Use of stability parameters for comparing safflower genotypes in multi-environment trials

In this study, some phenotypic stability parameters; ecovalence (W2i), regression coefficient (bi), coefficient of determination (R2i), coefficient of variation (CVi), stability variance (S2i) AMMI stability value (ASVi) and TOP (proportion of environments in which a genotype ranked in the top third), were used to select among 17 spring safflower genotypes for yield performance and stability simultaneously across 26 environments under rain-fed conditions of Iran during growing seasons 2004-06. The results of AMMI analysis showed that 83.78 % of the total sum squares (SS) was attributable to environment effects, only 1.37 % and 14.85 % to genotype and GE interaction effects, respectively. The results showed none of the parametric statistics per se was useful for selecting high yielding and stable genotypes. By simultaneous selection for yield and stability the genotypes G9, G10 and G11 were the best whereas the G1 and G17 with the highest yield performance were the most instable. In conclusion, both of yield and stability should be considered simultaneously to exploit the useful effect of GE interaction and to make selection of the genotypes more precise and refined