ALFACE CULTIVADA EM SISTEMA AQUAPÔNICO SOB DIFERENTES POPULAÇÕES DE PEIXES E VOLUMES DE MATERIAL FILTRANTE

Abstract

Aquaponics is a food production technique that, by using water as a common medium, symbiotically conjugates three living organisms (plants, fish and nitrifying bacteria) and offers proteins and vegetables to the end. Curiously, we noticed that the literature lacks studies where the physiological and nutritional characteristics of lettuce grown in aquaponic system were evaluated. Thus, the objective was to evaluate lettuce culture, cultivated in aquaponic system under different fish populations and volumes of filter material. The experiment was installed at IF Goiano, Rio Verde Campus, Rio Verde/Goiás, consisting of eighteen experimental units, each composed of reservoir (1 m³), decanter, biological filter, pump and aerator, as well as six hydroponic gutters in each experimental unit, which housed 11 plants/trough. The experimental design was block casualized, in a factorial arrangement with three fish populations ( 30, 60 and 90 fish m-3) and two volumes of filter material ( 40 and 60 liters of clay), for the first cycle and ( 50 and 70 liters of clay) for the second cycle, with three replications. The physiological variables and biometric analyses were performed at 45 days after sowing, when then, soon after, the samples were dried in a greenhouse, ground and sent to the laboratory for nutritional analyses. The data obtained were submitted to variance analysis and, the means were compared by the Tukey Test, using the Sisvar computer program. It was observed in water, values of macro and micronutrients discrepant, due to the high pH values, which caused the precipitation of these, being then discarded when the soda was removed. PH levels should be adjusted to decrease the concentration of toxic ammonia so as not to compromise the proper development of lettuce. Given the results, we conclude that a population of 30 fish is sufficient to ensure the growth and development of aquaponic lettuce and that a larger volume of filter material is better for the mineralization of organic compounds and subsequent availability of the nutrients needed for plants.