Efeitos de Lâminas de Irrigação e da Fertirrigação nitrogenada no cultivo da alface em ambiente protegido em Roraima

Abstract

Two studies were conducted in greenhouse with drip irrigation system on the lettuce (Lactuca sativa L) cv. “Verônica”. The first experiment was to evaluate the production of lettuce to water levels. The experimental design was completely randomized with six treatments (irrigation levels) and four repetitions. The treatments were based on percentages of Class A pan evaporation (20, 40, 60, 80, 100 e 120%). The sheets of water applied influenced the studied variables, demonstrating a quadratic effect under the total fresh mass, the number of leaves and the productivity. The water use efficiency decreased with the increase of the applied sheet. The second experiment analyzed the manuring nitrogen effect in covering, through fertirrigation, applied in uréia form on the lettuce culture, in edafoclimatics conditions of Boa Vista, Roraima. The appraised doses corresponded to 0, 60, 120, 180, and 240 kg of N ha-1, divided in eight equal applications along the cycle. The N doses applied influenced the studied variables, demonstrating a quadratic effect under the fresh mass of the aerial part, the mass evaporates of the aerial part and the mass evaporates of the root. However, the number of leaves decreased with the nitrogen increase.