Understanding floral biology and pollination behavior of Stylosanthes spp. to enhance improvement programs

The significance of a range legume Stylosanthes spp. is long established in grassland ecosystems. However, its potential for the nutritional security of livestock remains underexploited. A better understanding of floral behavior will assist in its improvement through improved hybridization techniques, seed production and breeding schemes. Only limited studies have been conducted on the floral biology of Stylosanthes spp. The current study focused on floral morphology, anthesis, longevity and pollen viability of four Stylosanthes spp. viz., S. hamata, S. seabrana, S. viscosa and S. scabra. The anthesis time varied among the Stylosanthes species studied here and the maximum anthesis occurred during Indian Standard Time (IST) from 8.00 AM to 10.00 AM. The flower longevity of Stylosanthes spp., lasted for a day after the anthesis. All the species were found to be protandrous, as pollen dehiscence occurred 1 to 2 hours before anthesis. The time of the highest pollen viability (85.08 ± 2.16%) coincided with stigma receptivity. After two hours of anthesis, higher receptivity and maximum activity of stigma was observed in S. hamata compared to other Stylosanthes species. Furthermore, S. scabra showed the maximum pollen count while estimating a number of pollen per anther and flower.