Salicylic acid alleviates salt stress on guava plant physiology during rootstock formation1

Abstract

Guava is a fruit widely produced in Northeast Brazil, a region that has sources of water with high levels of salts, making it difficult for irrigated fruit production to expand. Thus, it is extremely important to search for techniques that allow the management of these waters in irrigated agriculture. Thus, the objective of present study was to evaluate the photosynthetic pigments, the quantum yield of photosystem II, and the intercellular leakage of electrolytes in the leaf blade of ‘Paluma’ guava seedlings as a function of irrigation with water of different salinities and foliar application of salicylic acid during rootstock formation phase. The experiment was conducted in a greenhouse, using the randomized block design in a 5 × 5 factorial arrangement, which consisted of five values of electrical conductivity of water-ECw (0.6, 1.5, 2.4, 3.3, and 4.2 dS m-1) and five concentrations of salicylic acid (0, 0.8, 1.6, 2.4, and 3.2 mM L-1), with four replicates, and two plants per plot. Salicylic acid up to 1.3 mM L-1 increased the relative water content and decreased electrolyte leakage in the leaf blade of ‘Paluma’ guava seedlings. Foliar application of salicylic acid at a concentration of 1.7 mM L-1 attenuated the effects of salt stress on chlorophyll a of guava seedlings irrigated with water of up to 1.6 dS m-1. The deleterious effects of salt stress on carotenoid concentration and quantum efficiency of photosystem II were not attenuated by the application of salicylic acid.