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

G R Smitha,V Thondaiman

doi:10.1186/s40064-016-3709-9

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.

Highlights

IntroductionThe word Ashoka literally means “without sorrow”, a reference to this bark’s reputation for keeping a woman healthy and youthful (Nayak et al 2009; Pradhan et al 2009)
Botanical description Phenological studies The observations on season of flowering in all the three years data showed that the inception of flowering primordial in the leaf axils of ashoka occurred during early December
In view of the above, reproductive biology and pollination behavior of S. asoca was studied under ex situ conditions

Summary

Introduction

The word Ashoka literally means “without sorrow”, a reference to this bark’s reputation for keeping a woman healthy and youthful (Nayak et al 2009; Pradhan et al 2009) It is distributed in Central and East Himalaya, East Bengal, Burma, Western Peninsula, Ceylon and Malaya. Bark is extremely useful in gynecological problems, especially in the treatment of menstrual disorders associated with excessive bleeding, congestion, pain, dysmenorrhea, abdominal pain, and uterine spasms. It is used for leucorrhea and has an astringent but stimulative effect on endometrium and ovarian tissues (Nadkarni 1976; Nudrat and Usha 2005). There are various indigenous preparations available with Ashoka as a major constituent, of which the important ones include Ashokarishta, Ashokaghrita, Ashoka kwath (Ghose 1984; Pradhan et al 2009)

Methods

Results

Discussion

Conclusion