Excessive cobalt induced oxidative stress in groundnut

In groundnut (Arachis hypogea L.), cv. Kaushal excess concentration of cobalt (Co) in the growing medium developed visual symptoms of toxicity that intensified with increasing level and duration of metal supply. The tissue concentration of Co increased and Zn and Fe decreased with increasing level of Co supply. There was a marked increase in the activities of antioxidant enzymes, viz. superoxide dismutase, ascorbate peroxidase, nonspecific peroxidase and H₂O₂ content which suggest induction of oxidative stress under excessive cobalt. The pattern of increase in proline content and decrease in dry matter, yield, lipid peroxidation, catalase activity with increase in Co concentration suggests that groundnut is sensitive to excessive Co supply.