Penconazole and potassium upregulate antioxidant defense to conferring simulated drought tolerance in wheat plants

To explore the role of penconazole (PEN) and potassium (K) in controlling reactive oxygen species (ROS) production, accumulation of osmotically active substances and antioxidant defense system in wheat plants under drought conditions, an experiment was conducted. Two cultivars of wheat plant (Moghan and Sirvan) were treated by different PEG concentrations (0, 5, 10 and 15%) without or with PEN (15 mg L-1) and K (1 M). Drought caused damaging effects on growth attributes in both cultivar and Sirvan cultivar was more sensitive to drought stress. Enhanced levels of the hydrogen peroxide (H2O2) and malondialdehyde (MDA) were evident that drought stress induced oxidative stress in both cultivars. The activities of antioxidant enzymes were significantly declined under drought conditions. Drought stress enhanced accumulation of proline and soluble sugar as osmotic substance in both cultivars. In contracts to Sirvan cultivar, the content of antioxidant metabolites (total phenol, flavonol and anthocyanin) augmented under drought conditions. PEN and K application improved growth and regulated acclimation responses in wheat plants. Reduction in H2O2 and lipid peroxidation (MDA content) by PEN and K showed that PEN and K aided to alleviate drought-trigged oxidative stress in wheat plants. Noteworthily, soluble sugar dominated than proline in the osmotic regulation in stressed plants treated with PEN and K. PEN and K strengthened the enzymatic and non-enzymatic antioxidant systems in wheat plants. In summary, PEN and K provided a better defense to wheat plants against drought stress and positive impacts of PEN and K were related to improved physiological and metabolic processes under drought conditions.