Avaliação da suplementação de ferro para produção de cultivares de alface em sistema aquapônico com tilápia do Nilo

Abstract

The objective of this research was to evaluate iron supplementation in an aquaponic system for raising Nile tilapia (Oreochromis niloticus) and growing lettuce (Lactuca sativa), green (BRS Leila) and purple (Luminosa) varieties in two treatments: with supplementation iron (CF) and without iron supplementation (SF). Iron supplementation was carried out with EDDHA chelated iron, maintaining a concentration of 2 mg/L. The research was carried out at the Professor Dr. Raimundo Saraiva da Costa Aquaculture Station at the Federal University of Ceará (UFC). The experiment was conducted in two independent aquaponics systems. Each system was composed of three masonry tanks (repetitions), four hydroponic troughs, a decanter, a pressurized mechanical filter, a biological reactor, a degasser and an aeration system. 100 fish were stocked in each tank, with an average weight of approximately 25 g, totaling 300 individuals per treatment. The hydroponic bench for each treatment was composed of 75 green lettuces (BRS Leila) and 25 purple lettuces (Luminosa). Temperature, dissolved oxygen and pH were measured daily. Total alkalinity, total ammonia nitrogen and nitrite were evaluated every five days. Statistical analysis of the data was performed using the Student's t test (independent samples), using the BioEstat Program (version 5.3), at a significance level of 5%. At the end of the experimental period (46 days), Nile tilapia with an average weight of approximately 150 g were produced. A significant difference (p<0,05) was observed for the zootechnical performance parameters evaluated for Nile tilapia of final total length, allometric condition factor and specific growth rate, the others did not show a significant difference (p>0,05). A significant difference (p<0,05) was observed for all phytotechnical performance parameters evaluated, except the number of defective leaves, in both lettuce varieties tested. With the exception of nitrite, the water quality parameters evaluated remained adequate for the development of Nile tilapia. Data analysis allowed us to conclude that iron supplementation is essential for the good development of both lettuce varieties tested, without compromising the development of the fish.