Synergistic use of biochar, Trichoderma harzianum and Pseudomonas fluorescens to combat biotic stress by Phomopsis vexans in brinjal

The present study focuses on induced systemic resistance (ISR), where secondary metabolites and pathogenesis-related (PR) proteins are activated after the application of resistance inducers following the salicylic acid pathway. Biochar was used as an inducer to activate phenolic compounds and pathogenesis-related (PR) proteins, helping to combat Phomopsis vexans, which causes Phomopsis blight in brinjal. Physical and biochemical analysis showed biochar has significantly improved the yield of traits of the plant and reduced the amount of infection by increasing levels of total proteins, total phenols and sugar content. Increased levels of proteins and phenolic compounds with decreased levels of disease severity as shown by regression analysis, indicating a negative correlation (r) between soil pH, soil electrical conductivity (EC), plant height, number of branches, fruit yield, peroxidase activity, total protein content, total phenols and disease severity. The treatment T13 with 3 % biochar, Trichoderma harzianum and Pseudomonas fluorescens was found to be the best treatment that exhibited positive effects on yield attributing traits and managed disease severity (22.2 %), followed by biochar concentrations of 3.5 % (T6) and 3 % (T5) alone with disease severities of 24.42 % and 26.6 %, respectively. Mixed application of biochar, T. harzianum and P. fluorescens has shown a synergistic effect on yield attributing traits and contributed to improving final yield and reducing disease severity. The data indicated a negative correlation between disease severity and yield attributing parameters, underscoring the effectiveness of this integrated approach in promoting plant resilience and productivity.