The ratoon rice system with high yield and high efficiency in China: Progress, trend of theory and technology

•Five regions in China were designated based on the thermal energy available for cultivating main crop-ratoon rice.•A simple method for identifying ratooning ability is to examine ratio of ratooning buds to mother stems on the 5th day after main crop harvest.•An method for applying N fertilizer has been established based on spikelets per panicle, chlorophyll content, and target yield of ratoon rice.•The restrictive factors and future development trends in ratoon rice systems are clarified.