Responses of grain yield, water use efficiency, and greenhouse gas emissions of rice to alternate wetting and drying irrigation

ABSTRACT Rice is traditionally grown under continuous flooded (CF) conditions; however, it is a major source of CH4 and N2O emissions. The alternate wetting and drying (AWD) technique can reduce water usage and CH4 emission in rice cultivation, though its impact on grain yield remains uncertain. This study evaluated the AWD effects on grain yield, water use efficiency (WUE), CH4, and N2O emissions in rice cultivation. Three varieties, TT-30, TCS-10, and TTW-31, were cultivated in Taiwan during the 2023 wet season (WS-2023) and the 2024 dry season (DS-2024). The results, based on averages across both seasons and three varieties, indicated that AWD improved WUE by 8.9% but resulted in a 13.4% reduction in grain yield compared with CF. Additionally, AWD reduced CH4 emissions by 53.8% and lowered the global warming potential (GWP) by 21.6%. While AWD increased N2O emissions, these were relatively small compared with CH4 emissions. TT-30 produced the highest yield under AWD conditions. Our findings suggest that AWD reduces CH4 emissions and enhances WUE. Further research is needed to optimize irrigation strategies that conserve water without negatively impacting grain yield. Choosing rice varieties with stronger root systems and more panicles per plant can further enhance the benefits of AWD.