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Iron is an essential metal at micro-concentration for the growth of plants and their metabolic activities.
Excess Fe2+ concentration generate oxidative stress within sub cellular compartments of the plant cell
which are derived from the metabolism of oxygen. To combat the oxidative damage plants have the
antioxidant defense system to remove, neutralize and scavenge the Reactive Oxygen Species (ROS) which
is produced during heavy metal stress. The paper examines the effect of excess of FeSO4 on the activities
of some antioxidative enzymes, catalase and peroxidase in roots and shoots of Safflower seedlings. Fe2+
solution treated Safflower seeds with different concentrations were sown in plastic pots and incubated at
greenhouse conditions. Fresh roots and shoots were collected at different intervals to evaluate the enzyme
activity. Protein estimation and enzyme assay were carried out using standard methods. The activity of
peroxidase (POX) and catalase (CAT) of Carthamus tinctorius treated with Fe2+ mainly displayed
biphasic responses with increased metal concentration. In the present investigation, the excess of Fe2+
(100-200 mg.l1-) induced toxicity in root and shoot of C. tinctorius. The results indicated an enhancement
in the activity of peroxidase in shoots, suggesting that this enzyme serves as an intrinsic defense tool to
resist Fe-induced oxidative damage in safflower plants, while catalase did not appear to be an efficient
scavenger of hydrogen peroxide (H2O2) than POX. However, results indicated that the exposure of
C.tinctorius to iron provoke pronounced responses of antioxidative systems which protects the plants to
some extent against oxidative damage.
Key words: Antioxidant, Catalase, Peroxidase, Toxicity, Biphasic.