Naphthalene effect on some morphological and physiological features in Helianthus annus L.

Polycyclic Aromatic Hydrocarbons (PAHs) are one of the stresses that inhibit plant growth and distrupts balance between the production of Reactive Oxygen Species and antioxidant defense activities of plant. Naphthalene is the main pollutant in the petrochemical industry, which is located on the list of toxic pollutants. In this study to evaluate the effect of Naphthalene on some parameters of oxidative stress and anatomical features in Helianthus annuus L., an experiment was conducted in a randomized design with three replications in hydroponic culture. Seedlings that grew in normal conditions were transferred to a hydroponic culture, after 14 days of treatment with naphthalene (30, 50 mg/L) they were harvested and their anatomical and biochemical parameters were studied. The results showed that the activity of antioxidant enzymes (SOD, PO, APX) and the contents of malondialdehyde (MDA) and chlorophyll  a and b increased. Due to naphthalene treatment, reduction of root growth, white spots and necrosis in leaves were observed. Number of stem trichromes were elevated and stem xylem expanded,additionally there were changes in xylem formation and arrangement in stressed plants.