Effects of Water Stress and Nitrogen on Grain Filling and Yield of Corn (Zea mays L.)

Effects of nitrogen (100 and 200 kg/ha) and irrigation levels (water stress at 8-10 leaf stage، water stress at milk till dough ripening and full irrigaiton) on grain filling and yield of two corn (Zea mays L.) cultivars (SC 500 and SC 647) evaluated through conducting field experiment in research farm of Bu-Ali-Sina University. The experiment was established as a completely randomized block design in a factorial split arrangment with three replications in 2008 growing season. Fertilizer and irrigation levels allocated to main plots and corn cultivars conducted to the subplots. Plant growth rate at flowering per kernel (PGRflw-kernel)، grain filling rate (GFR)، effective grain filling duration (EGFP)، plant growth rate at milk till physiological maturity (PGRM-M)، kernel number، kernel weight، SPAD at grain dough ripening، correlation between these characteristics and indexes were measured. application of 100 kg/ha nitrogen and water deficit stress at grain milk till dough ripening stages lead to decrease in PGRM-M، reduction in grain filling rate and grain weight. Water deficit stress at 8-10 leaf stage، reduced duration of effective grain filling. Highest yield obtained from applying 200 kg/ha nitrogen and full irrigation. Least effect of water stress on yield obtained from application of 200 kg/ha nitrogen and water deficit stress at grain milk till dough ripening stage.