绿色木霉对茶园土壤N2O生成与还原过程影响的微生物生态学机制

Soil is the foremost source of N2O emissions to the atmosphere, and most of these emissions are generally attributed to microbiological processes includinge ammonia oxidation and nitrifier denitrification, heterotrophic denitrification，largely as a result of the overuse of application of nitrogenous fertilizers．Biofertilizer has become one of the principal means to control nitrogen fertilizer and improve soil environment. Our previous studies has reported that Biofertilizer (Trichoderma viride) could improve the quality and yield of tea and mitigate N2O emissions from tea fields in red soil of subtropical regions, but how T. viride influence the generation and reduction mechanism of N2O during nitrification-denitrification and how regulates its microbial process are still unclear. On the basis of previous work, we try to answer the following questions: First, whether T. viride affect the microbial community structure during the nitrification and denitrification? Second, whether T. viride affect the expression of functional gene? If it does, how does T. viride affect the expression of functional gene and microbial community structure during the nitrification and denitrification? The resolve of these questions will provide an important scientific basis in the mitigation N2O emissions as well as application of T. aviride in tea fields.

土壤是大气中N2O的最重要排放源，其中微生物驱动下的硝化作用（主要为氨氧化作用、硝化微生物的反硝化作用)和反硝化作用（主要为异养反硝化作用）成为土壤释放N2O的主要贡献单元。过量施用氮肥是土壤N2O排放增加的主要驱动因子，微生物肥料成为控制氮肥用量、改善土壤生境的重要手段之一。我们在前期的研究中发现了微生物肥料（绿色木霉）在提高茶叶品质与产量的同时可大幅降低亚热带红壤茶园N2O 排放通量，但是绿色木霉如何影响土壤硝化-反硝化过程N2O的生成与还原，其微生物生态学基础尚不清楚。本研究希望在前期工作的基础上，回答以下两个科学问题：（1）绿色木霉是否影响茶园氮循环功能微生物种群？（2）绿色木霉是否影响茶园微生物氮代谢的功能基因？如果影响，如何变化？以上科学问题的揭示将为茶园土壤N2O的减排与微生物菌肥的应用提供重要科学依据。

本项目围绕“绿色木霉是否促进了N2O的还原能力，其功能基因（nosZ）和功能菌群（N2O还原菌）如何变化”和“绿色木霉是否影响了氨氧化、硝化微生物的反硝化和异养反硝化过程中N2O的生成能力，其功能基因和功能菌群如何变化”两大科学问题，按照预定研究框架开展研究。截止2020年12月主要取得以下几方面进展：1.首先采取温室栽培的方法研究了施用绿色木霉生物肥对茶园土壤N2O排放的影响，结果发现施用生物肥后土壤N2O的排放量大大降低。进一步研究了不同种类生物肥对土壤N2O的减排效应，通过添加多粘菌生物肥不仅提升了茶树的品质和产量，还有效减少了N2O的排放。2.基于微生物在N2O减排中发挥的重要作用，评价和确定了生物肥料对土壤中微生物群落结构优化的有效性，相关的功能基因丰度也发生变化，表现出对农业生态系统中微生物氮转化过程的定向调控作用。生物肥料在减少N2O排放方面具有一定的应用价值。3.围绕茶园土壤N2O的减排，微生物在土壤氮循环过程发挥了重要作用，土壤环境的改良可以促进微生物群落结构的优化，淀粉厌氧消化液通过改善土壤的理化性质减少了氮淋失，缓解了土壤酸化问题，减少了N2O的排放。在项目执行过程中，在Environ. Sci. & Tec.和Sci. of the Total Environ.等环境领域著名期刊上发表SCI论文3篇；培养硕士研究生1人。