Integration of Biochar with Vermicompost and Compost Improves Agro-Physiological Properties and Nutritional Quality of Greenhouse Sweet Pepper

Applying organic fertilizers is an issue that is acquiring high attention in modern agriculture. This study aims to evaluate the impact of the co-application of vermicompost and biochar on the growth performance and productivity of sweet pepper plants grown under greenhouse conditions. The applied treatments were as follows: 100% vermicompost (T1), 75% vermicompost + 25% biochar (T2), 50% vermicompost + 50% biochar (T3), 50% biochar + 50% compost (T4), 75% compost + 25% biochar (T5), and 100% compost (control-T6). All applied treatments were distributed randomly, and each treatment was repeated three times over two seasons. The data analysis revealed that the application of vermicompost—alone or in combination with biochar—significantly increased the plant growth measurements (plant height, SPAD value, leaf area, No. of leaves, and No. of branches), leaf nutrient content (N, P, K, and Ca), and total yield in both seasons. The application of vermicompost—alone (T1) or in combination with biochar (T2 and T3)—on average over both seasons significantly increased the total yield by 31.12%, 26.47%, and 22.53%, respectively, compared with the control treatment (T6). Furthermore, the aforementioned treatments also increased the physical quality (fresh fruit weight, fruit length, fruit diameter, and flesh thickness) and chemical quality of sweet pepper fruits [total phenol content (TPC), total soluble solids (TSS), ascorbic acid (AsA), β-carotenoids (β-Carot), and titratable acidity (TA)]. In addition, the co-application of biochar with vermicompost and compost caused a significant reduction in the fruit nitrate concentration compared with the control (T6) over two seasons. In conclusion, the simultaneous application of biochar with vermicompost and compost is a promising strategy to improve the growth performance, nutrition status, total yield, and fruit quality of pepper plants, as well as to reduce the nitrate concentration in the fruits.