The cytogenetic effects of two carbetamide containing herbicides have been investigated in the roots of Allium cepa. These herbicides are carbetamex and paradone plus. The two herbicides exerted a marked mitodepressive action on mitosis and induced a number of chromosomal aberrations. Chromosomal aberrations produced are comprised of C-metaphase, C-anaphase, chromosomal stickiness, bridges, lagging and multipolar anaphases and telophases. Both herbicides also induced the formation of multinucleated cells, micronuclei and chromatin bridges in interphase cells. In addition to these aberretions chromatin lost its staining ability or appeared as dense granules and nuclei were vacuolated. Details of aberrations are described and probable reasons for their induction are discussed. The mutagenic potentiality of the two herbicides is pointed out.
