The effects of storage condition on starch metabolism and regeneration potentials of twin-scales and inflorescence stem explants of Narcissus tazetta

The natural propagation rate of Narcissus is very slow. In vitro micropropagation of Narcissus is more efficient than conventional propagation for rapidly building up aseptic stocks of varieties, especially for the establishment of new cvs. and the production of pathogen-free stock material. In the present study, Narcissus tazetta cv. 'Ziva' bulbs were used as the source of mother plants. The bulbs were kept at 30°C in a dark chamber until the start of the experiments. Prior to explant preparation, the bulbs were subjected to a cold treatment at 15°C in the dark for 6 wk to break dormancy. Twin-scales and inflorescence stem discs were isolated from aseptic bulb parts and were used as the initial explants. The polar orientation affected the regeneration of the inflorescence stem. Storage duration at 30°C followed by cold treatment were found to affect starch levels, adenosine diphosphate glucose pyrophosphorylase (AGPase) activities, and regeneration potentials. Starch levels were reduced significantly during a 10 mo. storage period at 30°C in both twin-scales and inflorescence stem disc explants. Regeneration was followed by an efficient acclimatization system with 98-99% survival. More than 500 highly uniform young bulbs were propagated from one mother bulb in a 12 mo. period.