Salicylic acid alleviates the effects of salt stress on the physiology, growth, and production of hydroponic okra

Abstract Application of salicylic acid can enable the use of brackish water in the hydroponic cultivation of okra in arid and semi-arid regions. In this context, the objective of the present study was to evaluate the effect of foliar application of salicylic acid in mitigating the impacts of salt stress on the physiology, growth, and production of “Canindé” okra cultivated in a hydroponic system. The experiment was carried out in a greenhouse, using an NFT—Nutrient Film Technique hydroponic system. A completely randomized design was adopted in a split-plot scheme, with four levels of electrical conductivity of the nutrient solution—ECns (2.1, 3.6, 5.1, and 6.6 dS m−1) considered as plots and four concentrations of salicylic acid—SA (0, 1.2, 2.4, and 3.6 mM), considered as subplots, with four replications, each of which consisting of two plants. Foliar application of salicylic acid at a concentration of 1.2 mM attenuated the harmful effects of salt stress on the physiology, growth, and production components of “Canindé” okra cultivated in a hydroponic system with ECns of up to 6.6 dS m−1. Plants cultivated with ECns of 6.6 dS m−1 and salicylic acid at a concentration of 1.2 mM obtained an increase of 11.13% (36.4 g per plant) in total production per plant compared to plants cultivated with the same ECns level and without application of salicylic acid. These results demonstrate that salicylic acid, when supplied by foliar application at adequate concentrations, can act as a signaling molecule and reduce the effects of salt stress on hydroponic okra.