Post-harvest fruit quality of grafted guava grown under salt stress and salicylic acid application¹

Qualidade pós-colheita de frutos de goiabeira enxertada sob estresse salino e aplicação de ácido salicílico

The semi-arid region of northeastern Brazil is characterized by irregular precipitation and high evapotranspiration, with a common occurrence of water sources with a high concentration of salts. In this context, this study aimed to evaluate the post-harvest fruit quality of grafted guava cv. Paluma under brackish water irrigation and foliar application of salicylic acid. The experiment was conducted under greenhouse conditions in Campina Grande, PB, Brazil, in a randomized block design, adopting a 2 × 4 factorial scheme, corresponding to two levels of electrical conductivity of 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 replicates. Electrical conductivity of 0.6 dS m^-1 and salicylic acid concentration of 2.4 mM resulted in higher levels of reducing sugars and soluble solids. Salicylic acid with concentration from 0.6 to 3.6 mM promoted increments in ascorbic acid and at concentrations of 1.9 and 1.5 mM increased the titratable acidity and total soluble sugars, respectively, in the pulp of guava irrigated with water of 3.2 dS m^-1. The hydrogen potential of the pulp increased with the application of salicylic acid, ranging from 1.2 to 3.6 mM, regardless of the electrical conductivity of the water.

Key words:
Psidium guajava L.; salinity; rootstock; phytohormone; chemical composition

Salicylic acid at a concentration of 2.4 mM increases reducing sugars under electrical conductivity of 3.2 dS m^-1.

Water salinity of 3.2 dS m^-1 and salicylic acid concentration of up to 3.6 mM promote higher contents of ascorbic acid.

The pH, total soluble solids, and ascorbic acid content obtained with water of 3.2 dS m^-1 meet commercialization standards.