水稻植株对稻田甲烷排放的影响

稻田CH4排放是稻田土壤中CH4产生、氧化和传输不同过程的净效应，水稻植株强烈影响稻田CH4的产生、氧化和传输过程，是导致稻田CH4排放季节性变化规律的一个重要因素，本文综述了水稻植株对稻田CH4排放过程的不同影响，水稻植株根系分泌物和脱落物作为产甲烷前体促进稻田土壤中CH4的产生，在水稻生长后期，植株根系分泌物和脱落物被认为是稻田土壤甲烷产生的主要基质，是导致这一时期稻田CH4高排放通量的主要原因；水稻植株根系泌氧在根际环境形成一个微氧区域氧化稻田甲烷，整个水稻生长季稻田土壤中产生的CH4大约36％～90％在植株根际环境中被氧化；约80％甚至更多的稻田CH4通过水稻植株的通气组织进入大气圈，植株对稻田CH4的传输具有十分重要的意义。

Effects of rice plants on methane emission from paddy fields

Methane emission from rice paddy fields is the net result of the combination of many processes, i.e., CH4 production, CH4 oxidation and CH4 transportation in paddy soil. Rice plants play a key role in the CH4 emission from paddy fields, particularly in all the processes involved. The positive and negative effects of rice plants on CH4 emission from paddy fields are well recognized as the main factors influencing the temporal variation of CH4 emission flux in paddy field. Process-based studies about the effects of rice plants on methane emission from paddy fields were summarized, and different roles of rice plants on this emission were discussed. Root exudates and litters of rice plants could serve as the substrate for methanogenesis and enhance the CH4 production of paddy soils, resulting in a high CH4 emission peak, particularly in rice late growing season. Rhizospheric CH4 oxidation induced by rice root-excreted oxygen constitutes a main biogenic sink of CH4, which could account for 36-90% of CH4 produced in paddy soil over the entire growing season of rice. Up to 80% and more of CH4 released from rice field during a growing season could be emitted by rice plant-mediated transport. The fully developed aerenchyma of rice plants could be of importance in CH4 emission during rice growing seasons, and responsible for the CH4 emission peak observed at rice early growing season.