Shifting the Sowing Date of Winter Wheat as a Strategy for Adaptation to Climate Change in a Mediterranean-Type Environment

Environmental stresses such as high temperature and drought due to climate change are strongly impacting crop production, including wheat. In this study, Statistical Downscaling Model (SDSM) was used under three Representative Concentration Pathways (RCP) scenarios (RCP2.6, RCP4.5, and RCP8.5) from 2015 up to 2100; the purpose was to know any possible climate changes at the Sanandaj (3525MODIFIER LETTER PRIME, 47 degrees 00MODIFIER LETTER PRIME) and Qorveh (35 degrees 16MODIFIER LETTER PRIME, 47 degrees 79MODIFIER LETTER PRIME) locations. Prediction of the flowering date, maturity date, grain-filling period, and potential yield of winter wheat during the studied period were carried out by using the LINTUL model. Then, seven possible sowing dates (from September 27 to November 27) were examined as a strategy for adoptation to the effects of future climate change and also possible changes of the developmental stages and evaluation of final grain yield of winter wheat under all the three RCP scenarios. The findings indicated that the maximum and minimum temperatures tend to increase at both locations under the RCP4.5 and RCP8.5 scenarios. In general, change in flowering date will not be significant, particularly at the Sanandaj location, but the maturity date will be earlier than current dates at both stations under all three scenarios. There will be a slight decrease in the grain-filling period, particularly at the Sanandaj location. The total decline in the grain-filling period for the Sanandaj station would be about 1.35, 1.7, and 3.8 days by the year 2100 for the RCP2.6, RCP4.5, and RCP8.5 scenarios, respectively. The average winter wheat yield changes for the 2015-2100 period would be about - 88.8, - 201.9, and - 364.9 kg ha(-1) at the Sanandaj location and 222.7, - 135.15, and - 348.5 kg ha(-1) at the Qorveh location, under the RCP2.6, RCP4.5, and RCP8.5 scenarios, respectively. Finally, it is found that earlier sowing dates would lead to earlier flowering and maturity dates. At Sanandaj and Qorveh stations, bringing sowing date forward from the current dates (October 27) to September 27 (first possible sowing date) would increase yield by 26 and 12 percent, and its delay to November 27 (the latest possible sowing date) would decrease yield by 19 and 11 percent, respectively. It seems that the expedition of the sowing date in the Mediterranean-type environment can act as a reliable strategy in response to future climate changes. Shifting the sowing date causes the grain-filling period to be less exposed to high temperatures and drought stress in late spring, which may results in even higher wheat yield.