Abstract

Water stress is vital factor limiting bean production wherever beans are grown. The development of bean cultivars having resistance to this stress is a cost-effective tools to address this constraint. This study assessed the performance of gene action and heritability in stress and non-stress conditions. The experiment was designed in randomized complete block design with three replication of two types of common bean including Taylor (P₁) and Aracuanol (P₂). These parents were crossed and then F₂, F₃, BC₁and BC₂ generation were derived. Then yield and vegetative traits include: Number of days to germination (V₁), number of days to appearance of primary leaves (V₂), number of days to appearance of a first trifoliate (V₃); number of days to appearance of a third trifoliate (V₄), height of plant and yield were considered. The genetic components of generation mean analysis were included: Mean (m), additive effect (d), dominate effect (h), additive × additive effect (i), additive × dominate effect (j) and dominate × dominate effect (l). These components were evaluated for all traits, while all the gene effects were not observed simultaneously in all traits. The dominant effect of genes was the most important genetic parameter for controlling the majority of the traits. Despite the significant result for additive effect the importance of dominant effect was more. The results of this study present that in the study of traits in both stress and non-stress conditions not only the additive and dominant effects are important but also the epistasis effect is considerable as well. Moreover, because of the high heritability of most of the traits, it may improve the resistance to drought in breeding projects.

Key words: Common bean, generation mean analysis, heritability, stress and non-stress conditions, action gene.