Effect of rainfall distribution on genotype x environment interaction in bean genotypes

Evaluations of common bean (Phaseolus vulgaris) germplasm from CIAT were conducted in Swaziland between 1987 and 1992. A sub-set of five genotypes, which were included continuously as entries in the trials, was analysed to assess stability. The relative contribution of rainfall to genotypic stability was subsequently determined after partitioning the genotype x environment interaction into stability variance statistics assignable to each genotype. The analysis of variance showed significant differences for genotype effects in all environments used in the study. The combined analysis of variance also revealed highly significant main effects, as well as interaction effects due to genotype x environments, suggesting that a simple additive model could not be adopted. G x E interaction was subsequently partitioned into specific genotypic variance components. The results showed that Carioca, PVBZ 1782 and Bonus were unstable while BAT 1713 and PVA 894 showed nonsignificant stability variances and are therefore more stable