Yield of two cultivars of lettuce (Lactuca sativa L.) in hydroponic and aquaponic systems
2018
Pineda-Pineda, J. | Valdez-Zamora, A. | Miranda-Velazquez, I. | Rodriguez-Perez, J. E. | Ramirez-Arias, J. A. | Lozano-Toledano, A.
This research was carried out in order to evaluate the performance of two cultivars of lettuce (Lactuca sativa L.) in an aquaponic system in comparison with a hydroponic system. The studied factor was the dose of food supplied with a commercial diet for tilapia (Oreochromis sp.); the treatments were 80, 100 and 120% of the recommended diet, and, as a control, the hydroponic Steiner universal nutrient solution, arranged in an experimental design of randomized complete blocks with four replications. The variables measured were related to vegetative development (plant height, stem diameter, diameter of foliage, fresh weight and dry matter) and nutrient contents of plant tissue (N, P, K, Ca, Mg, Fe, Cu, Zn and Mn) as well as nutrient concentrations (N-NH(4)+, N-NO(3)-, P-H2PO(4)-, P-HPO(4)2-, K+, Ca(2)+, Mg(2)+, SO(4)(2-), Fe(2+), Mn(2+), Zn(2+), Cu(2+) and H(3)BO(3)) in aquaponic nutrient solution during two crop cycles. Rocky mountain tilapia with a density of 20-25 kg m(-3) in tanks and 25 lettuce plants m-2 on beds were used. It was found that treatment with 120% of the recommended fish diet produced the best fresh weight of lettuce, above hydroponic control; in the analysis of plant tissue, no nutrient deficiencies were observed. Nutrients in the aquaponic nutrient solution were within the ranges reported as adequate for optimal crop development. Supplying 80 or 120% of the recommended tilapia diet decreased by 21% or increased by 10%, respectively, tilapia weight in relation to the normal diet. The level of food supply influenced the length and weight of tilapia, the concentration of nutrients in the water and in the tissue of lettuce; aquaponics equalled or exceeded hydroponics in nutrient capacity supply for 'Andrómeda' and 'Ruby Sky' lettuce.
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