Effect of Organic Nutrients and Biofertilizers on Vegetative and Chemo-Physiological Growth of Sweet Pepper (<i>Capsicum annuum</i> L.)

Abstract The experiment was conducted in Thi-Qar Governorate - Al-Nasiriya - Al-Mustafa area, during the agricultural season 2024/2025 in one of the protected greenhouses affiliated with the agricultural research station of the Horticulture Department at the College of Agriculture and Marshes, University of Thi-Qar. The study aimed to investigate the effect of adding organic nutrients and biofertilizer on sweet pepper (Capsicum annuum L.) in a sandy loam soil. A Randomized Complete Block Design (RCBD) was used for the experiment, which included three treatments for adding organic nutrients and biofertilizer: concentrations of (0) mL/L, (2) mL/L, and (4) mL/L. The results showed that the addition of organic nutrients at a concentration of (4 mL/L) resulted in the highest plant height, leaf area, number of leaves, dry weight, chlorophyll, carbohydrates, vitamin C, and capsaicin. The plant height reached 84.66 cm (plant −1 ), leaf area was 53.04 dm 2 (plant −1 ), number of leaves was 253.44 leaves (plant −1 ), dry weight was 53.78 g (plant −1 ), chlorophyll content was 13.30 mg (100 g −1 ), carbohydrates were 5.789 mg/g, vitamin C was 151.09 mg (100 g −1 fresh weight), and capsaicin was 0.11896 mg/kg, respectively. Additionally, the biofertilizer at a concentration of (4 mL/L) excelled in enhancing plant height, leaf area, number of leaves, dry weight, chlorophyll, and carbohydrates.