Effect of Colchicine Treatment on the Autotetraploidy Induction and Morpho-Physiological Traits Alteration in Catharanthus roseus cv. alba

In order to evaluatem the colchicine treatments on autotetraploidy induction in Madagascar periwinkle (catharanthus roseus cv. alba)، an experiment was carried out on the frame of completely randomized design with four concentrations of colchicine (0، 0. 1، 0. 2 and 0. 4%) in six replications. Colchicine was applied in full bloom stage، and flow cytometry was used to determine ploidy levels. Results indicated that increment of colchicine concentration had significant effect on percentage of autotetraploidy and plant mortality in targeted plants. The highest auototetraploidy (44%) was observed at 0. 4% of colchicine concentration، while the highest viability after control treatment was recorded at 0. 1% of colchicine concentration. Result also showed a significant increase in stem diameter، number of lateral branches، leaf number، leaf area، flower diameter، peduncle diameter، chlorophyll a content، chlorophyll b content and total content of chlorophyll in tetraploid compared to diploid plants. In contrast، enhancement of ploidy level reduced plant height، while peduncle length remained unchanged and had the similar type in terms of growth in diploid and tetraploid plants.