Abstract

The Indian germplasm of Withania somnifera (L.) Dunal shows remarkable genetic variability both in the cultivated and the wild populations. The utilization of this variability through conventional breeding requires a clear understanding of its reproductive biology and breeding system. It is an amphimictic species practicing open pollination. However, a proximal placement of the stigma and the anther and a synchrony between the receptivity and dehiscence of anthers strongly predispose the species to self pollination and selfing. However open pollination results in equally high percentage of fruit and seed set as on controlled selfing indicating that the species shows facultative autogamy. This raises the probability of genetic improvement through hybridization. The somatic complements revealed a diploid number of 2n=48 in all the accessions tested. The absence of karyomorphological differences indicated that numerical and structural changes do not have a role in controlling the genetic variability of the species. Experimental crosses between the cultivated and the wild accessions produced viable seeds. A significantly higher fruit set and seed germ inability in crosses involving the cultivated types as the seed parent point to the existence of maternal effect.

Key words: Withania somnifera, floral biology, autogamy, geitonogamy, open pollination, ovule ratio and reproductive effort.