Changes in planting methods will change the potential distribution of rice in South China under climate warming

Evaluation of and adaptation to climate warming have become major challenges, given the profound impacts of climate warming and technical advances in rice cropping systems. However, the dual influences of climate warming and planting methods on rice production remain unclear. Here, we developed a methodological framework based on temperature-based rice growth season determination and GIS spatial analysis to quantify the effect of climate warming and improvements in planting methods (transplanting to direct seeding) on the po-tential distribution of rice cropping systems in South China from 1960 to 2017. The accumulated temperature during the potential growing period of rice increased significantly, and the safe season for rice production extended substantially, which resulted in northward and westward expansions of the planting boundaries for rice cropping systems over the past few decades. Significant changes in planting boundaries and potential planting areas were observed for early maturity double rice (DR_Early) because of climate warming. Since transplanting requires less thermal time compared to direct seeding in the main field, the planting boundaries of DR would shift southward because of planting methods change. The planting boundaries of DR_Early and medium maturity double rice (DR_Medium) changed significantly, moving on average 267 and 159 km southward, resulting in a 13.3% decrease in the study area. The dual analysis showed that the change in planting methods would shift the rice planting boundaries southward, offset the impact of climate warming, and reduce the rice planting areas by 4.0%. Therefore, improvements in planting methods should be considered when evaluating the effects of climate warming on agricultural systems. This research provides new insights that could be used to optimize rice cropping systems, improve the utilization efficiency of thermal resources and adapt to climate warming.