Cu Tolerance and Accumulation by Centrosema Pubescen Benth and Mucuna Pruriens Var Pruriens
By Nwaichi, E.O. and Onyeike E.N.
In order to assess their practical capability for the absorption and accumulation of Cu, two common crop plants, i.e. Centro (Centrosema pubescens Benth) and Mucuna plants (Mucuna pruriens var pruriens) were tested in pot experiments using simulated crude oil polluted soil in the concentrations of 2, 4, 6, 8, and 10 % (v/w). A range of amendments of various types was tested for increasing the copper uptake with the test species and these included UREA fertilizer, NPK fertilizer and Chicken manure. Cu concentrations of the soil ranged from 201.1 to 271.5 mg/kg after spiking. Cu uptake and translocation into the shoots of Mucuna and Centro plants were 91 mg/kg and 6.25 mg/kg respectively, in the un – amended treatments at the highest contaminant dose of simulated spill. Amendments further took the observed levels to 90.1, 63 and 117 mg/kg Cu and 8, 23, and 10.92 mg/kg Cu for NPK, UREA and POULTRY amendments in Mucuna and Centro plants respectively. Cu root concentrations were markedly higher than those of the shoots for all Centro plants and the reverse for Mucuna species respectively. While POULTRY MANURE – assisted phytoextraction with Mucuna plants by all indices proved efficient, our study showed that Centro plants were not feasible to remediate the heavily or moderately contaminated soils simulated in order to achieve the target total metal soil concentrations irrespective of the amendments employed. Tests with NPK and UREA fertilizers indicated detrimental effects on copper uptake, biomass yield, and the translocation of copper from roots to shoots in Mucuna species.
Key Words: Copper; Phytoextraction; Toxicity; Amendments; Contamination; Bioconcentration factor (BCF).
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