The phenylurea cytokinin 4PU-30 protects maize plants against glyphosate action

The effects of the phenylurea cytokinin 4PU-30 and the herbicide glyphosate, applied alone and in combination on young maize plants were investigated. The influence of the compounds on the changes of growth, chlorophyll content, levels of hydrogen peroxide, and some stress markers, the activities of peroxidase, catalase, and glutathione-S-transferase, as well as glutathione amount were measured 3, 6, and 10 days after the treatment. The application of glyphosate increased the levels of lipid peroxidation, glutathione, and free proline content, ion fluxes, and the activity of catalase, guaiacol peroxidase, and glutathione-S-transferase, i.e., along with the inhibition of its target enzyme the herbicide induced also an oxidative stress. We found that the phenylurea cytokinin 4PU-30 alleviated in some extent the detrimental effects due to the glyphosate action. Moreover, we speculated that the cytokinin renders its protective action by induction of “hardiness” in the antioxidant defense systems in maize plants similarly to the effects observed after the application of some herbicide safeners.