Effect of flowering on the concentrations of some plant toxins and micronutrients in the leaf of Vernonia amygdalina (Bitter leaf)

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Research Paper 01/06/2017
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Effect of flowering on the concentrations of some plant toxins and micronutrients in the leaf of Vernonia amygdalina (Bitter leaf)


The developmental stages of plants generally influenced their chemical constituents and compositions as the physiology and biochemical reactions in plants vary with their developmental phases. It is against this back ground that the experiment was conducted to evaluate the influence of flowering on the concentrations of some plant toxins (cyanide, nitrate, soluble and total oxalates) and micronutrients (vitamin C, β-carotene (Provitamin A) and mineral elements (Fe, Mg, Zn, Cu, Ca, Na and K) in the leaf of Vernonia amygdalina grown on nitrogen and non-nitrogen treated soil. The leaves of V. amygdalina were harvested and analysed at market maturity and flowering. The concentrations of nitrate, cyanide, β-carotene and mineral elements were determined by spectrophotometric method while the concentrations of vitamin C, soluble and total oxalates were evaluated by titrimetric method. The results  showed that the concentrations of cyanide, nitrate, soluble and total oxalate, β-carotene and vitamin C increased significantly (p < 0.05) in the leaves of V. amygdalina during flowering irrespective of soil nitrogen levels, except that the elevation in β-carotene content was only significant in control. The concentrations of Fe, Mg, Ca and K decreased significantly (p < 0.05) in the leaves of V. amygdalina during the flowering; however, significant reduction in the concentration of Mg was observed only when nitrogen fertilizer was applied. The concentrations of Zn and Na were not significantly (p > 0.05) affected during flowering of V. amygdalina. The study concludes that the plant toxins are concentrated more during flowering than at at market maturity in V. amygdalina.


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