The effects of the food preservatives potassium metabisulphite (PMB) and potassium nitrate (PN) have been studied on root tips of Allium cepa L. (variety Kantartopu-3). Roots of A.cepa were treated with a series of concentrations, ranging from 50 ppm to 100,000 ppm for 3, 6, 12, 24 and 48 h. Examinations of roots were done in permanent root tip squash preparations stained by the Feulgen technique. PMB and PN effect on the relative duration of each mitotic stage as compared with the control. They are also caused reduction in the mitotic index, indicating mitotic inhibition and increased frequency of abnormal mitosis. The type of abnormalities induced are chromosome stickiness, c-metaphase, anaphase and telophase bridges, disturbed chromosomes of anaphase and telophase stages, anaphase lagging and forward chromosomes at anaphase and telophase and micronuclei formation at intephase cells.

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SummaryIn the present study effects of the polyamines; putrescine (Put), spermidine (Spd) and spermine (Spm) have been studied on root tip mitosis of Allium cepa L. Root tips of A. cepa were treated with a series of polyamine (PA) concentrations, ranging from 0.01, 1 and 2 mM for 3, 6, 12, 24 and 48 h. The roots were examined in permanent root tip squash preparations stained by the Feulgen technique. This research has confirmed that PAs have various effects on chromosomes. PA concentrations used, generally had a marked mitodepressive effect on mitotic index (MI) but at 6 h treatment of Spm, Spd and Put at all concentrations had increased MI. Polyamines affected the relative duration of each mitotic stage as compared to the control. They also increased frequency of abnormal mitosis.The types of abnormalities induced are: chromosome stickiness, c-metaphase, anaphase and telophase bridges, disturbed chromosomes of anaphase and telophase stages, lagging and forward chromosomes at anaphase and telophase. Binucleate cells and micronuclei formation at interphase cells were also observed.

In this paper, chromosome number, karyotype and pollen morphology of Centaureagoeksunensis Aytaç & H. Duman, described in 2005, are studied for the first time. Centaurea goeksunensis is found to be tetraploid (2n=4x=60). This is the second record of polyploidy in Centaurea sect. Psephelloideae (Boiss.) Sons. The basic chromosome number of C. goeksunensis was found to be x=15 and the haploid karyotype formula is 18 m+10 sm+2 st. The pollen grains of C. goeksunensis were found to be radially symmetric, isopolar and tricolporate. They are intersemiangular in polar view and prolate–sphaeroidal in equatorial view. The exine is thickened at the poles.