EVALUATION OF METAL-ION TOXICITY ON ROOT-TIP CELLS BY THE ALLIUM TEST

The effects of different concentrations of eleven different metals (al uminum chloride, chromium nitrate and potassium dichromate, lead nitra te, copper sulfate, manganous sulfate, cobaltous nitrate, zinc sulfate , magnesium sulfate, nickel sulfate, cadmium chloride, and mercuric ch loride) on cell division and nucleoli in root tip cells of Allium cepa were studied. The results showed that the metal ions could, in varyin g degrees, cause chromosome, nucleus, and nucleolus irregularities, in cluding c-mitosis, chromosome bridges, chromosome stickiness, irregula rly shaped nuclei, micronuclei, irregularly shaped nucleoli, some silv er-stained material scattered in the nucleus, the weakening of silver- staining reaction at the periphery of the nucleolus, and the release o f nucleolar material from the nucleus into the cytoplasm. The Allium t est may be useful for the rapid screening of chemicals involved in env ironmental problems.