In order to study the growth and flowering response of tulip (Tulipa sp.), narcissus (Narcissus sp.), and bulbous iris (Iris sp.), when they are grown in the non-heated greenhouse, harvested and graded bulbs received various high and low temperature treatments to break dormancy and to induce early flowering.
When tulip bulbs received 5 weeks of cold treatment and were grown under long day condition. ´Red Matador´ cultivar weighing 14∼15 g flowered at the end of January. In order to obtain more than 80 per cent flowering, large bulbs should be planted, paticularly with the ´President Kennedy´ cultivar.
High temperature and cold treatment given to the bulbs of Kings Alfred and Geranium narcissus also promoted flowering and when they are grown in flat, flowering was accelerated as compared to the plants grown in the raised bed. The requirement of high temperature and cold treatment varied according to the harvest date in native narcissus (Narcissus tazetta) in Jeju island.
It was possible to make the ´Blue Ocean´ and ´Ideal´ iris cultivars to flower in December by high temperature and cold treatment. However, with ´National Velvet´, flowering time was around March, although flowering was accelerated by high temperature treatment.
In ´National Velvet´, high temperature treatment during storage, not immediately after harvest, promoted flowering percentage which requires more detailed study in relation to the dormancy physiology and high temperature treatment.
|