Produção de alface (Lactuca sativa L.) sob níveis de salinidade no substrato

Abstract

Vegetable gardening is the cultivation of plants with short life cycles and intense cultural practices. The use of Plant growing media is an alternative for the production of lettuce in a protected environment, but inadequate management leads to the nutritional imbalance of the plants and the addition of salts in the substrate, increasing the electrical conductivity that results in loss of productivity and product quality. The objective of this work was to evaluate the production of lettuce (Lactuca sativa L.) under salinity levels in the substrate in a protected environment. The experiment was conducted in a greenhouse using the cultivar “Thais”, it was installed under five salinity levels in the nutrient solution, in a completely randomized design, with three replications, four pots for each salinity level, totaling 60 experimental units in winter and summer cultivation, using salinity levels were 1.0; 1.5; 2.0; 2.5 and 3.0 dS m−1 measured in nutrient solution by varying the concentration of sodium chloride in the solution. The evaluated parameters were fresh mass, number of leaves per pot, leaves with symptoms per pot, stem diameter and dry weight. The data were subjected to analysis of variance and regression analysis. For winter cultivation, all variables were significant, stem diameter expressed negative linear behavior and the others showed quadratic behavior with lower indices in electrical conductivity 2.0 dS m−1. In summer cultivation, only the variable leaves with symptoms per vase showed significance, also with a higher index in electrical conductivity 2,0 dS m−1. Only from the 2.5 dS m−1 level of electrical conductivity in the solution did significant damage begin in lettuce production in a protected environment, requiring higher conductivity to support in-depth studies on the behavior of lettuce under stress saline.