Evaluation of the Effect of Water Deficit Stress on Wheat Yield in a Moderate-Textured Soil in Khuzestan Province

Irrigation water scarcity is one of the major limiting factors in agricultural production. This study was conducted to investigate the effect of different intensities of water deficit stress on yield and water use efficiency of Chamran 2 wheat cultivar in a moderate-textured soil in Khuzestan province. In this research, 10 treatments including full irrigation and water deficit stress at three intensity levels (low, moderate, and severe) were applied under two conditions: during whole growing season or at a given stage of plant growth. This research was done as a completely randomized design with three replications. The salinity of studied soil was 2.95 dS m-1, and soil texture was silty clay loam. The mean water use in different stress treatments was less than full irrigation by 17% (moderate-intensity stress in the third growth stage of wheat) to 43% (high-intensity stress throughout the plant growth period). Applying different intensities of water stress caused reduction in wheat grain yield by 13% (low-intensity stress throughout the growth period) to 76% (high-intensity stress throughout the growth period). The results showed that water stress at stem elongation and grain filling stages of wheat reduced the grain yield more than stress at flowering and milk stages. The lowest value of mean thousand kernel weight (28 g) was observed in the treatments applied in the final growth stage of wheat, confirming the importance of irrigation effects during grain filling stage on the quality of grain. The overall water use efficiency in low-intensity water stress (0.78 g L-1) was higher than the full irrigation treatment (0.62 g L-1), probably due to the reduction of irrigation water losses by drainage and evaporation.