The Influence of Pb and Zn Contaminated soil on the Germination and Growth of Bambara Nut ( Vigna subterranea  )

This research work takes a look at the possible phytotoxic effects of Pb and Zn as Pb(NO₃)² and Zn(NO₃)² on Bambara nut (Vigna subterranea) planted in polluted. Lead and zinc are common environmental contaminant found in soils. Unlike Zn, Pb has no biological role, and is potentially toxic to microorganisms. The bambara nut seedlings were irrigated with various concentrations of Pb and Zn (100,150 and 200mgkg^-1) ^.Effect of these metals on the growth parameters (stem length/height, root length, leaf area, yellowness of leaves, fresh and dry weights) were measured. Influence of heavy metals on the microorganisms in the soil used for planting as well as the organic matter, pH and moisture content of the soil were also evaluated. The results showed that plant performance significantly reduced with increasing concentrations (100,150 and 200mgkg^-1) of Pb and Zn contamination. The results show that a negative relationship existed between the different metal concentrations in the soil and the growth parameters (stem height, root length, leaf area, yellowness of leaves, fresh and dry weight) measured compared to control experiment. This study therefore reveals that these heavy metals have great implications on the sustainability of V. subterranea’s growth. These metals could pass down to humans through the food chain if animals eat such plants during grazing. This will affect their health, which may eventually lead to their death due to bio concentration and bioaccumulation. There would therefore be a need to explore ways of improving bambara nut production in areas of metal pollution.

Keywords
V. subterranea; Bioaccumulation; Pollution; Phytotoxicity; Contamination; bioaccumulation