Impact of Litsea cubeba inter-row cover on the structure of bacterial community in the tea plantation

Abstract

Purpose: The application of bio-control plants in the agricultural processes is one of the effective ways to solve the traditional agricultural synthetic pesticide residues. This study will investigate the effect of bio-control plant Litsea cubeba branch inter-row cover on soil bacterial community, soil-enriched metabolites, and soil mineral nutrition in tea plantation, which will provide a basis for the use of bio-control plant in agroecological farming systems. Methods: The fruit-bearing (F-Pr) and vegetative (F-Ab) branches of Litsea cubeba were inter-row covered (the use of plants for partial coverage of soil between the rows) in the tea plantation. And we determined the soil microbial community, soil mineral nutriment, and soil-enriched metabolites composition with the methods of 16S rRNA gene sequencing, inductively coupled plasma-atomic emission spectroscopy (ICP-AEC), inductively coupled plasma-optical emission spectrometry (ICP-OES), and gas chromatography-mass spectrometry (GS-MS). We also predict the function of soil bacteria with the Tax4Fun software. Results: Litsea cubeba inter-row cover modified the soil microbial structure and diversity; Litsea cubeba inter-row cover significantly decreased the relative abundance of Acidobacteria, Chloroflexi, and Planctomycetes while increased the relative abundance of Proteobacteria. Litsea cubeba inter-row cover significantly antagonized the plant pathogen community, and its OTUs number decreased from 907 ± 81 in the control to 337 ± 25 in F-Pr treatment; compared with F-Pr treatment, F-Ab treatment had weaker effect on the abundance of nutrition metabolism and transport, carbohydrate utilization, and nitrate reduction A. The aluminum element in the F-Pr treatment was significantly reduced, while phosphorus was increased. The soil-enriched metabolites of F-Pr treatment contained some antibacterial substance, including 14.2 ± 3.32% citronellol, 10.38 ± 4.79% alpha-terpineol, and 8.25 ± 2.62% (+)-2-bornanone, which was the main environment factor that affects the soil bacterial structure and diversity. Conclusion: Litsea cubeba inter-row cover significantly affected bacterial structure and diversity, slightly increased the soil pH, and improved soil aluminum and phosphorus status; soil-enriched metabolites were the major environment factor affecting soil bacterial community and should be considered in the application of bio-control plants; Litsea cubeba vegetative branch inter-row cover will be a feasible measure for integrated pest management in tea plantation.