In this research the genotoxic effects of spirotetramat have been determined by the meaning of mitotic index (MI) and chromosomal abnormality in Allium cepa L. root tip meristematic cells. For this
purpose the A llium test was carried out exposing roots to spirotetramat for 24 and 48 hours at the concentrations of 1 mL/L, 2 mL/L, 4 mL/L After the spirotetramat applications, root tips have been harvested and standart mitotic test procedures have been realized. The mitot ic index was calculated as the number of dividing cells per number of 1000 1500 observed cells and the chromosomal aberrations also were scored for each group Our results have showed that the mitotic index significantly decreased with the
increase of dose s and exposure times when compare to their controls According to our results, MI value has been decreased as 56% and 65% in 4 mL/L spirotetramat application after 24 and 48 hours respectively. As a result of our research, it was understood that the chromosomal aberration frequency increased in all application groups when we compare with the control group. According to chromosomal aberration frequency results, when we compare with control group chromosome aberration frequency increased approximately s even fold in 4 mL/ L spirotetramat applications
after 24 and 48 hours respectively. Our results showed that spirotetramat induced significant increases of chromosomal aberrations such as table and pole shifting , chromosomal bridge In addition that mitotic index (MI) decreased significantly with increasing of spirotetramat doses and the exposure time as compared to their controls.