Judd Maxwell, North Carolina State Univ, Greenhouse Unit 3, Box 7629, Raleigh, NC 27695, J. P. Murphy, North Carolina State Univ, Box 7629,, Raleigh, NC 27695, David Van Sanford, Univ. of Kentucky Dept of Plant & Soil Sciences, 327 Plant Science Bldg., Lexington, KY 40546-0312, and Harold Bockelman, USDA-ARS, 1691 S 2700 W, Aberdeen, ID 83210.
Selection of superior genotypes
with wide adaptation across large complex environments or with specific
adaptations to regional environments is an important issue for plant
breeders. Generally, selection for
adaptability has been determined by performance in multi-environmental trials
(MET). However, the data produced by METs can be complex and selection decisions must consider
the genotype main effects (G) in combination with the genotype x environment interactions
(GE) simultaneously. GGEbiplot
software aids in the exploration of G and GE to identify superior genotypes
with wide and specific adaptation over a wide range of environments. Genotypes with wide adaptation perform well
over many test locations, while genotypes with specific adaptation perform well
in specific test locations. The
objective of this study was to determine how to effectively use GGEbiplot software with MET data to identify soft red
winter wheat genotypes with wide and specific adaptation for the southeastern United States. Identification of mega-environments and
evaluation of genotype adaptation was determined with four years of data from
the Uniform Southern Soft Red Winter Wheat Nursery. Three methods were used to identify genotypes
with wide and specific adaptation. Method 1 utilized the full data set to
identify the most discriminating environments and the genotypes with wide adaptation
for all tested locations. Method 2 culled
locations that were of little interest to the southeastern breeder. Method 2 clustered the locations into
mega-environments and identified genotypes that were widely adapted to their
respective mega-environments. Method 3 used
just the locations within a mega-environment to identify genotypes with wide adaptation
to the mega-environment and genotypes with specific adaptation to sub-regions
within the mega-environment. Results
indicated that a reduction and reorganization of the data can increase the
precision in comparing genotypes and aid in the identification of superior genotypes
adapted to different mega-environments.