Improve tea quality by enhancing the stability of bacterial community interaction and nitrogen-fixing function in pecan-tea interplanted plantation

Using the 16 S rDNA high-throughput sequencing, the effects of interplanted pecan (Carya illinoinensis) in a typical tea (Camellia sinensis) plantation on soil bacterial species composition and marker species were comparatively analyzed to determine whether nested pecan increases soil microbial diversity in the tea tree rhizosphere. We explored the effects of the underlying mechanisms of this complex ecosystem on tea quality by determining soil physicochemical properties using two types of planting modes: intercropping with pecan versus tea tree monoculture. Our results showed that Rhizobium (Allorhizobium, Neorhizobium, Pararhizobium, and Rhizobium), and Enterobacter, had pollution-degrading effects and were enriched in the soil bacterial communities of the pecan interplanted model. There was a significant enrichment of prebiotic functional bacteria, such as Pedosphaeraceae and Coriobateriaceae_UCG-002, which stimulate plant growth and improve disease resistance, while the functions of Chloroflexi and Firmicutes, which are dominant denitrifying bacteria in the soil, were inhibited. The average degree of soil microbial co-occurrence network increased from 13.40 to 18.17, and the number of nodes in the network increased from 117 to 166, indicating that the network increased in complexity and decreased in mutual exclusivity, and the complex interactions among bacterial populations tended to be stable. The intercropping mode reduced the phenol/ammonia ratio in tea from 2.37 to 1.38, improving the tea quality. Therefore, the soil microbial community composition under this complex model promotes material cycling in microecosystems and effectively reduces the transmission risk of soil-borne diseases. The soil microbial community structure of the tea rhizosphere could be re-balanced and shifted toward a more favorable tea quality formation by the introduction of pecan into tea plantations.