Genetic diversity Study of corn (Zea mays L.) genotypes for morpho-physiological traits under drought stress

This study was conducted with purpose of investigate the effect of drought stress on different growth stages of 20 maize hybrids in farm of Seed and Plant Improvement Institute in 2016. Drought stress levels consisted of four experiments (normal irrigation, stress in vegetative stage, reproductive stress and irrigation interruption as compared to control) in a randomized complete block design. The results of analysis of variance showed that genotypes in terms of traits in each non-stress condition, stress in vegetative stage, stress at reproductive stage and alternate condition have a significant difference at levels of 1 and 5%. According to the results obtained from genetic parameters, in the normal experiment, the number of days to tassel flower initiation, in the vegetative stress experiment tassel branching out number, in the reproductive stress experiment the number of aborted seeds and in the alternate condition days to the drying of the tassel had higher heritability. The tassel branching out number showed the highest phenotypic variation coefficient (77.15) and number of seeds per ear row, the highest genotype variation coefficient (75.6) in normal experiment. Respectively, the number of aborted grains (47.7%) and peduncle outside flag leaf (29.10%) in the vegetative stress test, had the highest phenotypic and genotypic diversity coefficients. The highest phenotypic and genotypic diversity coefficients in reproductive stress test were observed in number of seeds inoculated trait with 45.8% and 37.2%, respectively.