Developing the rice ideotype: Optimizing traits for methane mitigation and sustainable yield

Rice is a staple food for billions of people but also a major source of methane emissions, contributing approximately 10% of global agricultural methane. Therefore, this study aimed to conduct a correlation analysis of various traits gathered from years of research on the 120 Cheongcheong Nagdong Double Haploid (CNDH) population to identify key traits responsible for methane emission in rice. This study focused on practical plant traits, including culm length, spikelets per panicle, and grain weight, which have a positive correlation with methane emission. Shorter culm lengths produce less biomass, thereby reducing the organic matter available to feed methane-producing microbes. Increasing the number of spikelets per panicle increase boosts grain production, thereby reducing the development of root exudates that contribute to methane production. Our results indicate a positive correlation (r = 0.51) between grain weight and methane emissions, suggesting that selecting for heavier grains may actually increase methane emissions. Based on these features, we propose an rice ideotype variety that possibly minimizes the rice plant methane emissions while maintaining a high yield. This paper suggests that future studies should be extended to validate these current findings and explore the genetic components and ecological aspects of methane emissions to improve methane management in sustainable rice farming systems.