| Sekundarni povzetek: |  
            Japanese knotweed (Fallopia japonica) and Bohemian knotweed (Fallopia × bohemica) are invasive alien species. In this study, we aimed to determine the effects of aqueous extracts from the rhizomes of Japanese and Bohemian knotweed, as well as three allelochemicals (emodin, epicatechin, and resveratrol), on cell division in the root tips of garden radish (Raphanus sativus). We prepared 10 % aqueous solutions from knotweed rhizomes, and separately dissolved allelochemicals in 33 % methanol. Radish seeds were germinated for three days in Petri dishes, where they were exposed to different treatments. After germination, the roots were fixed in a mixture of formaldehyde, acetic acid, and ethanol, hydrolyzed, and stained with Feulgen reagent, followed by the preparation of microscopic slides. Using a light microscope at 400 × magnification, we examined at least 1000 nuclei per slide, counted the cells in different phases of the cell cycle, and calculated the mitotic index. The obtained data were processed and statistically analyzed using Microsoft Excel 2016 and GraphPad Prism. The findings showed that the extract of Bohemian knotweed decreased the mitotic index, particularly reducing the number of cells in prophase and metaphase, indicating an inhibition of cell division. In contrast, Japanese knotweed had no effect on the mitotic index. Among the allelochemicals, emodin increased the mitotic index, while epicatechin and resveratrol showed no statistically significant effects on cell division. |