Biochar Application for Enhancing Cucumber Growth and Fusarium Diseases Resistance through Systemic Induction and Pathogen Suppression

Cucumber plants in Egypt were found to be affected by Fusarium proliferatum (Matsush.) Nirenberg, Fusarium incarnatum (Desm.) Sacc., and Fusarium equiseti (Corda) Sacc., which caused significant seedling damping-off and root rot. Pathogenicity assays revealed that F. incarnatum was the most aggressive pathogen, followed by F. proliferatum, and F. equiseti. In vitro assay assessed the efficacy of three biochar types (rice straw, grape waste, and palm kernel) at concentrations of 0.5%, 1.0%, and 2.0%. In general, biochar treatments of grape waste and palm kernel significantly suppressed pathogen growth, with all concentrations demonstrating the greatest inhibition. Among the biochar types, rice straw biochar exhibited the lowest efficacy revealed that no inhibition of the three Fusarium sp. in vitro, followed by grape waste and palm kernel. In greenhouse trials conducted during 2023 and 2024 seasons, 2.0% biochar treatments notably reduced damping-off and root rot, with rice straw biochar providing the most effective disease control.Furthermore, biochar application enhanced the plant's defense mechanisms, as evidenced by increased catalase, peroxidase, and polyphenol oxidase activities, along with elevated total phenol contentions compared to untreated controls. These findings highlight biochar as a promising, sustainable strategy for managing Fusarium diseases in cucumbers, emphasizing the need to select the appropriate biochar type and concentrations for optimal disease suppression