Effect of excess zinc on the concentration of some mineral element and antioxidant responses of spearmint (Mentha spicata L.)

The conditions used for spearmints growth in this work have been adequate for testing range of tolerance and adaptation to excess zinc. For studying oxidative changes, antioxidanic responses and metal accumulation in Spearmint (Mentha spicata L.) in reply to zinc, plants remained in a controlled environment for 12 weeks in nutrient solutions that contained different doses of zinc. This study showed that Zinc as heavy metal induced oxidative stress as evidenced by an increase in lipid peroxidation (malondialdehyde and other aldehydes). Under Zn treatments, phenolic compounds such as flavonoids and anthocyanins were increased significantly compared to control plants. The total protein content in leaves increased significantly by increment concentration of Zn but decreased with higher Zn supply. Lipid peroxidation (MDA) was increased only in the highest concentration of zinc. High levels of Zn decreased the shoot to root translocation of Zn and Fe which caused accumulation of these metals in root. In general, the results of this investigation proved high antioxidanic capacity in spearmint plants.