Effect of optimal nitrogen application on water use efficiency of rain and rainfed wheat yield under different moisture conditions

In order to study the effects of nitrogen on grain yield of rainfed wheat, nitrogen agronomic efficiency (NAE) and rainfall use efficiency (RUE), two field experiments under different moisture conditions (rainfed and supplemental irrigation) were conducted in Kurdistan province in 2012-2014 growing seasons. The treatments comprised of five nitrogen rates (0, 30, 60, 90 and 120 kgha-1) as subplots, and three nitrogen application times as main plots (total in the fall, 2/3 in the fall퟽ in the spring, and 2/3 in the fall퟽ in the spring) with three replications as split-plot design in randomized complete block design. Under rainfed moisture conditions, application of 30, 60, 90 and 120 kg N.ha-1significantly increased grain yield 478, 961, 1086 and 850 kg.ha-1, respectively. By increasing nitrogen application, WUE was increased significantly (p