Effects of mechanical weeding on soil fertility and microbial community structure in star anise (Illicium verum Hook.f.) plantations

Abstract

Recently, the effects of weed control on crop yield, quality and soil fertility have been increasingly investigated. However, soil microorganism diversity under weed control, especially for aromatic plants, is little studied. Mechanical weeding effects on soil fertility and microbial diversity in star anise plantations remain unknown, limiting improvements in crop quality and yield through weed control. Therefore, mechanical weeding (MW) and no weeding (NW) zones were randomly designed in the same star anise plantation to study the mechanical weeding impacts on soil biological properties and microbial diversity. The phosphatase activity ofMWsoil was significantly higher than that of NW soil; however, aminopeptidase activity was significantly lower than that under NW. There was no significant difference in β-glucosidase activity between MWand NW. Moreover, soil microbial biomass C and N inMWsoil were significantly higher than those of NW, but soil microbial biomass P was significantly lower than that of NW. Proteobacteria, Acidobacteria, Actinobacteria, Chloroflexi, Planctomycetes, WPS-2, Firmicutes and Verrucomicrobia were the predominant bacterial phyla inMW and NW soils. Specifically, Bacteroidetes was enriched inMW soil, being the unique dominant bacteria. Ascomycota, Basidiomycota, unclassified_k_- Fungi, Rozellomycota and Mortierellomycota were the predominant fungi inMW and NW soils. The numbers of dominant bacterial genera (> 1%) were 26 and 23 for NW andMW soils, respectively. Among them, norank_f__norank_o__norank_c__Subgroup_6, 1921-2 and norank_f__norank_o__B12-WMSP1 went undetected inMWsoil. Moreover, the numbers of dominant fungi in soils of star anise plantations were 11 and 9 for NW and MW, respectively. Among them, only unclassified_f__Clavicipitaceae and Mortierella went undetected inMWsoils. Thus, soil microbial community structures are not significantly altered by mechanical weeding. The above results suggest that soil fertility can be improved and soil heath can be maintained by mechanical weeding in star anise plantations. Moreover, soilborne diseases maybe easily occurred under NW treatment in star anise plantation.