Genetic variation for drought resistance in small red seeded common bean genotypes
Common bean (Phaseolus vulgaris L.) productivity is low in major growing regions of Ethiopia mainly due to drought, caused by low and erratic rainfall. A field experiment was carried out at Gofa in Southern Ethiopia, to assess genetic variability for drought resistance in forty-nine small red seeded common bean genotypes of both local and foreign origin. The genotypes were evaluated under two soil moisture regimes, non-stress (NS) and drought stress (DS). Drought stress was initiated at flowering by withholding application of irrigation water. The average linkage method of clustering grouped the forty-nine genotypes grown under drought stress condition in five clusters. The maximum distance was found between Cluster I and Cluster III. Pattern of variation examined through principal component analysis (PCA) involving morpho-physiological traits showed that the first four PCs accounted for more than 74% of the total variation, of which 59.9% was contributed by the first two PCs. The first principal component alone explained 49.9% and was highly correlated with seed yield, harvest index and geometric mean. The second PC explained 9.7% of the total variation and was highly correlated with days to maturity and drought susceptibility index. Both PCs had higher relative contributions to the total diversity and were the ones that most differentiated the genotypes.