Polyploidy and comparison of diploid and autotetraploid seedling of Madagascar periwinkle (Catharanthus roseus cv. alba)

ABSTRACT: To study the autotetraploidy induction inMadagascar periwinkle (Catharanthus roseus cv. alba) was conducted with colchicine at two true leaves. After record morphological changes, some samples from each treatment were analyses by flow cytometry to determine ploidy levels. Identification and proof autotetraploid plants were performed by flow cytometry and other cytogenetic techniques, then plants were grown favorable conditions in greenhouse seed production stage. Seed germination of diploid andtetraploidseedlings was evaluated. The results showed that increase in the ploidy level, caused to a significant increase in seed weight in the tetraploid plants. Germination rate and percentage of seeds were reduced(P?0.05) with increasing ploidy level. The root and shoot length were higher in diploid than tetraploid seedlings. The dry and fresh weight of seedling was higher in tetraploid than diploid, which was due to increase in stem and root diameter in tetraploid seedling. The seed vigor index was significantly reduced in the tetraploid plants. There was no significant difference in root to shoot length ratio between diploid and tetraploid plants.