Sichuan Hanghui International Logistics According to the latest news from the Chinese Academy of Agricultural Sciences, the crop farming and ecological innovation team of the Institute of Crop Science of the Academy revealed the emissions of HI and CH4 by studying the impact of changes in the rice harvest index (HI) on methane (CH4) emissions. The relationship and biological mechanism of this is another major research result after the team revealed the emission reduction mechanism of modern high-yield rice varieties "promoting oxygenation of the arable layer-activating soil oxidizing bacteria-promoting CH4 oxidation". Related research was published in The latest issue of "Global Change Biology". The team's chief expert and researcher of the Chinese Academy of Agricultural Sciences Zhang Weijian said that rice is the world's second-largest ration crop, and rice fields are the world's most important anthropogenic emissions source of methane (CH4) and the largest source of carbon emissions for agriculture in China. He introduced that there are two ways to increase rice yield: increase biological yield; increase harvest index, which is the ratio of rice to straw in the harvest. The impact of different channels on CH4 emissions from paddy fields has not been determined so far. Existing research believes that rice photosynthetic products are the main carbon source of soil microbes in rice fields. By increasing HI and reducing the input of photosynthetic products to the ground, it can significantly reduce CH4 emissions and is the way to breed varieties with high yield and low carbon emissions. However, the team found that the impact of HI changes on CH4 emissions was only significant in the late rice period, and the CH4 emissions during this period were less than 20% of the total growth period; in addition, HI increase only had a reduction effect in long-term flooded rice fields The emission reduction potential is only 4.4%, and the current flooded paddy field accounts for less than 30% of the total paddy field area. It can be seen that the potential for reducing CH4 emissions by increasing HI is very limited. However, the increase in HI may reduce the amount of straw returned to the field in the next season, and there is a certain emission reduction potential. At the same time, the harvest index of modern rice high-yield varieties has reached a relatively high level (about 0.55), and it is very difficult to further increase significantly. Therefore, by simply increasing the harvest index of modern varieties, it is difficult to achieve a significant increase in rice yield and a significant reduction in CH4 emissions from rice fields. High-yield and low-emission variety selection and rice cultivation innovation require new wisdom.