GA)‐response cis‐elements were found nearby TATA box in the promoter region through the search of PlantCARE database and PLACE database search. AsEXP1 transcripts were detected by reverse transcription polymerase chain reaction (RT‐PCR) in Penn A‐4 leaves treated with ABA and GA, while no transcripts were detected in untreated plants. The AsEXP1 promoter was cloned into a binary vector fused to a β‐glucuronidase (GUS) marker gene (pAsEXP1‐GUS) and introduced into rice (Oryza sativa L.) callus (‘Kassalatha’). Reverse transcription polymerase chain reaction confirmed that the expression of pAsEXP1 in A. stolonifera was inducible by heat stress and exogenous applications of GA and ABA. Our results demonstrate that the AsEXP1 gene may be involved in the signal pathway of hormone regulation of plant responses to heat stress.
Germplasm Potential for Continuing Improvement of Fiber Quality in Upland Cotton: Combining Ability for Lint Yield and Fiber Quality
Authors: Zeng Linghe , Meredith William R. , Boykin Deborah L.
Published: December 2010

Exotic germplasm, that is, germplasm without commercial applicability, can broaden the genetic base in upland cotton (Gossypium hirsutum L.). The objectives of this study were to determine combining ability and identify parents from exotic germplasm for breeding. Twelve regionally adapted exotic germplasm lines were crossed with one cultivar and three elite germplasm lines in a North Carolina Design II scheme. The 48 F2 hybrids were evaluated at two locations with 4 and 3 replicates each in 2008 and 2009, respectively. General combining ability (GCA) effects were significant (p ≤ 0.001) for lint yield and all fiber properties. General combining ability effects were more important than specific combining ability (SCA) effects for most traits. Significant (p ≤ 0.05) favorable GCA effects were detected in all exotic germplasm parents for different fiber properties. Positive GCA effects for lint yield and favorable GCA effects for at least one fiber property were detected in some exotic parents: SP156 and SP224 for lint yield and strength; SP192, SP205, and JC65 for lint yield, micronaire, and elongation; and SP192 and SP224 for lint yield and short fiber content and fineness, respectively. Significant high parent heterosis (HPH) for lint yield was detected in F2 hybrids of FM832 × SP205 (14%) and MD15 × SP205 (26%). These results provide evidence for the potential of these germplasm lines in breeding for continuing improvement of lint yield and fiber quality.
Terminal Restriction Fragment Length Polymorphism for Soil Microbial Community Fingerprinting
Authors: Aiken Jane T.
Published: December 2010

Terminal restriction fragment length polymorphism (TRFLP) fingerprinting of 16S rRNA genes is a popular technique for analyzing bacterial communities. This review considers the technical aspects of deriving a community fingerprint with the goal of improving TRFLP as a tool for community ecologists, particularly those working in soil science. Analysis parameters are reviewed for samples run with GeneScan and the capillary system Peak Scanner software of ABI Prism genetic analysis units. Analysis parameters should be chosen using principles that preserve community composition and define inherent community variability, ensuring that methodology does not bias the distribution of an unknown population structure. Choices for fragment sizing include sizing algorithm, sizing accuracy, peak detection, split peak correction, peak smoothing options, minimum peak half width, baseline setting, and analysis range. Results indicate that a standard protocol should include choices of local southern sizing and use of a 35 relative fluorescence unit baseline with light smoothing. A size calling accuracy of 0.998 (for GeneScan gels) is recommended for each internal lane standard, based on the principle that the extent of linearity across the size standard selection is the given limit for an analysis range. Analysis baseline is a choice that in combination with heavy peak smoothing can halve the number of fragments detected. Heavy smoothing will increase the number of replicate polymerase chain reaction samples necessary to represent all fragments of a soil community DNA and it is proposed that using heavy smoothing will produce a biased community profile and loss of population information. Choices during profile and alignment editing are also discussed. Generated profiles should be edited to ensure a minimum integrity of one base pair resolution between consecutive fragments. Results indicate that profile editing, for a specified analysis range of 80 to 827 base pairs, can decrease the linear relationship between total fluorescence and fragment number and thus increase independence between abundance and species richness.
Soil Compaction above Long‐Term Lysimeter Installations
Authors: Lepore B. J. , Norman J. M. , Lowery B. , Brye K. R.
Published: December 2010

Equilibrium tension lysimeters are useful tools for monitoring soil water and solute fluxes. The potential residual effects of lysimeter installation procedures are unknown, however. During summer 2006, 12 lysimeters were excavated after long‐term installation, and soil deformations above the lysimeters and installation materials were observed and documented. Bulk density of soil clods collected from above lysimeters and of clods confined in the lysimeters' pans increased 11 and 8%, respectively, between 1995 and 1999 (grouped together) and 2001 installations. This compaction probably introduced some increasing amount of error to water flux measurements as the installations aged, although this could not be assessed. Minor modifications to installation methods including supporting the soil at the front of the excavated cavity, increasing support spring length, and eliminating the use of soil slurry above the lysimeter's porous plate may reduce the potential for soil compaction above lysimeters and increase performance longevity in field installations.