Abstract:To reveal the response of N2O emission to the abundances of ammonia-oxidizing bacteria (amoA) and narG (membrane-bound nitrate reductase) genes, a culture experiment was conducted with light saline soil (SA), heavy saline soil (SB) and saline soil (SC) under controlled temperature and moisture to study the effects of soil environmental factors on N2O emission rates and the abundances of amoA and narG genes by real-time PCR. Average N2O emission rates were 16.9, 30.8 and 69.6 μg/(kg.d) for SA, SB and SC, respectively, significantly increased with the degree of salinization. The abundances of AOB were 0.415×104 copies (SA), 6.91×104 copies (SB) and 9.44×104 copies (SC), while the abundances of narG were 2.61×104 copies (SA), 5.36×104 copies (SB) and 13.4×104 copies (SC), respectively, indicating that the salinity stimulates the abundances of AOB and narG-type denitrifying bacteria. The RDA analysis showed that the average N2O emission rate positively correlated with the abundances of AOB (r= 0.863, P<0.01) and narG (r=0.975, P<0.01). pH, conductivity, available potassium and soil organic carbon are the main environmental factors affecting N2O emission rate, they significantly correlated with N2O emission rate with the coefficients of 0.968, 0.983, 0.987 (P<0.01) and -0.800 (P<0.05), respectively. The correlations between N2O emission rate and soil available phosphorus and total nitrogen contents were not significant (P>0.05).