Simulating climate change effect on maize grain yield in Kermanshah province using a process-based simulation model

Rising temperature as consequences of climate change could affect on the various processes such as photosynthesis, respiration, partitioning of assimilates and ultimately grain yield of agricultural crops. The present experiment was conducted to simulate the impacts of climate change on maize grain yield under two future climate change scenarios (RCP4.5 and RCP8.5) using APSIM model in three counties of Kermanshah province (Kermanshah, Kangavar and Eslamabad Gharb). Future climate data were projected by using long-term climatic data for the baseline period of 1980-2010 and AgMIP methodology for the mid-future (2040-2070). The results showed that, on average, the mean temperature increased up to 11 and 23 percent under RCP4.5 and RCP8.5 scenarios when compared to the baseline, respectively. The maximum and minimum grain yields in the baseline were obtained in Kangavar (14399 kg.ha-1) and Kermanshah (7741 kg.ha-1), respectively. Simulation results also showed that average temperature during growing season rised (0.5 and 2 ˚C under RCP4.5 and RCP8.5, respectively) and length of growing season decreased (5 and 6 percent under RCP4.5 and RCP8.5, respectively) which resulted in a reduction in maize grain yield from 69 to 90 percent under RCP4.5 and RCP8.5, respectively. Results illustrated that under climate change conditions, flowering of maize may coincide with high temperatures and this may reduce maize grain yield, therefore, it can be suggested that changing the sowing dates in the target regions prevents the coincidence of the critical flowering stage with heat stress.