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There are many kinds of soil amendments that consist of different materials. The soil amendment is usually of benefit to plant health. However, the effects of the soil amendments on plant disease have rarely been compared and the involved mechanisms are largely unknown. In the present study, we investigated the influences of five contrasting soil amendments (i.e., potassium silicate (PS), calcium silicate (CS), biochar (BC), calcium silicate humic acid (SCHA), and bio-organic fertilizer (BOF)) on tomato bacterial wilt. In addition, we dissected the mechanism with high-throughput sequencing. The results showed that BC, SCHA, and BOF significantly reduced the incidence and delayed the disease, while BOF significantly reduced the incidence of bacterial wilt disease in the whole tomato growing period. In the early stage of the disease, BC, SCHA, and BOF significantly reduced the soil pH compared to CK. However, the contents of soil NH4+-N and NO3−-N were significantly increased. Some beneficial bacteria genera (Burkholderia, Mortierella, and Trichoderma) had a certain correlation with the incidence. Burkholderia and Mortierella were negatively associated with morbidity, but Trichoderma was positively associated with morbidity. Particularly, the Spearman correlation and the least partial squares path analysis indicated that Trichoderma was significantly positively correlated with the disease incidence, the soil physicochemical properties, and the numbers of soil pathogens (NSP) were significantly positively correlated with the number of root pathogens (NRP) and the physicochemical properties of plants were negatively correlated with the disease incidence. Moreover, BOF had better inhibitory effect on the occurrence of tomato bacterial wilt. Our results have implications for the better integrated management of tomato bacterial wilt. [ABSTRACT FROM AUTHOR]

Bacterial community and soil enzymatic activity depend on soil and management conditions. Fertilization is an important approach to maintain and enhance enzyme activities and microbial community diversity. Although the effects of fertilizer application on soil microbial community and related parameters are explored, the effects on the soil microbiome associated with those of wheat plant organs, including those associated with roots and spikelets, are not well-known. Therefore, in this study, by using a sequencing approach, we assessed the effects of inorganic fertilizers, manure, and biochar on soil enzyme activities, bacterial community diversity and structure in the bulk soil, rhizosphere, roots, and spikelet of wheat (Triticumaestivum L.). For this, different treatment biochar (BC), manure (OM), low mineral fertilizer (HL), high mineral fertilizer (HF), and no fertilizer (FO) were used for the enzyme activities and bacterial community structure diversity tested. The result showed that organic amendment application increased total nitrogen, soil available phosphorus, and potassium compared to inorganic fertilizer and control, especially in the rhizosphere. Enzyme activities were generally higher in the rhizosphere than in the bulk soil and organic amendments increased activities of acid phosphatase (AcP), β-1,4-N-acetyl-glucosaminidase (NAG), and phenol oxydase (PhOx). Compared with soil and rhizosphere, bacterial diversity was lower in wheat roots and evenlower in the spikelet. From the bulk soil, rhizosphere to roots, the fertilization regimes maintained bacterial diversity, while organic amendment increased bacterial diversity in the spikelet. Fertilization regimes significantly influenced the relative abundances of 74 genera across 12 phyla in the four compartments. Interestingly, the relative abundance of Proteobacteria (Citrobacter, Pantoea, Pseudomonas, and unclassified Enterobacteriaceae) in the spikelet was decreased by increasing inorganic fertilizer and further by manure and biochar, whereas those of Actinobacteria (Microbacterium and an unclassified Microbacteriaceae) and Bacteroidetes (Hymenobacter and Chitinophagaceae) were increased. The results suggest that potential bacterial functions of both roots and above-ground parts of wheat would be changed by different organic amendment regimes (manure and biochar). [ABSTRACT FROM AUTHOR]