Okra cultivation under irrigation with saline water and foliar application of hydrogen peroxide

Abstract

Foliar application of hydrogen peroxide can induce plant defense mechanisms against salt stress, favoring plant acclimation in regions with qualitative and quantitative scarcity of water resources, such as the Brazilian semi-arid region. From this perspective, this study aimed to evaluate the effects of foliar hydrogen peroxide application on chlorophyll a fluorescence, growth, and production of okra under irrigation with saline water. The experiment was conducted under field conditions in Pombal, PB, using a randomized block design with a 5 × 3 factorial arrangement corresponding to five electrical conductivity levels of water – ECw (0.3, 1.3, 2.3, 3.3, and 4.3 dS m-1) and three hydrogen peroxide concentrations – H2O2 (0, 25, and 50 μM), with five replications. Irrigation water salinity levels up to 2.2 dS m-1 increase the maximum fluorescence of okra plants 75 days after transplanting. Foliar application of 50 µM hydrogen peroxide proved to be beneficial for plant height, stem diameter, stem dry matter, root dry matter, and total dry matter of okra when plants were grown in low-salinity water. The hydrogen peroxide concentrations of 25 and 50 µM increased the number of leaves. However, these concentrations reduced the average weight of the okra dry fruits. Foliar application with 50 µM hydrogen peroxide had a significant effect on the dry leaf phytomass of the okra cv. Clemson American 80 regardless of the electrical conductivity of irrigation water. Foliar hydrogen peroxide application at concentrations up to 50 µM intensifies the deleterious effects of salt stress on the total weight of dried okra fruits. Keywords: Abelmoschus esculentus L., acclimation, salt stress.