オーニソガラム・アラビカム（Ｏｒｎｉｔｈｏｇａｌｕｍ ａｒａｂｉｃｕｍ Ｌ．）の開花に及ぼす温度の影響

Abstract

This study was carried out to observe the progress of flower formation under natural conditions and also to investigate the effect of temperature on the initiation and development of flower buds in Ornithogalum arabicum L.Florets are normally initiated in early September. The primordia of the outer and inner tepals of the first floret appear in late October and carpel primordia are formed in late December. Further development of flower buds continues slowly until mid-April, when the pollen tetrads are formed and the plants bloom in mid-May.Plants which were moved in late October from outdoors to the greenhouse kept above 20 °C flowered in late February. Cut flowers with long scapes were obtained in March by exposing plants to the natural low temperature until late January.When plants were subjected to 5°13 °C for 8 weeks from tepal to outer stamen formation stages, flowering and scape elongation were accelerated. However, within the range from 5° to 13 °C, higher temperature hastened the development of flower buds to carpel primordia formation and resulted in earlier flowering. This accelerating effect was obtained even when plants were exposed to 9 °C from bract primordia formation stage. Flowering of bulbs exposed from 5° to 13 °C were similarly accelerated, the wet ones more so than dry ones.The percentage of bulbs producing flowers increased with increasing storage period at 30 °C after harvest over those stored at 20 °C. This implied that exposure of bulbs to 30 °C was more favorable to flower bud formation than 20 °C.