effect of drought stress on cell membrane stability, photosynthesis rate, relative water content and grain yield of pinto bean (phaseolus vulgaris l.) cultivars

pinto bean is a susceptible plant to drought stress. however, there is genotype variation for this trait in this plant. in order to investigate the effects of drought stress on physiological traits and grain yield of pinto bean genotypes cultivated in zanjan province, an experiment was conducted as spilt plot based on a completely randomized block design with four replications at zanjan university research farm. irrigation levels (control and drought stress) and genotypes (talash, g14088, khomein and cos16) were set in the main and subplot, respectively. results indicated that cos16 showed maximum photosynthesis rate, cell membrane stability and relative water content under drought stress. also, cos16 genotype exhibited the least reduction for photosynthesis rate and relative water content reduction under drought stress in comparison to control. in addition, this cultivar had maximum seed yield and minimum seed yield reduction under drought stress in comparison to control. thus, it seems that under drought stress, cultivars with stable cell membrane will produce higher seed yield because of higher photosynthesis rate.