【目的】通过6年长期定位试验,比较设施菜田不同碳氮管理下反硝化菌结构和功能的差异。【方法】采用末端限制性片段多态性(T-RFLP)和变性梯度凝胶电泳(DGGE)方法分别分析nir K/nir S和nos Z型反硝化菌群结构特征,利用自动连续在线培养监测体系(Robot系统)测定分析NO/(NO3-+NO2-)和N2O/(N2O+N2)产物比,并通过乙炔抑制法测定反硝化酶活性。【结果】传统施肥处理(CN)显著改变了nir K和nos Z型反硝化菌的结构,增加了NO/(NO3-+NO2-)和N2O/(N2O+N2)产物比。nir S型菌受碳氮管理影响较小。减氮(RN)和添加秸秆处理(RN+S)的nir K和nos Z型反硝化菌结构与CN处理的差异性显著,且会显著降低NO/(NO3-+NO2-)和N2O/(N2O+N2)产物比;与CN和RN相比,RN+S显著增加反硝化酶活性。【结论】设施菜田长期传统施肥措施改变了反硝化菌的结构和功能,增加土壤自身的NO产生能力并减弱了N2O还原N2的能力。减氮和添加秸秆管理能形成自身的反硝化菌群结构,并降低NO和N2O排放风险;秸秆的添加会促进反硝化潜在速率,降低菜田NO3-淋洗风险。
[Objective] Based on a 6-years greenhouse cropping field, the objective of the present study was to find out the differences of the structure and function of denitrifier community under different carbon and nitrogen managements. [Methods] We used terminal restriction fragment length polymorphism (T-RFLP) and denaturing gradient gel electrophoresis (DGGE) methods to analyze the structure of microbial communities containing nirK/nirS and nosZ, respectively, a robotized incubation system to measure NO/(NO3-+NO2-) and N2O/(N2O+N2) product ratio and an acetylene inhibition method to determine denitrification enzyme activity. [Results] Conventional N management (CN) significantly changed the structure of denitrifier communities containing nirK and nosZ and increased the NO/ (NO3 +NO2-) and N2O/(N2O+N2) product ratio, nirS-denitrifiers were less affected by carbon and nitrogen managements. Reduced N (RN) and reduced N plus straw (RN+S) management had significant changed the denitrifier communities containing nirK and nosZ and reduced NO/(NO3-+NO2-) and N2O/(N2O+N2) product ratio compared with CN treatment. In contrast to CN and RN treatments, RN+S significantly increased denitrification enzyme activity. [Conclusion] Conventional N management significantly changed the structure and function of denitrifier community, and promoted the formation of NO and N20. RN and RN+S managements could form new denitrifier community structure addition, straw application promoted potential leaching in greenhouses. and reduced the risk of NO and N2O emissions. In denitrification rates and reduced the risk of NO3-leaching in greenhouses.