Effect of sewage wastewater on the mitotic index of the root tips of Allium cepa in koya city /Kurdistan region of Iraq

The purpose of the experiment was to investigate onion (Allium cepa) root growth, cell division, and mitotic index. The onions were placed into four different water samples (Control water, Azadi bridge, Sar Razan, and Sar Baskan) for 72 hours in beakers. The results showed that the number of divided cells decreased significantly in the sewage water compared with the control water. The control water had a high percentage of divided cells (18%), whereas the Sar Razan sewage water had the least percentage of divided cells (1.3%). The percentage of divided cells in Sar Baskan sewage water was 2%, and the percentage of divided cells in Azadi Bridge was 2.6%. It was found that the mitotic index and the number of divided cells increased in the control water compared to the sewage water. The results showed that sewage water has a greater impact on root growth, cell division, and mitotic index of root tips of Allium cepa.