Simulating Wheat Production Potential Under Near-future Climate Change in Arid Regions of Northeast Iran

Water scarcity is the key challenge in arid regions, which exacerbates under climate change (CC) and must be considered to assess the impacts of CC on cropping systems. A climate-crop modelling approach was employed by using the CSM-CERES-Wheat model in some arid regions of northeast Iran to project the effects of CC on irrigated wheat production. Current climate data for 1990-2019 and climate projections of three climate models for 2021–2050 under RCP4.5 and RCP8.5 emission scenarios were used to run the crop model. Two irrigation scenarios with different irrigation efficiencies were also simulated to investigate the impacts of water scarcity associated with changing climate and irrigation management on wheat productivity. Results indicated that mean temperature is projected to increase at the rates of 1.74–2.73 °C during the reproductive growth period of winter wheat over the study areas. The precipitation projections also indicated that the precipitation rates would decrease over most of the wheat-growing period. The length of the vegetative growth period will extend in some regions and shorten in others under the near future climate. However, the grain filling duration will reduce by about 2–4 days across all regions. The mean seasonal PET is expected to decrease by about 11 mm from 2021 to 2050 over the study areas. A mean overall reduction in winter wheat yield due to future climate conditions would be about 12.3 % across the study areas. However, an increase of 15-30% in the irrigation efficiency will be able to offset yield reductions associated with limited water supply under future climate scenarios. The results suggest that CC will exacerbate limited irrigation water availability, so implementing high-efficiency irrigation systems should be a priority to adapt to climate change in an arid cropping system.