Variations of potato yield and water use efficiency in China under future global warming scenarios

Rising temperature and varying precipitation have posed huge challenges to the potato production in the world. Revealing changes of potato yield and water use efficiency (WUE) under 1.5 and 2.0 ℃ global warming, has significance for food security in China. In this study, based on the different climate conditions and cropping systems found in China, we divided the entire potato planting area across China into four zones, i.e., the north single cropping system zone, the central double cropping system zone, the south winter cropping system zone and the southwest mixed cropping system zone. Then, the 1.5℃ and 2.0 ℃ warming scenarios were generated based on the baseline period of 1986-2005, and the two warming scenarios were anticipated during 2016-2035 and 2028-2047. 7 typical potato cultivars were selected for whole potato planting area in China. APSIM-Potato model (version 7.6) was used in this study. To assess the impacts of global warming on potato water use, APSIM-Potato was drive by daily climate data under three climate scenarios of baseline, 1.5 ℃ and 2.0 ℃ warming under rainfed and irrigated treatment. Results showed that: Rainfed potato yield, evapotranspiration (ET) and WUE were 0.05-52.40 t/hm2, 7-454 mm and 3-193 kg/(mm·hm2), respectively during the baseline period (1986-2005). Compared with base line period, under 1.5 ℃ global warming scenario, rainfed potato yield increased by 1.50% and 1.90% in north single and central double cropping system, and the ET increased by 3.10% and 2.90% in the two regions, in south winter and southwest mixture cropping systems, the yield decreased by 4.50% and 12.70%, and ET decreased by 2.20% and 8.40% in the two regions. WUE decreased by 0.10%-6.60% in the four potato planting regions across China. Under 2.0 ℃ global warming scenario, potato yield increased by 15.50%, 1.50% and 3.30% in the north single, central double and south winter cropping systems, and the ET increased by 12.10%, 4.60% and 4.20% in the three regions, while the yield and ET decreased by 8.80% and 8.30% in southwest mixture cropping systems. WUE increased by 9.80% in north single cropping system, while decreased by 0.60%-3.30% in other three regions. Irrigated potato yield, ET and WUE were 6.80-59.60 t/hm2, 151-631 mm and 7.90-163.60 kg/(mm·hm2), respectively during the baseline period. Under 1.5 ℃ global warming scenario, potato yield increased by 3.60% and 3.00% in north single and central double cropping systems, while decreased by 1.10% and 11.80% in south winter and southwest mixture cropping systems. ET increased by 4.60%, 4.00% and 2.10% in north single, central double and south winter cropping systems, while decreased by 4.90% in southwest mixture cropping systems. WUE decreased by 0.70%-11.40% in the four potato planting regions across China. Under 2.0℃ global warming scenario, the yield increased by 5.60%, 6.80% and 6.50%, respectively in north single, central double and south winter cropping systems, and the ET increased by 11.90%, 8.60% and 7.10%, respectively in the three regions, potato yield and ET decreased by 8.60% and 5.30% in southwest mixture cropping systems. WUE decreased by 1.10%-6.70% in the four planting regions across China. This study showed that future global warming would have positive impacts on potato yield in north single and central double cropping system, while decrease the yield in south winter and southwest mixture cropping systems. This study can provide a theoretical guidance for potato production to adapt to future climate change in China.