The genotoxic effect of lead and zinc on bambara groundnut (Vigna subterranean)

The effects of lead and zinc treatments on the chromosomes of bambara groundnut was investigated. The seeds of bambara groundnut were placed in Petri dishes in three replicates and allowed to germinate for five days in different concentrations: 25, 50 and 100 mg/L of both lead and zinc nitrates while the control group had distilled water. The total aberrations were examined. The mitotic index was calculated and the results were statistically evaluated by the analysis of variance at 5% significant level. The mitotic index decreased as the concentration increased (p<0.05). The highest mitotic index value was 3.40±0.88 for the control while the least was 1.30±0.48 for the 100 mg/L Pb treatment. The results show the most frequent chromosomal anomalies induced by these heavy metals as stickiness and bridges. Pb is much more genotoxic than Zn, as it induced more aberrations having percentage abnormalities of 92.3% while Zn had 30.0% for the highest concentration tested. Increased metal pollution can lead to some irreversible cytogenetic effects in plants and higher organisms. The study is an attempt to corroborate the toxic effect of lead and zinc on the chromosomes of plants. These results will be useful in environmental monitoring of the cytotoxicity of metals.Key words: Heavy metal, aberrations, genotoxic, cytogenetic, mitotic index

Cytogenotoxicity evaluation of two industrial effluents using Allium cepa assay

The cytogenotoxic effects of the industrial effluents from paint (0, 7.2, 18, 36 and 72%) and textile (0, 1.6, 4, 8 and 16%) manufacturing were evaluated using root tip cells of Allium cepa. In this study, root length and chromosomal aberration assays were used to determine the 96 h effective concentration (96 h EC50), root growth inhibition, mitotic index and chromosome aberration rate. Based on the 96 h EC50, textile effluent was 4.5 times more toxic than the paint effluent. Analysis of Variance (ANOVA) showed that there was significant difference (P < 0.05) in the mean root length of A. cepa exposed to different concentrations of the industrial effluents. This indicated that the root growth inhibition was concentration dependent. The mitotic index (MI) decreased with increasing concentrations of paint and textile industrial effluents. The two industrial effluents induced chromosomal aberrations in root tip cells of A. cepa with vagrant chromosome, bridges and fragments and sticky chromosomes being most frequently observed. At lower concentrations bridges and fragments were the most common aberration. The suitability of A. cepa chromosomal assay as a tool for monitoring the genotoxic effects of industrial effluents and wastewater is discussed

Removal of Pb and Zn from Soil using cowpea (Vigna unguiculata) and maize (Zea mays) Plants

This study investigated the potential of cowpea (Vigna unguiculata) and maize (Zea mays) plants to remove Pb and Zn from soil. The crops were exposed to three concentrations (100, 150 and 200 mgkg-1) of each metal salts during the study. When the plants were treated with lead nitrate at a concentration of 150 mgkg-1, the amount and percentage of Pb removed and accumulated within plants’ tissues were 65.68 m mgkg-1g/kg (44.79%) and 78.93 mgkg-1 (53.0%) for cowpea and maize with bioconcentration factors 0.80 and 0.78 respectively. However, when the plants were assisted they had greater bioconcentration factors. Farmyard manure enhanced metal uptake by cowpea and maize significantly than EDTA. Maize extracted more Pb into its roots and translocated to shoots when assisted with EDTA than cowpea. Maize was able to translocate more Pb while cowpea translocated more Zn through the vascular system, thereby acting as phytoextractors for the different metals respectively

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