不同连作年限对黄瓜根际土壤理化性质及微生物群落结构多样性的影响OA

Soil continuous cropping obstacle induced by long-term monocropping of greenhouse cucumber is a key issue constraining the sustainable development of the industry.To elucidate the interaction patterns between soil physicochemical properties and microbial communities under long-term continuous cropping,this study took the rhizosphere soil of greenhouse cucumber in Chifeng,Inner Mongolia as the research object.Treatments were set up as continuous cropping for 1 year(C1),5 years(C5),12 years(C12),and a non-planted control(C0).The changes in soil physicochemical properties and microbial community structure were systematically analyzed.The results showed that,regarding soil physicochemical properties,the contents of organic matter,total phosphorus,available phosphorus,total nitrogen,and alkali-hydrolyzable nitrogen all exhibited a trend of first increasing and then decreasing with increasing continuous cropping years.All these parameters were highest under the continuous cropping treatment for 5 years and lowest under the 12-year continuous cropping treatment(C12).Soil electrical conductivity gradually increased with continuous cropping years and was highest under the C12 treatment.Regarding the microbial community,long-term continuous cropping significantly reduced the α-diversity andβ-diversity of both soil bacterial and fungal communities and reshaped their community structures.At the phylum level,compared with C0,the relative abundances of Proteobacteria and Firmicutes in soil bacteria under different continuous cropping years(except for C1)significantly increased,while the relative abundances of Acidobacteria and Chloroflexi(except for C1)significantly decreased.For fungi,the relative abundance of Ascomycota(except for C1)significantly increased,whereas the relative abundances of Zygomycota(except for C5)and Glomeromycota significantly decreased.At the genus level,harmful bacteria(Fusarium)were significantly enriched,while some beneficial bacteria(RB41)significantly decreased.The correlation analysis of the heat map showed that soil physicochemical factors were closely coupled with the evolution of microbial communities.Organic matter content,total phosphorus content,available phosphorus content,pH value and available potassium content were the main physicochemical factors influencing soil bacteria and fungi,while available nitrogen content and electrical conductivity were the primary factor affecting soil bacteria,and total nitrogen content was the primary factor affecting soil fungi.At the phylum level of bacteria,Gemmatimonadota,Chloroflexi and Acidobacteriota were significantly influenced by physicochemical properties.At the phylum level of fungi,Glomeromycota,Rozellomycota,Zygomycota and Chytridiomycota were notably affected by physicochemical properties.In summary,the occurrence of continuous cropping obstacles in cucumber was closely associated with the deterioration of soil physicochemical properties,decreased microbial diversity,imbalance in community structure,and enrichment of pathogenic bacteria.