Evaluation of drought tolerance in corn (Zea mays L.) new hybrids with using stress tolerance indices

In order to study the effect of drought stress on morphophysiologic characteristics,yield and yield components of 8 new hybrids of corn (Zea maize L.) and KSC704commercial hybrid as control resistant to drought and warm (which were bred andscreened in Khozestan province condition), an experiment was conducted in aRandomized Complete Block Design (RCBD) with three replications underdrought stress and normal irrigation at Khorasan-Razavi Agriculture ResearchCenter, Mashhad, Iran on June 10, 2011. The results of analyze variance showedthat under normal irrigation and drought condition, there was a significantdifference (p<0.01) between the hybrids. Mean comparison of hybrids revealedthat in normal irrigation H6 and in drought stress H8 hybrid had the maximumgrain yield (12.85 and 6.75 ton/ha, respectively). Based on the grain yields ofstudied hybrids, stress tolerance index (STI), stress susceptibility index (SSI),tolerance index (TOI), mean productivity (MP), geometric mean productivity(GMP), harmonic mean (HM) and golden mean (GM) were estimated. Resultsshowed that among drought tolerance indices, MP, GMP, STI and HM were thebest indices for corn and KSC704 hybrid and H4 had the highest tolerance todrought in Mashhad weather condition.