长期有机无机肥配施对东北黑土真菌群落结构的影响

【目的】分析长期有机无机肥配施对土壤真菌丰度、多样性及其群落特征的影响，探讨东北黑土真菌群落变化与施肥的相关性，为进一步调节土壤微生物结构，改善其生态功能提供参考依据。【方法】依托黑龙江省农业科学院36年长期定位试验站，选取4个不同施肥处理:不施肥处理（CK）、有机肥处理（M）、氮磷钾无机肥处理（NPK）和有机肥配施无机肥处理（MNPK）的耕作层土壤为研究对象，以真菌ITS基因为分子标靶借助qPCR技术和Illumina Miseq高通量测序平台，研究不同施肥处理对黑土中真菌群落丰度、多样性和组成的影响，并与土壤化学性质进行偶联分析，揭示群落与施肥的相关性。【结果】长期施用无机肥显著降低土壤pH，而有机无机配施可以有效缓解土壤酸化。NPK处理的ITS基因丰度显著高于MNPK；MNPK处理的细菌/真菌比值（26.91104）显著大于NPK，各处理比值由高到低为MNPK M CK NPK。细菌/真菌比值与土壤pH正相关；MNPK处理的真菌多样性指数值略大于NPK。Ascomycota和Zygomycota为土壤中主要真菌门，不同施肥处理之间真菌组成的相对丰度存在显著差异，对照处理Ascomycota的相对丰度为45.35%，MNPK和NPK处理分别为50.93%和56.16%。有机肥有利于降低病原真菌相对丰度，具有高度侵染性的Cochliobolus在MNPK（0.41%）和M（0.39%）中的相对丰度显著小于CK（3.25%）和NPK（2.08%）。CCA分析表明，土壤理化性质共解释土壤真菌群落结构变化的73.3%，有效磷（贡献量为32.4%，P=0.002）、铵态氮（贡献量为14.8%，P=0.01）和硝态氮（贡献量为16.2%，P=0.048）是3个重要的影响因子。【结论】不同施肥条件下土壤真菌丰度、多样性，以及菌群组成特征不同。与无机肥相比，有机肥无机肥配施能够有效改善真菌群落结构，降低真菌的丰度，增加真菌多样性，并提高土壤pH，减缓土壤酸化。土壤有效磷、铵态氮和硝态氮含量是影响黑土土壤真菌群落结构变化重要因素。

Structure of soil fungal communities under long-term inorganic and organic fertilization in black soil of Northeast China

Objectives] The abundance,diversity and composition of fungal community were identified,and the main relationship between soil fungi community variation and soil fertilizer would be revealed in this paper.Methods] Based on 36-years' fertilization experiment in Heilongjiang Academy of Agricultural Sciences,four treatments were selected to study:no fertilizer (CK);manure (M);chemical N,P and K fertilizer (NPK);and manure with NPK(MNPK).The ITS gene was applied as target gene,using Illumina Miseq sequencing and quantitative PCR method.The fungal abundance,diversity and composition in black soil were analyzed.The relationship of fertilization and fungi community was calculated.Results] Long term application of chemical fertilizers reduced soil pH and led to soil acidification,while manure did not show same impact.ITS gene abundance in ratio in MNPK (26.91 × 104) was significantly higher than that in NPK,and the ratio was in order of MNPK ＞ M ＞ CK ＞ NPK.NPK treatment was more than in MNPK.Bacteria-to-fungi ratio was positively correlated with soil pH.Alpha diversity of fungi community of MNPK was slightly greater than that of NPK.Ascomycota and Zygomycota were the top two majority fungi found in black soil.The relative abundance of the fungi community was significantly different among the four fertilization treatments.The relative abundanceof Ascomycota in CK was 45.35％,in MNPK and NPK were 50.93％ and 56.16％,respectively.Manure reduced the relative abundance of pathogenic fungi.The relative abundances of highly aggressive Cochliobolus in MNPK (0.41％) and M (0.39％) were significantly lower than those of CK (3.25％) and NPK (2.08％).Canonical correlation analysis indicated that the selected soil properties could explain 73.3％ of the variation,and fungal communities were closely positively correlated with soil available P (Contribution =32.4％,P =0.002),NH4+-N concentration (Contribution =14.8,P =0.01) and NO3-N concentration (Contribution =16.2％,P =0.048).Conclusions] Long-term fertilization affects fungal abundance,diversity and community characteristics of black soil.Compared with chemical fertilizers,manure alone and manure combined with chemical NPK fertilizers will improve the fungal communities structures,decrease fungal abundance and increase diversity activity,enhance the soil pH,slowed down soil acidification.Among the soil fertility factors,the soil available P,NH4+-N and NO3--N concentrations are the three dominant factors determining the variation of fungal communities structures.