Abstract

A study was conducted to evaluate common bean (Phaseolus vulgaris L.) genotypes for drought tolerance in the Southern Highlands of Tanzania. Treatments included 18 genotypes laid out in a 3×18 split plot arranged in randomized complete block design with three replications. The data on yield under water stress and non-water stress treatments were used to calculate indices that can be used for predicting tolerant genotypes. This was accomplished by ranking the yield indices within the selection indices. Results showed that, selection index, YI, identified BFS60, KG104-72 and SER16 as the most tolerant genotypes, while STI, MP and GM identified SER16, BFS60 and KG104-72. Another index, SSPI, identified RCB266, 41-EX-VAM and SER83 as most sensitive genotypes to water deficit while HM showed BFS60, SER16 and KG104-72 as genotypes tolerant to drought. In contrast, SSI discriminated 41-EX-VAM, RCB266 and PASS as most susceptible genotypes under drought. Ranking the means of yield indices, genotypes SER16, BFS60 and KG104-72 were identified as the most drought tolerant genotypes. Correlation analysis showed that Yp were highly significant (p < 0.001) and positively correlated with STI, SSPI, MP, HM, and GM while Ys were highly significant (p<0.001) and positively correlated with YI, STI, MP, HM and GM. The findings suggest that these indices are effective for discriminating genotypes with higher yields under non stress and stress conditions, respectively. Genotypes, SER16, BFS60 and KG104-72 are among the most tolerant to drought conditions therefore are recommended for cultivation in drought prone environments and subsequently as parental materials in breeding for drought tolerance.

Key words: Common bean, drought, selection indices, yield indices ranks.