Defense response by inter-active bio-protector and chitosan to Sclerotium rolfsii Wilt disease on cowpea, Brazilian Oxisol

Pathogenic microorganisms increase enzyme production and plant response, causing injuries and even plant death. Chitosan has shown potential to induce reactions in plant pathogens. An “in vitro” assay determines the action of chitosan and evaluates the optimal concentration to act against (Sclerotium rolfsii). The anti-microbial activity of chitosan and the bio-protector produced by the inter-active bacteria Beijerinckia indica and fungus Caenorhabditis elegans that contain chitosan were tested in a pot experiment against S. rolfsii on cowpea grown in a Brazilian Oxisol. Biofertilizer and chitosan in foliar application were used with and without S. rolfsii. The plants were analyzed, and the disease severity index, soluble protein and enzymatic activities were determined. The “in vitro” test showed chitosan effectiveness against S. rolfsii. The pot experiment with sterilized and non-sterilized soil confirmed the ability of the bio-protector that contains chitosan from C. elegans and chitosan application to increase enzymatic activities processed by S. rolfsii. The higher concentrations of the bio-protector and chitosan (4.0 and 6.0 mg mL-1) were directly related to the catalase and peroxidase activities controlling plant resistance and the disease severity index. The bio-protector may be a viable alternative to soluble fertilizer, and recommended for organic and sustainable agriculture. These findings are important for the establishment of sustainable agriculture and to avoid the use of pesticides. Key words: Antifungal activity, biopolymer, enzyme activities, plant resistance, postharvest analyzes, sustainable agriculture.