Effect of Irrigation, Planting Date, Cultivar and Nitrogen on Yield and Concentration and Composition of Starch and Oil of Dent Maize Grain

Studies to assess quality of dent maize grain are noteworthy because of its wide use as food, feed and ethanol production. This study aimed to evaluate the concentration and composition of starch and oil in maize grain in response to different cultivars (KSC704 and KSC260), planting dates (20 June and 21 July), irrigation (12-day and 6-day intervals) and nitrogen (0 and 184 kg N ha-1) rate as the strip-plot factorial statistical model during the 2018 growing season in Pakdasht county of Iran. The results suggested that nitrogen application increased grain yield by one tonnes ha-1. In addition, KSC260 had higher grain yield than KSC704 by 0.96 tonnes ha-1. All compositional variables except stearic acid were affected by the interaction effect of irrigation and nitrogen rate. In low irrigated treatments, nitrogen application reduced the amount of oil, palmitic acid, oleic acid, linoleic acid and linolenic acid. In low irrigated condition, nitrogen application had no effect on increasing the concentration of starch and amylopectin. The use of nitrogen fertilizer reduced the amount of stearic acid by 0.05 g kg-1. In conclusion, the balance between irrigation and nitrogen utilization seems to be important for improving the oil and starch properties of maize grain.