秸秆还田配施化肥对砂姜黑土固碳细菌的影响

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。

Effects of straw returning combination to fertility on the CO2-assimilating bacterial community in the lime concretion black soil

72.4% in W-NF. In CK-F treated soil, the dominant cbbL-containing bacteria were Nitrosomonas and Mesorhizobium, and their relative abundances were 33.3% and 17.6%, respectively. In W-F treated soil, the dominant cbbL-containing bacteria were Nitrosomonas and Bradyrhizobium, and their relative abundances were 26.4% and 24.5%, respectively. Fertilization and straw incorporation both increased the diversity of cbbL-containing bacterial communities. Fertilization had a stronger effect on soil bacterial diversity and structure than straw incorporation. Fertilization or straw incorporation both increased bacterial cbbL abundance (1.32×10⁷-3.29×10⁷ copies·g^-1 soil) with the highest cbbL copy number (3.29×10⁷ copies·g^-1 soil) in the W-F treated soil. All above results indicated that fertilization and straw incorporation significantly influenced the CO₂ fixation bacterial community structure as well as increased bacterial abundance and diversity.