Evaluation of the Toxicity of Urea Using Allium cepa L. Assay

Abstract

Considering the present abuse of fertilizer application today, an experiment was conducted to evaluate the toxic effects of urea on plants using the Allium cepa L. assay.  Onion bulbs were first placed in water for 48 hours to initiate root growth, then they were placed in different concentrations of urea (0%, 0.005%, 0.01%, 0.025%, 0.05%) for 24 hours. Both macroscopic and microscopic parameters show the toxic effect of urea. Root length and root number dropped in value with increase in treatment concentration. Likewise, the actively dividing mitotic cells also reduced in number with treatment concentration, thus giving rise to a drop in the mitotic index and a corresponding increase in mitotic inhibition with increase in treatment concentration of urea. These results all gave rise to a visible drop in root mass of the onion bulbs.

Keywords: Urea, Allium cepa assay, toxicity, mitotic index

DOI: 10.7176/JBAH/9-4-04