An assessment of copper-contaminated soil using Kenaf (Hibiscus cannabinus l.) as a phytoaccumulator

A pot experiment was conducted to study the potentials of Kenaf (Hibiscus cannabinus L.) as a Copper (Cu) phytoaccumulator at different levels of artificial contamination. Copper was applied as cupric sulphate (CuSO4.5H2O) and the treatments were 0, 50, 100 and 150 mg kg-1 of Cu. Kenaf was grown in each of the treated pots for 10 weeks, following which, leaf, stem and root samples were collected and analysed for Cu contents. The soil was analysed for physicochemical properties [viz. pH, electrical conductivity (EC), organic carbon (OC), exchangeable acidity (EA), exchangeable cations (Ca2+, Mg2+, Na+, K+) and extractable and total Cu contents) before treatments/contamination and after harvesting. Kenaf showed symptoms of toxicity at 100 and 150 mg kg-1 treatments of Cu. It was observed that, compared with the levels of contamination of Cu, the concentration in kenaf was generally insignificant; thus, the concentration reduction in the soil at one cycle of cropping may not berealistic.  Copper treatments at different levels significantly changed soil pH and EC. Therefore, more cycles of growth are needed to effectively remediate Cu-contaminated soils using Kenaf as Cu phytoaccumulator.