Plant breeders generally conduct the selection phase of their program at few locations, mainly on the basis of geography and resource limitations. We conducted this study to identify test locations that optimize genotype selection on the basis of discriminating ability and representativeness. GGE Biplot Pattern Explorer was used to rank six test locations in Louisiana for cotton (Gossypium hirsutum L.) lint yield and fiber length using data from the 1993 to 2003 Louisiana Official Variety Trials (early and medium maturity). Biplots were generated and distances between the “ideal” and actual test locations were measured. Locations with shorter distances were closer to the ideal location and were considered more desirable test locations for the traits of interest. Each test location's distance was standardized by the mean distance of all locations for each biplot. For lint yield, on the basis of its close proximity to the ideal test location and the low standard deviation, the most desirable selection location was St. Joseph loam (Commerce silt loam; fine‐silty, mixed, nonacid, thermic, Aeric, Fluvaquent). Winnsboro nonirrigated and Bossier City were not good selection locations for lint yield. For fiber length, Winnsboro irrigated was ranked first and St. Joseph loam was ranked third. Winnsboro nonirrigated was ranked sixth. A composite distance, reflecting the distance between the actual and “ideal” location for lint yield weighted at 60% and fiber length weighted at 40%, was used to determine the desirability of test locations on the basis of simultaneous selection for lint yield and fiber length. St. Joseph loam ranked first, Winnsboro irrigated ranked second, and Winnsboro nonirrigated ranked sixth. St. Joseph loam or Winnsboro irrigated should be used for selecting cultivars for lint yield and fiber length. Winnsboro nonirrigated should not be used for selecting cultivars because of its low level of discrimination and unique behavior.

No abstract

The study of genotype × environment interaction is critical for accurate cultivar evaluation in large multi‐environment trials. Cultivars that exhibit high levels of mean performance and stability across a wide range of environmental conditions are desirable for rice production. Pure‐line varietal and hybrid rice cultivars are commercially produced in the U.S.; however, little research has been conducted comparing their stability for grain yield and milling quality. In this study, 15 hybrid and varietal cultivars were grown in 10 environments from 2005 to 2007 to determine the performance and stability of rough rice yield, whole milled rice percentages, and whole‐grain rice yield. Stability was analyzed using the coefficient of variation, Shukla's Stability Variance statistic with environment means as a covariate, and the Cultivar Superiority Measure. The hybrid rice cultivars XP723 and CLXL730 were ideal for high and stable rough rice and whole‐grain rice yields on the basis of the cultivar superiority measure; however, for whole milled rice percentage alone, they were among the least desirable cultivars. Among the varietal cultivars, Catahoula and Jupiter were ideal cultivar selections for high and stable whole‐grain rice yields. The results of this study indicate that the stability and performance of hybrid and varietal cultivars differ according to the trait of interest.

The National Plant Germplasm System (NPGS) is a cooperative effort among State, Federal and Private organizations aimed at preserving one of agriculture's greatest assets: plant genetic diversity.The NPGS serves the scientific community by collecting, storing, and distributing germplasm as well as maintaining a searchable database of trait descriptors. Serving the NPGS,

During the past 9 yr, a new race of Fusarium (Fusarium oxysporum f. sp. vasinfectum [FOV Race 4]) has increasingly impacted cotton (Gossypium spp.) in the San Joaquin Valley of California. To assess the vulnerability of upland cotton (G. hirsutum L.) in California to FOV disease, elite upland germplasm lines from 13 U.S. public breeding programs across the Cotton Belt and commercial cultivars were evaluated for disease resistance to FOV Races 1 and 4. Ten independent replicated field trials were conducted: three in 2008, four in 2010, and three in 2011. Significant differences (P ≤ 0.05) were observed for disease severity index of leaves, vascular root staining, and plant survival values among the elite germplasm lines in all 3 yr for the levels of resistance–response to FOV Races 1 and 4. Also, significant interactions among germplasm lines, FOV races (1 and 4), and evaluation sites indicated that germplasm lines differed in mechanisms of plant‐defense response for the two FOV races. Selected lines from programs in the states of Alabama, Arkansas, Louisiana, and Mississippi showed at least a moderate level of tolerance to both FOV races; however, several of these lines produced weak and coarse fibers. Based on these evaluations, many of the entries in public breeders’ current elite upland germplasm pools may be more susceptible than expected to some FOV races, and sources of acceptable levels of resistance may be limited when tested under infestation levels that resulted in only 5 to 35% plant survival in susceptible check cultivars.