Evaluation of Yield, Yield Components, and Water Use Efficiency of Drought-Resistant and Susceptible Wheat Varieties under Deficit Irrigation in Mashhad Plain

A field experiment was conducted to evaluate wheat response to low irrigation at the Ferdowsi University of Mashhad, in 2011. Experimental design was split plot with 7 irrigation treatments (main plot), 2 cultivars (sub plot), and 3 replications. Irrigation treatments included full irrigation (FI), without irrigation during spring (NI), irrigation at stem elongation and pollination stages (SP), irrigation at stem elongation and beginning of grain filling stages (SG), irrigation at pollination and beginning of grain filling stages (PG), irrigation at stem elongation, pollination and beginning of grain filling stages (SPG), irrigation at stem elongation, pollination and beginning and middle part of grain filling stages (SPGG). The varieties included Pishgam (drought-resistant) and Gascogne (drought-susceptible). The Results showed that the grain yield of SP، SG، PG، SPG و SPGG treatments decreased by 36%, 40%, 47%, 31%, and 17% compared with the control (FI), whereas their water use decrement were 59%, 58%, 57%, 49%, and 38%, respectively. The drought-resistant cultivar had higher biological and economic yield than the drought-susceptible one, but the biological yield difference between them was more than their economic yield (14% vs. 5%). The highest and the lowest rates of WUE were related to SPGG (1.71) and NI (0.69) treatments. In overall, stem elongation and pollination were the most drought sensitive stages based on this experiment results, therefore, in order to reach high yield under water shortage, irrigation at both of these stages are essential.