Cultivo hidropônico de manjericão sob estresse salino: crescimento, produção e aspectos bioquímicos

Abstract

The present work evaluated the production of basil cv. Folha de Alface in the hydroponic system, submitted to different concentrations of sodium chloride (NaCl), recirculation frequencies of the nutrient solution and times of exposure to saline stress. The research was developed in two experiments. In the first one, the experimental design was completely randomized, in a factorial scheme 3 x 2 + 1, where the first factor represents the concentrations of NaCl (0, 40 and 80 mM) and the second factor the recirculation frequencies of the nutrient solution (4 or 6 hours) in a hydroponic system of deep flow (DFT), and an additional treatment only with nutrient solution in hydroponic laminar flow system (NFT), making a total of seven treatments and three replicates, in 21 plots. The second experiment was installed in a completely randomized design with five treatments, represented by the plant exposure times and the concentration of 60 mM NaCl, with four replications, in 20 plots. The duration of saline stress was 0, 7, 14, 21 and 28 days. In both experiments, water consumption, growth, phytomass production, growth rates, essential oil production and the accumulation of inorganic and organic solutes in basil plants were evaluated. As a result of the first experiment, the reduction of the frequency of recirculation of the nutrient solution to six hours does not cause significant reductions in all variables analyzed; water consumption, growth, phytomass production, absolute growth rate and basil oil production reduced with the use of saline nutrient solution, 40 and 80 mM NaCl; basil plants subjected to salinity of 40 mM and 80 mM NaCl accumulate higher concentrations of Na+, Cl- and organic solutes; the contents of K+ and the K+ /Na+ ratio decrease as a function of salinity; the choice of the DFT or NFT hydroponic system does not cause significant changes in the variables analyzed in the basil. In the econd experiment, plant exposure to salinity of 60 mM NaCl for 21 and 28 days resulted in significant reductions in water consumption, growth, phytomass production, absolute and relative growth rates, net assimilation rate and production of essential oil of basil, under these conditions the duration of saline stress promotes the accumulation of higher concentrations of Na+ and Cl- and of organic solutes; in contrast, the contents of K+ and the K+/Na+ ratio decrease; it is possible to use, under the conditions evaluated, the saline nutrient solution of 60 mM NaCl for up to 14 days without significant growth, phytomass and essential oil production of basil.