Increased Water Productivity of Wheat under Supplemental Irrigation and Nitrogen Application in a Semi-arid Region

Limitations of water and nitrogen in soil usually restrict plant growth. The objective of this study was to evaluate the effects of different amounts of supplemental irrigation at different growth stages and application of different rates of nitrogen fertilizer on grain yield and water productivity of wheat cultivars. A field experiment was conducted in the agricultural research station of Shahrekord University, Iran, for 2 years. The experiment had a split-split plot design with 3 replications. Five irrigation treatments occupied the main plots, two wheat cultivars were the sub-plots, and three levels of nitrogen were allocated to the sub-subplots. Seed yield and water productivity increased with the total amount of water available to plants. Water productivity increased linearly with increasing additional irrigation from the jointing stage to the seed filling stage, in both years. However, the rate of grain yield and water productivity in irrigation treatment at the jointing stage was greater than the other irrigation treatments. Both wheat varieties showed positive response to supplemental irrigation treatments and nitrogen fertilizer, but the rate of grain yield and water productivity was greater in Azar2 cultivar. Additional nitrogen fertilizers also increased seed yield and water productivity in both years. Generally, the combination of supplemental irrigation at jointing stage and application of 100 kg nitrogen ha(-1) have important roles in the improvement of seed yield and water productivity of Sardari wheat cultivar under semi arid region.