Effect of Sewage Sludge Amendment on Non-enzymatic Antioxidants in Vetiver Plants (Vetiveria zizanioides L. Nash.)

Abstract

The study was conducted to evaluate the influence of sewage sludge application on the activity of non-enzymatic antioxidants in vetiver grass such as proline, ascorbic acid, total phenol and total free amino acids. Vetiver plants were grown in poly-ethylene U-V stabilized grow bags (24 X 24 X 40) for a period of three months (90 days), where the soil was treated with different sewage sludge concentrations (0, 25, 50,75 and 100%). After the experimental period, plants were harvested and analysed. The result showed activity of proline, ascorbic acid and total free amino acids was high in roots compared to that of leaves in the experimental plants, while the total phenol content was high in leaves than that in the roots. It was also noted that with an increase in the concentration of sewage sludge application, activity of all the selected antioxidants was also increased significantly (p < 0.05). Increased antioxidant activity in plants may be due to various environmental stresses to prevent damages due to ROS formation. Sewage sludge is a mixture of toxic compounds including PCBs, flame retardants, heavy metals, nano-materials, hormones, dangerous pathogens etc., which may induce the antioxidant defence system in vetiver plants to protect them from oxidation due to the generation of ROS. Therefore, the induction of non-enzymatic antioxidants in the present study is considered to be an important protective mechanism to minimize oxidative damage in vetiver plants grown in sewage sludge polluted environment. The study pointed out that the vetiver plants growing in sludge amended area have potentially developed the defence strategy to combat against toxicity induced stress. Therefore, the highly tolerant vetiver plants (Vetiveria zizanioides, L. Nash) may be used for phytoremediation purposes.