Protected polyhouse and open-field bell pepper (capsicum) cultivation faces persistent yield threats from moisture-loving soil fungi and foliar pathogens, specifically Phytophthora blight / stem rot (Phytophthora capsici), damping-off (Pythium spp.), and post-harvest fruit anthracnose (Colletotrichum spp.). Phytophthora capsici attacks stems, roots, and fruit, causing rapid crown wilting and dark, water-soaked lesions that ruin fruit quality. Soil drenching and root dipping with Bacillus subtilis establish a dense, defensive bacterial barrier throughout the root zone and basal stem area. The bacteria secrete cyclic lipopeptides (surfactin, iturin, fengycin) that disrupt fungal spore motility, inhibit zoospore germination, and stop fungal hyphae from invading root tissues.

In addition to disease control, Bacillus subtilis serves as a key plant growth-promoting rhizobacterium (PGPR) in high-value capsicum farming. It solubilizes fixed soil phosphorus, mobilizes micro-nutrients via siderophore production, and synthesizes natural growth regulators that encourage adventitious feeder root expansion. Improved root mass drives vegetative stem strength, reduces flower drop, and supports thicker pericarp (fruit wall) development in colored and green bell peppers. Regular foliar applications safeguard developing fruit surfaces from latent anthracnose spots. Because Bacillus subtilis leaves zero chemical residues, it enables harvesting up to the day of picking, extending post-harvest storage and shelf life for long-distance market transport.

Importance of Bacillus subtilis in Bell Pepper Cultivation

Bell pepper is a nutrient-demanding crop that requires continuous nutrient uptake and a healthy root system throughout the production cycle. Soil-borne diseases damage roots and interfere with water and nutrient absorption, resulting in poor flowering, fruit abortion, reduced fruit size, and lower quality.

Bacillus subtilis rapidly colonizes the rhizosphere and competes with disease-causing fungi and bacteria for nutrients and space. It also produces natural antimicrobial compounds that suppress pathogens while promoting beneficial microbial activity.

Healthy roots support vigorous vegetative growth, better flowering, improved fruit development, and higher productivity.