Fisiologia e crescimento inicial de quiabeiro utilizando soluções nutritivas salinas sob aplicação de ácido salicílico.

Abstract

Hydroponic cultivation has been an alternative to the limited availability of water with low electrical conductivity for irrigation in the Northeastern semi-arid region, which has restricted food production, making it necessary to use strategies to reduce the effects of saline stress on plants. Among the alternatives, the foliar application of salicylic acid stands out. In this context, the objective of this study was to evaluate the effects of foliar application of salicylic acid in mitigating effects of salt stress in gas exchange, chlorophyll a fluorescence, photosynthetic pigments, and growth of hybrid okra 'Canindé' in a hydroponic system. The study was carried out in a greenhouse, in Pombal - PB, using the hydroponic cultivation system the Nutrient Laminar Flow Technique - NFT. The experimental design used was completely randomized in a split-plot scheme, with four levels of electrical conductivity of the nutrient solution - ECsn (2.1, 3.6, 5.1, and 6.6 dS m-1) considered as plots and four concentrations of salicylic acid - AS (0, 1.2, 2.4, and 3.6 mM), as the subplots, with four replicates and two plants per plot. Salicylic acid at a concentration of 3.6 mM minimized the effect of nutrient solution salinity on chlorophyll a fluorescence and promoted an increase in the synthesis of chlorophyll b in okra plants. Nutrient solution salinity above 2.1 dS m-1 negatively affected gas exchange, relative water content, photosynthetic pigments, growth and increased electrolyte leakage in the leaf blade of okra plants.