Determining suitable growth period for ratoon rice cultivation in the Yangtze river basin

Ratoon rice cropping is recognized as a resource-efficient cultivation method that utilizes the stubbles of main season rice crop to regenerate and produce new crop following the harvest of the primary crop. This is vital in improving multiple cropping indices, maintaining consistent grain yields, and strengthening regional food security in China, especially in the regions of inadequate light and temperature resources for two full-growing rice seasons. Ratoon rice cultivation method is practiced across the different regions of the southern China but its efficiency significantly varies due to the diverse climatic and ecological conditions. There is a lack of systematic classification for ratoon rice varieties that resulted in an identical cultivation methods that failed to optimize temperature and solar radiation. This study categorized growth periods into short (SGS), medium (MGS), and long (LGS) which are based on the main season crop. The SGS exhibited the lowest yields during the main season but the highest yields during the ratoon season. While, LGS exhibited an opposite trend, as maximum yield in the main season but lowest in ratoon season. The main season’s yield in SGS significantly correlated with cumulative solar radiation (CSR) after heading (0.497**). Furthermore, the yield of the MGS in the main season demonstrated a significant correlation with effective accumulated temperature (EAT) before heading (0.317**) and in the total growth period (0.335**) during the main season. There was a positive correlation between the main season yield and EAT (0.331*) after heading as well as CSR (0.282*); additionally, in LGS, the ratoon season’s yield shown a positive correlation with EAT in the total growth period (0.296*) in ratoon season. This research investigation suggested that ratoon rice cultivation is suitable for areas along the middle-lower reaches of the Yangtze River basin, and varieties with SGS and MGS growth periods are suitable for this region. These findings improve our under-standing of optimizing temperature and solar radiation in ratoon rice.