Abstract: We analyzed the effects of Bacillus fertilizer and agent supplementation at different concentrations in the replanted soil by examining the growth of young peach trees, soil nutrients, enzyme activities, and fungal commu-nity. The aim of this study was to provide theoretical basis for alleviating peach replant diseases. One-year-old potted ‘Yuanmeng' peach trees were subjected to eight treatments: replanted soil without supplementation (RS), non-replanted soil without supplementation (NS), replanted soil with 1%, 4%, 8% Bacillus fertilizer supplementation (BF₁, BF₂, BF₃), and 0.1‰, 0.5‰, 1‰ Bacillus agent supplementation (B₁, B₂, B₃), respectively. The results showed that shoot growth and root biomass under NS treatment were greater than that under other treatments, and the contents of soil organic matter, available nutrients and soil catalase activity were greatly enhanced. Peach trees treated with BF and B treatments showed better root development than RS, among which, BF₃ and B₁ treatments were the best, and B₁ treatment had similar effects as NS treatment. Compared with RS, BF and B treatments significantly increased the activities of soil catalase and urease during new shoot development, while B treatment significantly increased soil sucrase activity after the growth cessation of new shoots. Bacillus fertilizer and agent increased soil fungal diversity and the relative abundance of Ascomycota, Chaetomium and Penicillium, and decreased that of Basidiomycota. Considering the comprehensive parameters, BF₃ and B₁ showed more significant effects. In summary, our findings indicated that the supplementation of Bacillus fertilizer and agent to replanted soil could improve soil fertility, fungal community, and root development of roots, and thus provided a feasible method to alleviate peach replant diseases.

Key words: peach, replant disease, Bacillus, soil nutrient, soil enzyme activity, soil fungal community