不同土壤管理模式对锥栗园土壤真菌群组成的影响

Effects of different soil management patterns on soil fungal community composition in a Castanea henryi orchard

【目的】探究不同土壤管理措施对锥栗果园土壤真菌群落组成和多样性的影响。【方法】以建瓯锥栗果园为研究对象,采用高通量测序法分析生草、喷施草甘膦和清耕模式0~10 cm土层土壤真菌群落组成、多样性及特异菌属。【结果】与清耕相比,3种生草模式均显著提升了土壤水解性氮、速效磷和速效钾含量,其中以种植鼠茅草的提升效果最为明显,而喷施草甘膦则显著降低了土壤微生物生物量碳、微生物生物量氮、水解性氮和速效钾含量及土壤蔗糖酶和脲酶活性,分别为0.64 g·kg^(-1)、19.96 mg·kg^(-1)、47.10 mg·kg^(-1)和176.37 mg·kg^(-1)及15.49 U·g^(-1)和0.62 U·g^(-1)。种植生草和喷施草甘膦均降低了土壤真菌丰富度和多样性。土壤真菌优势菌属分别为红菇属、被孢霉属和蜡蘑属。LEfSe分析发现,种植鼠茅草模式下红菇属相对丰度显著高于其他模式,喷施草甘膦模式显著提升了珊瑚属真菌的相对丰度(2.92%),而牛肝菌属在清耕模式中的相对丰度最高,为3.08%。经筛选对比发现,粒毛盘菌属为种植鼠茅草模式的特异菌属;空团菌属和柱孢霉属是黑麦草模式中出现的特异菌属;光叶紫花苕模式的特异菌属为单顶孢属;湿伞属和圆盘属真菌分别存在于喷施草甘膦和清耕的模式中。【结论】发现鼠茅草不仅能提升土壤速效养分含量,还能明显促进红菇属真菌在锥栗园的扩繁;粒毛盘菌属和单顶孢属分别出现在种植鼠茅草和光叶紫花苕模式中,这两类真菌均与线虫防治有关,柱孢霉属真菌存在于种植黑麦草模式中,该菌属为一种潜在病原真菌;种植鼠茅草和黑麦草模式与清耕模式土壤真菌群落组成较为相似,但与种植光叶紫花苕和喷施草甘膦模式间存在较大差异。综上,在锥栗园种植鼠茅草较为适宜,另外在生产经营中应减少草甘膦的施用。

【Objective】Soil management is the key link of orchard production.Different soil management measures can directly or indirectly affect the growth and development of fruit trees by changing soil nutrients,microorganisms,and enzyme activities,thus affecting fruit quality and yield.Soil fungi are important parts of the soil ecosystem.Their diversity and community composition can be sensitive to the changes of soil under natural or human disturbance.The purpose of this study was to explore the effects of grass cropping,no-tillage,and clean tillage on soil fungal diversity and community composition in the topsoil of a Castanea henryi orchard,so as to provide a theoretical basis for the selection of soil management measures in a C.henryi orchard in combination with the changes of soil available nutrient content and enzyme activity.【Methods】The orchard with C.henryi trees in Jian’ou was taken as the research site.In October 2018,concentrated and contiguous experimental plots 10 hm2 with basically the same site conditions were selected and divided into several experimental plots with an area of 0.3-0.5 hm2.Randomized block design was used to construct Vulpiamyuros,Lolium perenne,and Vicia villosa and spraying glyphosate and clear tillage,with three replicates for each treatment.The sowing amount was 30 kg·hm-2,and the whole ground grass was planted.In October 2020,in every plot,three types of rootstocks(Corylus mandshurica Maxim.)were selected with‘Bailuzi’as a scion of,which were healthy,and tree height and DBH were basically the same.One meter away from the tree trunk,the litter on the surface was removed,and the soil was collected from 0-10 cm soil layer in four directions:East,West,South,and North.After mixing the soil samples from the same plot,the roots and other impurities were removed,and then the soil samples were put into a sterilization bag and brought back to the laboratory in an icebox.High-throughput sequencing technology was used to detect and analyze the soil fungal diversity and community composition in the 0-10 cm soil layer under different soil management conditions,and to combine with the number of OTUs to screen the specific bacteria genus.【Results】The results showed that the contents of hydrolytic nitrogen,available phosphorus and available potassium in grass growing modes were significantly higher than those in clean tillage mode.However,spraying glyphosate significantly reduced the contents of microbial biomass carbon,microbial biomass nitrogen,hydrolytic nitrogen,and available potassium contents,which were 0.64 g·kg^(-1),19.96 mg·kg^(-1),47.10 mg·kg^(-1) and 176.37 mg·kg^(-1),respectively.The soil fungal Chao1 index,Observed-species index,Shannon index and Simpson index in the C.henryi orchard decreased after grass planting and glyphosate spraying,and the Chao1 index was lowest in the mode of V.villosa,which was 1532.15;the Observed-species index and Simpson index of L.perenne mode were lowest,which were 1343.33 and 0.88,respectively;the Shannon index of V.myuros mode was lowest,which was 6.39.The Unweighted UniFrac distance matrix indicated that soil fungal communities between V.myuros and L.perenne modes were less different.At the genus level,the most dominant fungi with different soil management measures were different.Russula was the most dominant fungi in the modes of V.myuros,L.perenne and glyphosate spraying,and the relative abundance was 45.40%,24.63%and 17.70%,respectively;the most dominant fungus in the cultivation mode of V.villosa was Mortierella,and its relative abundance was 11.65%;Laccaria was the most dominant fungus in clear tillage mode,and its relative abundance was 16.62.The similarity cluster tree analysis showed that the establishment of V.myuros,L.perenne and clean tillage modes could be classified into one category,the composition of soil fungal community among the three modes was similar,the establishment of V.villosa and spraying glyphosate modes could be classified into the other one.LEfSe difference analysis showed that the relative abundance of Russula fungi in the V.myuros mode was significantly higher than that in other modes;spraying glyphosate significantly increased the relative abundance of Clavaria(2.92%),while the relative abundance of Boletus in the clear tillage mode was significantly higher than that in other modes(3.08%).The results of redundancy analysis showed that the Alpha diversity index of soil fungi was negatively correlated with soil pH;Cat,Suc,and Ure’s activities and the hydrolyzed nitrogen content were the main environmental factors affecting the composition of the soil fungal community.Through screening and comparison,it was found that Lachnum was a specific genus of V.myuros,which can secrete metabolites(such as A[(+)-mycorrhizin A]and A[(+)-chlormy-corrhizin A])to kill nematodes.Cenococcum and Cylindrocarpon were the special genera in Lolium perenne mode,the former can promote the growth of plants,while the latter may harm the fruit trees of C.henryi.The specific genus of V.villosa model was Monacrosporium,which could prey on nematodes through a three-dimensional net.Hygrocybe and Orbiliawere were found in glyphosate spraying and clear tillage modes,respectively.【Conclusion】In this study,it was found that V.myuros could not only increase the content of soil available nutrients,but significantly promote the propagation of Russula fungi in the C.henryi orchard.Lachnum and Monacrosporium were found in the V.myuros and V.villosamodes,respectively,which were related to nematode control.Cylindrocarpon was found in the L.perenne mode,which was a potential pathogenic fungus.The composition of soil fungal community in the planting mode of V.myuros and L.perenne was similar to that in the clean tillage mode,but different from that in the planting mode of V.villosa and spraying glyphosate mode.In conclusion,it is more suitable to build V.myuros in the C.henryi orchard,and the application of glyphosate should be reduced in production and management.