W. RODER¹, S. TSHERING², J. DORJI³, C. SAMDUP⁴ and P. WANGCHUK⁵

¹RNR-Research Center Jakar,
²RNR-Outreach Center Tingtingbi,
³RNR-Research Sub Station Lingmethang,
⁴RNR-Outreach Center Pemagatsel, and
⁵RNR-Research Sub Station Bhur, Bhutan

Abstract

Desmodium intortum is a promising fodder legume for subtropical areas in the Himalayan region and has shown outstanding performance across a range of conditions in Bhutan. However, its promotion has been limited by the lack of seed. In an effort to develop technologies for local seed production, effects of location, altitude, spacing, irrigation, closing date and physical support on flowering and seed production were evaluated at locations between 26°–28°N. Silverleaf desmodium (D. uncinatum) was added in some of the studies to expand the scope of the investigations. In 1997, average yields at 3 locations were 0–23.0 g/m² for Greenleaf desmodium and 0.6–78 g/m² for Silverleaf desmodium. Across the elevation range of 640–1590 m, location and elevation had no consistent effect on flowering date and seed production of Greenleaf desmodium. Irrigation treatments applied over 2 years had no effect at a location with an annual rainfall of 1100 mm. Greenleaf desmodium seed yield was not affected when row spacing was increased from 50 cm to 100 cm and yield was only marginally reduced (16%, P < 0.08) when the spacing was increased further to 150 cm. Cutting in May and June reduced seed yield. Providing support with bamboo sticks increased pod formation and seed yield consistently over 3 years. The results established that Greenleaf desmodium seed production is feasible in the Himalayan foothills and allowed for the release of recommendations for commercial seed production.