Genotoxicity of Atrazine, Avenoxan, Diuron and Quizalofop-P-ethyl Herbicides using the Allium cepa Root Chromosomal Aberration Assay

Cytogenetic effects of different herbicides viz. Atrazine, Avenoxan, Diuron and Quizalofop-P-ethyl (QPE), were evaluated in the root tip meristem cells of Allium cepa. In the Allium root growth test, the effective concentration (EC50) value was determined as approximately 0.5 ppm in the case of Atrazine and Avenoxan and 1.0 ppm in the case of Diuron and QPE herbicides with a control for each combination. Mitotic index decreased with increasing herbicide concentration at each exposure time. In anaphase-telophase cells, the total percentages of different chromosomal aberrations like stickiness, bridges, break(s), ring chromosomes, vagrant chromosomes, c-mitosis, delayed anaphase, laggard(s) and micronuclei at high concentration (1 ppm) were calculated as 31.85% (Atrazine), 29.94% (Avenoxan), 36.66% (Diuron) and 41.04% (QPE). The total number of chromosome aberrations increased as herbicide concentration increased. Micronucleated cells were observed at different stages of the cell cycle. The frequency of the micronucleus was markedly higher at 1 ppm than at other test concentrations. _____________________________________________________________________________________________________________