In vitro bulb formation of Narcissus asturiensis, a threatened species of the Amaryllidaceae

The culture conditions for in vitro production of bulbs of Narcissus asturiensis were determined. The process was initiated using twin-scales as primary explants that were cultured on a modified MS medium supplemented with IBA (4.9 muM) + BA (8.87 muM) or NAA (0.65 muM) + BA (26.6 muM). Both media were appropriate for shoot induction and proliferation, although the multiplication rate of leafy shoots was higher on the medium with NAA and BA. After 60 d of culture on both media, tiny bulb-like structures appeared at the base of the leaves; however, the medium with IBA was the most suitable for bulb induction. Further growth of the bulbs was achieved on a similar basal medium with only NAA and with an increased sucrose content (9%). After 90 d of culture on this growth medium, bulbs attained a mean diameter of 8 mm but the production of roots was low. Root induction was performed on four rooting media (MS salt solution with NAA or IBA and half strength MS salt solution with NAA or IBA), the highest number of rooted bulbs was on the medium with reduced inorganic salt concentration plus NAA. Rooted bulbs adequately prepared for ex vitro culture were then transferred to a glasshouse and the success of transplantation is under evaluation.