Physiological responses of mulungu submitted to salt stress and application of salicylic acid

Abstract

Mulungu (Erythrina velutina Willd.) is a forest species native to the Northeast region of Brazil, being used for economic and medicinal purposes. However, its physiological performance can be compromised by several biotic and abiotic factors, among them, saline stress. That way, the application of salicylic acid, phytohormone of phenolic origin, becomes a promising strategy in the search to minimize these deleterious effects. Thus, the objective was to learn the physiological responses of mulungu irrigated with saline water associated with the application of salicylic acid. The design was a randomized complete block, in an incomplete factorial scheme, using the Box Central Composite (CCB) matrix with five levels of electrical conductivity of irrigation water (0.5; 1.74; 4.75; 7.76 and 9.0 dS m-1), and five salicylic acid doses (0.0, 0.29, 1.0, 1.71 and 2.0 mM), with four replicates. Gas exchange, fluorescence and chlorophyll indices were evaluated 60 days after irrigation with saline water. Data were submitted to analysis of variance by the F test, in cases of significance polynomial regression analysis was performed. The salinity of irrigation water causes deleterious effects on the gas exchange of Erythrina velutina Willd. The chlorophyll indices were positively affected by saline levels applied and the initial fluorescence of the plants was attenuated by the application of salicylic acid.