Pretreatment with H2O2 in maize seeds: effects on germination and seedling acclimation to salt stress

The aim of this study was to evaluate the effects of H2O2 on germination and acclimation of maize plants subject to salt stress. Three experiments using BRS3003 seeds, a triple hybrid of maize, were carried out in a growth room and in greenhouse. In the first experiment, H2O2 accelerated the germination percentage of seeds at 100 mM, but not at 500 mM. In the second experiment, the pretreatment of seeds was observed to induce a pronounced increase in ascorbate peroxidase (APX) and catalase (CAT) enzyme activity after 30 h of soaking in H2O2. It was also observed that guaiacol peroxidase (GPX) activity was smaller in the seeds soaked in H2O2 for 12, 24, 30, 36 and 42 h, in relation to those soaked in distilled water. The superoxide dismutase (SOD) activity was not affected by the pretreatment of seeds, except for the 24 h treatment. Only one CAT isoform was detected. In the third experiment, seeds were pretreated with 36 h soaking in 100 mM H2O2 solution or in distilled water and later cultivated in Hoagland's nutrient solution or nutrient solution with 80 mM NaCl. The results showed the pretreatment of seeds with H2O2 induced acclimation of the plants to salinity. It decreased the deleterious effects of salt stress on the growth of maize. In addition, the differences in antioxidative enzyme activities may explain the increased tolerance to salt stress of plants originated from H2O2 pretreated seeds.