The Effect of Irrigation-off atsome Growth Stages on Remobilization of Dry Matterand Yield of Corn Hybrids

ABSTRACT: In order to study the effect of irrigation-off at some growth stages on remobilization of dry matter and yield of corn hybrids, an experiment was conducted in split plot based on the randomized complete block design (RCBD) with three replications in a farm located in 15 kilometers to Ahvaz during the summer of 2011. In this research irrigation treatments included irrigation during all stages of growth (control), irrigation-off at tasselling stage and irrigation-off at milking stage as the main factors were located in main plots,and second factor included K.S.C. 701 and K.S.C. 704 corn hybrids were located in subplots. The results indicated that the maximum accumulation of dry matter has been at the maturity stages and irrigation treatment in all stages of growth (control) and the maximum mobilization of dry matter to grain has happened in irrigation-off treatment at milking stage. Exerting drought stress in vegetative and reproductive stages led to a significant decrease in biological and grain yields. The results showed that the amount of accumulation of dry matter, mobilization of dry matter to grain, biological and grain yields were more in 701 hybrids. This study showed that 701 hybrid has more endurance to drought stress. Much sensitivity of this hybrid to drought stress in pollination stage led to significant decrease of the number of grains. Also, drought stress after pollination had the most effect on grains weight, and it led to decrease of grain weight through reduction of grain filling period. In sum, the results showed that irrigation-off at any of the growth stages decreases the grain yield significantly. This decrease was more intensive in tasselling stage in which sensitivity to moisture is high. Moreover, 701 and 704 hybrids have high endurance and yield respectively in irrigation-off conditions.