Technical Note: Vetiver Can Grow on Coal Fly Ash Without DNA Damage

Abstract

Fly ash is a by-product of coal-fired electricity generation plants. The prevalent practice of disposal is as slurry of ash and water to open lands or ash ponds located near power plants and this has lain to waste thousands of hectares all over the world. Wind and leaching are often the causes of off-site contamination from fly ash dumpsites. Vetiver (Vetiveria zizanioides) grown on fly ash for three months showed massive, mesh-like growth of roots which could have a phytostabilizing effect. The plant achieved this without any damage to its nuclear DNA as shown by comet assay done on the root nuclei, which implies the long-term survival of the plant on the remediation site. Also, when Vetiver is used for phytoremediation of coal fly ash, its shoots can be safely grazed by animals as very little of heavy metals in fly ash were found to be translocated to the shoots. These features make planting of Vetiver a practical and environmentally compatible method for restoration of fly ash dumpsites. Lack of DNA damage in Vetiver has been compared to that in a sensitive plant i.e. Allium cepa. Our results suggested that apart from traditional end-points viz. growth parameters like root length, shoot length and dry weight, comet assay could also be included in a battery of tests for initial, rapid and effective selection of plants for restoration and phytoremediation of polluted sites.

KEY WORDS:

• comet assay
• heavy metals
• phytostabilization
• Vetiveria zizanioides

Notes

^a V. zizanioides grown for 3 months in garden soil.

^b V. zizanioides grown for 3 months in fly ash sample.

^a A. cepa grown for 5 days and V. zizanioides grown for 3 months in garden soil.

^b A. cepa grown for 5 days and V. zizanioides grown for 3 months in fly ash sample.

*Significant at P ≤ 0.001; ns- non-significant at P ≤ 0.001.