Differential antioxidative enzyme responses of Jatropha curcas L. to chromium stress.

Chromium (Cr) tolerant and accumulation capability of Jatropha curcas L. was tested in Cr spiked soil amended with biosludge and biofertilizer. Plants were cultivated in soils containing 0, 25, 50, 100 and 250 mg kg(-1) of Cr for one year with and without amendment. Plant tissue analysis showed that combined application of biosludge and biofertilizer could significantly reduce Cr uptake and boost the plant biomass, whereas biofertilizer alone did not affect the uptake and plant growth. Antioxidative responses of catalase (CAT), ascorbate peroxidase (APX) and glutathione S-transferase (GST) were increased with increasing Cr concentration in plant. Hyperactivity of the CAT and GST indicated that antioxidant enzymes played an important role in protecting the plant from Cr toxicity. However, APX took a little part in detoxification of H(2)O(2) due to its sensitivity to Cr. Therefore, reduced APX activity was recorded. Reduced glutathione (GSH) activity was recorded in plant grown on/above 100 mg kg(-1) of Cr in soil. The study concludes that J. curcas could grow under chromium stress. Furthermore, the results encouraged that J. curcas is a suitable candidate for the restoration of Cr contaminated soils with the concomitant application of biosludge and biofertilizer.