Effect of phenanthrene oil pollutant on physiological and biochemical characteristics of vetiver plant (Chrysopogon zizanioides)

Vetiver plant is from Poaceae family with high resistance, environmental compatibility and high ability for pollutants absorption, so can be used in environmental pollutions removal processes. Among petroleum compounds, polycyclic aromatic hydrocarbons are known as primary pollutants due to their stability in the environment. Phenanthrene usually has the highest concentration and most polluting among the petroleum aromatic compounds. In this study, vetiver was planted in pot with phenanthrene concentrations of zero (negative control), zero with acetone (positive control), 250, 500, 1000, 2000 and 4000 mg/kg soil dry weight and its physiological effects were investigated. At the highest concentration of phenanthrene the amount of chlorophyll and carotenoids decreased 20% and 21%, respectively, but phenolic compounds, proline and antioxidant activity were increased. Root and shoot weight at a concentration of 250 mg phenanthrene was significantly reduced compared to the control, but at subsequent concentrations, its decreasing slope was reduced. Root length and root volume also decreased. As phenanthrene is accumulated in root, so shows more decreases compare to shoot. Maximum accumulation of phenanthrene in vetiver root was 519 ppm in 4000 mg/kg soil dry weight phenanthrene concentration. Due to the resistance of vetiver to high concentrations of phenanthrene and its accumulation in roots, this plant can be used as a very suitable plant for the phytoremediation process of petroleum compounds.