Covering rice demand in Southern China under decreasing cropping intensities and considering multiple climate and population scenarios

In recent years, rice (Oryza sativa L.) cropping intensity has been decreasing in Southern China, characterized mainly by the gradual conversion of double rice to single rice. However, few studies have evaluated the balance between rice supply and demand under different climate, population, and cropping intensity scenarios in this region. Here, the Crop Environment Resource Synthesis (CERES)-Rice model was used to investigate the effects of climate change on rice yield in southern eight provinces. The future cultivation areas of single rice and double rice were predicted by linear regression equations based on current area trajectories and official policies. Additionally, the rice demand was determined by the predicted population. Results indicated that the conversion of double rice to single rice appeared in Anhui, Hubei, Hunan, and Jiangxi. The present rice cultivation areas in other provinces were very close to the minimum rice cultivation areas proposed by local governments. The early rice yield showed a significant upward trend under global warming. The yields of single rice and late rice exhibited an insignificant upward trend under a moderate warming scenario but a significant downward trend under an aggressive warming scenario. Interestingly, the yield sum of double rice was more resilient to climate change due to the higher and more stable yield. At the provincial level, in the cultivation area conversion experiments in this study, the rice supply could generally cover the demand in Anhui, Hubei, Hunan, and Jiangxi; the supply in the other four provinces was less than or just close to the demand, while the demand was gradually reduced. Moreover, the total rice supply of the eight provinces could meet the demand, except for the most populous scenario during 2081-2100, and the supply could be improved by adjusting the conversion rate of double rice to single rice. These results have implications for the adjustment of rice cropping intensity and are important for ensuring rice sustainable production and food security under future climate change.

Automated summary

In Southern China, the conversion of double rice to single rice has been occurring, leading to a decrease in rice cropping intensity. This study used the CERES-Rice model to examine the impact of climate change on rice yield. The results showed that the conversion of double rice to single rice was mainly observed in certain provinces, while other provinces were close to meeting the minimum rice cultivation areas proposed by local governments. The study also highlighted the significance of adjusting rice cropping intensity to ensure sustainable production and food security under future climate change.