Impact of microbial biofertilizers on the growth, yield, fruit quality, and biochemical characteristics of two sweet pepper (Capsicum annuum L.) cultivars

Abstract

Sweet pepper (Capsicum annuum L.) is a commercially essential vegetable crop globally, valued for its nutritional content and economic returns. Due to the environmental concerns associated with the excessive use of chemical fertilizers, there is a growing necessity for sustainable agricultural alternatives. This study evaluated the effects of three commercial biological formulations applied as foliar sprays: Bio-Arc (Bacillus megaterium), Bio-Nagy (Trichoderma asperellum), and Bio-Zied (Trichoderma album). The treatments were applied at concentrations of 1, 2, and 3 g L?¹ on two sweet pepper cultivars ('Topy Star' and 'Madrid' hybrid) grown under field conditions across two consecutive seasons (2023 and 2024). The application of these biofertilizers significantly enhanced plant growth, fruit quality, and biochemical parameters compared to untreated control. Specifically, Bio-Nagy at 3 g L?¹ produced the firmest fruits (8.19 and 8.10 kg cm?² in 'Topy Star' and 'Madrid', respectively) and the highest total sugar content (35.34% and 37.44%). The 'Madrid' hybrid treated with Bio-Zied at 3 g L?¹ recorded the highest total soluble solids (TSS) (8.07%) and vitamin C content (145.60 mg 100 g?¹ FW). Furthermore, biochemical profiles, including chlorophyll and phenolic compounds, exhibited substantial increases under all biological treatments. Vegetative parameters such as fresh shoot weight and average fruit weight were also significantly improved, with the 'Madrid' hybrid reaching an average fruit weight of 12.70 g under the Bio-Zied (3 g L?¹) treatment. In conclusion, the foliar application of T. asperellum, T. album, and B. megaterium meaningfully improves the physiological performance, yield, and nutritional quality of sweet pepper. These findings strongly support the integration of microbial biofertilizers as a viable, eco-friendly alternative to chemical fertilizers in sustainable horticultural practices.