Reproductive biology and breeding system of Saraca asoca (Roxb.) De Wilde: a vulnerable medicinal plant

Abstract

Ashoka (Saraca asoca) is a perennial, evergreen tree valued for its ornamental flowers and medicinal values. This species is classified as ‘vulnerable’ under IUCN list due to its dwindling population because of destructive harvesting from natural habitats. Therefore, conservation and multiplication of this species is need of the hour to utilize its astonishing medicinal uses eternally. Conservation approaches of any plant species require in-depth study of its reproductive biology, which is lacking in this species. The present study is the first detailed report on reproductive biology of S. asoca. This tree bears fragrant flowers in paniculate corymbose inflorescence from December end to May, with peak flowering during February–March. The fruits attain its maturity during last week of May–July. Seeds were dispersed from the pod to the tree premises upon complete maturity. The time of anthesis in this species is noticed in the early morning from 3.00 to 5.30 am, which coincided with anther dehiscence, stigma receptivity and insect activity. The length of the stamen and pistil points towards the pollination compatibility in both male and female parts. Pollen viability was maximum within 2 h of anthesis, which decreased thereafter and no pollens were viable after 6 h. The stigma was receptive at the time of anthesis and continued for 24 h. The tree produces bright colour attractive flowers, which changed from yellow/light orange to scarlet/red from the inception of buds to wilting. The bright color of the flowers attracted floral visitors/pollinators thereby facilitated the pollination in this species. The observations of the floral biology and breeding system indicated the cross pollination behaviour, which limited the production of selfed seeds and would help to maintain the sustainable levels of heterozygosity among the various populations. Considerable amount of seeds produced in this species indicated that the species is capable of sustaining its progenies in the natural populations. Polyembryony to an extent of 5% was also recorded in this species.

Flowering Phenology and Seed Production of Santalum album L.

“…A superfluity of workers reported the existence of significant differences in flowering biology in various tree species like Faidherbia albida (Gassama Dia et al, 2003), Butea monosperma (Rajesh Tandon, 2003), Acacia saligna (George et al, 2009), Terminalia pallid (Solomon Raju et al, 2012), Pittosporum dasycaulon (Gopalakrishnan and Thomas, 2014), Syzygium alternifolium (Solomon Raju et al, 2014), Cinnamomum sulphuratum (Shivaprasad et al, 2015), Pterospermum reticulatum (Keshavanarayan et al, 2015), Saraca asoca (Smitha and Thondaiman, 2016), Santalum album (Ratnaningrum et al, 2016) and Croton scabiosus (Nagireddy, 2016) which thus lend support to the current findings in Santalum album.…”

Assessment of genetic diversity of Saraca asoca (Roxb.) De Wilde: a commercially important, but endangered, forest tree species in Western Ghats, India

“…regions are ecologically very encouraging signs that indicate genetic mixing is occurring naturally via pollination. Earlier studies on the breeding system and floral biology of this species indicate the strong predominance of outcrossing, which helps to maintain the heterozygosity in the various populations (Smitha and Thondaiman 2016). Therefore, the gene pool is not likely to be threatened immediately.…”

Reproductive Biology of Rheum webbianum Royle, a Vulnerable Medicinal Herb From Alpines of North-Western Himalaya

“…Phenological events (sprouting, vegetative phase, flowering, fruiting, seed maturation, and senescence) were monitored on tagged plants (seven plants from each site) at their three locations on a population basis. During the flowering period, observations were carried out on a daily basis, while for fruit and seed traits, the observations were carried out once a week (Tandon et al, 2003;Verma et al, 2003Verma et al, , 2004Smitha and Thondaiman, 2016).…”