Simulation of Wheat Yield under Rainfed and Supplemental Irrigation and Presentation of Superior Management Scenarios in Upper Karkheh Basin

The objective of this study was to calibrate and validate the AquaCrop (Ver. 4.0) model for wheat (variety¡ Azar2) under rainfed and supplemental Irrigation and definition of the best management scenario in order to enhance yield and WP of rainfed wheat in upper Karkheh basin. The model was calibrated using Matlab software and data collected in research farms in 2005-2006¡ also the model was validated using data collected in 2006-2007. The on-farm trials included three irrigation treatments (rainfed¡ single irrigation only at planting time¡ single irrigation only in spring). The result showed that the model was able to accurately simulate grain yield and biomass of wheat under rainfed and single Irrigation. For grain yield and biomass¡ RMSE¡ NRMSE¡ D-Index and NSE and R2 were obtained equal to (0.16 ton/ ha¡ 5%¡ 0.99¡ 0.99 and 0.86)¡ (0.32 ton/ ha¡ 4%¡ 0.99¡ 0.99 and 0.86) respectively. The result shows that the suitable sowing date in Honam region is between Oct.28 to Nov.2 in 2013-2014. The results indicated by changing sowing dates from Oct.23 to Nov.2¡ the simulated grain¡ biomass and the WP were increased up to 7¡ 6 and 11%¡ respectively. The results showed that in Honam region the proper depth and time of single irrigation in spring is 50 millimeters and the middle of flowering stage (198 days after planting time)¡ respectively.