bluuebunny/crossref_metadata_2025_split huggingface dataset:
Demand for Genetic Resources and the U.S. National Plant Germplasm System
Authors: Rubenstein Kelly Day , Smale Melinda , Widrlechner Mark P. 
Published: March 2006

ABSTRACTAlthough genetic resources have strong public‐goods characteristics, public genebanks often have struggled for adequate funding. A review of economic literature on the value of plant genetic resources indicated that more information is needed about germplasm use. The data compiled in this paper examine patterns of germplasm use for one of the world's largest national genebank networks, the U.S. National Plant Germplasm System (NPGS). Data on 10 major crops, gathered directly from within the NPGS and from end‐users, revealed patterns of usage for germplasm during the period from 1995 to 1999. Data were collected describing the characteristics of NPGS users, the types of germplasm requested, the purpose of requests, and, when applicable, the specific traits sought. From these findings, we estimated the utility of distributed materials, their secondary use, and projected future demand for NPGS resources. To explore relationships between the usefulness of germplasm samples and accompanying data in a more systematic fashion, we estimated a linear regression. The regression model suggests that accompanying data make germplasm more useful. We conclude that demand for NPGS resources was substantial and came from broad range of users. Utilization rates were higher than suggested by past studies. Countries with developing economies made greater use of NPGS resources, relatively speaking, than did countries with high‐income economies. Finally, demand for NPGS resources is likely to increase, especially among users in countries with developing economies.
Quantitative Trait Loci for Resistance to Banded Leaf and Sheath Blight in Maize
Authors: Zhao Maojun , Zhang Zhiming , Zhang Shihuang , Li Wanchen , Jeffers Daniel P. , Rong Tingzhao , Pan Guangtang 
Published: March 2006

ABSTRACTBanded leaf and sheath blight (BLSB) caused by Rhizoctonia solani Kühn in maize (Zea mays L.) is an important disease in China as well as South and Southeast Asia. The identification of quantitative trait loci (QTL) for resistance to this disease would facilitate the development of disease resistant maize hybrids. A mapping population consisting of 229 F2 individuals derived from the cross of inbreds R15 (resistant) and 478 (susceptible) was used in this study. A genetic linkage map was constructed containing 146 single sequence repeat (SSR) markers, which covered 1666 cM of the maize genome, with an average distance of 11.4 cM. All F2:4 population individual plants were artificially inoculated by anastomosis groups AG1‐IA of R. solani at two locations for disease evaluations. Composite interval mapping (CIM) identified 11 QTL for resistance to BLSB located on chromosomes 1, 2, 3, 4, 5, 6, and 10, but only four QTL located on chromosomes 2, 6, and 10, were identified across both locations. The range of phenotypic variation explained by the QTL was 3.72 to 10.35%. The information gained from mapping resistance can be used in a marker‐assisted selection (MAS) program for the development of BLSB resistant germplasm.
Spectral Reflectance to Estimate Genetic Variation for In‐Season Biomass, Leaf Chlorophyll, and Canopy Temperature in Wheat
Authors: Babar M. A. , Reynolds M. P. , van Ginkel M. , Klatt A. R. , Raun W. R. , Stone M. L. 
Published: March 2006

ABSTRACTSpectral indices as a selection tool in plant breeding could improve genetic gains for different important traits. The objectives of this study were to assess the potential of using spectral reflectance indices (SRI) to estimate genetic variation for in‐season biomass production, leaf chlorophyll, and canopy temperature (CT) in wheat (Triticum aestivum L.) under irrigated conditions. Three field experiments, GHIST (15 CIMMYT globally adapted historic genotypes), RILs1 (25 recombinant inbred lines [RILs]), and RILs2 (36 RILs) were conducted under irrigated conditions at the CIMMYT research station in northwest Mexico in three different years. Five SRI were evaluated to differentiate genotypes for biomass production. In general, genotypic variation for all the indices was significant. Near infrared radiation (NIR)–based indices gave the highest levels of association with biomass production and the higher associations were observed at heading and grainfilling, rather than at booting. Overall, NIR‐based indices were more consistent and differentiated biomass more effectively compared to the other indices. Indices based on ratio of reflection spectra correlated with SPAD chlorophyll values, and the association was stronger at the generative growth stages. These SRI also successfully differentiated the SPAD values at the genotypic level. The NIR‐based indices showed a strong and significant association with CT at the heading and grainfilling stages. These results demonstrate the potential of using SRI as a breeding tool to select for increased genetic gains in biomass and chlorophyll content, plus for cooler canopies.
Persistence and Yield Stability of Intersubspecific Alfalfa Hybrids
Authors: Riday Heathcliffe , Brummer E. Charles 
Published: March 2006

ABSTRACTLong‐term persistence and sustained biomass yields of alfalfa (Medicago sativa L.) stands are important to producers. Yield performance and persistence of intrasubspecific crosses between alfalfa subspecies sativa and falcata after the first post‐establishment year are unknown. The objectives of this study were to measure biomass yields, persistence, and biomass yield stability in inter‐ and intrasubspecific alfalfa crosses derived by mating nine elite sativa clones and five falcata clones in a half‐diallel. Progeny were space planted in 1998 at Ames and Nashua, IA, and evaluated for persistence, biomass yield, and biomass yield stability from 1998 through 2002. Medicago sativa subsp. sativa (sativa) × M. sativa subsp. falcata (falcata) hybrids produced substantial biomass yield and exhibited heterosis through the first post‐establishment year, but declined in subsequent years. From 1998 through 2002 the intersubspecific hybrids had persistence equivalent to the more persistent parental subspecies, with the effect becoming more apparent as time progressed. Intrasubspecific hybrids had less biomass yield stability than the more stable intrasubspecific sativa crosses. The results indicate that selection of improved falcata germplasm for long term persistence and higher yield is needed.
Structure and Genetic Diversity of Wild Populations of Lima Bean (Phaseolus lunatus L.) from the Yucatan Peninsula, Mexico
Authors: Martínez‐Castillo Jaime , Zizumbo‐Villarreal Daniel , Gepts Paul , Delgado‐Valerio Patricia , Colunga‐GarcíaMarín Patricia 
Published: March 2006

ABSTRACTThis study was conducted to determine the genetic diversity, structure and gene flow of 11 wild populations of Phaseolus lunatus L. in four regions of traditional agriculture in the Yucatan Peninsula, Mexico, part of the putative domestication area of its Mesoamerican gene pool. Analyzing eight microsatellite loci, the populations showed high values of diversity: observed heterozygosity (Ho) 0.46 to 0.9; Nei's index of diversity (H) 0.35 to 0.59 and average number of alleles per locus (A) 2.37 to 3.38. Both Nei's index of populations differentiation (Gst) and analysis of molecular variance (AMOVA) indicated strong differentiation. The Bayesian analysis of grouping and the Mantel test suggested isolation among agricultural regions as a major factor for population differentiation. Even though a low long‐term gene flow (Nm = 0.66) and low rates of recent migration among populations were observed, there were some cases where the accidental transport of seeds could be favoring a gene flow at a long distance. Data found in this study suggest a positive correlation between agricultural intensification and increase in diversity, suggesting that wild populations are favored by the intensification of disturbance in situations involving at least 3 yr of fallow. However, the opposite could be true at higher levels of intensification as has been reported in the Central Valley of Costa Rica, where the diversity is diminishing.
Response from Selection for Pectin Concentration and Indirect Response in Digestibility of Alfalfa
Authors: Tecle Isaak Y. , Viands Donald R. , Hansen Julie L. , Pell Alice N. 
Published: March 2006

ABSTRACTGenetic improvement of alfalfa (Medicago sativa L.) for increased pectin concentration, estimated by neutral detergent soluble fiber (NDSF), would improve the efficiency of utilization of its high protein and digestibility by ruminants. The objectives of this study were to: (i) estimate the realized direct response from one cycle of phenotypic selection for NDSF concentration; (ii) evaluate association of NDSF concentration with other forage quality traits, and; (iii) determine the impact of selection for NDSF concentration on in vitro dry matter digestibility (IVDMD) of alfalfa. Selection for NDSF was applied to five alfalfa populations from 1996 to 2000 and synthetic generation two seed was produced. Progress from selection for NDSF concentration was evaluated in plot trials for 2 or 3 yr at two locations near Ithaca, NY. Populations divergently selected for NDSF were 1.62 to 5.15 g kg−1 of dry matter (DM) higher and 2.26 to 4.20 g kg−1 DM lower, respectively, than their respective base populations. Neutral detergent soluble fiber concentration was negatively correlated with total cell wall concentration (CW), and proportions of neutral detergent fiber (NDF), cellulose, and lignin in the CW. A positive correlation existed between NDSF concentration and crude protein (CP) concentration and IVDMD. Populations bred for higher or lower NDSF concentration had 0.20 to 8.82 g kg−1 DM higher IVDMD and 0.63 to 15.06 g kg−1 DM lower IVDMD than their respective base populations. Selection for NDSF concentration and indirectly for CP, total CW concentration and composition, and IVDMD of alfalfa forage was successful.
Fine Mapping of a Major Insect Resistance QTL in Soybean and its Interaction with Minor Resistance QTLs
Authors: Zhu S. , Walker D. R. , Boerma H. R. , All J. N. , Parrott W. A. 
Published: March 2006

ABSTRACTUtilization of native insect resistance genes can be an important component for managing insects in soybean [Glycine max (L.) Merr.]. A major quantitative trait locus (QTL‐M) for insect resistance from PI 229358, controlling antibiosis and antixenosis, was previously identified on linkage group (LG) M and was found to increase the effectiveness of a Bacillus thuringiensis (Bt) transgene in soybean. The objectives of this study were to fine‐map QTL‐M using recombinant substitution lines (RSLs) identified from a ‘Benning’ backcross population, and to evaluate the main effects and the epistatic interactions between QTL‐M and other resistance QTLs on LGs G and H using near‐isogenic lines (NILs) in a Benning genetic background. The effect of QTL‐M was still detectable in the Benning NILs when they were evaluated for resistance to corn earworm [CEW, Helicoverpa zea (Boddie)]. The two minor resistance QTLs only provided insect resistance when QTL‐M was also present in the Benning NILs. The QTL‐M was fine‐mapped to an approximately 0.52‐cM region after the first round of phenotyping the RSLs for resistance to CEW and soybean looper [SBL, Pseudoplusia includens (Walker)]. These results should increase the feasibility of cloning QTL‐M and help guide the development of insect resistant soybean cultivars.
Nonparametric Methods for Interpreting Genotype × Environment Interaction of Lentil Genotypes
Authors: Sabaghnia Naser , Dehghani Hamid , Sabaghpour Syyed Hossain 
Published: March 2006

ABSTRACTAnalysis of multienvironment trials (METs) of crops for cultivar evaluation and recommendation is an important issue in plant breeding research. Evaluating both stability of performance and high yield is essential in MET analyses. The objective of this investigation was to compare 10 nonparametric stability methods and apply nonparametric tests (which do not require distributional assumptions) for genotype‐by‐environment (G × E) interaction to 11 lentil (Lens culinaris Medik) genotypes. Nine improved lentil genotypes and two local cultivars were grown in 20 semiarid environments in Iran from 2002 to 2004. Results of nonparametric tests of G × E interaction and a combined ANOVA across environments showed there were both crossover and noncrossover G × E interactions and genotypes varied significantly for yield. In this study, high values of TOP (proportion of environments in which a genotype ranked in the top third) and low values of rank‐sum (sum of ranks of mean yield and Shukla's stability variance) were associated with high mean yield, but the other nonparametric methods were not positively correlated with mean yield and instead characterized a static concept of stability. The results of principal component (PC) analysis and correlation analysis of nonparametric stability statistics and yield indicated that only rank‐sum and TOP methods would be useful for simultaneously selecting for high yield and stability. These methods recommended FLIP 92–12L as stable and FLIP96–6L as unstable genotypes. A biplot of the first two PCs also revealed that the nonparametric methods grouped as three distinct classes that corresponded to different agronomic and biological concepts of stability.
Planting Date Effects on Winter Triticale Grain Yield and Yield Components
Authors: Schwarte Aaron J. , Gibson Lance R. , Karlen Douglas L. , Dixon Philip M. , Liebman Matt , Jannink Jean‐Luc 
Published: March 2006

ABSTRACTWinter triticale (×Triticosecale Wittmack) has the potential to introduce valuable economic and environmental benefits to U.S. grain production systems. To maximize triticale's value, research was conducted to identify planting dates that allow maximum productivity after soybean [Glycine max (L.) Merr.]. Winter triticale was planted at 10‐d intervals from 15 September to 15 October at three Iowa locations: central, NE, and SW, during three growing seasons: 2001–2002, 2002–2003, and 2003–2004. Grain yield decreased with planting dates after late September at the NE and SW locations in 2002–2003, and the central, NE, and SW locations in 2003–2004. Yield reductions from planting in mid October rather than late September ranged from 13 to 29%. At the NE location in 2001–2002 and the central location in 2002–2003, grain yield was 15% less for mid September than late September planting, similar for late September and early October plantings, and 13 to 15% less for mid October. Grain yield did not change with planting date at central Iowa in 2001–2002. The greatest yields occurred for planting dates where between 533 and 955 growing degree days (GDD, 0°C base temperature) accumulated between planting and 31 December. Winter triticale would most likely be placed after soybean in Iowa, suggesting that a 2‐wk period would be available for planting winter triticale without diminished yield caused by late planting.
Can Spring Wheat‐Growing Megaenvironments in the Northern Great Plains Be Dissected for Representative Locations or Niche‐Adapted Genotypes?
Authors: Navabi Alireza , Yang Rong‐Cai , Helm James , Spaner Dean M. 
Published: March 2006

ABSTRACTCharacterizing variety testing sites and identification of sites with negligible genotype × environment crossover interaction is important for plant breeders wishing to identify superior germplasm and (or) cultivars for a wide range of environments. Long‐term multilocation grain yield data from the regional hard red spring wheat (Triticum aestivum L.) variety trials from 1981 to 2002 (472 location years assessing 64 wheat genotypes) in Alberta, Canada, were employed for this study. The shifted multiplicative model (SHMM) and the site regression model (SREG) were used to group testing sites into subsets with reduced crossover interaction. Both models identified yearly subsets of testing sites with negligible crossover interaction. However, the yearly site groupings did not generally follow a repeatable pattern over years. Clustering did not correspond with provincial agroclimatic classification, nor did it correspond with site‐specific yield potential. Genotype × environment patterns were therefore inconsistent over the years, mainly because of complex, highly variable, and unpredictable year × location effects. We identified sites appearing to be more discriminative and predictive of average genotype performance. This suggests that regional variety trials may be conducted at a fewer more representative locations predictive of average varietal performance. We conclude that the spring wheat growing areas in Alberta (and in the northern Great Plains in general) belong to a single megaenvironment with unpredictable crossover interaction patterns. Because of the highly variable and unpredictable genotype × environment interaction patterns in Alberta, genotypic selection targeting wide adaptation is recommended. Although genotype × environment patterns were not repeatable, the yearly high yielding and stable varieties were repeatedly selected over years. These varieties were the most popular varieties grown by farmers during the testing time period.
Kernel Size Variation in Naked Oat
Authors: Doehlert Douglas C. , Jannink Jean‐Luc , McMullen Michael S. 
Published: March 2006

ABSTRACTKernel size in naked oat (Avena sativa L.) is of interest because of the importance of groat size in determining flake size in “old fashioned” style oat flakes. Here we compared naked oat kernel size distributions with those of hulled oat (Avena sativa L.). Most hulled oat spikelets have two kernels, where the primary kernel is distinctly larger than the secondary kernel. Although naked oat panicle architecture was similar to that of hulled oat, naked oat had a distinctive multiflorous spikelet architecture that contained from one to six kernels. Because single and double‐kernel spikelets were most abundant in naked oat, the mean kernel number per spikelet did not differ between hulled oat and most naked genotypes. Like hulled oat, naked oat kernel size decreased with increasing kernel order. All hulled oat and most naked genotypes had size distributions departing from normality, but some naked genotypes had normal kernel size distributions. Variances of naked oat kernel size were much smaller than those of hulled genotypes, indicating a greater degree of kernel sizes uniformity in naked genotypes. However, the increased variation in the hulled oat kernel size appeared to be due to the presence of the hull and hulled oat groats had about the same size variation as did naked oat groats.
Blending Hard White Wheat to Improve Grain Yield and End‐Use Performances
Authors: Lee Kyung‐Min , Shroyer James P. , Herrman Timothy J. , Lingenfelser Jane 
Published: March 2006

ABSTRACTTwo hard white wheats (Triticum aestivum L.), ‘Betty’ with high protein and good processing quality and ‘Trego’ with good yield potential, were blended at percentages of 0, 10, 30, 50, 70, 90, and 100% Betty and planted at three locations in western Kansas during 2001 to 2003. Grain yield and wheat end‐use quality were evaluated to assess the impact of blending two cultivars in an attempt to optimize yield and processing quality. A significant two‐way interaction between blend and location was observed for grain yield, test weight, grain protein, single kernel properties, flour extraction, mixograph tolerance, and bread loaf volume per gram of protein. The different yield and quality response of the Betty–Trego blends among locations resulted, in part, from the presence of stripe rust (caused by Puccinia striiformis Westend.) during 2 of the 3 yr (2001 and 2003). Test weight, single kernel weight and size, grain yield, and flour extraction decreased in response to increasing Betty in the blend, whereas grain protein, kernel hardness index, mixograph water absorption, mixograph tolerance, and bread loaf volume increased with the blending level of Betty. Some variables did not exhibit a statistical linear response to the percentage of Betty, indicating that blending Betty and Trego was a good strategy to stabilize agronomic performance and end‐use quality.
Genetic Gain Equation with Correlated Genotype × Environment Effects
Authors: Helms T. C. , Hammond J. J. 
Published: March 2006

ABSTRACTThe genetic gain formula has been used to determine the best allocation of resources. The assumptions of this formula are that genotypes are selected based on the mean of data averaged across several locations within years. When plant breeders select genotypes after the first year of replicated yield tests, the assumptions of the genetic gain formula are violated. For this reason, information provided by the genetic gain formula is not useful for determining the optimum allocation of replicates and environments. Our objectives were to (i) develop a heritability formula that included covariances between genotype‐by‐environment (G × E) interaction effects for the same genotype evaluated in different environments; and (ii) show how these G × E covariances influence resource allocation strategies to maximize genetic gain. Our operational genetic gain formula considers genetic gain to be a correlated response between the test and target environments and allows for G × E covariances between the same genotype evaluated at two selection sites. When selection was conducted at two sites that had a small G × E component of variance and also conducted at two sites with a large G × E component of variance, the realized gain was equal in the target environments. Optimal resource allocation cannot be decided, based on the genetic gain formula.
Inheritance of Resistance to Gray Leaf Spot Disease in Perennial Ryegrass
Authors: Han Yuanhong , Bonos Stacy A. , Clarke Bruce B. , Meyer William A. 
Published: March 2006

ABSTRACTGray leaf spot disease, caused by Pyricularia oryzae Cavara, is an important disease in perennial ryegrass (Lolium perenne L.) turf. Host resistance is an ideal and promising approach to disease control. In this study, two diallel crosses involving six parents and eight parents, respectively, of perennial ryegrass were established to investigate the inheritance of gray leaf spot resistance. Parents and progenies were evaluated for gray leaf spot resistance in growth chamber experiments where they were inoculated with a mixture of five pathogen isolates. A field experiment was conducted on the progenies of one diallel cross. Effects of both general combining ability (GCA) and specific combining ability (SCA) were significant in both growth chamber and field tests. However, the GCA variance accounted for the major portion of the total genotypic variance. Narrow‐sense heritability calculated by midparent–offspring regression ranged from 0.57 to 0.76, indicating additive gene effects were the major genetic component in control of gray leaf spot. Estimates of minimum number of genes ranged from 2.1 to 4.4, suggesting resistance to gray leaf spot was controlled by a small number of genes. All the results suggested that a breeding program basing on recurrent selection should be effective to improve the resistance to gray leaf spot in perennial ryegrass.