Effects of exposure of bulbs to high temperature on flowering of Allium cowanii Lindl.

The effect of exposing bulbs to high temperatures just after harvest on the flower-bud initiation and development in Allium cowanii was examined. Bulbs, stored at various temperatures under dry conditions were potted in early October and grown in a greenhouse kept above 10°C. 1. Bulbs which were harvested from plants grown the previous season in an unheated plastic house and thereafter stored in the same house for 2 months, flowered 27 days earlier than those harvested from plants grown outdoors and stored in a shed. 2. When bulbs were exposed to 25 or 30°C for various periods and stored at 9°C for 3 months, those exposed to 25 or 30°C for more than 12 or 4 weeks, respectively, initiated inflorescences. 3. When bulbs were exposed to 25, 30, 35 or 35/25°C (day/night) for 8 weeks from early May, followed by storage at 25°C for 3 months, those stored at 30 and 35°C produced 3 inflorescences per plant during December. Bulbs which were exposed to 30°C for 0, 4, 8 and 12 weeks, followed by the storage at 25°C for 3 months, flowered at different times ; those stored for 4 or 8 weeks flowered the earliest. 4. Bulbs stored at 30°C for 8 weeks, at 25°C for 2 months, and at 20°C for 1 month from early May flowered in mid-December and produced 3 inflorescences successively.