Effects of Soil Salinity on Microbial Community Structure in Rhizosphere of Greenhouse Vegetables
[Objective]The aim was to unveil the influence of soil salinity on the soil microecology of facility vegetable fields in coastal saline-alkali area,in order to explore the response processes of ion composition and microbial community structure in the rhizosphere soil of greenhouse vegetables under different salt concentrations.[Method]Two vegetable varieties(Luffa cylindrica L.and Brassica chinensis L.)were used to investigate the response of soil base ions and soil microbial community on soil salinity stress(severe,moderate and light)by the use of qPCR and high-throughput sequencing technology.[Result]The results showed that soil main salt cation Na+was significantly correlated with K+,Mg2+,SO42-and HCO3-,and main salt anion SO42-was significantly correlated with K+,Na+,Ca2+,Mg2+,HCO3-and Cl-.Na+and Cl-in the soil under high salt content were higher than that of low salt content,and SO42-,HCO3-and Cl-in the rhizosphere soil of Luffa cylindrica L.were significantly lower than that of Brassica chinensis L.With the increase of salinity,the amount of soil bacteria and fungi in the facility vegetable fields increased firstly and then decreased.Different soil salt levels affected fungal community structure more than bacteria,and fungi were more sensitive to soil salinity than bacteria.Comparing the soil microbial communities in the greenhouse vegetable fields under low and high salt content,the results showed that the relative abundance of two bacteria genus(Sphingomonas and norank_f_Methyloligellaceae)and eight fungi genus(Humicola,Mortierella and etc.)were significantly different between the two soil salinity conditions.Under medium and high levels of salt content,the abundance of Humicola and Neocosmospora in the rhizosphere soil of Luffa cylindrica L.and Brassica chinensis L.increased greatly.[Conclusion]The contents of Na+and Cl-in the rhizosphere soil of two vegetables were increased under high salt stress.Greenhouse vegetables mainly enhance their salinity tolerance by increasing the number and richness of salt-tolerant microorganisms in the rhizosphere soil,such as Humicola and Neocosmospora.These findings contribute valuable insights into the salt tolerance mechanism of greenhouse vegetables mediated by rhizosphere microbiome,offering a theoretical reference for advancing saline-alkali field agriculture in the future.
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