Genotypic variation among common bean (phaseolusvulgaries L.) varieties for drought tolerance

Seventeen varieties of phaseous vulgaris L. produced both commercially and for local consumption in Tanzania were studied in the field for drought tolerance. A split plot design was used with water treatments as main plots and varieties as subplots. Variation among the varieties was observed for all the traits studied indicating the possibility of identifying better performing genotypes. Water stress reduced plant height, days to flowering, maturity, number of pods per plant, seeds per pad, weight and seed yield per ectare (Kg/ha). However using relative water content, stomatal resistance and electrical conductivity as indicators of water stress tolerance TM0 192 was shown to be the most drought tolerant variety followed by TM0 125, TM0 114, TMO 216, and TMO 101 and thus their yield performance was slightly better than most other varieties used in this study. A correlation study among the various traits studied have revealed that relative water content, stomatal resistance, electrical conductivity, pods per plant, 100 seed weight are strongly correlated to geed yield indicating their possible use in the development of a selection index for improving bean yield. This work has shown that TMO 192, TMO 125, TMO110 and TMO 216 are more drought tolerant compared with TOM 101 which has been shown to be very drought tolerant in the recent studies of Tesha (1984). The results further give us hope that drought tolerant varieties can be achieved. It is also suggested that more screening work be done on the available germplasm material to identify more drought tolerant varieties for direct release to farmers or for use in breeding.