アリウム・コワニーの生育と開花に及ぼす温度の影響

Abstract

In this study, the growth periodicity of plants of Allium cowanii (syn. A. neapolitanum with large flowers), grown in an unheated plastic house, was clarified. Simultaneously, the effect of temperature on the initiation and development of flower buds was investigated.A bulb shows a sympodial branching system from mid-September to early December; 2 to 3 inflorescences are initiated as a result of repeated sympodial branching. The first inflorescence initiated in mid-September, the primordium of florets becoming visible in early and mid-October; the tepals and stamen are differentiated from late October to mid: November, leading to anthesis in mid-February of the following year. A second inflorescence is initiated in mid-October and bears flowers in early March. To assess a) the starting time of bulb storage, b) duration of storage, and c) storage temperature, bulbs were stored at 15°, 20°, 25°C, or 30°C from 1 July to 1 October or at 9°, 15°, 20°, 25°C, or 30°C from 1 August to 1 October. At the end of the storage periods, the initiation of the first inflorescence was observed at all temperetures below 25°C, but the optimum temperature was 15°20°C. Most bulbs stored at 30°C were in the vegetative state.When bulbs were grown in a greenhouse kept above 10°C after different periods of temperature treatment, those stored at lower temperatures bloomed earlier, except for those stored at 15°C from 1 July; they had low percentages of flowering plants. However, the number of flowering inflorescences per bulb was small.Plants grown above 20°C after planting in early October flowered 18 days earlier than did those grown at above 10°C. The early blooming scapes were shorter and had fewer florets than did the late blooming ones.