Journal of Environmental Biology

Impact of cadmium and lead on  Catharanthus roseus - A phytoremediation study

S. Pandey*¹, K. Gupta² and A. K. Mukherjee²

*spandey_01@rediff.com

¹Department of Botany, B. B. College, Asansol, Burdwan-713 303, India

²Department of Botany, The University of Burdwan, Burdwan-713 104, India

(Received: August 11, 2005 ; Revised received: November 06, 2006 ; Accepted: January 17, 2007)

Abstract: The Madagascar Periwinkle, Catharanthus roseus (L.) G. Don (a valued medicinal plant) was exposed to different concentrations of heavy metals like, CdCl₂ and PbCl₂ with a view to observe their bioaccumulation efficiency. Germination was inhibited by both the heavy metals in the seeds previously imbibed in GA₃ and KNO₃ for 24 hr. EC₅₀ (the effective concentration which inhibits root length by 50%) was recorded as 180 µM for CdCl₂ and 50 µM for PbCl₂. Both a-amylase and protease activity were reduced substantially on treatment of seeds with increasing concentrations of CdCl₂ and PbCl₂. Malondialdehyde (MDA) a product of lipoxigenase (LOX) activity also increased due to the treatment of both CdCl₂ and PbCl₂. When two-months-old plants grown in normal soil were transferred to soils containing increasing amounts of these two heavy metals, senescence of lower leaves and extensive chlorosis were noticed after four days of transfer. However, plants gradually acclimatized and after 20 days the chlorophyll content was almost comparable to normal. Plants receiving CdCl₂ treatment (250 µg g^-1 and less) became acclimatized after two weeks and started normal growth. But PbCl₂ of 432 µg g^-1 and less could not affect the plant growth throughout, after a preliminary shock was erased. In case of CdCl₂ treatment, a stunted growth with reduced leaf area, reduced biomass and sterility were recorded after six months, while plants show normal growth and flowering in case of PbCl₂ treatment. Total alkaloid was also found to be decreased in the roots of CdCl₂ treated plants. No change was observed in case of PbCl₂. GA₃ treatments to the CdCl₂ treated plants show internode elongation and increase in leaf area with relatively elongated leaves and thinning of stem diameter. AAS analyses of leaves of treated plants exhibited 5-10% accumulation of cadmium, but there was no accumulation of lead at all.

Key words:   Toxicity Cd and Pb stress, Phytoremediation, Catharanthus

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