Cultivation of Watermelon (Citrullus lanatus (Tunb.)) in a Temperate Climate: Agronomic Strategies and Phytochemical Composition

This study investigates the phytochemical composition and cultivation strategies for watermelon (Citrullus lanatus (Thunb.)) in Lithuania’s temperate climate, focusing on its biological activity. Employing innovative grafting techniques and clear plastic film mulching, we successfully countered fusarium wilt while promoting growth and bioactive compound accumulation. Our analysis showed significant cultivar-dependent variations in total phenolic content (ranging from 94.34 ± 8.12 to 327.42 ± 9.14 mg GAE/kg fw in pulps and from 120.46 ± 7.52 to 364.27 ± 6.85 mg GAE/kg fw in rinds), lycopene (ranging from 1.15 ± 0.42 to 103.60 ± 1.69 mg/kg fw in pulps), sugar, and nitrate levels, revealing the influence of genetics and environment on the fruit’s phytochemical profile. Moreover, several Lithuanian watermelon cultivars exhibited comparable or superior levels of key bioactive compounds relative to imported varieties. These findings underscore the potential of watermelon rind and pulp as valuable sources of antioxidants and other bioactive phytochemicals, relevant for nutritional enhancement and medicinal applications. The results contribute to a deeper understanding of watermelon cultivation in Lithuania and highlight opportunities for optimizing agricultural practices to enhance the health benefits associated with this important fruit.