Effects of Ethylene Exposure on Dormancy and Flowering for Early Forcing of Dutch Iris cv. Blue Magic

Bulbs of ‘Blue Magic’ were exposed to ethylene at different times following harvest to investigate effects of ethylene on dormancy breaking and flowering. When bulbs were in a state of dormancy, ethylene showed a slight promotive effect on their sprouting but little effect on flowering. After bulbs experienced high temperature and their dormancy was broken, ethylene increased markedly the flowering percentage, even when using bulbs of 7cm size which were too small to induce flower buds.Ethylene may cause non-dormant bulbs, emerged from dormancy, to progress from a juvenile phase into the stage of ripeness to flower and thus augment the accelerating effects of low temperature following ethylene treatment. As a result, high flowering percentage can be obtained in early forcing of Dutch iris.