Evaluation of nitrogen application management on drought tolerance and water use efficiency of rain in rainfed wheat

In order to study the effects of rates and timing of nitrogen application on grain yield, drought tolerance (DT) and water use efficiency of rain (WUE) in rainfed wheat, two experiments were carried out including rainfed and suplimentalirrigation conditions.Treatments were different rates of nitrogen consist of 0, 30, 60, 90 and 120 kg.ha-1 as sub-plots and time of nitrogen application included T1- total in the fall, T2- 2/3 in the fall 1/2 in the spring and T3- 2/3 in the fall 1/3 in the spring as main-plots with three replications in splitplot test as randomized complete block design in Kurdistan province during (2012-2014). The results showed that application of nitrogen was increased drought tolerance of wheat rainfed. Nitrogen increased water use efficiency (WUE) of rain, nitrogen agronomic efficiency (NAE) and DT of rainfed wheat. Fall application of 60 kg N.ha-1 had the highest grain yield, NAE, WUE and STI index and was the best treatment with respect to DT. There was synergistic relationship between N and K concentrations in leaf. This is could be confirmed increasing of DT of rainfed wheat by nitrogen optimized management.