Organic or Inorganic Amendments Influence Microbial Community in Rhizosphere and Decreases the Incidence of Tomato Bacterial Wilt

Abstract

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.