Abstract
This study evaluates the effects of the biological products “Trichodermin” (Trichoderma viride, strain Trv1, titer 1×10⁸ c/mL), “Extrasol” (Bacillus subtilis, titer 1×10¹⁰ CFU/mL), and a bacterial formulation based on Enterobacter cloaceae (titer 1×10¹⁰ CFU/mL) on biometric parameters, productivity, early yield, and the immune response of greenhouse-grown pepper (Capsicum annuum, cv. “Piruet F1”) to white mold infection.
The experiments were conducted from 2021 to 2023 at the Maritsa Vegetable Crops Research Institute, Plovdiv, in an unheated steel-glass greenhouse. Pepper plants were cultivated under a 90/60/40 cm spacing scheme. The biological products were applied via pre-sowing seed soaking for 4 hours in undiluted mother solutions, followed by two soil treatments (10 mL/10 L water per 20 m²) — after transplanting and during mass flowering.
The results demonstrated the positive effects of Bacillus subtilis, Enterobacter cloaceae, and Trichoderma viride on plant biometric parameters, disease resistance, and yield. Treated plants showed an increase in plant mass by 14%–23%, root mass by 21%–32%, and leaf mass by 24%–36%. Total yield increased by 23%–28%, while early yield improved by 12.5% with “Extrasol”, 19% with Enterobacter cloaceae, and 24% with “Trichodermin”. Artificial infection with Sclerotinia sclerotiorum using the decapitation method confirmed that the biological products enhanced the immune response in pepper plants. The reduction in necrosis caused by white mold was 56% with “Trichodermin”, 44.8% with “Extrasol”, and 35.5% with Enterobacter cloaceae.
Keywords: antagonists, Capsicum annuum, growth stimulation, non-specific induced resistance, productivity, Sclerotinia sclerotiorum