摘要：

探明秸秆深翻还田年限对西辽河平原连作玉米田土壤细菌群落的影响,为持续秸秆还田培肥地力提供理论指导。以玉米秸秆离田为对照(CK),基于细菌16S rDNA V3~V4区高通量测序技术,结合生物信息学,分析持续秸秆还田2(SR2),5(SR5),10 a(SR10)玉米田0~20 cm和20~40 cm 2个土层有机质、氮素养分、土壤细菌群落结构及多样性变化特征。结果表明,SR2土壤有机质和氮素养分含量与CK差异不显著,而SR5和SR10显著提高土壤有机质和氮素养分含量;不同秸秆还田年限下,土壤细菌多样性存在差异且都有独有的OTU,其中SR10 OTU数目最多;Alpha多样性指数表明,土壤细菌群落的相对丰度和多样性2个土层均为SR2与CK差异不显著,SR5和SR10显著增加,且SR10与CK差异最大;在门水平上共获得51个细菌类群,相对丰度>5%的细菌门包括放线菌门、变形菌门、酸杆菌门、泉古菌门、绿弯菌门,且变形菌门、酸杆菌门和绿弯菌门的相对丰度随还田年限的增加而提升。RDA聚类分析表明,土壤细菌群落结构0~20 cm土层SR2与CK相似,SR5与SR10群落较为相似;20~40 cm土层,不同秸秆还田年限各处理均与CK存在差异,SR2与SR5群落结构相似,SR10与SR5、SR2群落结构差异均较大。土壤硝态氮、铵态氮、有机质和全氮含量对细菌菌群均有影响,表现为土壤硝态氮>铵态氮>有机质>全氮。持续秸秆还田2 a的土壤有机质和氮素养分含量与CK相比差异不显著,持续秸秆还田5,10 a显著提高。综上,细菌微生物多样性和丰富度在持续秸秆还田2 a 0~20 cm和20~40 cm土层均变化甚微,持续秸秆还田5,10 a后 2个土层均显著增加;细菌群落结构0~20 cm土层持续秸秆还田2 a与CK相似,20~40 cm土层持续秸秆还田2,5,10 a均改变了细菌菌群结构。

关键词: 西辽河平原, 秸秆还田年限, 土壤细菌, 细菌群落结构, 细菌多样性

Abstract:

To explore the influence of straw returning years to the field after deep turning back on soil bacterial community in continuous cropping corn fields in the West Liaohe Plain,and provide theoretical guidance for continuous straw returning to improve soil fertility.This study takes corn straw leaving the field as a control (CK),based on the high-throughput sequencing technology of bacterial 16S rDNA V3-V4 region,combined with bioinformatics,we analyzed the characteristics of organic matter,nitrogen nutrients content,soil bacterial community structure and diversity changes in 0-20 cm and 20-40 cm soil layers of corn fields with continuous straw returning for 2(SR2),5(SR5) and 10 a (SR10).The results showed that SR2 had no significant difference with CK in soil organic matter and nitrogen nutrients content,while SR5 and SR10 significantly increased soil organic matter and nitrogen nutrient content;under different straw returning years,soil bacterial diversity was different and each had its own unique OTU,among which SR10 OTU had the largest number;alpha diversity index showed that the relative abundance and diversity of soil bacterial community were not significantly different between SR2 and CK,SR5 and SR10 increased significantly,and SR10 and CK had the largest difference;a total of 51 bacterial groups were obtained at the phyla level,including Actinobacteriota,Proteobacteria,Acidobacteriota,Crenarchaeota and Chloroflexi,whose relative abundance was more than 5%.The relative abundance of Proteobacteria,Acidobacteriota and Chloroflexi increased with the increase of returning years.RDA clustering analysis showed that the soil bacterial community structure of 0-20 cm soil layer SR2 was similar to CK,SR5 was more similar to SR10,20-40 cm soil layer,different straw returning years,treatments were different from CK,SR2 and SR5 were similar,SR10 had significant differences in community structure compared to SR5 and SR2.The contents of soil {\mathrm{NO}}_3^{-}-N, {\mathrm{NH}}_4^{+}-N,OM,and TN all had effects on bacterial flora,and they were soil {\mathrm{NO}}_3^{-}-N> {\mathrm{NH}}_4^{+}-N>OM>TN.The contents of soil organic matter and nitrogen nutrient had no significant difference between continuous straw returning for 2 a and CK,while continuous straw returning for 5 and 10 a were significantly increased.In summary,the microbial diversity and richness of bacteria showed minimal changes in the soil layers of 0-20 cm and 20-40 cm after continuous straws returning for 2 a.After continuous straws returning for 5 and 10 a,both soil layers significantly increased;the bacterial community structure continuous straw returning for 2 a was similar to CK in the 0-20 cm soil layer,while the bacterial community structure continuous straw returning for 2,5,10 a were changed in the 20-40 cm soil layer.

Key words: West Liaohe Plain, Straw returning years, Soil bacteria, Bacterial community, Bacterial diversity