Effects of temperature on the growth and flowering of Allium unifolium kellogg

Abstract

The growth periodicity of Allium unifolium plants grown in an unheated plastic house was assessed while simultaneously investigating the effect of temperature on the initiation and development of flower buds. In bulbs grown in an unheated plastic house, the first inflorescences were initiated in mid-November. They formed tepals and stamens in mid-January of the following year and bloomed from early to mid-April. Two weeks later, the 2nd and 3rd inflorescences were initiated in axillary buds and bloomed in mid to late April. When bulbs, which were planted in early October were grown in an unheated plastic house or a greenhouse kept above 10 °C, they flowered satisfactorily. However, those grown in a greenhouse kept above 20 °C had fewer flowered and shorter scapes. When bulbs were stored at 9°, 20°, 25°or 30 °C from 1 August to 1 October, flower bud initiation occurred at 9°to 20 °C, but the optimum range was 9°-15 °C. Bulbs stored at 9 °C bloomed earlier, but had fewer inflorescences when they were grown in a greenhouse kept above 10 °C. Flower buds of bulbs stored at 10 °C for 3 months were the earliest to differentiate; they flowered in mid-January if the greenhouse was kept 10 °C. Bulbs harvested from plants grown in an unheated plastic house in the previous season flowered 1 month earlier than did those harvested from plants grown outdoors, when they were stored at 10 °C for 3 months (early July to October) and grown at or above 10 °C.