Induced Tetraploidy in <i>Vinca rosea</i> Linn

Abstract

Tetraploidy was induced in Vinca rosea Linn. by treating seeds with. 0.4%/ of aqueous colchinine. By selfing the C1 plants, C2 progeny was raised. The tetraploid is characterised by possessing a stout stem and branches, broader and shorter leaves, larger stomata, slower rate of growth, larger pollen grains and high pollen sterility. The total alkaloid content is more in both generations of the tetraploid plants. Mitosis in the tetraploid is almost normal. Meiosis in both Cl and Cz plants is irregular. It is analysed statistically. The presence of univalents, micronuclei of different shape, spindle abnormalities followed by aggregation of chromosomes into groups at metaphase, and anaphase, irregular anaphase and formation of polyads have been frequently observed in the PMC's.The coefficient of correlation between the abnormalities at different stages of meiosis and pollen sterility has been determined. There is no significant correlation between these irregularities and pollen sterility.