Enhancing Antioxidant Properties of Lettuce through Nutritional Deficiency in Aquaponic Systems with Aeroponic Cultivation

This research presents a comparative analysis of the yield and nutritional quality of lettuce (Lactuca sativa L.) cultivated in an aeroponic system with two distinct nutrient solutions: (i) commercial hydroponic fertilizers and (ii) aquaponic water without added fertilizers. Both systems were maintained under the same controlled conditions, enabling the comparison of growth parameters, leaf area, antioxidant activity, mineral content, and sensory characteristics of the lettuce. The hydroponic system demonstrated superior performance concerning the fresh weight of lettuce head and root, leaf count, and leaf area. In contrast, the aquaponic system produced a higher dry weight of lettuce heads and a more extensive root-to-shoot ratio. Concerning nutrient concentration, the hydroponic nutrient solution composition exhibited elevated levels of NO3–, P, NH4+, and K in contrast to the aquaponic nutrient solution, which had a more significant S, Cl–, Na, and Mg content. Regarding the nutritional value, lettuce from the hydroponic system exhibited significantly higher levels of K, S, P, Zn, Fe, Mn, and vitamin B2. In contrast, lettuce from the aquaponic system exceeded with higher content of Ca, Na, Mg, Al, B, and Si. Remarkably, the lettuce cultivated in the aquaponic system demonstrated significantly enhanced total flavonoid and phenol content, and antioxidant capacity compared to its hydroponically grown counterpart.