Effects of water deficit and nitrogen levels on grain yield and oil and protein contents of maize

This research was conducted in 2014, to evaluate the effects of water deficit and nitrogen fertilizer on grain yield, oil and protein contents of maize (cv. double Cross 303). The experiment was arranged as split-plot based on Randomized Complete Block design (RCB) with three replications. Irrigation treatments (irrigation after 60, 90, 120 and 150 mm evaporation) and nitrogen levels (0, 46 and 92 kg N/ha) were located in the main and sub plots, respectively. Mean grain yield per unit area decreased with decreasing water availability, but it was improved with increasing nitrogen fertilizer. Grain oil percentage significantly decreased, but protein percentage slightly increased as a result of water deficit. In general, oil and protein yields significantly decreased under moderate and severe water stress, mainly because of decreasing grain yield under these conditions. Nitrogen application decreased oil percentage, but increased protein percentage significantly. Nevertheless, nitrogen fertilizer enhanced oil and protein yields per unit area, with no significant difference between nitrogen rates. These results were positively related with grain yield per unit area in maize.