Aplicação exógena de peróxido de hidrogênio como atenuante ao estresse salino em quiabeiro.

Abstract

Salinity is one of the main abiotic stresses that limit plant growth and productivity, particularly in the semiarid region of northeastern Brazil, aggravated by low rainfall, high temperatures and evaporation. In this context, it is necessary to search for strategies that alleviate salt stress in plants, highlighting the exogenous application of hydrogen peroxide as a promising alternative. Therefore, this study aimed to evaluate the morphophysiology, production, water consumption and efficiency in the use of okra water under irrigation with water of different saline levels and exogenous application of hydrogen peroxide, where the plants were conducted in 20 L lysimeters under field conditions, at the Agrifood Science and Technology Center belonging to the Federal University of Campina Grande, Pombal, PB. The treatments were distributed in a randomized block design, in a 5 x 3 factorial arrangement, with five levels of electrical conductivity of the irrigation water (0.3; 1.3; 2.3; 3.3 and 4.3 dS m-1) and three concentrations of hydrogen peroxide (0, 25 and 50 μM), with five replications, totaling 75 plants. The okra plants cv. Clemson Americano 80 were sensitive to water salinity from 0.3 dS m-1, showing a reduction in plant growth, gas exchange, production components, water consumption and water use efficiency. Foliar application of 25 μM of H2O2 promoted greater reduction in production per plant, number of fruit and water use efficiency of okra plants, at 82 days after transplanting. The inhibition of CO2 assimilation rate of okra plants was associated with stomatal and non-stomatic factors. Hydrogen peroxide at a concentration of 50 μM attenuated the effects of salt stress on transpiration, CO2 assimilation rate, instantaneous carboxylation efficiency, dry mass of leaves and average fruit weight of okra cv. American Clemson 80.