不同施肥模式对大麦-双季稻田甲烷氧化菌多样性及活性影响的研究

Methane is an important trace gases, which is important effects of energy budget and climate change of the earth. Warming potential of Methane is considered to have 25-30 times more radioactively active than CO2. It is well known that paddy field is the major sources of methane in atmospheric. China is one of the major countries of planting rice in the world. Oxidation of endogenous methane is an important process affecting the real flux of methane from rice paddies, which is generated and mediated by methanotrophs living in topsoil. In preliminary studies, effects of long-term fertilization on the methane emission from late rice field in barley-double rice cropping systems were investigated. The results showed that the long-term fertilization had significant effects on the methane emission from late rice field in barley-double rice cropping systems. But its formation mechanism is still not clear. Therefore, the static chamber-GC technique with manual method will used to determine the effects of long-term fertilization on the methane emission in barley-double rice cropping systems. And the methane oxidizing activities, diversity of methanotrophs and methanotroph of paddy soil will be studied by DGGE, Q-PCR, RT-PCR technology. In order to explored the mechanism of methane emissions under different long-term fertilization practices in barley-double rice cropping systems. Meanwhile, we will be studying the methanotrophs of paddy soil response to agronomic measures, such as application of different fertilizers and crop residues. Therefore, we should be discovery the key effect factors of diversity of methanotrophs and methanotroph of paddy soil. Hence, it will be provided theory for construction the modern farming system of saving energy and reduce methane emission with the implementation of this subject in double rice cropping systems.

甲烷是大气中一种重要的温室气体，甲烷的增温潜势是二氧化碳的20-30倍，稻田是大气中甲烷的主要排放源，我国是世界上水稻种植大国。稻田内源甲烷的氧化是稻田甲烷减排的重要途径，甲烷氧化菌是土壤中甲烷氧化的主要施动者。前期研究中，课题组已初步探明了长期不同施肥模式下大麦-双季稻晚稻田甲烷排放速率具有显著差异，但其形成机理仍不清楚。本项目以长期施肥模式定位试验为基础，应用静态箱-气相色谱法探明不同施肥模式下大麦-双季稻田甲烷排放的变化规律；应用变性梯度凝胶电泳技术、实时定量PCR技术、反转录与cDNA聚合酶链式扩增相结合技术研究稻田甲烷氧化菌氧化能力、多样性与活性表达，阐明不同施肥下大麦-双季稻田甲烷排放差异的机理；从不同肥料种类与作物秸秆配合施用等角度阐述甲烷氧化菌对农艺措施的响应，揭示影响稻田甲烷氧化菌多样性与活性的关键因子；为构建双季稻田节能减排型现代农作制提供理论依据。

甲烷是大气中重要的温室气体之一，稻田是大气中甲烷主要的排放源，甲烷细菌和甲烷氧化细菌是土壤中甲烷排放的主要施动者。稻田甲烷排放受较多环境因素的影响，施肥措施是影响稻田甲烷排放重要的农艺措施之一。本项目运用静态箱-气相色谱法、滚管法、PCR和高通量基因测序技术及常规实验分析方法等，分析了长期不同施肥模式对双季稻田甲烷排放特征、土壤甲烷细菌和甲烷氧化菌多样性与活性机制理的影响。根据项目任务书的要求，本课题在长期施肥模式双季稻田定位试验基础上，运用静态箱-气相色谱法探明了不同施肥模式下大麦-双季稻田甲烷周年排放特征、排放量及温室效应。结合常规实验分析方法测定了稻田土壤Eh、土壤温度和土壤水分动态变化规律，明确了稻田甲烷排放的影响因素，探明了甲烷排放与影响因素之间的关系。采用滚管法，探明了不同施肥模式下大麦和早、晚稻各个主要生育时期稻田土壤甲烷细菌和甲烷氧化菌结构与数量变化规律。应用高通量基因测序技术，系统分析了大麦和早、晚稻各个主要生育时期不同施肥处理稻田土壤甲烷细菌和甲烷氧化菌多样性与活性的分子机理；证明秸秆还田和有机无机配合施用能显著增加稻田土壤甲烷细菌和甲烷氧化菌多样性。对作物各个生育期稻田土壤甲烷氧化菌中的8个属测序分析结果表明，大麦分蘖期、齐穗期和成熟期各处理以Methylococcus属的OTU丰度值较大；早稻分蘖期、齐穗期各处理以Methylobacter属的OTU丰度值较大；晚稻分蘖期、齐穗期和成熟期各处理以Methylobacter属的OTU丰度值较大。项目研究期间，发表研究论文8篇，课题组4名成员职称晋升一级，全面实现了项目的设计，并完成了项目的研究目标。通过本项目研究实施，探明了各施肥模式双季稻田甲烷周年排放特征、排放量及相关分子机理，其研究结果为双季稻田节能减排现代农作制的开展提供了科学的理论依据。