Effects of High Temperatures on Rainfed Crops during Their Reproductive Stage Under Multi-Climate Scenarios in the Korean Peninsula: A Case Study of the Korean Soybean.

The effects of higher temperatures on the growth of rainfed crops during reproductive stage were evaluated for 6 sites in South Korea. The 8 future climate scenarios of GCMs for RCP8.5 were collected from the CMIP5 archive using daily data from 1981 to 2100. From July to August is an important period for crop reproduction; therefore, the temperature data used in the study were taken during these months. In the case of the Korean soybean cultivar, critical thresholds of daily maximum and minimum temperature of soybean used in this study were 39¡ÆC and 28¡ÆC, respectively. We calculated the number of days on which daily maximum and minimum temperature would exceed the threshold while the cultivar is in the reproductive stage, using the 8 future scenarios of the six sites, and used that number to determine the frequency of high-temperature occurrences. The frequency at which daily maximum temperature exceeded the threshold could not be determined for six sites during the 2040s. However, the frequency of high-temperature occurrences in minimum temperature increased in 5 sites beginning in the 2040s. The frequency of occurrences of temperatures exceeding daily minimum was observed to increase by 14 times more than the frequency of occurrences of temperatures exceeding daily maximum in Jeonju in the 2070s. This study concludes that the impact of increase in minimum temperature could be larger than that of increase in maximum temperature. The impact of higher temperatures on the yield of Korean soybeans will be discussed in the next work. Neither research nor modeling of rainfed crops for Korean cultivars is popular in South Korea. The preliminary results of this study will serve to raise awareness of the importance of investigating the effects of climate change on rainfed crops in the Korean Peninsula. Acknowledgement: this study was supported by RDA Program (PJ011425032016).