Abstract

Chromium (Cr) is one of the most toxic heavy metal and is discharged into the environment through various anthropogenic and mining activities. Current investigation have made a comparative assessment on toxic impacts of varying doses of hexavalent chromium with respect to its antioxidative enzyme (Catalase and Guaiacol Peroxidase) response and proline accumulation in two cultivars (IC-283169 and IC-336684) of Indian wild rice (Oryza nivara) grown in hydroponics. Catalase activity showed significant gradual reduction with increasing treatment dose of Cr6+ in IC-283169 cultivar of O. nivara after 14 days of exposure period. A constant insignificant impact of Cr6+ up to the treatment concentration of 25 μM was observed in IC-336684 cultivar of O. nivara. Catalase activity was highly stimulated showing a value of 20 μkat g-1 fresh weights with the treatment of 50 μM Cr6+ for 14 days of seedling growth. At an early stage of seedling growth i.e. for 7 days treatment, seedlings of IC-283169 cultivar of O. nivara showed high peroxidase activity (maximum at 75 μM Cr6+ treatment) as compared to that of IC-336684 cultivar. After 14 days treatment, IC-336684 cultivar showed high peroxidase activity (maximum at 100μM Cr6+ treatment). Proline content was maximum in IC-283169 cultivar of O. nivara after 14 days growth period at 100μM Cr6+ treatment. Above results revealed the toxic impacts of Cr and plant response in respect to its free radical scavenging potentiality as an antioxidative protective system

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