The Japanese knotweed (Fallopia japonica) is nowadays in Europe known as a strongly invasive alien plant species. Its dissemination success is related with the effect of the secondary metabolites which are released to the soil by the plant. So-called alelopatic compounds can be found in the leaves and roots or also in other parts of the Japanese knotweed. The alelopatic effect is mostly noticeable as an inhibition of the germination and as growth of the roots and shoots of the close growing plants. The inhibition of the roots growth can be related to the reduced number of the cell division in the root tips.
In this dissertation we tried to discover how the leaf and the root extract of the Japanese knotweed have an impact on the root growth and the cellular division in the root tip of the radish. The seeds of the radish were watered with 5 % extract of the leaves and roots of the Japanese knotweed. From the third to the seventh day of the sprouting we made notes on the germination of the seeds and the length of the roots of the cotyledons. We fixed the root tips and prepared the specimen with coloured genetic material. We counted the number of the divided and undivided cells of the root tip under the microscope. We expressed the proportion with the mitotic index. The results were compared with the t-test.
The seeds, treated with the extract of the leaves of the Japanese knotweed, germinated with a delay. The length of the roots of the treated cotyledons was shorter than the length of the control cotyledons wherein the leaf extract decelerated the growth of the roots with more strength than the root extract. Adding of the leaf and root extract of the Japanese knotweed resulted as a lower mitotic index in the root tip of the radish.
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