Ácido salicílico como atenuante do estresse salino no cultivo hidropônico de pepino japonês.

Abstract

In the last decade, with the accelerated population growth and the scarcity of water resources, it has become a necessity to use increasingly efficient cultivation systems to guarantee food production. However, for the use of brackish water, it is essential to use strategies capable of minimizing the deleterious effects of saline stress on plants. In this context, the objective of the present study was to evaluate the effect of salicylic acid concentrations on the physiology, growth, production and postharvest quality of Japanese cucumber fruits cultivated under saline nutrient solutions in a hydroponic system. The work was carried out in a greenhouse, in Pombal - PB, using the hydroponic cultivation system of the Nutrient Laminar Flow Technique - NFT. A completely randomized design in a split-plot scheme was used, with the plots consisting of four levels of electrical conductivity of the nutrient solution - ECsn (2.1, 3.6, 5.1, and 6.6 dS m1 ) and the subplots salicylic acid concentrations (0, 1.8, 3.6 and 5.4 mM) with four replications and two plants per plot, salicylic acid concentrations were applied via foliar application. The electrical conductivity of the nutrient solution above 2.1 dS m-1 negatively affected growth, photosynthetic pigments, physiology, production and postharvest quality of cucumber. The concentration of 3.7 mM salicylic acid, together with a saline nutrient solution of 5.1 dS m-1 , resulted in higher relative water content in the leaf blade of Japanese cucumber plants. The concentration of 1.8 mM salicylic acid increased the relative growth rate in leaf area of cucumber plants under 2.1 dS m-1 saline nutrient solution. The exogenous application of 5.4 mM salicylic acid, combined with a 6.6 dS m-1 saline nutrient solution, increased the root/shoot ratio of the plants. Salicylic acid at concentrations of 1.4 to 2.0 mM reduced the negative effects of saline stress on production and postharvest quality of cucumber fruits under 2.1 dS m-1 nutrient solution.