Cytological Effect of the Herbicide 2,4-D isooctylester 48% on Root Mitosis of Allium cepa.

Abstract

The effect of the herbicide 2, 4-D isooctylester 48% (Esteran 48) has been studied on root mitosis of Allium cepa. Root tips of Allium cepa were treated with a series of concentrations, ranging from 50 ppm to 50, 000 ppm for 3, 6, 12, 24 h. Examinations of roots were done in permanent root tip squash preparations stained by the Feulgen technique. Esteran 48 effects the relative duration of each mitotic stage as compared with the control. It also caused reduction in the mitotic index, indicating mitotic inhibition, and increased in the frequency of abnormal mitosis.The type of the abnormalities induced : chromosome stickiness, C-metaphase, tetraploid cells, bridges, laggards, tripolar anaphases-telophases and micronuclei.The effect of Esteran 48 on root mitosis simulates that of colchicine in the type of abnormal metaphase (C-mitosis) and induction of polyploidy cells as well as the accumulation of metaphases