短期落干对水稻土反硝化微生物丰度和N2O释放的影响

为了探明水稻土落干过程对温室气体排放和反硝化微生物的影响，通过模拟水稻土淹水落干过程，系统监测了落干开始后24 h内N2O的释放和氧化还原电位(Eh)的变化，并利用实时PCR(qPCR)方法测定了反硝化功能基因narG和nosZ的丰度.结果表明：落干开始后4 h N₂O释放量就明显增加，在24 h时N₂O的释放量比淹水对照增加了5倍多；narG和nosZ基因丰度也随着落干过程的推移而快速增加；而且N₂O排放通量与narG基因呈极显著相关(P<0.01).表明水稻土短期淹水落干过程中，含narG基因反硝化微生物是驱动N₂O释放的主要功能微生物.

Effect of short time drought process on denitrifying bacteria abundance and N2O emission in paddy soil.

In order to investigate the impact of drying process on greenhouse gas emissions and denitrifying microorganisms in paddy soil, wetting drying process was simulated in laboratory conditions. N₂O flux, redox potential (Eh) were monitored and narG and nosZ containing denitrifiers abundances were determined by real time PCR. N₂O emission was significantly increased only 4 h after drying process began, and it was more than 6 times of continuous flooding (CF) at 24 h. In addition, narG and nosZ gene abundances were increased rapidly with the drying process, and N₂O emission flux was significantly correlated with narG gene abundance (P<0.01). Our results indicated that the narG containing deniteifiers were the main driving microorganisms which caused the N₂O emission in the short-time drought process in paddy soil.