Impact of Extreme climatic events on Production risk of Winter wheat in Climate Change Condition (Case study: Khorasan Razavi Province)

In recent years, there is much more attention to extreme climatic events. Also, it is proved that changes in intensity and frequency of these events have more destroyer effects on the human health, social and natural systems that change in the mean climatic situation. The objective of this study was a recognition of the effective extreme climatic indexes on winter wheat yield in Khorasan Razavi province. So, daily maximum, minimum temperature and rainfall data of 20 stations of this region were used in the 1982-2011 period. Also, the daily data of CORDEX project in the 2021-2050 with RCP2.6 and RCP 8.5 were analyzed. The yield was simulated with the calibrated and evaluated a model of AquaCrop. Mean yield in the past, future with RCP2.6 and RCP 8.5 were 3.79, 4.88 and 5.24 tons per hectare, respectively. Increase in temperature and CO2 concentration was the reason for this increase in yield. Results of regression analysis showed that in all periods, effective extreme indexes were temperature-based. The indexes of a number of frost days and days with a minimum temperature lower than the minimum air temperature in the stem period’s threshold were effective in all periods. The production risk was calculated based on probability and the impact of extreme climatic indexes. Results showed that the northern and central regions of the Khorasan Razavi province have the high to moderate and the southern parts have low risks. Also, it is concluded that the percent of low to very low risk was decreased and moderate to high risk was increased in the future. This means, however, the yield will increase, but the regions with low risk of extreme events will be decreased.