Production from both wild harvest and cultivation: The cross-border Swertia chirayita (Gentianaceae) trade.

ETHNOPHARMACOLOGICAL RELEVANCE

Swertia chirayita is the most widely traded species in a genus of 150 species, many of which are used in traditional medicine. S. chirayita is used mainly in Ayurvedic and Tibetan systems of medicine and the homoeopathic system of medicine as well as in regional folk medicine. Primarily wild collected, with some cultivation. S. chirayita is traded as a medicinal substance and exported in the forms of dried whole plant or extract of whole plant individually and/or as active ingredients of Ayurvedic medicines. S. chirayita export valuations continue to make S. chirayita one of Nepal's highest foreign exchange earning medicinal plant species.

AIMS OF THE REVIEW

The aims of this review were first, to assess the scale of the global trade in S. chirayita, second, to review evidence from plant population biology and from studies on the impacts of wild harvest on S. chirayita populations and cultivation as an alternative source of supply.

METHODS

The taxonomy and trade names for S. chirayita were reviewed, followed by a synthesis of published information on Swertia population biology and studies on impacts of wild S. chirayita harvest from across the geographic range of this species. Data on the prices paid for S. chirayita were then compiled for the period 2001-2017, followed by an analysis of global trade data for S. chirayita.

RESULTS AND CONCLUSIONS

Based on India import data and assuming an estimate in an earlier study that 60% of Nepal's S. chirayita production goes to India and 35% to Tibet, then Nepal's 2013 annual production was about 711 metric tonnes (MT) of which about 675.6 MT would be exported (India + Tibet). Nepal's 2014 annual production would be an estimated 503.25 MT of which about 478 MT would be exported. Declines in S. chirayita populations have been widely noted across its range. In India, since 2004, a ban was placed on the export of wild harvested S. chirayita by the Government of India, where the Director General of Foreign Trade prohibited export of S. chirayita plants, plant portions and their derivatives and extracts obtained from the wild with the exception of 'formulations'. Cultivation of S. chirayita to meet commercial demand has been an important part of a solution to over-exploitation of wild stocks in eastern Nepal for 25 years, producing significant quantities that enter the export trade to India and Tibet. In Sankhuwasabha district, for example, 53.1 MT of S. chirayita were produced in 2013/014, just over half of which (27 MT) were exported to India, with the remainder exported to Tibet. Based on value-chain analysis and cost-benefit assessments, S. chirayita cultivation has been shown to be profitable in Nepal. However, since the first cost-benefit assessment was done (2013), prices dropped from NRs750/kg in April 2013 to a low of 250 NRs/kg in December 2017). Taking inflation into account further highlights the steep decline in the profitability for local farmers, who have limited options for value-adding. Consequently, farmers prefer to grow more profitable alternative crops, such as Nepal cardamom (Amomum subulatum Roxb.).