选择连续4年进行水稻-紫云英轮作的田块，在0 ~ 10、10 ~ 20、20 ~ 40和40 ~ 80 cm剖面深度分别采集土样，利用PCR-DGGE技术分析水稻-紫云英轮作对土壤不同剖面深度固氮菌 nifH 基因丰度与群落多样性的影响，并对固氮菌群落与8个环境因子进行了典范对应分析（CCA）。试验结果表明，水稻-紫云英轮作能提高滩涂土壤固氮菌的丰度和多样性。水稻-紫云英轮作处理10 ~ 20 cm土壤剖面中固氮菌丰度最大，水稻-休闲处理40 ~ 80 cm土壤剖面中的最小，其Shannon-Weaver 多样性指数分别为3.18和1.51。滩涂土壤环境因子中，总氮与NH₄⁺-N、EC与有效磷、pH与速效钾，两两之间的相关性最高；CCA 排序图表明土壤有机质、NH₄⁺-N和有效磷是影响滩涂土壤固氮菌群落的主要因子。

In order to study the characteristics of soil nitrogen-fixing microbial communities, an experiment of rice- astragalus smicus rotation was conducted for 4 consecutive years in mudflat soil, nifH gene abundance and community diversity in different depth of profile (0-10, 10-20, 20-40 and 40-80 cm) were investigated by PCR-DGGE, and canonical correspondence analysis (CCA) was used to study the correlation between nitrogen-fixing microbes and environmental factors. The results showed that rice-astragalus smicus rotation increased the richness and diversity indexes of nitrogen-fixing microbes in mudflat soil. The abundance and diversity indexes of nitrogen-fixing microbes were the highest in 10-20 cm soil under rice-astragalus smicus rotation and was the lowest in 40-80 cm soil under rice-fallow rotation, with Shannon-Weaver diversity indexes of 3.18 and 1.51, respectively. High correlations were observed between soil total nitrogen and ammonium nitrogen, EC and available P, pH and available K. CCA ordination analysis indicated that soil organic matter, ammonium nitrogen and available phosphorus were the main factors affecting nitrogen-fixing microbial communities in mudflat soil.

S154.3

科技部星火计划(2015GA680001)，上海市农业科学院卓越团队建设计划(农科创2017A-03)，上海市科委成果转化项目(153919N0402)，崇明县科技攻关项目(CKS2016-02)和上海市科技兴农推广项目(沪农科推字2015第2-2号)资助。