The wild Ricinus communis was found to accumulate more nickel from sewage water contaminated soil (Krishnasamy et al., 2004). Though the wild type removed more Ni from the contaminated soil, the farmers don't prefer this for phytoremediation purposes because of its perennial nature and less remuneration. So, this effort has been taken to screen Ricinus communis cultivars for Ni accumulation.

Green house experiment was conducted to screen Ricinus communis varieties viz., TMV 5, TMV 6, TMVCH 1 and wild type for Ni accumulation by growing them in two different Ni contaminated soils viz., sewage water and electroplating effluent contaminated soils. Tissue metal concentrations was analyzed using Atomic Absorption Spectrophotometer, spectra, 200. The metal accumulation ratios were calculated by using the formula outlined by Barman et al. (2000). Metal concentration in plant (mg kg-1) Metal accumulation ratio = Total metal concentration in soil (mg kg-1)

The bioaccumulation of Ni was higher in wild type (1551 mg kg-1) followed by the cultivable variety TMV 5 (1373 mg kg-1), which might be a function of their metabolic status. The wild type was more efficient in transforming Ni from soil to plant (8.55) followed by TMV 5 (7.52 ). The efficiency was more pronounced when grown in sewage water contaminated soil than electroplating effluent contaminated soil (2.56 and 2.33 respectively). Roots of all varieties accumulated more Ni from the contaminated soil followed by grain. From the above results, it was inferred that wild type was found to be effective accumulator of Ni irrespective of the source of pollution and no much difference was observed between wild castor and the variety TMV 5, with respect to the Ni accumulation pattern. Hence, these two varieties can be recommended for the decontamination of the Ni contaminated soils.

Keywords: bioaccumulation, electroplating, metal accumulation ratio, nickel, phytoextraction,

REFERENCES

Barman, S.C., Sahu, R.K., Bhargava, S.K. and Chaterjee, C. 2000. Distribution of heavy metals in wheat, mustard and weed grown in field irrigated with industrial effluents. Bull. Environ. Contam. Toxicol. 64 : 489 – 496. Krishnasamy, R., Malarkodi, M. and Chitdeshwari, T. 2004. Remediation of metal contaminated soils by using indigenous hyper accumulators. In: Third International Workshop on Chemical Bioavailability in the Terrestrial Environment, Adelaide, South Australia. Pp: 193 –194.