Métodos de aplicação de peróxido de hidrogênio na atenuação do estresse salino no algodoeiro.

Abstract

In the semi-arid region of the Brazilian Northeast, the occurrence of water with high salt concentrations promotes osmotic and ionic limitations on plants, a situation that can be mitigated by the application of physiological conditioners, such as hydrogen peroxide. In this context, the present work aimed to evaluate the morphophysiology and production of cotton cv. BRS Jade under saline stress and hydrogen peroxide application methods. The research was carried out in a field belonging to the Federal University of Campina Grande, located in the municipality of Pombal, Paraíba. The experimental design used was randomized blocks, in a 5 × 4 factorial arrangement, with five levels of electrical conductivity of irrigation water (0.3; 2.0; 3.7; 5.4, and 7.1 dS m-1) and four methods of application of hydrogen peroxide -H2O2 (M1 - without application of H2O2, M2 - application via seed imbibition, M3 - application by foliar spraying and M4 - application by imbibition of seeds and foliar spraying), with three replicates and one plant per experimental unit. Increased water salinity reduces plant height, number of leaves, mass of cotton lint and total weight of seeds of 'BRS Jade' colored cotton. The method without hydrogen peroxide application provided greater chlorophyll a synthesis, photosystem II quantum efficiency and total dry phytomass. The hydrogen peroxide application method via seed imbibition attenuates the deleterious effects of irrigation salinity on stem diameter and leaf area. Hydrogen peroxide concentrations above 50 μM (via imbibition + foliar spraying) promoted reductions in leaf number and leaf area at a concentration of 7.1 dS m-1 of 'BRS Jade' colored cotton plants.