Influence of Supplemental Irrigation and Applied Nitrogen on Wheat Water Productivity and Yields

A field experiment was conducted for three growing seasons to study the effects of seasonal water use and applied N fertilizer on yield attributes and water productivity indices of wheat in an arid region of Iran. The results revealed that yield attributes were significantly affected by irrigation and nitrogen treatments and year, and their interactions. Crop height, maximum leaf area index and biological yields were increasingly affected by the available water and N fertilizer. The findings indicated that the grain yield response to N was associated with water application levels. The water productivity indices were influenced by irrigation strategies and deficit irrigation effectively boosted productivity of irrigation water (WI). The highest WI was obtained at a seasonal irrigation water of 156 mm for different levels of applied nitrogen. For levels of applied N1 (application 70% of the required nitrogen), N2 (required nitrogen), and N3 (application 120% of the required nitrogen), WI ranged between 0.93 and 2.28, 1.30 and 2.75, and 0.98 and 2.47 kg m-3, respectively. The data generated here suggest that under deficit irrigation, maximum water productivity (WET) would be achieved when 98 kg N ha?1 is combined with a 156 mm of supplemental irrigation. In this seasonal water use, WET value may be increased to 30% with N appropriate practice (practice N2). Consequently, when limited irrigation water is combined with N fertilizer appropriate management, wheat water productivity can be substantially and consistently increased in the region.