Karyotype Analysis of Ten Species of Ipomoea Jacq.

抄録

The genus Ipomoea with about 500 species is distributed in the tropical and subtropical regions of the world. The species are not only among the most beautiful ornamental plants, they are also important because of their medicinal value. The present study deals with the karyotype analysis of 10 species of Ipomoea growing in Maharashtra state of India. All the species analysed are diploid, showing 2n=30. I. aquatica has the smallest chromosomes, 1.25 to 2.67 μm, with a mean length of 1.99(±0.38), and the total length of the haploid component as 29.88 μm, while I. carnea has the longest chromosomes, at 2.13 to 4.79 μm, with mean length as 3.39(±0.74) and total length of the haploid component at 50.83 μm. The karyomorphological investigations revealed that none of the species had a symmetrical karyotype. The degree of asymmetry was, however, low. Amongst the several parameters studied, that of Stebbins (1971) and the AI values were found to be the most reliable for assessing asymmetry. The species falling under group 2B of Stebbins had higher AI values as compared to those of group 1B, proving that they are more evolved. The heterogeneity within the 10 species could be traced by AI values.