Evaluation of drought tolerance of some corn (Zea mays L.) hybrids in Iran

The effect of drought stress on yield and its components was studied on 28 new hybrids of maize along with 6 commercial control hybrids at the Khorasan Razavi Agricultural Research and Natural Resources Institute Mashhad, Iran in 2010. The study was conducted in a completely randomized block design with three replications under normal irrigation and drought stress conditions. There were significant differences among hybrids under both conditions for all traits. The mean grain yield of SC500 hybrid in the normal irrigation condition and N11 hybrid in the stress condition was highest. Result of simple correlation between traits under stress condition showed that number of kernel in row was the highest correlation with yield and in normal irrigation ear diameter was higher than other traits correlated. In order to identify the tolerant genotypes, drought resistance indices were calculated. SC500 and SC250 hybrids were the best genotypes under normal condition and H11 and SC250 showed the best behavior under drought stress condition. In summary, it seems Harm, STI and GMP indices have a similar ability to separate drought sensitive and tolerant genotypes. We also used cluster analysis (Ward’s method) to classify tolerance hybrids in similar classes.