Biochemical quality of green-harvested chili: effects of cultivation structures, watering applications, and cultivars diversity

Secondary metabolites play a crucial role in shaping chili’s nutritional value and stress tolerance (Capsicum annuum L.). However, their levels are significantly influenced by environmental factors and water supply. This study investigated the effects of cultivation systems, watering levels, and cultivar variation on green chili’s secondary metabolites and antioxidant activity. The research was conducted at Padjadjaran University, Sumedang, Indonesia, from August 2024 to June 2025. The experiment used a split-split plot design with four cultivation structures (greenhouse, screenhouse, rain shelter, and open field), four watering levels (100, 75, 50, and 25% of field capacity), and two cultivars (Tanjung and Unpad). Key metabolites—flavonoids, phenolics, capsaicin, and dihydrocapsaicin—and antioxidant activity were measured. Cultivation structure and irrigation significantly influenced metabolite accumulation, with cultivar-specific responses. Tanjung showed elevated flavonoid (668.64 mg QE/100 g) and phenolic (1,198.91 mg GAE/100 g) levels in the screenhouse at 75% FC, while Unpad exhibited higher phenolic content (1,096.06 mg GAE/100 g) in the greenhouse at 50% FC. Capsaicinoids peaked in Tanjung under screenhouse conditions at 100% FC. Antioxidant activity was consistently higher in Unpad, reaching 3,545.26 mg/L at 25% FC in the screenhouse. The screenhouse with watering (75% FC) provided optimal conditions for enhancing secondary metabolites, while Unpad demonstrated greater resilience across treatments. These findings highlight the role of cultivation design and water management in improving chili fruit quality, offering climate-adaptive and resource-efficient production strategies.