Aquaponics offers sustainable cultivation by integrating aquaculture and hydroponics, yet nutrient limitations often constrain plant performance. This study evaluated the effects of three nutrient solutions (aquaponics, Hoagland, and Hoagland + aquaponics) combined with foliar applications of iron and potassium (1000 mg/L) on morphological, physiological, and biochemical characteristics of green and purple basil (Ocimum basilicum L.) cultivars in a completely randomized factorial design with three replications. Results demonstrated that aquaponics nutrient solution significantly enhanced plant height (39.81%), internode length (43.32%), stem diameter (30.88%), shoot (40.41%) and root (105.43%) biomass, leaf number (51.92%) and leaf area (51.95%) compared to Hoaglandtreated plants. Foliar potassium and iron applications substantially improved growth parameters across both cultivars, with green basil showing superior performance overall. Photosynthetic pigments (chlorophyll a, b) were highest in green basil under aquaponics with potassium spray, while purple basil accumulated more anthocyanins compared to green basil. Mineral analysis revealed that K concentration was lower in aquaponics, although foliar K treatments effectively increased K concentrations in leaves, in all nutrient solutions. Essential oil content was notably higher in aquaponics-grown plants and further enhanced by potassium and iron foliar applications, particularly in green basil. Strong positive correlations were observed between growth parameters, and essential oil production. These findings demonstrate that combining aquaponics with strategic foliar supplementation of potassium and iron represents an effective approach for optimizing basil production, quality, and essential oil yield in sustainable cultivation systems.
