Seed Pelleting with Gum Arabic-Encapsulated Biocontrol Bacteria for Effective Control of Clubroot Disease in Pak Choi.

Clubroot is one of the most serious soil-borne diseases on crucifer crops worldwide. Seed treatment with biocontrol agents is an effective and eco-friendly way to control clubroot disease. However, there is a big challenge to inoculating the seed with bacterial cells through seed pelleting due to the harsh environment on the seed surface or in the rhizosphere. In this study, a method for microbial seed pelleting was developed to protect pak choi seedlings against clubroot disease. Typically, a biocontrol bacterium, ZF129, was encapsulated by the spray-drying method with gum arabic as wall material, and then pak choi seeds were pelleted with the microencapsulated ZF129 (ZF129m). The morphology, storage stability, and release behavior of ZF129 microcapsules were evaluated. Compared with the naked ZF129 cells, encapsulated ZF129 cells showed higher viability during ambient storage on pak choi seeds. Moreover, ZF129m-pelleted seeds showed higher control efficacy (71.23%) against clubroot disease than that of nonencapsulated ZF129-pelleted seeds (61.64%) in pak choi. Seed pelleting with microencapsulated biocontrol ZF129 proved to be an effective and eco-friendly strategy for the control of clubroot disease in pak choi.