Investigating the Response of Dryland Wheat to Nitrogen Consumption under Supplementary Irrigation Conditions

Bread wheat with a scientific name Triticum aestivum is one of the most adaptable types of cereals, which plays a central role in Iran's agriculture, and the flour obtained from it is mainly used to produce bread. Today, one of the problems and threats facing the realization of food security in human societies is the ever-increasing population and the decreasing of production resources, so increasing the amount of production per unit area is necessary .Therefore this research to evaluate of rainfed wheat cultivars and lines to nitrogen and supplemental irrigation applications, an experiment was carried out.

The experiment was carried out in randomized complete block design in split plot arrangement with three replications in Dryland Agricultural Research sub Institute (Kermanshah) and in two cropping seasons (2018-2020). The main plots included supplemental irrigation in two levels of 50 mm supplemental irrigation in planting time and 50 mm supplemental irrigation in planting time +30 mm supplemental irrigation at the booting stage. The sub-plots included two nitrogen (N) application times (autumn N application (total) and split N; 2:3 in the autumn+1:3 topdressing at the booting stage (spring)). The sub-sub-plots included nitrogen rates; 0, 40, 80, and 120 kg N.ha-1, and the sub-sub-sub-plot included Shalan and Rizhav cultivars and DARI line.

The results showed that performing two irrigation stages increased the biological yield of seed yield and straw yield by 1450, 777 and 673 kg.h-1 respectively. The time of autumn application and split of nitrogen had no significant effect on yield and yield components, but autumn application of nitrogen caused an increase of 74 kg.ha-1 in grain yield. Nitrogen application could significantly increase grain, biological and straw yields in a linear manner. No significant difference was observed between two cultivars and one line used in response to nitrogen, although the effect of increased nitrogen fertilizer consumption on seed yield in Shalan cultivar had a more regular increase. The effect of nitrogen application time on two varieties and one line was the same, although the autumn application of nitrogen caused a slight increase in biological yield, grain and straw.

The nitrogen requirement of dryland wheat in the conditions of single irrigation is 60 kg per hectare at the same time as planting and for two stages of irrigation, 80 kg of nitrogen per hectare is recommended in the form of 2:3 in autumn and 1:3 at of the second stage the supplementary irrigation. Autumn application of nitrogen caused a slight increase in biological yield, grain and straw. Shalan variety had more Fertilization. Finally, it can be concluded that the optimal use of water and nitrogen moderates the effects of heat and drought stress in Rainfed conditions and by using this operation, the amount of dry wheat production can be improved in difficult conditions.