Survival and phyto-extraction of heavy metals by Nauclea diderrichii (De Wild. & T. Durand) Merr. plantlets in spent engine oil medium

Investigation was carried out on the phyto-extraction potentials of Nauclea diderrichii grown in tissue culture medium contaminated with spent engine oil with a view to determining the suitability of this tree species to remediate polluted soils for reclamation. This experiment was carried out in the Biotechnology Research Center, Forestry Research Institute of Nigeria, Ibadan, Oyo State. The experimental design used for this study was Completely Randomized Design with 9 treatments replicated 5 times. Concentrations 0 (control), 0.1, 0.2, 0.3 0.4 ml of spent engine oil (SEO) from diesel and petrol engines were applied to the medium of the plantlets. The survival of the plantlets was monitored while amount of heavy metals (Lead and Cadmium) present in the plantlets were assessed after 2 months. Data collected were subjected to descriptive analysis. After 2 months, results showed that 100 % of the plantlets without the application of SEO (control) survived, 60% of the plantlets subjected to 0.1 ml of SEO from diesel engine (D) and 0.1 ml of SEO from petrol engine (P) survived. Forty percent (40 %) of the plantlets subjected to 0.2 ml SEO from D and 0.2 ml SEO from P survived, 20 % of the plantlets subjected to 0.3 ml SEO from D and 0.3 ml SEO from P survived while plantlets subjected to 0.4 ml SEO from D and 0.4 ml SEO from P did not survive. There was difference in the amount of lead and cadmium of N. diderrichii plantlets subjected to different SEO from diesel and petrol engines. The Pb and Cd content in the tissue of plantlets subjected to SEO from petrol engine was higher than that of plantlets subjected to SEO from diesel engine. This might be due to the viscousity of the different SEO. The study revealed that contamination of the culture medium with SEO from both diesel and petrol engines can lead to a gradual accumulation of heavy metals showing the phytoremediation potentials of N. diderrichii. This study has been able to show that tissue cultured plantlets of N. diderrichii have the ability/potential to phyto-extract heavy metals from SEO contaminated medium.