Impact of Climate Change on Two Rice Cultivar Yields and Options for Adaptation Using CERES-Rice Model in Cambodia.

Impact of climate change on two rice cultivar yields and options for adaptation using CERES-Rice model in Cambodia Qingguo Wang1, JongAhn Chun1, Sanai Li1, and Seng Vang2 1APEC Climate Center, 12 Centun 7 ro, Haeundae-gu, Busan 612 020, Republic of Korea 2Cambodian Agricultural Research and Development Institute, National Road No 3, Prateah Lang Commune, Dangkor District, Phnom Penh, Kingdom of Cambodia. Rice (Oryza sativa L.) is the overwhelmingly predominant food crop and the principal source of employment and income in rural areas in Cambodia. Cambodia’s rice cultivation faces greatly increased demands for food security and export, and threats to production due to climate change. There are many factors affecting the Cambodian rice yield, such as climate, inadequate fertilizer, underdeveloped irrigation facilities, poor farming practices and use low yield cultivars. It is, therefore, important to quantify the impacts of climate change on rice yields and options for adaptation. The potential yields of two wet season rice cultivars (Sen Pidao and Phka Rumduol) were simulated using DSSAT/CERES-Rice model in Cambodia under two climate change scenarios, six fertilizer rates, two irrigation conditions. The experiments were conducted at the Cambodian Agricultural Research and Development Institute (CARDI), Cambodia (E 11o28'34.4", N 104o48'36.5") in 2010, 2011 and 2013. Based on two IPCC greenhouse gas concentration scenarios (RCP4.5 and RCP8.5), the future climate data for CARDI simulated by HadGEM3 were used for estimating the effects of climate change on rice yield. Simulated rice yields of both cultivars showed curvilinear response to increasing CO2 concentration at combinations of six fertilizer rates and two irrigation conditions. Generally, depending on the temperature changes in maximum, minimum and mean values, the response of yield to temperature showed different patterns. For Sen Pidao, the rice yield would increase with decreasing temperature and decrease with increasing temperature. For Phka Rumduol, the optimal temperature of the yield was higher than current temperature. Comparing with baseline, the effects of climate change and elevated CO2 on the yields for two cultivars for climate scenarios RCP4.5 and RCP8.5 for the period of 2021-2030, 2041-2060 and 2081–2090, suggested that the yields of Sen Pidao rice will decrease, and the yield of Phka Rumduol could increase or decrease depending on fertilizer rates, irrigation and simulated period. The simulations for various adaptation strategies showed that changes in plant density and planting date may increase yield and minimize the impacts of climate change depending on the cultivar, fertilizer rates, irrigation condition and cultivation year. In general, the variation of effects of climate change on yields were more sensitive to fertilizer rate at low fertilizer, and less sensitive at high fertilizer. The benefits of rice yield from planting date were more sensitive to irrigation conditions.