The role of soil microorganisms and physicochemical properties in determining the germinate of invasive Solidago canadensis L.

Background and aims Several studies have shown that soil microorganisms and physicochemical properties are crucial for the successful colonisation of invasive plants. However, most researchers have focused merely on the impacts of invasive plants on soil-internal ecosystems to reveal their invasive mechanisms and ecological effectiveness. On this basis, this paper aims to investigate the role of soil physicochemical properties and microbial communities on plant invasion and the associated mechanisms. Methods Solidago canadensis L. was used as the research object, with seed germination characteristics as the indicator of invasion capability. Comparative treatments were conducted from three dimensions: soils from invasive/native regions, sterilised/non-sterilised soil, and sterilised/non-sterilised seeds. Germination capacity was verified using seed germination experiments, and the mechanism was elucidated by 16S rRNA high-throughput sequencing of soil microorganisms and the determination of physicochemical properties. Results The results indicated that the seed germination characteristics of invasive soils, non-sterilised soils, and non-sterilised seed treatments were higher than those of their respective controls. The invasion of S. canadensis changed soil physicochemical properties and promoted the cycling of nitrogen and phosphorus, which affected the microbial community composition and abundance, reversing the soil to facilitate continued invasion. Soil microorganisms, including Proteobacteria, Actinobacteriota, Acidobacteriota, Chloroflexi, Firmicutes, Basidiomycota, Chytridiomycota, and Glomeromycota, promoted S. canadensis invasion by increasing seed germination rate. Seed-borne microbial communities were beneficial to seed germination, and the sterilisation to seeds significantly reduced their germinability. Conclusion This study clarified the invasion mechanism of S. canadensis regulated by soil microorganisms and physicochemical properties.