Effect of irrigation and nitrogen interactions on phenologic characteristics and growth indices of seed corn

This research was done in order to study the effects of irrigation (I) and nitrogen (N) levels on occurrence time of phenological stages and growth indices of seed corn, SC704 cultivar. The experiment was conducted at Campus of Agriculture and Natural Resources, Razi University, Kermanshah, Iran, during 2014 and 2015 growing seasons as split-plot based on randomized complete block design with three replications. Main-factor was four I levels including supply 120, 100, 80 and 60% of water requirement. Sub-factor was four levels 140, 100, 70 and 40% of recommended N based on soil analysis. Results showed that tasseling, anthesis and silking stages delayed by reducing of water supply. Increasing of N supply has not significant effect on date of tasseling and anthesis, but silking accelerated. Deficiency of I and N supply led to increasing of anthesis until silking interval. In 120, 100 and 80% of I supply, physiological maturity occurred later by increasing of N. Increasing of N supply, in each I treatment, increased leaf area index and crop growth rate, but the positive effect of N was decreased due to I deficit treatments. Under optimum I conditions, increasing of N supply increased amount and rate of dry matter accumulation, and delayed end of dry matter accumulation.