A Comparative Study on the Reproductive Success of Two Species of Sesamum L. (Pedaliaceae)

A comprehensive knowledge on reproductive traits of a species is a prerequisite in utilizing the existing germplasm efficiently for crop improvement and to develop superior plants for grower acceptance and market profitability. Studies on floral biology and reproductive behaviour of the wild and cultivated species of Sesamum viz, S. radiatum and S. indicum from Kerala were carried out in the present investigation. Analysis of floral morphology revealed flowers were bisexual, zygomorphic and hypogynous with characteristic pink coloured flowers in S. radiatum and white in S. indicum. The study on phenoevents of the species showed earlier blooming and anther dehiscence in S. indicum compared to S. radiatum. Pollen fertility was found to be high in both species. Field observations on floral visitors showed that the flowers were regularly foraged by various insects such as ants, bees and beetles, of these the most frequent one was a species of Xylocopa. Hybridization studies revealed high percentage of crossability in the cross S. radiatum x S. indicum, while the reciprocal cross failed to set fruit, that may be due to the reproductive barriers existing between the species.