秸秆添加量对土壤生物固氮速率和固氮菌群落特征的影响  

Effects of Straw Addition on Soil Biological N_(2)-Fixation Rate and Diazotroph Community Properties

作　　者：李旭 董炜灵 宋阿琳[1] 李艳玲 卢玉秋 王恩召 刘雄舵 王萌[1] 范分良[1] LI Xu;DONG WeiLing;SONG ALin;LI YanLing;LU YuQiu;WANG EnZhao;LIU XiongDuo;WANG Meng;FAN FenLiang(Institute of Agricultural Resources and Regional Planning,Chinese Academy of Agricultural Sciences/Key Laboratory of Plant Nutrition and Fertilizer,Ministry of Agriculture and Rural Affairs,Beijing 100081)

机构地区：[1]中国农业科学院农业资源与农业区划研究所/农业农村部植物营养与肥料重点实验室,北京100081

出　　处：《中国农业科学》2021年第5期980-991,共12页Scientia Agricultura Sinica

基　　金：国家重点研发计划(2016YFD0800707,2016YFD0200109);国家自然科学基金(41571297);中央级公益性科研院所基本科研业务费专项(1610132019011,1610132019021)。

摘　　要：[目的]研究不同秸秆添加量对土壤固氮速率及固氮菌群落结构的影响,为我国秸秆还田及化肥减施增效提供支持。[方法]采用室内培养试验,除对照(C0:0)外共设5个秸秆添加梯度(Cl:0.2 mg·g^(-1);C2:1.0 mg·g^(-1);C3:2.0 mg·g^(-1);C4:4.0 mg·g^(-1);C5:10.0 mg·g^(-1)),采用15N2标记的方法,在黑暗条件下培养28 d后收集土壤样品,进而对生物固氮速率进行定量,利用Illumina PE250高通量测序和荧光定量PCR技术分析固氮功能基因nifH的丰度及群落特征。[结果]随着秸秆添加量的增加,土壤硝态氮含量显著下降,铵态氮含量无显著变化,土壤pH有下降趋势。同时,生物固氮速率显著增加,C3、C4及C5处理在培养期间(28d)潜在固氮速率为87-96 kgN·hm^(-2)·a^(-1),相比于对照提高了38.1%-52.4%。各处理固氮微生物nifH基因拷贝数变化范围为5.48×10^(7)—9.20×10^(7) copies/(g soil),其中,相比于C0,C4及C5处理固氮微生物nifH基因拷贝数均显著提高(P<0.05)。随着秸秆添加量的增加,C4、C5水平的香农-威尔指数显著低于其他4个处理(P<0.05),其他4个处理多样性无显著差异。主成分分析(PCoA)结果显示土壤固氮微生物群落结构主要因秸秆添加量差异而聚集为不同组别。固氮微生物在门水平上分为变形杆菌(Proteobacteria),蓝细菌(Cyanobacteria),厚壁菌(Firmicutes)和放线菌(Actinobacteria)和螺旋体菌(Spirochaetes)。随着秸秆添加量的增加,蓝细菌相对丰度有先增加再降低的趋势;在属水平上,不同优势菌属对秸秆添加量的响应存在明显差异,慢生根瘤菌(Bradyrhizobium)为数量最丰富菌属,随着秸秆添加量的增加,C5相较于C0、C1、C2、C3水平相对丰度差异显著(P<0.05),显著增加了12.07%-14.13%。与生物固氮速率呈正相关的贺氏伪枝藻属(Scytonema hofmanni)随着秸秆添加量的增加其相对丰度逐渐增加,但当秸秆添加量达C5水平其相对丰度反而降低(P<0.05)。同时,最小偏二乘�[Objective]The purpose of this study was to analyze the effects of different straw additions on soil N2-fixation rate and diazotroph community structure,which was crucial for the management of crop residue and mineral fertilizer application in China.[Method]Using indoor incubation experiment,in addition to the control(CO:0),a total of 5 straw addition gradients(C1:0.2 mg·g^(-1);C2:1.0 mg-g^(-1);C3:2.0 mg·g^(-1);C4:4.0 mg·g^(-1);C5:10.0 mg·g^(-1)),using the ^(15)N_(2) labeling method,and soil samples were collected after 28 days of incubation in dark conditions.As a direct measure of N2-fixation,15N2 gas labeling method could quantify the rate of biological N2-fixation,and destined for characterization of nifH gene marker and diazotroph community by using the Illumina PE250 sequencing and PCR techniques.[Result]With the increase of straw addition,the content of NO_(3)^(-)-N in soil decreased significantly,while the content of NH4+-N did not change significantly.The pH of soil decreased and the rate of biological N_(2)-fixation increased significantly.C3,C4 and C5 treatments could reach 2.71-3.05μg N·g^(-1) DW during the incubation period(28 d),which was about 87-96 kg N·hm^(-2)·a^(-1),compared with C0,the rate of biological N2-fixation increased by38.1%-52.4%.The copy number of nifH gene ranged from 5.48×10^(7) to 9.20×10^(7) copies/(g soil)under all treatments.Compared with C0,the copy number of nifH gene was significantly increased under C4 and C5 treatments,and the number and activity of diazotroph were significantly increased(P<0.05).However,when the amount of straw added reached 4.0 mg·g^(-1),increasing the amount of straw had no significant effect on the copy number of nifH gene of soil diazotroph.With the increase of straw addition,Shannon-Weill index of C4 and C5 levels was significantly lower than that of the other four treatments(P<0.05),and the diversity of the other four treatments had no significant difference.The result of PCoA showed that diazotroph community structure was clustered into

关 键 词：固氮微生物 秸秆还田 固氮速率 ^(15)N_(2)定量 NIFH 

分 类 号：S154.3[农业科学—土壤学]