关键词: 减氮施肥, 小麦根际土壤, 氨氧化细菌, 氨氧化古菌, 微生物多样性

Abstract: In order to explore the effects of decreasing the amount of nitrogen application on microbial populations in wheat rhizosphere soil during farmland planting,thus provide theoretical basis for preventing nitrogen environmental pollution and increasing agricultural planting benefits, based on the highthroughput sequencing technology of Illumina Miseq,the effects of different fertilization levels on the diversity of ammonia-oxidizing bacteria(AOB)and ammonia-oxidizing archaea(AOA)in wheat rhizosphere soil were analyzed at different growth stages.Redundancy analysis(RDA)was used to explore the relationship between soil environmental factors and ammonia-oxidizing microbial communities.The results showed that the main dominant phylum of AOB and AOA in soil samples were Proteobacteria and unclassified group,respectively.The relative abundance of Nitrosospira in Proteobacteria was 2.78%—3.06%,which was higher than that of Nitrosovibrio.The Chao indexes (58.00~69.17) of rhizosphere soil AOA of different nitrogen application treatements at different growth stages were higher than those of AOB.Except that the Chao index of AOA of the nitrogen reduction treatment was higher than that of no nitrogen treatment and conventional fertilizer application treatment at standing stage of wheat,different nitrogen application levels had no significant effects on the diversity of AOA and AOB.Redundancy analysis indicated that AOB may dominate the nitrification of the wheat rhizosphere.The results indicated that there were more AOAs in the rhizosphere soil of wheat.Both AOA and AOB were involved in the nitrification of wheat rhizosphere soil,but AOB may play a leading role in nitrification.In the wheat growing season,reduction of nitrogen fertilizer did not significantly decrease the diversity of AOA and AOB compared with conventional fertilization,and did not inhibit the potential nitrification rate.

Key words: Nitrogen reduction fertilization, Wheat rhizosphere soil, Ammonia oxidizing bacteria, Ammonia oxidizing archaea, Microbial diversity