Influence of storage temperature and its duration before or after ethylene exposure on the formation of flower buds in Dutch iris cultivar ‘Blue Magic’

Abstract

Exposing bulbs of Dutch iris ‘Blue Magic’ to ethylene (C 2H 4) immediately before subjecting them to precooling (9°C for 9 weeks) resulted in a high percentage of flower bud formation. If bulbs exposed to C 2H 4 were stored at 15, 20 or 25°C for more than 8 weeks and at 30°C for more than 16 weeks before precooling them, the promotive effect of C 2H 4 was gradually lost. The C 2H 4 response could be restored by exposing the stored bulbs to C 2H 4. Bulbs stored at 15,20 or 30°C before exposure to C 2H 4 showed a high percentage of flower bud formation, but those stored at 10°C did not form flower buds even after C 2H 4 exposure. Among the storage temperatures, 30°C was the most effective. To optimize flowering of Dutch iris cultivar ‘Blue Magic’, especially when using small bulbs, bulbs should be stored at 30°C, exposed to C 2H 4 and then precooled as soon as possible.