Aplicação exógena de peróxido de hidrogênio e sacarose e tolerância de genótipos de soja ao excesso de manganês

Abstract

We investigated the relationship between the tolerance to waterlogging and manganese excess, and the effects of the pretreatments with hydrogen peroxide and sucrose in the tolerance of soybeans genotypes to manganese excess. For this, plants of soybeans from BRS Taura RR, BMX Apolo RR and AN 8500 genotypes in V1 stage were transferred to nutrient solution and were acclimated for 21 days. Then, plants were sumitted to four treatments: normal Mn, Mn excess, 10 mM H2O2 pretreatment for six hours followed by manganese excess, 90 mM sucrose pretreatment for six hours followed by hypoxia with manganese excess. Manganese concentrations were 2 μM for hypoxia and 1 mM for manganese excess treatments and the pH of the nutriente solutions was set for 4.5. After 15 days of treatment, plants that were in V5 stage were harvested for the analysis. We evaluated the intensity of manganese toxicity symptons, dry matter, activity of antioxidant enzymes, ascorbate and hydrogen peroxide levels, photosynthetic pigments, ecophysiological parameters and manganese quantification. There was a relationship between the tolerance of the genotypes to waterlogging and manganese excess. BRS Taura RR showed physiological reponses that are typical of stress sensitive plants, while BMX Apolo RR and AN 8500 had a similar behavior under stress, with typical tolerant responses to manganese excess. Hydrogen peroxide pretreatment was more effective in promoting adaptative responses in BMX Apolo RR and AN 8500, while sucrose was more efficient for BRS Taura RR.