Mecanismos redutores de temperatura da solução nutritiva hidropônica de cultivares de alface (Lactuca sativa L.)

Abstract

The hydroponic cultivation of vegetables has expanded throughout Brazil, but in regions with a tropical climate, where high temperatures and high humidity prevail, problems in the production of these species represent the main problem to be solved, as the hydroponic solution absorbs heat and energy from the environment. thus the answers of these plants are to be desired. Lettuce (Lactuca sativa L.) is the main broadleaf cultivated in Brazil under hydroponic conditions. In the region of Manaus/AM, it has presented problems with the appearance of diseases related to high temperature, not only environmental but also the cultivation solution. In this context, this work aimed to evaluate two temperature-reducing mechanisms of the hydroponic nutrient solution, in a greenhouse under Manaus conditions. For this, system 1 was tested, without the presence of PVC current in the return of the nutrient solution and in system 2, the presence of this current, in the cultivation of three cultivars of crisp lettuce (BRS Lélia, BRS Leila and BRS Mediterrânea). The experiment was carried out in a completely randomized design, in a 2 x 3 factorial scheme (temperature reduction mechanism and lettuce cultivars), with 04 replications of 10 plants each for agronomic and post-harvest evaluation. The presence of a temperature reducer influenced the physical variables of production of lettuce cultivar BRS Mediterrânea, in the conditions of the region of the city in question. The Mediterrânea cultivar showed the best agronomic yield in the system with reduced temperature. For post-harvest variables, the cultivar Mediterrânea in System 1 had the best response, for pH and AT it was Mediterranean in System 2.