evaluation of drought tolerance indices in different sweet corn hybrids

in order to comparison and determination of the best drought tolerance indices in sweet corn hybrids, an experiment was conducted using a randomized complete block design in split plot lay out with three replications at seed and plant improvement institute in karaj in 2006. three irrigation levels (irrigation after 75 as control, 100 and 125 millimeters cumulative evaporation from class a evaporation pan) were assigned as main plots and 12 sweet corn hybrids include ksc403su, chase, esquire, rival, reveille, diva, shimmer, shaker, ps107, golda, royalty and rana were considered as sub plots. mean productivity (mp), tolerance index (tol), geometric mean productivity (gmp), stress susceptibility index (ssi), stress tolerance index (sti) were used to evaluate tolerance or sensitivity to drought stress of the hybrids. sti and gmp indices had a positive and significant correlation with grain yield in non-stress and stress conditions (mild and severe stress treatments). sti and gmp indices showed that hybrids diva and golda had optimum yield in non-stress condition but their yield decreased in severe stress condition. hybrids ksc403su, esquire, shimmer and shaker had low yield in non-stress but they had suitable yield in severe stress condition. hybrids chase, rival and reveille had low yield in non-stress and severe stress conditions. hybrids ps107, royalty and rana had optimum yield in both non-stress and stress condition. therefore, they can be recommended to use in stress and optimum conditions.