Morpho-physiological indexes of lettuce produced on different substrates under protected environment

Abstract

Lettuce is considered the most important leafy vegetable in Brazil. The production in a greenhouse or protected environment, using substrate, also called cultivation without soil, has been gaining prominence in the world scenario, due to the need for soil conservation. Thus, the search for alternative materials to compose substrates is necessary and relevant, taking into account the agro-industrial aptitude of each region in order to allow the use of waste that is abundantly available and the reduction of production costs. The objective of evaluating industrial residues used as substrates, and their effects on the development and production of lettuce grown in a protected environment. This experiment was developed at the Federal Rural University of the Amazon, campus of Paragominas, in the experimental area of ​​Horticulture. A completely randomized design was used with four treatments (rice straw, soy residue, mixture = rice straw (35%) + soy residue (35%) + black sand (30%) and black sand as a control). The following characteristics were evaluated: number of leaves, Weight (kg), Root weight (g), cycle, stem length (cm), economic productivity (kg), leaf area (RA) (cm2), leaf area index (IAF), Leaf Area Ratio (RAF) (cm2 g-1), specific leaf area (AFE) (cm2 g-1), leaf weight ratio (RPF), amount of water in the aerial part (QAPA), weight leaf specific (PEF) (g cm2). All data obtained were analyzed statistically through analysis of variance, with the F test. The Tukey test (5%) was used to compare means. The best substrate for lettuce production, without soil, in a greenhouse, is the soy residue, because in this substrate the cultivar veneranda showed the highest productivity and the best morphophysiological indexes, demonstrating the possibility of using this industrial residue as an alternative substrate.