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农田生态系统是陆地生态系统中最活跃且固碳潜力最大的碳库之一,其中,细菌在农田生态系统生物固碳过程中发挥着重要作用。采用PCR-克隆测序技术、末端限制性酶切长度多态性分析技术(T-RFLP)及荧光定量PCR技术研究了不施肥(CK),施氮磷钾肥(CK-F),单独秸秆还田(W-NF)和施氮磷钾加秸秆还田(W-F)4种施肥管理对砂姜黑土固碳细菌群落结构、多样性及丰度的影响。结果表明,秸秆还田土壤的固碳细菌主要包括Nitrosomonas,Mesorhizobium和Bradyrhizobium等。在CK和W-NF处理中,土壤固碳细菌以严格自养菌为主,优势种群为亚硝化单胞菌属(Nitrosomonas),相对丰度分别为73.2%和72.4%。在CK-F和W-F处理中,土壤固碳细菌中严格自养菌相对丰度减小,而兼性自养菌相对丰度大幅增加。其中,CK-F的优势种群为亚硝化单胞菌属(Nitrosomonas)和中慢生根瘤菌属(Mesorhizobium),相对丰度分别为33.3%和17.6%。W-F的优势种群为亚硝化单胞菌属(Nitrosomonas)和慢生根瘤菌属(Bradyrhizobium),相对丰度分别为26.4%和24.5%。施用化肥及秸秆还田均显著提高了土壤固碳细菌群落的多样性,其中化肥的影响大于秸秆还田。主成分结果显示施肥对土壤固碳细菌群落结构的影响大于秸秆还田。4个处理土壤固碳功能基因(cbb L)丰度为1.32×107~3.29×107拷贝·g-1(干土),施肥及秸秆还田均能显著提高土壤细菌cbb L基因丰度,其中秸秆还田配施化肥的cbb L基因丰度最大。上述结果表明了施肥及秸秆还田对土壤固碳细菌群落结构,多样性及数量均有显著的影响。
Farmland ecosystem is one of the most active carbon sequestration potential in terrestrial ecosystems, and bacteria plays an important role in bio-carbon sequestration in farmland ecosystems. The effects of non-fertilization (CK), application of CK-F (CK-F), single-stalk return to straw W-NF and WF treatments on the community structure, diversity and abundance of carbon sequestration in Shajiang black soil. The results showed that the carbon sequestration of straw in soil mainly includes Nitrosomonas, Mesorhizobium and Bradyrhizobium. In CK and W-NF treatment, the soil autotrophic bacteria were dominant, while the dominant species were Nitrosomonas, with the relative abundance of 73.2% and 72.4%, respectively. In CK-F and W-F treatments, the relative abundance of strictly autotrophic bacteria in soil-fixing carbon bacteria decreased while the relative abundance of autotrophic bacteria increased significantly. Among them, the dominant species of CK-F were Nitrosomonas and Mesorhizobium, with the relative abundance of 33.3% and 17.6%, respectively. The dominant populations of W-F were Nitrosomonas and Bradyrhizobium, with relative abundances of 26.4% and 24.5%, respectively. The application of chemical fertilizers and straw returning significantly increased the diversity of soil carbon sequestration bacterial communities, and the effect of chemical fertilizers was greater than that of straw returning. The principal component analysis showed that the effect of fertilization on the community structure of soil-fixing carbon bacteria was greater than that of straw returning. The abundance of cbb L was 1.32 × 107 ~ 3.29 × 107 copies · g-1 (dry soil), and the fertilization and straw returning could significantly increase the abundance of soil bacterial cbb L genes, of which, The straw mulched with fertilizers cbb L gene abundance. The above results show that fertilizer and straw application have a significant effect on the community structure, diversity and quantity of soil carbon sequestration bacteria.