Effect of irrigation and nitrogen fertilizer on grain yield, yield components and dry matter remobilization of maize cv. SC260

Nitrogen management under water limitation condition is an important factor to obtain high grain yield of maize (Zea mays L.). To study the effects of irrigation and different nitrogen fertilizer levels on dry matter remobilization, grain yield, chlorophyll and carotenoid contents of maize cv. SC 260, a field experiment was conducted in Research Station of Islamic Azad University of Shiraz, Iran in 2012 and 2013. The experimental design was split-plot arrangement in randomized complete block design with four replications. The main plots consisted of four soil moisture depletion (MD): MD1 (20% MD), MD2 (40% MD), MD3 60% MD) and MD4 (80%MD). Four rates of nitrogen fertilizer application: 150, 200, 250 and 300 kg.ha-1 were randomized in subplots. Results showed that grain yield, biological yield, chlorophyll index, chlorophyll a, b were significantly higher in MD1 than the other treatments. However, the highest contribution of stem and leaf dry matter remobilization to grain and carotenoid were obtained in MD4 and 300 kg N ha-1and the lowest in the MD1 treatment and 150 kg N ha-1. In general, nitrogen application increased all traits of maize; however, there were no significant difference between 250 and 300 kg N ha-1.Nitrogen fertilizer relieved the negative effects of water scarcity and 250kg N ha-1at all levels of soil moisture had the greatest effect. Nitrogen application at each moisture level increased the proportion of drymatter remobilization to grain yield, and the greatest contribution of remobilization was obtained at the highest rates of N fertilizer with the highest moisture content. Results showed that increasing nitrogen application enhanced the contribution of dry matter remobilization to grain under water deficit conditions.