Impacts of different carbon and nitrogen managements on the structure and function of denitrifier community in a greenhouse vegetable cropping system

Abstract:

[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 N2O. RN and RN+S managements could form new denitrifier community structure and reduced the risk of NO and N2O emissions. In addition, straw application promoted potential denitrification rates and reduced the risk of NO3? leaching in greenhouses.

Key words:Solar greenhouse, Trace gases, Diversity, Denitrifier, Product ratio