长期施肥对黄棕壤水稻土真菌群落结构的影响

Response of soil fungal community structure to long-term fertilization in yellow-brown paddy soil

【目的】探究长期不同施肥措施对黄棕壤水稻土土壤肥力和真菌群落结构的影响,为绿色农业提供理论依据。【方法】位于湖北武汉的黄棕壤水稻土长期施肥定位试验始于1981年,包括5个施肥处理:不施肥(CK)、单施氮肥(N)、氮磷钾化肥(NPK)、常量有机肥(OM)、氮磷钾+常量有机肥(OMNPK)。2020年5月,在各处理小区内取0—20 cm土层土壤样品,利用Illumina MiSeq高通量测序技术、FUNGuild和生态网络方法,综合分析了土壤养分含量、酶活性、真菌群落结构。【结果】1)与CK比较,N处理降低了土壤速效养分含量,NPK处理维持了土壤养分稳定,OM和OMNPK处理显著提高了土壤速效养分含量。OMNPK处理显著降低了α-葡萄糖苷酶、硫酸酯酶活性,却显著提高了β-纤维二糖苷酶活性;OM和OMNPK处理提高了亮氨酸氨基肽酶活性,却降低了乙酰氨基葡萄糖苷酶活性,N和NPK处理对这两种酶活性的影响与之相反。2)与CK相比,N处理显著降低了真菌多样性,而NPK和OM处理显著提高了真菌多样性。菌群结构在N、NPK、OM处理间明显不同,而OM、OMNPK和CK处理比较接近。LEfSe分析结果发现,N处理土壤中的差异物种是Entrophospora属和Sympoventuriaceae科,OMNPK处理的差异物种是Microascales目和Microascaceae科,OM处理的差异物种是盘菌目(Pezizales)、Pyronemataceae科和Pseudaleuria属。冗余分析结果显示,β-葡萄糖苷酶、β-木糖苷酶、磷酸酶、亮氨酸氨基肽酶、乙酰氨基葡萄糖苷酶、硫酸酯酶和pH是影响土壤真菌群落结构的重要因素。3)施肥提高了病理营养型(pathotroph)真菌的相对丰度,减少了腐生营养型(saprotroph)真菌的相对丰度。与CK比较,N、NPK、OM和OMNPK处理的病理营养型真菌相对丰度分别提高了190.5%、141.4%、71.5%和250.2%,腐生营养型真菌相对丰度分别降低了30.6%、33.3%、19.4%和49.5%,共生营养型(symbiotroph)真菌相对丰度分别提高了310.8%、956.8%、424.3%和435.1%。各施肥处理相比,OM处理病理营养型真菌相对丰度最低,而OMNPK处理最高。病理营养型中,OMNPK、N、NPK和OM处理的动物性病原体丰度比CK分别提高了322%、184%、105%和85%;N和NPK处理较CK处理还显著提高了植物性病原体丰度,OMNPK和OM处理对植物性病原体丰度无显著影响。有机肥处理提高了真菌网络的边数、正相关数、平均加权度、图密度、网络直径和连接部件,增强了网络的复杂性。【结论】长期施用有机肥能够培肥地力,增加真菌群落的多样性和物种交互复杂性,减少病理营养型真菌相对丰度,而有机无机肥配合施用提高土壤肥力的效果显著高于单施有机肥,但也增加了动物性病原体丰度,增加了病害的潜在风险。

【Objectives】We studied the dynamics of soil fertility and fungal community structure in yellowbrown paddy soil under long-term different fertilization measures,to scientifically clarify a pathway towards sustainable rice production.【Methods】The long-term experiment of yellow-brown paddy soil,located in Wuhan,Hubei Province was established in 2005.There were five treatments:no fertilizer control(CK),N fertilizer(N),NPK fertilizers(NPK),organic manure(OM),NPK and organic manure(OMNPK).In 2020,soil samples at 0-20 cm depth were collected from the treatment plots to determine the nutrient contents and enzyme activities using standard procedures,and the fungal community structure using the Illumina MiSeq highthroughput sequencing,the FUNGuild and ecological network methods.【Results】1)N treatment reduced,NPK treatment maintained,while OM and OMNPK treatments significantly increased soil available nutrients compared with CK.OMNPK treatment significantly decreased the α-glucosidase and sulfatase activity,but increased β-cellobiase activity;OM and OMNPK increased leucine aminopeptidase activity but decreased glucosamine activity;whereas N and NPK treatments elicited opposite trends on these two enzymes.2)N treatment significantly reduced,while NPK,and OM treatments increased fungal diversity.The LEfSe analysis showed that the differential species were Entrophospora genus and Sympoventuriaceae family in N treatment,were Microascales order and Microascaceae family in OMNPK treatment,and were Sphaeria,Pyronemataceae and Pseudaleuria genus in OM treatment.The redundancy analysis revealed that β-glucosidase,β-xylosidase,phosphatase,L-leucine aminopeptidase,N-acetyl-glucosaminidase,sulfase,and pH were important factors affecting soil fungal community structure.3)Fertilization increased the relative abundance of pathotroph fungi and reduced that of saprotroph fungi.Compared with CK,the treatment N,NPK,OM and OMNPK increased the relative abundance of pathotroph fungi by 190.5%,141.4%,71.5% and 250.2%,decreased those of saprotroph fungi by 30.6%,33.3%,19.4% and 49.5%,increased those of symbiotroph fungi by 310.8%,956.8%,424.3%,and 435.1%.The abundance of animal pathogen was dominant in the pathotroph fungi,OMNPK,N,NPK,and OM treatments increased the animal pathotrogh abundance by 322%,184%,105% and 85%,compared to CK.N and NPK treatments also led to higher plant pathotrogh fungi than CK,while OMNPK and OM treatments did not.The OM and MNPK treatments increased the edge number,positive correlation number,average weight,graph density,network diameter,and connection components of the fungal network,and enhanced the complexity of the network.【Conclusions】Long-term sole organic fertilizer application improved soil fertility,increased the diversity of fungal community and the complexity of species interaction,and reduced the abundance of pathological fungi.The combination of organic and inorganic fertilizers resulted in markedly higher effect,but also increased the potential risk of animal pathogen disease.