Influence of selenite and selenate on growth, leaf physiology and antioxidant defense system in wheat (Triticum aestivum L.).

BACKGROUND: Selenium (Se) induced oxidative stress as well as synthesis of non-specific selenoproteins has been attributed to its toxicity in plants. Selenium toxicity can affect growth, chlorophyll and protein synthesis and crop yield. This study reveals the effects of different sources (sodium selenite and sodium selenate) and levels (2 and 4 mg Se kg-1 soil) of Se on its uptake, leaf physiology, antioxidant defense system, isoenzymic patterns and mitochondrial activity in wheat cultivar PBW621 at tillering and ear-initiation stages. RESULTS: Higher Se accumulation in leaves of wheat plants was observed in selenate than control and selenite treatments. Selenium tolerance index, chlorophyll, photosynthetic efficiency, mitochondrial reduction test, electron transport system activity, lipid peroxidation, proline and glutathione in Se-treated wheat plants decreased significantly as compared to control. Significant increase in hydrogen peroxide and activities of antioxidant enzymes, namely catalase, peroxidase, superoxide dismutase, glutathione reductase in leaves was due to the presence of Se-induced oxidative stress in wheat plants. CONCLUSION: Wheat cultivar PBW621 could adapt to applied selenite concentrations by developing antioxidant defense system but selenate treated plants could exhibit toxicity tolerance up to 2 mg kg-1 and died at high concentrations due to damage to tissue development and function. © 2018 Society of Chemical Industry.