Assessment of Yield Optimization and Water Use for Local Rice under Water Deficit Conditions in Nekuabad Irrigation Network in Isfahan, Iran

Simulation models are important for evaluation of the effects of environmental stress on crop yield. The AquaCrop model is a valuable tool for improving farm-level water management because of its excellent crop yield simulation under full, deficit, and supplemental irrigation. The present study evaluated the AquaCrop model over two years of experimental data for the Zayandehrud rice cultivar on research conducted in the Nekuabad irrigation network, which features clay soil texture and mildly saline water. The irrigation treatments consist of continuous flooding to depths of 22 and 35 mm and alternative wetting-and-drying soil saturation levels from 0 (saturation) to 15 mm in depth. The model was able to accurately simulate rice yield under full irrigation and mild deficit irrigation scenarios. Increasing the water stress decreased the accuracy of model simulation for grain yield and canopy cover. The results of the reliability indices were 1.03 for root mean square error, 0.71 for index of agreement, and 0.6 for coefficient of residual mass. The model provided excellent simulations of grain yield, biomass and canopy cover. The best fitted curve for the crop water production function for the cultivar and region was a second-order function with an acceptable coefficient of determination of R2 = 0.91.