The effect of rice plant traits on methane emissions from paddy fields: A review

Rice is the most important stable food in China and rice paddies constitute a major source of methane (CH₄) emission. Rice plant traits not only play an important role in rice yield, but also significantly affect CH₄ emission from paddy fields. However, there have been wide gaps in the understanding of the effects of rice plant traits on CH₄ emissions from paddy fields. Thus research status and progress on the impact of rice plant on CH₄ emissions were reviewed in terms of plant morphological and physiological characteristics (especially photosynthetic characteristics), plant-environment interactions, etc. The effects of aboveground plant traits (e.g. tiller, plant height and leaf area) on CH₄ emissions from paddy fields have remained inconclusive. The belowground system plays a key role in CH₄ emission. Optimizing photosynthate allocation can reduce CH₄ emission in continuously flooded paddy fields. High biomass rice plants can increase CH₄ emission in low C paddy soils, but reduce CH₄ emission in high C paddy soils. Based on the summary of the effects and the underlying mechanisms reported in existing studies, further efforts were needed, such as assessment of the effects of root morphological and physiological characteristics and plant-environment interactions on CH₄ production, oxidation and emission. There was also the need to pay more attention on the underlying mechanisms that combines microcosmic and field experiments and other new research methods. Meanwhile, the interaction and underlying mechanisms of carbon and nitrogen in plant-soil systems needed further exploration in future studies. A good understanding of the impact of rice plants on CH₄ emissions can provide the theoretical basis for rice cultivar breeding and innovative rice cropping with less greenhouse gas emissions and high yields.