Hydrogen peroxide in the acclimation of yellow passion fruit seedlings to salt stress

Abstract

ABSTRACT The objective of the present study was to evaluate the effect of exogenous application of hydrogen peroxide on the emergence, growth and gas exchange of yellow passion fruit seedlings subjected to salt stress. The experiment was conducted in pots (Citropote®) under greenhouse conditions, in the municipality of Campina Grande, PB, Brazil. Treatments were distributed in a randomized block design, in a 4 x 4 factorial arrangement, with four levels of electrical conductivity of irrigation water (0.7, 1.4, 2.1 and 2.8 dS m-1) associated with four concentrations of hydrogen peroxide (0, 25, 50 and 75 μM), with four replicates and two plants per plot. Irrigation using water with electrical conductivity above 0.7 dS m-1 negatively affects the emergence and growth of passion fruit. Hydrogen peroxide concentrations between 10 and 30 μM induce the acclimation of passion fruit plants to salt stress, mitigating the deleterious effects of salinity on the relative growth rate in stem diameter and leaf area, stomatal conductance, transpiration, CO2 assimilation rate and instantaneous carboxylation efficiency. Irrigation water salinity combined with hydrogen peroxide concentrations above 30 μM causes reduction in passion fruit growth and physiology.