phytotoxic nature of different concentrations of zinc nanoparticles on Allium cepa L. root meristem cells.

This paper conducted to study the effect of different levels of zinc nanoparticles at concentrations (0,20, 40, 80, 100) µg/ml on the meristematic cells of plant roots Allium cepa, were used at different periods24, 42 and72 hour by estimating their effect on root length, root morphology, cell morphology, chromosomal abnormalities, mitotic index, Mitotic inhibition (Minh), micronucleus and percentage of abnormal cells in different phases of cell division and comparing them with control by hydroponics of A. cepa . The results showed the cytogenetic and genotoxic effects of ZnO NPs on the meristematic cells of A. cepa roots at high concentrations, as it had a negative effect on growth, as it was shown that the elongation of roots was severely inhibited at the highest concentration of zinc oxide NPs compared to the control (untreated A. cepa roots), significant effects of zinc nanoparticles were also observed on the chromosomal aberration and mitotic index with increasing concentration by decreasing of divided cell rates ,chromosomal aberration were also observed in divided cells of onion roots, which exposed to different concentrations at different period ,the higher frequent type of this chromosomal aberrations which observed are stickiness , disturbed, micronucleus and binucleated, no chromosomal aberration was observed in the control (untreated onion root tips) as for the percentage of abnormal cells in different stages of mitosis, it increased with the increase of ZnO NPs concentration, while division stages in root tips were clearly normal in control.