Effect of drought stress and application of nitrogen fertilizer on morphological and agronomic characteristics of wheat (Triticum aestivum L.) in two regions of Lorestan province

This research was conducted in order to investigate the effect of drought stress and the type and amount of nitrogen fertilizer on the yield, yield components and some physiological characteristics of bread wheat in 2016-1397 in two temperate regions of Lorestan province. The test factors include drought stress (at three control levels, irrigation until the stage of the appearance of inflorescences and irrigation until the milky-paste stage of the seeds) in the main plots, as well as the factors of the type of nitrogen fertilizer (including urea and ammonium nitrate fertilizers) and the amount of nitrogen fertilizer. (at three normal levels based on soil test, 50% higher and 50% lower than normal) were factorially placed in sub-plots. The results showed that the highest plant height was in control and the occurrence of drought stress led to a decrease in plant height. The application of ammonium nitrate caused the internode length to be higher than the factor of urea application). The application of 50% nitrogen fertilizer more than the normal amount caused the highest weight of flag leaf to be obtained at the factor level without drought stress and ammonium nitrate fertilizer at the level of full irrigation factor resulted in the highest level of leaf area index occurrence of drought stress led to a decrease in leaf area index. The number of seeds per plant was also affected by the nitrogen fertilizer application factor and the highest amount was obtained with the use of ammonium nitrate. The seed weight and seed yield in the control factor was higher than the irrigation cut factor and the seed yield in the factor without drought stress was higher than the other two factors and also with the application of ammonium nitrate fertilizer higher than urea fertilizer. Drought stress led to a decrease in biological yield and its amount in the ammonium nitrate factor and in the level of the factor without drought stress by 14908 kg and also reduced the harvest index. The results of this study showed that in the Lorestan region, it is possible to achieve the maximum grain yield in the case of full irrigation of Baharan wheat by applying higher than normal amounts of nitrogen fertilizer. Also, to improve seed yield, ammonium nitrate fertilizer can be used instead of urea.