Effects of herbicides Illoxan and Racer on mitosis and chromosomes in the root tip cells of Allium cepa

EFFECTS OF HERBICIDES ILLOXAN AND RACER ON MITOSIS AND CHROMOSOMES IN THE ROOT TD? CELLS OF ALLIUM CEPA ( Ph. D. Thesis) Deniz YÜZBAŞIO?LU GAZI UNIVERSITY INSTITUTE OF SCIENCE AND TECHNOLOGY July 2001 ABSTRACT The effects of illoxan and racer herbicides on mitosis and chromosomes in the root tips of Allium cepa were investigated. LD50 values of both herbicides were determined using root growth inhibition test and then the treatment concentrations were selected. LD50 value of illoxan and racer were determined as 150 ppm and 80 ppm, respectively. The treatment concentrations were choosed as LD50, LD50/2, LD50/4. The roots of A. cepa were treated with these concentrations for 12, 24 and 48 hours. Mitotic indices and mitotic phase frequencies were calculated for each concentration and treatment period. The results indicated that both herbicides clearly reduced the mitotic indices at 48 hr treatment of LP50 values. The total percentage of mitotic aberrations increased with increasing of concentrations and period of treatments for both of illoxan and racer herbicides. The most common types of mitotic abnormalities are micronuclei, chromosome stickiness, C-metaphase, fragments, bridges, laggards and multipolarity. Both herbicides induced chromosomal abnormalities as well. These abnormalities are: fragments, chromosome and chromatid breaks, sisterunion and poliploidy. Science code : 401.01.03 Key Words : Herbicide, mitosis, mitotic abnormalities, chromosomal aberrations. Page number : VII+105 Adviser : Assoc. Pof. Dr. Fatma Ünal