Abstract: 【Objective】The microorganisms in soil of root-zone are important factors affecting root environment, carbonized apple branches are the low oxygen pyrolysis products of the abandoned fruit trees. The purpose of this study was to understand the structure of soil bacteria and fungi in apple root-zone and the response of their diversities to carbonized apple branches, and to provide a theoretical basis for the reasonable application of carbonized apple branches and the improvement of soil biological characters in orchard. 【Method】 In the spring, the 2-year-old ‘Fuji’ apple trees (rootstock for Malus hupehensis Rehd) in similar growth were transplanted to the potting soil, the soil was mixed with different mass ratios (0-4%) of carbonized apple branches beforehand. Soil samples were collected after 120 days of transplanting, genomic DNA was extracted, and PCR amplification was made to establish libraries. In this study, the 16S rRNA genes V3+V4 regions of soil bacteria and fungal ITS1 regions were sequenced by Illumina high-throughput sequencing technology on Miseq platform, and related biological analysis was conducted to explore the changes of soil bacterial and fungal abundances, diversities and structures.【Result】A total of 16 656 bacterial operational taxonomic units (OTUs) and 435 fungal OTUs were obtained from 15 apple root-zone soil samples, among them, Proteobacteria, Bacteroidetes and Acidobacteria were the dominant bacteria which the total relative abundance was 70.68%-72.80%, and Basidiomycota, Ascomycota and Zygomycota were dominant fungi which the total relative abundance was 68.00%-75.14%. The richness indices of Chao and Ace showed that 1% (w/w) carbonized apple branches increased the abundance of bacteria by 15.42% and 3.89% compared with the control, respectively. 0.5% (w/w) carbonized apple branches increased the richness of fungi by 2.80% and 3.61%,respectively. Simpson and Shannon diversity index analysis showed that 0.5%-4% (w/w) carbonized apple branches reduced the diversity of soil bacteria, increased the diversity of soil fungi; bacteria Shannon diversity index was the lowest at 1% carbonized apple branches and fungi Shannon diversity index was the highest at 0.5% carbonized apple branches. Application of 1%, 2% and 4% carbonized apple branches to the soil, the relative abundance of Proteobacteria, Acidobacteria and Basidiomycota all decreased and the relative abundance of Bacteroidetes and Zygomycota all increased in apple root-zone soil at different degrees. The relative abundance of Hymenochaetaceae (31.99%-46.74%) was the highest in Basidiomycota. 1%, 2% and 4% carbonized apple branches all made it decrease. Carbonized apple branches at 0.5%-4% dosage could increase the number of bacteria unique OTUs significantly and affect the bacteria groups, wherein the number of bacterial unique OTU was one to three times of the common OTU numbers, but they had no significant effect on the fungal groups.【Conclusion】The 0.5%-4% (w/w) carbonized apple branch applied to the soil of apple root-zone, the abundance and diversity of soil bacteria and fungi had obviously changed, and the specific bacterial species under each dosage increased too. The soil bacterial richness increased significantly in root-zone applied 1% carbonized apple branches.

Key words: carbonized apple branches, root-zone soil, Illumina high-throughput sequencing, soil bacteria, soil fungi