Investigation the Effect of Climate Change and Planting Date on Maize Yield using WOFOST Model

Given the advancement of technology and the growing population in the world, the need to recognize and pay attention to the phenomenon of climate change is inevitable. The purpose of this study is to investigate the changes in maize yield for future years in Gorgan with a change in planting date. In this research, the grain yield of maize SC late maturing for future conditions was investigated using WOFOST model in Gorgan city based on different deficit irrigation treatments and different planting dates. Irrigation treatments including 100% (T1), 75% (T2) and 50% (T3) of water requirement. For this purpose, using SDSM statistical model and HadCM3 general circulation model for all scenarios, the fifth microscale report was performed in the next two thirty-year periods (2020-2050 and 2050-2080). Data for the period 1980-1995 were used to calibrate the SDSM model and data for the period 1995-2010 were used for validation. The WOFOST model was calibrated by the measurement data of 1391 and then the data of 1392 were used for validation. Statistical indices of root mean square error (RMSE), compatibility index (d), model efficiency coefficient (E), explanation coefficient (R2) and residual coefficient (CRM) related to grain yield simulation in calibration period was equal to 0.217 tons per hectare, 0.97, 0.94, 0.93 and 0.15, respectively and in the validation period, was obtained 0.241 tons per hectare, 0.98, 0.93, 0.96 and 0.14, respectively. The numbers obtained indicate the good performance of the WOFOST model. Also, the maize grain yield was simulated for four different planting dates in three treatments of T1, T2 and T3. In the period 2020-2050, the lowest yield was predicted 4.3 tons per hectare in T3 treatment under the RCP8.5 scenario on 2 June, which is a decrease of 32.81% compared to the base period. In the period 2050-2080, the lowest yield was predicted 3.3 tons per hectare in T3 treatment under the RCP8.5 scenario on 2 June, which is a decrease of 48.43% compared to the base period. The best planting date for corn in Gorgan city is June 23, which can be used for better management of cultivation and irrigation in Gorgan.