小麦与不同作物多样化轮作对土壤真菌群落的影响

Response of Soil Fungal Communities in Diversified Rotations of Wheat and Different Crops

为明确华北平原冬小麦与不同作物多样化轮作下的土壤真菌群落差异,为生态可持续种植制度的构建和优化提供理论依据,采用实时荧光定量PCR和高通量测序技术研究了连续冬小麦-夏玉米M、冬小麦-夏花生(夏玉米)PM和冬小麦-夏大豆(夏玉米)SM轮作处理的土壤真菌群落丰度、组成和多样性.结果表明,与连续冬小麦-夏玉米处理相比,轮作花生PM2和大豆SM2处理显著降低了土壤真菌ITS序列拷贝数,轮作花生或大豆处理增加了土壤真菌群落丰富度和多样性.非度量多维尺度分析(NMDS)结果显示,不同轮作茬口之间土壤真菌群落存在明显分离,轮作作物对土壤真菌群落结构的影响达显著水平.华北平原砂壤质潮土中不同作物轮作处理的土壤真菌群落均以Ascomycota为优势菌门,以Sordariomycetes和Eurotiomycetes为优势菌纲.不同轮作茬口土壤真菌群落组成存在差异显著的类群,Neocosmospora、Plectosphaerella和Gibellulopsis等潜在病原真菌在冬小麦-夏花生(夏玉米)轮作处理中显著富集,而Penicillium和Zopfiella等潜在有益真菌在冬小麦-夏大豆(夏玉米)轮作处理中显著富集.与连续冬小麦-夏玉米处理相比,轮作花生或大豆处理增加了病理营养型、病理-共生营养型和腐生-共生营养型土壤真菌的相对丰度,而腐生营养型土壤真菌相对丰度有所降低.综上,在连续冬小麦-夏玉米轮作体系中,加入夏花生或夏大豆替代夏玉米进行不同周期轮作,可增加土壤真菌群落丰富度和多样性,显著影响土壤真菌群落结构;其中,夏大豆茬口利于土壤潜在有益真菌的富集.

Crop-soil microorganism interactions and feedback are critical to soil health and crop production.The aim of this study was to clarify the difference in soil fungal communities under diversified rotations of wheat and different crops in the North China Plain and to provide a theoretical basis for the construction and optimization of ecological sustainable planting systems.The soil fungal community abundance,composition,and diversity of continuous winter wheat-summer maize M,winter wheat-summer peanut(summer maize)PM,and winter wheat-summer soybean(summer maize)SM treatments were studied using real-time quantitative PCR and high-throughput sequencing technology.The results showed that,compared with those of the continuous winter wheat-summer maize treatment,the peanut rotation treatment PM2and soybean rotation treatment SM2significantly reduced soil fungal ITS sequence copy numbers(P<0.05);there was no significant difference in soil fungal ITS sequence copy numbers between other rotation treatments and those of the control(P>0.05).Rotation treatments with peanut or soybean increased soil fungal community richness(Chao1 and ACE indices)and diversity(Shannon and InvSimson indices),in which the community richness of all rotation treatments and the community diversity of SM1/SM2treatments varied significantly(P<0.05).The result of non-metric multidimensional scaling(NMDS)analysis showed that the soil fungal community among different rotation crops were obviously separated.The rotation crops significantly affected soil fungal community structure(PERMANOVA:r2=0.350,P=0.001;ANOSIM:r=0.478,P=0.001).Ascomycota(73.67%-85.48%)was the dominant phylum,whereas Sordariomycetes(30.53%-48.19%)and Eurotiomycetes(11.12%-31.19%)were the dominant classes of the fungal communities of sandy-loam fluvo-aquic soil in the North China Plain.There were significantly different taxa of soil fungal communities in different rotations.Potential pathogens such as Neocosmospora,Plectosphaerella,and Gibellulopsis were significantly enriched in the rotations of winter wheat-summer peanut(summer maize),whereas potential beneficial fungi such as Penicillium and Zopfiella were significantly enriched in the rotations of winter wheat-summer soybean(summer maize).Compared with that under the continuous winter wheat-summer maize treatment,rotations with peanut or soybean increased the relative abundance of pathotroph,pathotroph?symbiotroph,and saprotroph-symbiotroph fungi and decreased the relative abundance of saprotroph fungi.The soil fungal community richness and structure were significantly related to soil organic carbon and available nutrients,and the Shannon diversity index was significantly related to soil mineral nitrogen and available phosphorus.In summary,on the basis of continuous winter wheat-summer maize rotation in the North China Plain,adding summer peanut or summer soybean instead of summer maize for rotations with different interval years could increase the richness and diversity of soil fungal communities and significantly change soil fungal community structure.In particular,summer soybean as the preceding crop had a positive effect on the enrichment of potential beneficial fungi.