Evaluation of climate change effects on irrigated wheat CV. Mehregan yield under drought stress condition (Case study: Varamin)

To evaluate the effects of climate change on irrigated wheat yield, Cv. Mehregan, under drought stress condition, a completely randomized block design (CRBD) experiment was carried out during 2019-2020 cropping season in Varamin, Iran. Five treatments of Control (T1), without stress, drought stress in booting stage (T2), flowering stage (T3), milking stage (T4) and doughing stage (T5) were assigned to three replications. In this study, simulation of the future climate, 2025 and 2055 (2010-2039 and 2069-2040), were performed using the outputs of HadGEM general circulation model under RCP4.5 and RCP8.5 climate scenarios. For this purpose outputs of AgMIP model were employed using long-term climatic data of the base period (1980-2009). Based on these findings, under RCP4.5 and RCP8.5 scenarios, the minimum and maximum temperature parameters might increase for the 2025 and 2055 periods. Also, under RCP4.5 scenario rainfall might increase by 9.4% and 21%, for 2025 and 2055 periods, respectively. However, under RCP8.5 scenario, it might decrease by 1.9% and 2.8%, respectively. Drought stress shortened the phonological stages, the number of days after planting to flowering, ripening and the grain filling periods under climate change conditions. The results also showed that under RCP4.5 scenario in 2025 period the highest decrease in dry matter (4 percent) and seed yield (10.2 percent), due to stress condition, occur during booting and flowering stages, respectively.