Grain yield stability of spring safflower (Carthamus tinctorius L.)

Abstract

The additive main effect and multiplicative interaction (AMMI) model and the phenotypic stability parameters, ecovalence (W2), regression coefficient (b), coefficient of determination (R2), coefficient of variation (CV), stability variance (S2), AMMI stability value (ASV), and TOP (proportion of environments in which a genotype ranked in the top third), were used to evaluate simultaneously the yield performance and stability of 17 spring safflower genotypes and to evaluate 26 rainfed environments during 2003–05 in Iran. These parameters were designated as Type-A and Type-B for genotypes and environments, respectively. Among Type-B parameters, Spearman’s rank correlation showed that the AMMI stability value (ASVj), ecovalence (Wj2), genotypic variance (Sj2), and coefficient of variation (CVj) were significantly and positively associated (P < 0.01), indicating that one of these parameters can be used as an alternative to the others, but were significantly and negatively correlated with the genotypic selectivity (bj) parameter. The results showed that none of the Type-A statistics per se was useful for selecting high-yielding and stable genotypes. Based on these parameters, the genotypes G9, G10, and G11 combined high and stable yields while the highest yielding genotypes G1 and G17 were the most instable. Type-A and Type-B stability parameters are useful to identify genotypes with specific and large adaptations and the contrasting environments with high contribution to genotype × environment interaction.