GROWTH AND ANTIOXIDATIVE RESPONSES TO EXCESS CADMIUM IN KENAF (Hibiscus cannabinus L)

摘要

In order to study the mechanisms responsible for cadmium (Cd) detoxification in Kenaf (Hibiscus cannabinus L), the growth and antioxidative responses of the plant grown on a Cd polluted soil were investigated. Kenaf seeds were grown in artificially contaminated soils containing increasing concentrations of Cd as CdCl_2 (0, 150, 300, 450 and 600 mg Cd kg~(-1)) for 14 weeks in a screenhouse. Growth parameters (plant height and stem girth), Cd concentration, oxidative lipid peroxidation, glutathione (GSH) content, activity of antioxidant enzymes, superoxide dis-mutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) were measured using established techniques. Cd inhibits growth as shown by decrease in plant height and stem girth at all concentrations used compared with control. Plant Cd concentrations increased with soil Cd concentrations, with maximum Cd uptake being 73.37±8.82 mg kg~(-1) dry weight at 600 mg Cd kg~(-1). The content of malondialdehyde (indication of lipid peroxidation) showed a significant (p<0.05) increase in Kenaf shoots at 150 and 300 mg Cd kg~(-1) level of treatment, while the content of non-enzymatic antioxidant, GSH, showed a significant (p< 0.05) depletion at all treatment levels compared with control. Activity of SOD was increased while the activities of CAT and APX were inhibited at all Cd concentrations used. Results show that Cd induces oxidative stress in Kenaf and that both enzymatic and non-enzymatic antioxidants play significant roles in Cd detoxification in Kenaf.