Physiological aspects and growth of cashew under salt stress and salicylic acid in pre-flowering phase

ABSTRACT The use of water with high concentration of salts in cashew cultivation is a necessity in the semi-arid region of Northeast Brazil, due to water scarcity and poor rainfall distribution. Excess salts in water are a limiting factor for agricultural production. In this scenario, strategies have been employed to mitigate the harmful effects of salt stress on plants, and the use of salicylic acid stands out. With this, the aim of this study was to evaluate the effects of foliar application of salicylic acid on the physiology and growth of early dwarf cashew grown under salt stress in the pre-flowering stage. The experiment was conducted in a greenhouse using a randomized block design, in a 5 × 4 factorial arrangement, with five levels of electrical conductivity of irrigation water (ECw - 0.4, 1.2, 2.0, 2.8, and 3.6 dS m-1) and four concentrations of salicylic acid (SA - 0, 1, 2, and 3 mM), with three replicates. Salicylic acid, applied at a concentration of 1 mM, mitigated the negative impacts of salt stress on the morphophysiology of cashew during the pre-flowering phase, especially in plants irrigated with ECw of up to 1.2 dS m-1. On the other hand, the concentration of 3 mM SA exacerbated the effects of salt stress on the relative water content, electrolyte leakage, photosynthetic pigments, gas exchange, and growth of early dwarf cashew, particularly at ECw of 3.6 dS m-1.