Abstract: To explore the characteristics of nitrous oxide-reducing bacteria abundance in dryland and paddy soils and their influencing factors, real-time quantitative PCR was used to measure the abundance of nosZⅠ and nosZⅡ genes in the soils of dryland peanut and flooded paddy fields from 16 sites in Jiangxi Province. The main influencing factors were analyzed. The results showed that the copy number of the nosZⅡ gene in both dryland and paddy soils was significantly higher than that of nosZⅠ, indicating that nosZⅡ-type nitrous oxide-reducing bacteria dominated in acidic agricultural soils. The abundance of nosZⅠ in dryland soils was 2.28×10⁸ copies·g^-1, significantly higher than that found in paddy soils (1.33×10⁸ copies·g^-1), indicating that nosZⅠ-type nitrous oxide-reducing bacteria may prefer dryland soils over paddy soils. However, there was no significant difference in the abundance of nosZⅡ genes between dryland and paddy soils. In dryland soils, the total carbon content was the most important factor influencing the copy numbers of nosZⅠ and nosZⅡ genes, possibly because nitrous oxide-reducing bacteria are heterotrophic microorganisms with total carbon as the carbon sources and energy. Meanwhile, available phosphorus content and pH value were the most important factors explaining the variations of copy numbers of nosZⅠ and nosZⅡ genes in paddy soils, likely because the total carbon content in paddy soils is high and not a limiting factor, making phosphorus and pH more influential. In summary, the abundance of nitrous oxide-reducing bacteria differed in dryland peanut and paddy soils in Jiangxi Province, with nosZⅠ-type nitrous oxide-reducing bacteria favoring dryland soils and nosZⅡ showing no significant preference.

Key words: land use pattern, nitrogen cycle, nitrous oxide, nosZⅠ, nosZⅡ