Identifying discriminating locations for cultivar selection in Louisiana

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.