Elevated levels of atmospheric CO2 (eCO2) promote rice growth and increase methane (CH4) emissions from rice paddies, because increased input of plant photosynthate to soil stimulates methanogenic archae. However, temporal trends in the effects of eCO2 on rice growth and CH4 emissions are still unclear. To investigate changes in the effects of eCO2 over time, we conducted a two-season pot exper-iment in a walk-in growth chamber. Positive effects of eCO2 on rice leaf photosynthetic rate, biomass, and grain yield were similar between growing seasons. However, the effects of eCO2 on CH4 emissions decreased over time. Elevated CO2 increased CH4 emissions by 48％–101％ in the first growing season, but only by 28％–30％in the second growing season. We also identified the microbial process underlying the acclimation of CH4 emissions to atmospheric CO2 enrichment: eCO2 stimulated the abundance of methanotrophs more strongly in soils that had been previously exposed to eCO2 than in soils that had not been. These results emphasize the need for long-term eCO2 experiments for accurate predictions of terrestrial feedbacks.

Institute of Crop Sciences,Chinese Academy of Agricultural Sciences,Beijing 100081,China;Jiangsu Key Laboratory of Low Carbon Agriculture and GHGs Mitigation,College of Resources and Environmental Sciences,Nanjing Agricultural University,Nanjing 210095,Jiangsu,China;Soil and Fertilizer&Resources and Environmental Institute,Jiangxi Academy of Agricultural Science,Nanchang 330200,Jiangxi,China;Jiangxi Key Laboratory of Crop Physiology,Ecology and Genetic Breeding,Jiangxi Agricultural University,Nanchang 330045,Jiangxi,China;Center of Agriculture and Climate Change,Institute of Resource,Ecosystem and Environment of Agriculture,Nanjing Agricultural University,Nanjing 210095,Jiangsu,China;Jiangsu Collaborative Innovation Center for Modern Crop Production/Key Laboratory of Crop Physiology and Ecology in Southern China,Nanjing Agricultural University,Nanjing 210095,Jiangsu,China;Department of Geography,College of Life and Environmental Sciences,University of Exeter,Exeter EX44RJ,UK

[1]Haoyu Qian;Yaguo Jin;Jin Chen;Shan Huang;Yunlong Liu;Jun Zhang;Aixing Deng;Jianwen Zou;Genxing Pan;Yanfeng Ding;Yu Jiang;Kees Jan van Groenigen;Weijian Zhang-.Acclimation of CH4 emissions from paddy soil to atmospheric CO2 enrichment in a growth chamber experiment)[J].作物学报（英文版）,2022(01):140-146

photosynthate,archae

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