Study on Genotype×Environment Interaction through GGE Biplot in Spring Safflower (Carthamus tinctorius L.)

GGE (genotype + genotype×environment) biplot is one of the new graphical methods to study genotype×environment interaction in which the effects of genotype and G×E interaction are not separated and selection is based on both of these effects. In the present research, GGE biplot was used to study 14 safflower genotypes over six research stations under water stress and non-stress conditions in spring planting. The results of analysis of variance showed that 93.9% of total variation was due to environment and 6.1% due to genotype and G×E interaction. The polygon-view of GGE biplot recognized six superior genotypes and four mega-environments. The best genotypes within each environment were determined. The seven genotypes located in sectors that no environment was placed indicated that these genotypes were poor in most of the environments. Simultaneous evaluation of yield and stability through average environment coordinate biplot showed that Hartman, Gila and Sina with high seed yield had higher yield stability. Hartman was the nearest variety to ideal genotype (assumed genotype with the highest yield and stability) and Gila and Sina varieties were also close to ideal genotype, too. Biplot of correlation among environments revealed that Shirvan and Kohdasht were similar environments, so that water stress and non-stress conditions were not able to make differences between these locations. Zanjan, Ghamlo, Kohdasht and Sararood environments under non-stress conditions had higher discriminating ability.