High Ratoon Season Rice Yield is Achieved Through Optimized Variety, Nitrogen Management and Temperature-Solar Radiation Resources

Ratoon rice (RR), recognized as an efficient method of rice cultivation, plays a crucial role in the food production system. By enabling two harvests-during the main season rice (MSR) and the ratoon season rice (RSR)-from a single planting, this cropping system significantly enhances the utilization of land and temperature-solar radiation resources, thereby providing essential support for food security. However, the yield formation of RSR is constrained by several factors, including the adaptability of the rice variety, nitrogen fertilizer management strategies, and the uneven distribution of temperature and solar radiation resources, which collectively hinder the actual realization of its yield potential. This research first employed a meta-analysis approach to identify the optimal nitrogen management practices for ratoon rice. Through multi-location field experiments, high-yielding ratoon rice varieties with strong ecological adaptability were selected. Then, the selected high-yielding and adaptable varieties were cultivated under field conditions by using the optimal nitrogen management practices to compare the yield formation differences and underlying mechanisms among the MSR, RSR, and late-season rice (LSR) with synchronous heading. The research findings indicated that the yield of RSR was significantly lower compared to both MSR and LSR with delayed panicle emergence. Nevertheless, considering that its growth period constituted only 53.52% and 55.47% of the growth periods of MSR and LSR with delayed panicle emergence, respectively. Its daily grain yield (DGY) was 28.33% and 13.56% higher than that of MSR and LSR with delayed panicle emergence. Furthermore, RSR exhibited significant advantages in terms of effective panicle (EP) and seed setting percentage (SSP), although its number of grains per panicle (NP) and 1000-grain weight (TGW) were notably lower than those of MSR and LSR. Subsequent analysis demonstrated that enhancing the utilization efficiency of temperature and solar radiation resources can significantly increase the EP and SSP in RSR. By extending the days before flowering and augmenting accumulated temperature and radiation before flowering, there is a significant notable increase in NP and TGW, thereby overcoming the yield limitations. This study offers a theoretical foundation and technical support for the high-yield and efficient cultivation of RSR.