Salinidade da água e aplicação foliar de ácido salicílico no cultivo de goiabeira enxertada.

Abstract

The northeast region of Brazil, especially the semi-arid region, stands out every year in the production of fruit, among them guava has great socioeconomic importance due to its various forms of consumption. However, the main sources of water used for irrigation in this region have high concentrations of salts, standing out as a limiting factor for agricultural production. In this context, the use of strategies that mitigate the deleterious effects of saline stress on plants is extremely important. Among the alternatives, the foliar application of salicylic acid stands out. Given the above, the objective of this work was to evaluate the growth, physiology, production and postharvest quality of guava cv. Paluma under saline stress and foliar application of salicylic acid. The experiment was carried out under greenhouse conditions, in a randomized block design, in a 2 × 4 factorial scheme, with two levels of electrical conductivity of the irrigation water - ECw (0.6 and 3.2 dS m-1) and four concentrations of salicylic acid (0; 1.2; 2.4 and 3.6 mM), with three replications. Irrigation with 3.2 dS m-1 water promoted reductions in gas exchange, in chlorophyll a and b levels, in the relative water content, and increased electrolyte extravasation in the leaf blade of guava plants, at 150 days after transplanting. . Water with electrical conductivity of 3.2 dS m-1 reduced rootstock and scion diameter, crown diameter, crown volume, and vegetative vigor index, as well as gas exchange and production components. The application of salicylic acid with concentrations ranging from 0 to 3.6 mM did not mitigate the effects of salt stress in guava plants cv. Paluma, at 390 days after transplanting. The concentrations varying from 0.6 to 3.6 mM of salicylic acid promoted an increase in the titratable acidity, total soluble sugars, ascorbic acid and soluble solids, respectively, in the pulp of guava fruits cv. Paluma irrigated with water of 3.2 dS m-1. The levels of reducing sugars, lipids and flavonoids in guava fruits were reduced under irrigation with water of electrical conductivity of 3.2 dS m-1, regardless of the applied salicylic acid concentration. The hydrogenic potential increased with the application of 3.6 mM salicylic acid and water with an electrical conductivity of 3.2 dS m-1.