EFFECT OF TEMPERATURE ON THE FLOWERING OF OMITHOGALUM-ARABICUM L

This study was carried out to observe the progress of flower formation under natural conditions and also to investigate the effect of temper ature on the initiation and development of flower buds in Ornithogalum arabicum L. Florets are normally initiated in early September. The pr imordia of the outer and inner tepals of the first floret appear in la te October and carpel primordia are formed in late December. Further d evelopment of flower buds continues slowly until mid-April, when the p ollen 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 degrees C flowered in late February. Cut flowers with long scapes were obtained in March by exposing plants to the natural low temperatu re until late January. When plants were subjected to 5 degrees similar to 13 degrees C for 8 weeks from tepal to outer stamen formation stag es, flowering and scape elongation were accelerated. However, within t he range from 5 degrees to 13 degrees C, higher temperature hastened t he development of flower buds to carpel primordia formation and result ed in earlier flowering. This accelerating effect was obtained even wh en plants were exposed to 9 degrees C from bract primordia formation s tage. Flowering of bulbs exposed from 5 degrees to 13 degrees C were s imilarly accelerated, the wet ones more so than dry ones. The percenta ge of bulbs producing flowers increased with increasing storage period at 30 degrees C after harvest over those stored at 20 degrees C. This implied that exposure of bulbs to 30 degrees C was more favorable to flower bud formation than 20 degrees C.