施氮量对番茄根际土壤细菌群落及氮转化功能的影响

Effects of nitrogen application on tomato rhizosphere bacterial community and nitrogen transformation function

为探究施氮量对番茄根际土壤细菌群落组成、结构和氮转化功能的影响,以设施番茄根际土壤为研究对象,通过盆栽试验,设置不施氮处理(CK,0 kg·hm^(-2))、低氮处理(L,115 kg·hm^(-2))、中氮处理(M,225 kg·hm^(-2))和高氮处理(H,450 kg·hm^(-2)),采用高通量测序技术与FAPROTAX(Functional annotation of prokaryotic taxa)功能预测相结合的方法进行研究。结果表明,放线菌门(Actinobacteria)为主要优势细菌门,相对丰度为35.99%~40.06%,与CK处理相比,M处理放线菌门(Actinobacteria)的相对丰度显著提高,而H处理放线菌门的相对丰度显著降低。M处理的根际土壤细菌群落中,有益细菌属Gaiella、Geminicoccus、红杆菌属(Solirubrobacter)、节杆菌属(Arthrobacter)的比例高于其他处理。施氮量变化未对根际土壤细菌群落的α-多样性产生显著影响,但显著改变了氮转化功能类群的比例。FAPROTAX功能预测结果表明施氮提高了根际固氮、硝化和反硝化功能群的比例,而降低了铁呼吸功能群的占比。LEfSe富集分析结果显示,进行硝化作用的硝化杆菌属(Nitrobacter)和硝化螺菌属(Nitrospira)分别在L、M处理中占比较高。施氮显著改变了根际细菌群落结构,土壤硝态氮、全氮和电导率是驱动细菌群落结构变化的主要因子。综上所述,氮肥施用所引起的根际微环境变化改变了根际土壤细菌群落的组成和结构,并影响氮转化关键功能群的比例。225 kg·hm^(-2)的施氮量提高了根际土壤有益细菌的比例,有益于番茄生产。

To investigate the effects of nitrogen application rate on bacterial community composition,structure,and function in tomato rhizosphere soil.A pot experiment was conducted with four nitrogen application treatments:0 kg·hm^(-2)(CK),115 kg·hm^(-2)(low N treatment,L),225 kg·hm^(-2)(medium N treatment,M),and 450 kg·hm^(-2)(high N treatment,H).The bacterial community and functional prediction of the rhizosphere soil were assessed via high-throughput sequencing and functional annotation of prokaryotic taxa(FAPROTAX).Actinobacteria was the dominant bacterial phyla,with a relative abundance of 35.99%-40.06%,Compared with CK,M treatment significantly increased the relative abundance of Actinobacteria,whereas H treatment significantly reduced its relative abundance.The proportion of beneficial bacteria,such as Gaiella,Geminicoccus,Solirubrobacter and Arthrobacter in the rhizosphere soil,was higher in the M treatment than in the other treatments.Nitrogen application rate did not significantly affect theα-diversity of the bacterial community of the rhizosphere soil,but significantly affected the proportion of nitrogen transformation functional groups.Moreover,the FAPROTAX function prediction showed that nitrogen application increased the proportion of nitrogen fixation,nitrification,and denitrification functional groups in the rhizosphere,but decreased the proportion of iron respiration functional groups.LEfSe analysis showed that Nitrobacter and Nitrospira,which are closely associated with nitrification,accounted for the highest proportion in L treatment and M treatment,respectively.Soil NO-3-N,total nitrogen,and electrical conductivity were the main factors driving the changes in the bacterial community structure in the tomato rhizosphere.In conclusion,the variation in rhizosphere micro-environmental factors caused by nitrogen application changed the composition and structure of the rhizosphere soil bacterial community and significantly affected the proportion of key functional groups in nitrogen transformation.Additionally,225 kg·hm^(-2)increased the proportion of beneficial bacteria in the rhizosphere soil and would be beneficial to the growth and production of tomatoes in greenhouses.