Effect of Climate Change on the Phenology and Yield of the White Seedless Grape (Case Study: Golmakan Agricultural Weather Station)

This study aimed to evaluate the potential effects of climate change on the phenological statges and yield of grape. First, the daily values of temperature (minimum, maximum) and precipitation based on HADCM3 model in the past and future periods based on the scenarios of RCP8.5, RCP4.5 for the future period of (2020-2050) has been downscaled using change factor method. Then, phenological stages and yield were analyzed using MATLAB2019 software using the observation data and downscaled output of the model based on the dynamic neural network.. Climate model output shows increasing of temperatures and decreasing of rainfall in the future periods when comparing to the baseline.The maximum RCP4.5 and RCP8.5 temperatures were increased by 2.7 and 3.2 °C, respectively, and at least RCP4.5, RCP8.5 increased by 1.8 and 2.9 °C, respectively. Results also showed that mean annual precipitation over the Golmakan station will be decreased by 34 and 49 percent under RCP4.5 and RCP8.5 scenarios. The phenological stages including bud flowering stage to fruit ripening under both scenarios will be completed at earlier time it is 15 days in RCP4.5 and 24 days in RCP8.5 in advance. Results showed that, grape yield under RCP4.5 and RCP8.5 will be decreased by 2.04 to 2.7 under RCP4.5 and 2.3 to 3 under RCP8.5 T/HK (as an average 0.54 to 0.86 T/HK). Results show that changing the date of growth period will change in all stages of phenology and reduce yield in the future.