IN-VITRO PRODUCTION OF BULBS OF NARCISSUS-BULBOCODIUM FLOWERING IN THE FIRST SEASON OF GROWTH

A procedure for in vitro production of bulbs of Narcissus bulbocodium was developed. For the induction of shoots, twin-scales were used as p rimary explants and four media were compared. Using the basal MS mediu m supplemented with BAP (4 mg/l)+NAA (0.12 mg/l) or BAP (2 mg/l)+IBA ( 1 mg/l) resulted in shoot initiation and leaf development. The first m edium also caused the production of amorphous achlorophyllous tissue a t the base of the shoots to a,a greater extent than the second medium. Both media were also appropriate for abundant shoot proliferation and when shoot clumps were cultured on the medium with BAP+IBA for a long period (70 days) tiny bulbs developed at the base of senescent leaves . The growth of these bulbs was achieved after two additional periods of culture on similar basal medium with or without NAA (0.12 mg/l), bo th with an increased sucrose content (9%). The presence of NAA did not significantly increase the final size of the bulbs but caused the dev elopment of a better root system. Bulbs grown on the media with 9% suc rose with 8.0 to 14.5 mm in diameter, after fungicide treatment, were transplanted into a soil mixture and grown for 1 month under a 12 degr ees C/9 degrees C regime to release the dormancy. Then, they were tran sferred to a glasshouse where they produced normal plants. The evaluat ion in three experiments, involving 3600-3720 bulbs, gave a figure of 92%-95% transplantation success and 90% of the bulbs flowered during t his first growing season. The procedure described here allows an in vi tro bulb production adapted to a successful transplantation and with t he capacity to flower in the first growing season. (C) 1998 Elsevier S cience B.V. All rights reserved.