Antioxidant Responses of Helianthus annuus L. under Vanadium Stress.

Abstract

<span><span style="font-family: Calibri;"><span style="font-size: medium;">Vanadium (V) is a transition metal consistently distributed in the Earth's crust. At trace concentrations, it has been described as a beneficial element for some organisms; however, it is toxic at higher concentrations. This study was conducted hydroponically in a complete randomized design to investigate effects of V (0, 3.25, 7.5, and 15 mg L</span>^{<span style="font-size: small;">-1</span>}<span style="font-size: medium;">) on antioxidant system of sunflower. Results showed that all applied concentrations of V significantly decreased the plant growth, but increased the free amino acids, proline, malondialdehyde and H</span>_{<span style="font-size: small;">2</span>}<span style="font-size: medium;">O</span>_{<span style="font-size: small;">2</span>}<span style="font-size: medium;"> contents of plants. The antioxidant enzymes activities increased in response to the increase in V concentration. The activity of (Guaiacol) peroxidase showed a significant increase at 15 mg L</span>^{<span style="font-size: small;">-1</span>}</span><span style="font-family: Calibri; font-size: medium;"> V while the activities of catalase, glutathione reductase, and ascorbate peroxidase decreased significantly by application of V. There was a slight increase in the superoxide dismutase activity at different concentrations of V.<span> </span>The study concludes that the applied concentrations of V induced oxidative stress in sunflower and (Guaiacol) peroxidase was a more effective antioxidant enzyme in scavenging the free radicals in this plant.</span></span>