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Genetic Variability and Association of Traits in Yellow Gray Common Bean (Phaseolus vulgaris L.) Genotypes for Yield and Yield Related Traits in Sidama Region, Southern Ethiopia

Esrael Kanbata Kayamo

The study of genetic variability in crop plants is important for improving the crops including common beans and enhancing production. This research was undertaken with the objectives to determine the magnitude of genetic variability and association of yield and yield related traits. Thirty six genotypes were evaluated using simple 6 × 6 lattice design at Hawassa. The analysis of variance revealed significant difference among genotypes for 13 traits studied except days to 50% emergence and number of primary branch. Highest GCV and PCV was found for plant height followed by number of pods per plant and number of seeds per plant; whereas, lowest GCV and PCV were observed for days to 50% flowering. Heritability in broad sense ranged from 96.7% for hundred seed weight to 14.7% for number of primary branches and genetic advance as percent of mean ranged from 63.8% for number of primary branches to 2.2% for days to 90% maturity. Highest broad sense heritability and high genetic advance as percent of mean were obtained for days to 50% emergence followed by plant height and number of pod per plant indicating the presence of additive gene action for the inheritance of these traits. Seed yield had significant and positive phenotypic and genotypic correlations with days to 90% maturity, stand count at harvest, number of seeds per plant, biological yield hundred seed weight and harvest index. Path analysis revealed that stand count at harvest, number of seeds per plant, biological yield, hundred seed weight and harvest index showed positive direct effect on seed yield. Whereas, number of pods per plant and protein content of seed had negative direct effect on seed yield at both phenotypic and genotypic level. The 36 common bean genotypes were grouped in to four clusters based on D² analysis. Maximum inter cluster distance was observed between cluster II and III (3734); whereas, minimum inter cluster distance was observed between cluster I and III (26.05). The genotype belonging to the distant clusters could be used for breeding program to obtain a wider range of variability. The first five principal components, whose Eigen values greater than one, accounted for 71% of the total variation among the genotypes. The variability of traits, which were exhibited among the genotypes, can serve in planning selection and crossing programs for the future common bean improvement. However, it requires multi location and over season trials to verify the stability of existing genotypic variability.