Cytological effects of fungicide topsin in Allium cepa.

Cytogenetic Effects of Fungicide Afugan on the Meristematic Cells of Allium cepa L.

“…The chromosomal bridge formation can be due to the general stickiness of the chromosomes at metaphase or because of breakage and reunion of chromosomes indicating clastogenic effect of the chemical used (Tomkins andGrant 1972, Badr 1988). Bridges were also observed in the mitosis of A. cepa after treatment with the fungicide dithane and denmart (Badr 1988) and topsin (Somashekar et al 1984). In the present study, fragments were also observed in some treatments.…”

“…60 ppm concentration of afugan was toxic in 48h treatment and no dividing cells was observed. Decreasing in mitotic index have been reported to other pesticides (Cortes et al 1982, Somashekar et al 1984, Badr 1988, Ahmad and Yasmin 1992. Decreasing of the MI could be due to blocking of G 1 suppressing DNA synthesis (Schneiderman et al 1971) or a blocking of G 2 preventing the cell from entering mitosis (Van't Hof 1968).…”

“…C-mitosis indicated that, the chemical inhibited spindle formation similar to the effect of colchicine (Badr 1988), and induction of C-mitosis commonly associated with spindle poisons, indicating turbogenic effect (Shahin and El-Amoodi 1991). Several investigations were able to induce C-mitosis in plant cells using different fungicides (Somashekar et al 1984, Badr 1988, Shahin and El-Amoodi 1991.…”

“…Sticky chromosomes indicated that the chemical highly toxic, usually not reversible effect and probably leading to cell death (Fiskesjö 1985). Several fungicides have been reported to induce stickiness (Somashekar et al 1984, Badr 1988, Ahmad and Yasmin 1992.…”