Response of tilapia and tomato to the complementation of nutrients in an aquaponic system

Aquaponics, the symbiotic integration of aquaculture and hydroponics, is a sustainable technology for food production. However, the aquaponic nutrient solution has low concentration of N, K and Ca to satisfy plant requirement. The aim of this work was to increase the tomato (Solanum lycopersicum L.) fruit yield in an aquaponics system through the incorporation of nutrients in the tilapia (Oreochromis sp.) nutrient solution and also supplying these nutrients through foliar fertilization. A hydroponic system was taken as a control (T1) to compare three aquaponic treatments: aquaponics + N-K-Ca-S in nutrient solution + foliar fertilization (T2), aquaponics + N-K-Ca-S in nutrient solution (T3), and aquaponics without nutrient complementation (T4). Considering a completely randomized treatment design, plant height, stem diameter, number, weight, diameter and fruit yield were measured; pH, electrical conductivity (EC), nutrient concentration (N, P, K, Ca, Mg, Fe, Mn, Cu) in hydroponic and aquaponic nutrient solution, water consumption, and weight, length and width of fishes also were obtained. Growth, dry matter and fruit yield were similar between aquaponic and hydroponic treatments, but stem and fruit diameter were different, T4 showed the highest values. The higher macronutrient concentrations in leaves and fruit tissue were obtained in T2, although this effect did not influence growth and plant development. Nutrient complementation to the aquaponic system did not decrease the weight, length and width of the fishes. Water consumption in aquaponic systems was less than in the hydroponic system.