Genotoxicity testing of quizalofop-P-ethyl herbicide using the Allium cepa anaphase-telophase chromosome aberration assay

Cytogenetic effects of phenoxy herbicide viz. quizalofop-P-ethyl (QPE, ethyl (R)-2-[4-[(6-chloro-2-quinoxalinyl)oxy]phenoxy] propionate) were evaluated in the root meristem cells of Allium cepa. In the Allium root growth test, the effective concentration (EC50) value was determined as approximately 1.5 ppm. Cytological experiments were carried out using QPE concentrations of 0.75 (EC50/2), 1.5 (EC50) and 3 ppm (EC50x2) at 24, 48, 72, and 96 h, with a control for each combination. Mitotic index decreased with increasing the herbicide concentration at each exposure time. In anaphase-telophase cells, the total percentages of stickiness, bridges, vagrant chromosomes, c-anaphase, multipolarity, and fragments according to total cells with chromosome aberrations were calculated as 38.57, 28.42, 16.67, 14.10, 1.60, and 0.64%, respectively. The total chromosome aberrations increased with an increasing the QPE concentration. Micronucleated cells were observed at interphase. The frequency of the micronucleus was markedly higher at 3 ppm compared to other test concentrations.