次生盐渍化对设施菜地土壤强温室气体N2O释放的影响

As the most productive industries, facility vegetable cultivation has developed rapidly in China during the recent decades. However, due to intensive cultivation, widespread irrational using fertilization, hot and humid environment, lack of rainout and so on, facility vegetable soils present the main feature of secondary salinization. The present study is aiming at the emission and influence mechanism of nitrous oxide when facility vegetable soils under the influence of the secondary salinization, taking facility vegetable soils in Shouguang of Shandong Province as the main research object. Firstly, effect of secondary salinization on nitrous oxide flux and emission pathway with 15N-isotope dilution method will be made clear based on filed experiment. Secondly, through the modern molecular biology method,the relationship between flux of nitrous oxide and activity of relevant enzyme will be discussed, and the influence of secondary salinization on microbial community structure, diversity and richness, will also be dsecribed. Besides, colony libraries that have different nitrous oxide fluxes will be constructed by combining functional genes (amoA and nosZ ) and 16S rDNA. These libraries will find the important contribution strains for emission of nitrous oxide in secondary salinization of facility vegetable soils, so that it can reveal the microbiology mechanism that secondary salinization influence the emission of nitrous oxide. The results can offer the scientific basis for reducing nitrous oxide emission in facility vegetable soils.

我国是世界上设施蔬菜栽培面积最大的国家，而且设施蔬菜种植规模仍在不断扩大。由于集约栽培、不合理施肥、高温高湿、缺少雨水淋洗，设施菜地土壤呈现次生盐渍化的主要特征。本项目以山东省寿光市设施菜地土壤为主要研究对象，研究次生盐渍化下设施菜地土壤强温室气体N2O的释放特征，明确次生盐渍化对设施菜地土壤N2O通量的影响；并利用15N同位素示踪法解析次生盐渍化对N2O产生途径的影响；采用现代分子生物学方法为主，研究N2O产生过程中相关酶的活性与N2O通量的关系，次生盐渍化对设施菜地土壤微生物的群落结构、多样性、丰度的影响，将amoA和nosZ功能基因与16S rDNA相结合，建立不同N2O通量下的克隆文库，明确次生盐渍化设施菜地土壤中对N2O释放贡献大的菌种，揭示次生盐渍化对N2O释放影响的微生物学机制。研究结果为减少设施菜地N2O的排放提供科学依据。

我国是世界上设施蔬菜栽培面积最大的国家，而且设施蔬菜种植规模仍在不断扩大。由于集约栽培、不合理施肥、高温高湿、缺少雨水淋洗，设施菜地土壤呈现次生盐渍化的主要特征。本项目以山东省寿光市、平度市设施菜地土壤为主要研究对象，研究次生盐渍化下设施菜地土壤强温室气体 N2O 的释放特征，明确次生盐渍化对设施菜地土壤 N2O 通量的影响；解析次生盐渍化对 N2O 产生途径的影响；采用PCR-DGGE、荧光定量PCR等分析方法，将N2O产生相关的功能菌对应的amoA和nosZ功能基因与16S rDNA相结合，研究盐渍化程度对设施菜地土壤微生物中硝化、反硝化细菌的群落结构、多样性、丰度的影响，阐明了硝化、反硝化过程中关键功能基因与N2O通量之间的关系。结果表明山东半岛设施土壤均有不同程度的次生盐渍化现象，其中潍坊地区设施土壤次生盐渍化现象较为严重。田间试验和室内培养试验结果均是中度盐渍化设施菜地土壤N2O排放通量显著高于非盐渍化、轻度盐渍化和重度盐渍化土壤的释放量(p＜0.05)。室内培养试验中重度盐渍化处理土壤的N2O累计排放量显著高于非盐渍化和轻度盐渍化处理土壤（p<0.05），非盐渍化和轻度盐渍化处理的土壤之间差异不显著（p>0.05）。次生盐渍化离子种类、浓度对设施菜地土壤N2O排放产生影响，钾离子（100mg/kg）处理N2O的累积排放量显著高于对照和其他处理(p＜0.05)，钠离子对土壤N2O的排放影响不显著。钙、镁离子、硫酸根离子和氯离子对土壤N2O的排放影响不显著（p>0.05）。DGGE结果表明盐渍化程度对设施土壤中细菌群落结构有较大的影响，功能基因amoA和nosZ对应的DGGE图谱条带较少，条带数差异较小，条带亮度差异大。荧光定量PCR结果表明中度盐渍化处理的土壤反硝化细菌的nosZ基因显著高于其他处理，此时促进了反硝化微生物的活性，最终增加了土壤N2O的排放量。研究结果将为减少设施菜地 N2O 的排放提供科学依据。