The garlic plant (Allium sativum L) is a suitable indicator plant for the determination of potential genotoxic agents in the samples taken from the environment. Polyploidy has the utmost importance in horticulture for the development of new varieties with desirable morphological traits referring to plant size and vigor, leaf thickness, larger flowers with thicker petals, intense color of leaves and flowers, long lasting flowers, compactness, dwarfness and restored fertility. Polyploidy may occur naturally due to the formation of unreduced gametes or can be artificially induced by doubling the number of chromosomes in somatic cells. Usually, natural polyploid plants are unavailable, so polyploidy is induced synthetically with the help of mitotic inhibitors. Colchicine is a widely used mitotic inhibitor for the induction of polyploidy in plants during their cell division by inhibiting the chromosome segregation. The aim of this study was to determine the effect of various concentrations and duration of colchicine treatment on root length, number of roots and stomatal densities Allium sativum L.