Evaluation of the Effects of Amount and Salinity of Irrigation Water on Yield and Yield Components of Wheat cv. Sirvan

Salinity and drought stress are the most important factors that limit plant growth, especially in dry and semi-arid regions. To investigate the effects of irrigation water levels and salinity on yield and yield components of wheat cultivar Sirvan, a factorial experiment was conducted in a complete randomized block design with three replications in the research field of agricultural faculty of the University of Birjand during the growing season of 2017-18. The treatments included irrigation at four levels (125%, 100%, 75%, and 50% water requirement) and water salinity in three levels (1.6 dS.m-1, 6 dS.m-1, and 7.8 dS.m-1). The results showed that yield components, biological yield, and grain yield of wheat were affected by water irrigation levels and water salinity. Moreover, these treatment significantly reduced the yield components, harvest index, and water use efficiency (WUE). In biological and grain yield of wheat, the highest and the lowest amounts belonged to 125% water requirement × salinity of 1.6 dS m-1 by 1535and 588.76 g m-2, respectively. In biological yield and grain yield, there was no significant difference observed between 125% wheat water requirement × salinity’s of 1.6% dS.m-1 and 100% water requirement × salinity of 1.6% dS.m-1 treatments. Biological and grain yield of wheat decreased to 65% in 50% water requirement × salinity of 7.8 dS m-1 compared with 125% water requirement × salinity of 1.6% dS.m-1. According to results of this experiment, 125% and 100% water requirement treatments had the highest biological and grain yield. Although 125% wheat water requirement had the highest value in all traits but they were not significant compared to 100% water requirement treatment. In water salinity treatments, non-stress levels had the best performance. According to the results of this study, to avoid salt accumulation in the root zone under saline water irrigation and to decrease negative salinity effects, irrigation must be applied based on wheat water requirement.