Study on Genotype×Environment Interaction Through GGE Biplot for Seed Yield in Spring Rapeseed (Brassica Napus L.) in Rain-Fed Condition

In recent decade use of graphical approach or GGE biplot for study G×E interaction become popular in plant breeding programs. In this approach the effects of genotype and G×E interaction are not separated and selection is based on both of above effects. In this study GGE biplot has been used to study 9 spring rapeseed genotypes over four locations in two years and another location in one year (totally 9 environments). The results of analysis of variance showed that 79. 2 percent of total variation was due to environment، 9. 3 percent due to genotype and 11. 5 percent due to G×E interaction. The polygon-view of GGE biplot recognized six superior genotypes and two megaenvironments so that the best genotypes within each environment were determined. The three genotypes located in sectors that no environments were placed in it indicated that these genotypes were poor in most of the environments. Simultaneous evaluation of yield and stability through average environment coordinate biplot showed that Hyola401 hybrid with the highest seed yield was the most unstable genotype. Option500 and Kristina with high seed yield and relative high yield stability selected. These two were the nearest varieties to ideal genotypes. Biplot of correlation among environments revealed that environmental vectors of Sarpol-e-zahab and Pol-e-Dokhtar were near to 90◦ so، these locations were different environments. All environments had high discriminating ability so that could able to show differences between genotypes. Masjedsolyman and Pol-e-dokhtar (second year) were the nearest environments to ideal environment so، they had the highest discriminating ability and representativeness.