不同施氮水平对小麦根际土壤氨氧化微生物的影响

Effects of Different Nitrogen Levels on Ammonia Oxidizing Microorganisms in Wheat Rhizosphere Soil

为探究农田种植中氮肥施用量减少对小麦根际土壤微生物的影响,以减少氮素环境污染,增加农业种植效益,为可持续发展农业提供理论依据。基于Illumina Miseq高通量测序技术,分析不同生育时期不同施肥水平对小麦根际土壤氨氧化细菌(AOB)和氨氧化古菌(AOA)多样性的影响,并通过冗余分析(Redundancy analysis,RDA)探究土壤环境因子与氨氧化微生物群落的关系。结果显示,土壤样品中AOB和AOA的主要优势菌门分别为变形菌门(Proteobacteria)和未知类群(Unclassified group)。在变形菌门中亚硝化螺菌属(Nitrosospira)的相对丰度在2.78%~3.06%,高于亚硝化弧菌属(Nitrosovibrio)。不同生育时期不同施氮量小麦根际土壤AOA的Chao指数(58.00~69.17)均高于AOB。除起身期减氮施肥处理(NR)AOA的Chao指数高于不施氮肥处理(CK)和常规施肥处理(TN)外,不同施氮水平对AOA和AOB多样性没有显著影响。冗余分析表明,AOB可能主导着根际的硝化作用。研究结果表明,小麦根际土壤中存在较多的AOA,AOA和AOB均参与了小麦根际土壤中的硝化作用,而AOB起主导作用。在小麦生长季中,相对于常规施肥,减氮施肥没有明显减少AOA和AOB多样性,同时对潜在硝化速率也没有消减作用。

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 high-throughput 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.