Progress and challenges of rice ratooning technology in Sichuan Province, China

Sichuan Province is the primary region of ratoon rice production in China. This review summarizes the research progress of theories and technologies relating to the efficient cultivation of high-yielding ratoon rice based on the following: (1) ratoon rice planting area in Sichuan can be divided into three climatic zones based on the thermal energy availability, i.e. highly suitable, suitable, and sub-suitable zones; (2) grain yield in the ratoon season in Sichuan is 1.80–3.90 ​t ​ha−1 lower than that in southeastern and central China. The lower ratoon-season yield in Sichuan was associated with fewer panicles m−2 and spikelets panicle−1; (3) the effects of rice cultivars selection, optimal nitrogen fertilizer and water management, timely harvest of the main crop, suitable rice stubble height, and sheath blight control on improving the ratooning ability of rice cultivars were examined; (4) factors restricting ratoon rice production in Sichuan include unstable ratoon rice yields, lack of suitable rice cultivars as simplified cultivating for ratoon rice, lack of high-efficiency and specialized rice harvester for ratoon rice, large yield gap between demonstration area and farmer’ paddy fields, and rolling damage from mechanical harvesting of main crop; and (5) new ratoon rice technologies relating to future development trends in Sichuan are clarified, including simplified cultivation techniques, integration of agricultural machinery and agronomy techniques, screening high-efficiency and specialized rice harvester, and desirable traits for breeding rice cultivars with strong ratooning ability and suitable growth duration in ratoon rice system.