Potential rice exposure to heat stress along the Yangtze River in China under RCP8.5 scenario

Along with the global warming, heat events will tend to heighten and should be a matter of concern to rice production. Spatiotemporal changes in single-season rice exposure to heat stress along the Yangtze River during 1971-2100 were evaluated using datasets of single-season rice phenology observation and downscaled daily temperature projections from the 21 models. The results from top two best models which performed well in reproducing daily and seasonal temperatures were compared with that from all 21 models using the ensemble mean method under RCP8.5 scenario. It was found that obvious advances of the date of inflorescence emergence and ripening occurred in most parts of the study region through the period of 2021-2050 and 2071-2100. Duration of exposure to heat stress which was defined as an event of at least 3 successive days with daily mean temperature ≥30 °C or maximum temperature ≥35 °C tended to increase although length of crucial phenology period subjected to heat stress shortened. Mid-eastern Hubei, central Anhui, western Jiangsu, northern Zhejiang and northeastern Hunan were hot spots prone to heat stress. Heat stress for the entire region in the two future periods of 2021-2050 and 2071-2100 increased significantly, with an upward trend of 0.13 and 0.09% d per year for all 21 models and top two best models from 1971 to 2100 respectively. Understanding the potential exposure to heat stress can help decision makers to develop mitigation strategies to ensure rice production security.