Abstract

                                The present study aimed to visualize the chromium reduction in the rhizosphere of vetiver. Vetiver was grown in rhizoboxes supplemented with metal solutions such as Ni, Pb, Zn, and Cr(III) with sand as a medium for 30 days. At the end of the experiments, it was observed that Cr(III) (40.0 mg kg-1) was accumulated more in the roots than the shoots compared to Ni (14.5 mg kg-1), Pb (12.0 mg kg-1) and Zn (11.6 mg kg-1). But on the contrary, Zn is accumulated more (58.5 mg kg-1) in shoots than in the roots compared to Ni (23.1), Pb (19.3), and Cr(III) (21.9). In order to validate this, root exudate activity of Vetiver was observed visually as a change in pH using bromocresol purple as an indicator. More root acidification was triggered by Pb and Cr(III). The rhizofiltration of Cr(III) to roots can be attributed to the enhanced root acidification and hence more accumulation. The Cr(VI) reduction was also visualized around vetiver roots using DPC as an indicator. This method is test verified and can be used as a quick method to screen plants for their root exudation potential for metal mobilization or filtration onto roots.

Key words : Heavy metals; Vetiver; Phytoremediation; Root exudation activity