analysis of correlation coefficients between grain yield and yield components in cowpea genotypes under normal and drought stress conditions

in order to deliberate correlation coefficient between grain yield and yield components among 31 cowpea genotypes under normal irrigation (non-stress) and drought stress (water withholidng after flowering stage until maturity) an experiment was performed in a randomized complete block design (rcbd) with three replications at research field of university of tehran located at karaj during 2011-2012 growing season. the traits measured comprised of plant height, branches number per plant, pods number per plant, seeds per pod, biological yield, grain yield per plant and 100 seed-weights. results showed that under both irrigation regimes, biological yield and pods number per plant were highly correlated with grain yield. stepwise regression analysis revealed that biological yield and pods number per plant had the highest effect on grain yield of cowpea genotypes under both irrigation conditions. path analysis showed that the highest direct positive effect of biological yield and pods number per plant on grain yield under both conditions. therefore, in breeding programs, to boosting grain yield in cowpea genotypes, it is better that the selection to be based on the biological yield and number of pod per plant traits.