摘要
Elevated levels of atmospheric CO_(2)(eCO_(2))promote rice growth and increase methane(CH_(4))emissions from rice paddies,because increased input of plant photosynthate to soil stimulates methanogenic archae.However,temporal trends in the effects of eCO_(2)on rice growth and CH_(4)emissions are still unclear.To investigate changes in the effects of eCO_(2)over time,we conducted a two-season pot experiment in a walk-in growth chamber.Positive effects of eCO_(2)on rice leaf photosynthetic rate,biomass,and grain yield were similar between growing seasons.However,the effects of eCO_(2)on CH_(4) emissions decreased over time.Elevated CO_(2)increased CH_(4)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 CO_(2)enrichment:eCO_(2)stimulated the abundance of methanotrophs more strongly in soils that had been previously exposed to eCO_(2)than in soils that had not been.These results emphasize the need for long-term eCO_(2)experiments for accurate predictions of terrestrial feedbacks.
基金
supported by the National Key Research and Development Program of China(2017YFD0300104,2016YFD0300903,2015BAC02B02)
the National Natural Science Foundation of China(32022061)
the Special Fund for Agroscientific Research in the Public Interest(201503118,201503122)
the Agricultural Science and Technology Innovation Program of CAAS(Y2016PT12,Y2016XT01)
the Modern Agricultural Development of Jiangsu Province(2019-SJ-039-07)
the GEF Project of Climate Smart Staple Crop Production in China(P144531)。
