The Characteristics of the Root-Zone Soil’s Biological Properties and Microbial Community Structure in Grafted Star Anise Plantations

Extensive management seriously affects the output, quality, and sustainable development of star anise, and grafting is commonly used to improve its production and quality. Although many studies have explored the effects of grafting on soil microorganisms for other plants, there is a lack of research on aromatic plants, especially on the soil ecosystems of star anise plantations. The effect of grafting star anise on the soil’s biological characteristics and microbial composition remains unclear. The soil’s enzyme activities, soil microbial biomass, and microbial community composition in grafted and non-grafted star anise plantations in Guangxi, China were studied using high-throughput sequencing technology. The results showed that the microbial biomass carbon and phosphorus contents in the soils of grafted star anise were significantly lower and the phosphatase activity was significantly higher than in the soils of non-grafted star anise. In comparison with the soils of non-grafted star anise plantations, the proportions of Proteobacteria, Acidobacteria, Actinobacteria, and WPS-2 decreased and the proportions of Chloroflexi, Planctomycetes, and Verrucomicrobia increased in the grafted star anise plantations. Meanwhile, Bacteroidetes was a dominant bacterial phylum unique to the soil of the grafted star anise plantations. Moreover, the proportions of Ascomycota and Basidiomycota increased and the proportions of Mortierellomycota and unclassified_k_Fungi decreased in the soils of the grafted star anise plantations. Furthermore, Basidiomycota and Rozellomycota had significant dominance in the grafted star anise plantations. In general, grafting can improve soil fertility and maintain soil health by promoting soil nutrient cycling and increasing the soil’s microbial diversity.