摘要： The effects of different concentrations of manganous sulphate on root growth,cell division,chromosome and nucleus morphplogy and nucleoli in root tip-cells of Allium cepa L.were studied.With increasing the concentration of Mn and duration of treatment,manganese inhibited root growth and cell division,and had toxic effects on chromosomes,nuclei and nucleoli.Manganese Could induce mitotic irregularities,comprising cmitosis,anaphase bridges and chromosome stickiness.The nuclei became irregular in shape and many micronuclei were scattered in the cytoplasm.Some similar silver-stained particulate materials were found scattered in the nucleus in root tip cells.The possible mechanism behind these phenomena is also briefly discussed.

关键词: Allium cepa, manganese, chromosome aberration, mitosis, nucleolus