长期不同施肥黑土细菌和古菌群落结构及主效影响因子分析

摘要

[目的]依据黑龙江省农科院34年的长期定位试验,探讨影响东北黑土细菌和古菌区系的主效环境因子.[方法]试验采集不施肥( CK)、施氮磷肥( NP)、施氮钾肥( NK)、施磷钾肥( PK)、施氮磷钾肥( NPK)5个施肥处理的耕层土样,借助传统化学分析方法和Illumina Miseq高通量测序技术解析土壤化学性状和细菌与古菌的群落结构特征,并对细菌和古菌群落结构与环境因子进行相关性分析. [结果]1)不同施肥处理土壤细菌和古菌群落结构存在显著差N,与CK相比,4种施肥处理均降低了古菌丰富度,NPK处理增加了土壤细菌的丰富度、 多样性以及古菌的多样性;变形菌门( Proteobacteria )、酸杆菌门( Acidobacteria )是所有土样中的优势菌群,占细菌与古菌总量的38.2% 42.9%. 施肥条件下,放线菌门( Actinobacteria )、 浮霉菌门( Planctomycetes )、 绿弯菌门( Chloroflexi )、蓝藻门( Cyanobacteria )的相对丰度降低,芽单胞菌门( Gemmatimonadetes )、厚壁菌门( Firmicutes )的相对丰度升高,而其他菌门的相对丰度对不同施肥处理的响应不同. 2)施用氮肥显著改变了土壤化学性状,长期施氮(尿素)处理的土壤全氮、速效氮和有机质含量显著高于不施氮处理,而pH则显著降低. 3) RDA分析结果显示,pH对土壤细菌和古菌群落结构的影响最大,解释了66.5%的变化;其他环境因子则共解释了细菌与古菌群落33.5%的变化,各因子的贡献率依次为pH >速效钾 >有效磷 >有机质. Pearson相关性分析结果也表明,细菌和古菌群落与土壤化学指标间存在密切的相关关系. [结论]解析了长期不同施肥条件下土壤细菌和古菌的群落结构特征,确定了pH是影响土壤细菌和古菌区系的主效环境因子,氮磷钾均衡施肥不仅显著提高了作物产量和丰富了土壤养分含量,同时也增加了土壤细菌的丰富度、多样性以及古菌的多样性,有利于维持良好的土壤生态环境. 研究结果对揭示东北黑土肥力演变机制、建立合理的施肥制度具有重要的理论价值.%[Objectives] This paper was aimed to investigate the characteristics of soil bacterial community shifts under long-term fertilization regimes of black soil in northeast China .Combined with the soil physiochemicalcharacteristics, the main driving factors would be determined .[Methods] Five treatments including CK ( without fertilizer ) , application of combined NP ( nitrogen-phosphorus ) , NK ( nitrogen-potassium ) , PK ( phosphorus-potassium ) and NPK ( nitrogen-phosphorus-potassium ) were sampled .Ten cores ( 2.5 cm in diameter ) were randomly collected from the plough layer (5-20 cm) of each plot of experimental field and mixed together .The changes of bacterial communities and soil nutrients were investigated via pyrosequencing and conventional chemical analysis , respectively .A correlation analysis was carried out to determine the main important factors influencing bacterial community composition.[Results] 1) Compared to CK, NP and NPK treatments increased the richness of soil microorganisms while they decreased under PK treatment .NPK treatment increased the biodiversity of soil microorganisms while NK treatment decreased .Different fertilization practices greatly changed the soil bacterial community structures . All the fertilized treatments decreased the relative abundances of Acidobacteria , Cyanobacteria , Planctomycetacia and Chloroflexi , and increased Gemmatimonadetes and Firmicutes , compared to the unfertilized treatment , while others varied differently in different fertilization treatments . These results mentioned above showed soil bacterial communities have significantly changed under long -term fertilization regimes . 2) The use of urea significantly changed the soil physiochemical conditions .Soil total N, available N and organic matter in N-containing treatments were significant higher than those in N-deficiency treatment , while pH was lower . 3 ) There were significant correlations between soil microorganisms and physiochemical characteristics .The change of soil pH, resulted from continuous nitrogen fertilizer application , was approved to be the most important factor determining bacterial community composition , and pH contributed 66.5% of variation.All the physiochemical characteristics being exploited contributed to 100% of the variations .[Conclusions] Our research demonstrated the effects of long-term different fertilization on bacterial community , and found pH was the most important factor determining bacterial community structures . The results may provide a new insight in understanding of the microorganisms in black soil , and will be very meaningful to the rational utilization of fertilizer and agricultural sustainable development .