Coating Seeds with Paenibacillus polymyxa ZF129 Microcapsule Suspension Enhanced Control Effect on Fusarium Root Rot and Promoted Seedling Growth in Cucumber

<i>Fusarium</i> root rot, a destructive soil-borne fungal disease, necessitates eco-friendly biocontrol strategies. This study developed a microbial seed-coating approach using the antagonistic strain <i>Paenibacillus polymyxa</i> ZF129, formulated into a microencapsulated powder (10⁸ CFU/g) and a suspension (CS-ZF129). CS-ZF129 application enhanced cucumber resistance, achieving 46.30 ± 0.02% disease suppression while promoting root growth. The maximum increase in the fresh weight of the root in the promotion of rectangular growth was 47.16%. The colonization dynamics of ZF129 in the rhizosphere were systematically tracked, revealing its antagonistic correlation with Fusarium proliferation. An enzymatic activity analysis further uncovered the underlying regulatory mechanisms, demonstrating induced defense responses through pathogenesis-related protein activation. These findings highlight ZF129's dual functionality as a biocontrol agent and a plant growth promoter, offering a sustainable strategy against soil-borne pathogens.