Ex-situ cultivation at lower altitude and evaluation of Swertia chirayita, a critically endangered medicinal plant of Sikkim Himalayan region, India

Abstract

Swertia chirayita (family Gentianaceae) is internationally renounced and one among the 32 prioritized medicinal plants by National Medicinal Plants Board, New Delhi, Government of India. S. chirayita is a critically endangered plant of temperate Himalayas. Deplete population of S. chirayita from wild has necessitated its conservation through ex-situ cultivation. The study is therefore taken up for the ex-situ cultivation of S. chirayita in lower altitude (tropical hills) of Sikkim Himalayan region. The produce of the plants cultivated ex-situ and in niche environment was compared and evaluated as per Ayurvedic Pharmacopoeia of India (API) norms and for swertiamarin content. As per API norms the total ash and acid insoluble ash was below the permissible limits of 6% and 1%, respectively. Leaves harvested from the ex-situ cultivated plant showed lower 0.68% acid insoluble ash compared to 0.78% in leaves of mature plants harvested from niche environment. The alcohol-soluble extractive, water soluble extractive and total bitter content were higher (16.84%, 22.44%, and 4.57%, respectively) in leaves of the ex-situ cultivated plant compared to the leaves harvested from plants cultivated in niche environment (15.28%, 15.96%, and 3.95%, respectively). Besides the API norms, swertiamarin content was higher (0.27%) in leaves of the ex-situ cultivated plant compared to leaves harvested from plants cultivated in niche environment (0.22%). The stem harvested from plants cultivated in niche environment failed as per API specifications due to lower alcohol and water soluble extractives and very low swertiamarin content. The study shows successful harvesting of leaves with high swertiamarin content up to one year of the growth period from the ex-situ cultivated plants at lower altitude. Two additional harvestings are suggested from the plant cultivated in niche environment while maintaining the plant for further growth before final yield. Seeds harvested from mature plants cultivated at higher altitude are suggested for utilization for the ex-situ cultivation of crop at lower altitude in Sikkim Himalayan region.