Ratoon rice utilizes the axillary buds sprouting from the remaining stubble of the main crop after harvest to form panicles, enabling a second harvest. However, mechanized harvesting often resulted in damage to the rice stubbles in the rolling zone, potentially leading to reduced yield. Enhancing the number of tillers in the rolling zone through optimized agronomic measures was crucial for achieving higher yield. However, research on water and fertilizer management corresponding to low stubble ratoon rice under mechanized harvesting was limited. A two-factor experiment was conducted to assess the impacts of water regimes (flooded; alternate wetting and drying) and nitrogen fertilizer management (0 kg N ha(-1); Tiller promotion fertilizer 90 kg N ha(-1); Split nitrogen application: Tiller promotion fertilizer 60 kg N ha(-1) + Booting stage fertilizer 30 kg N ha(-1)) on the yield formation, greenhouse gas emissions, and carbon footprint of low stubble ratoon rice. The results indicated significant effects of water regimes and nitrogen fertilizer on yield. Compared to single application of tillerpromoting fertilizer coupled with continuous flooding (N-FL), Split application of tiller-promoting fertilizer coupled with alternate wetting and drying (SN-AWD) significantly increased average annual yield by 25.4%. SNAWD significantly increased the ratoon ability of the basal first and second nodes compared to N-FL. The soil quality index and ecosystem multifunctionality under SN-AWD increased by an average of 32.37% and 10.16 times, respectively, compared to N-FL. This increase resulted in significant enhancements in root length and root surface area, consequently improving pre-anthesis and post-anthesis dry matter accumulation and ultimately enhancing yield. Although N2O emissions increased under SN-AWD compared to N-FL, CH4 cumulative emissions decreased significantly by 37.86% on average over two years, leading to a 23.02% reduction in total greenhouse gas emissions and a 38.62% reduction in carbon footprint per unit grain. SN-AWD attained maximum net ecosystem economic benefit (NEEB), increasing by 35.42% compared to N-FL. Overall, the comprehensive analysis suggested that SN-AWD was a sustainable water and fertilizer management approach beneficial for balancing ratoon season yields, environmental footprint, and economic benefits.

Agronomic measures are the key to promote the sustainable development of ratoon rice by reducing the damage from mechanical crushing to the residual stubble of the main crop, thereby mitigating the impact on axillary bud sprouting and yield formation in ratoon rice. This study used widely recommended conventional rice Jiafuzhan and hybrid rice Yongyou 2640 as the test materials to conduct a four -factor block design field experiment in a greenhouse of the experimental farm of Fujian Agricultural and Forestry University, China from 2018 to 2019. The treatments included fertilization and no fertilization, alternate wetting and drying irrigation and continuous water flooding irrigation, and plots with and without artificial crushing damage on the rice stubble. At the same time, a 13 C stable isotope in -situ detection technology was used to fertilize the pot experiment. The results showed significant interactions among varieties, water management, nitrogen application and stubble status. Relative to the long-term water flooding treatment, the treatment with sequential application of nitrogen fertilizer coupled with moderate field drought for root -vigor and tiller promotion before and after harvesting of the main crop, significantly improved the effective tillers from low position nodes. This in turn increased the effective panicles per plant and grains per panicle by reducing the influence of artificial crushing damage on rice stubble and achieving a high yield of the regenerated rice. Furthermore, the partitioning of 13 C assimilates to the residual stubble and its axillary buds were significantly improved at the mature stage of the main crop, while the translocation rate to roots and rhizosphere soil was reduced at the later growth stage of ratooning season rice. This was triggered by the metabolism of hormones and polyamines at the stem base regulated by the interaction of water and fertilizer at this time. We therefore suggest that to achieve a high yield of ratoon rice with low stubble height under mechanized harvesting, the timely application of nitrogen fertilizer is fundamental, coupled with moderate field drying for root -vigor preservation and tiller promotion before and after the mechanical harvesting of the main crop.