Multidirectional effects of exposing freesia corms to chilling on flower bud initiation, flower bud development and flower stalk elongation, and corm formation.

摘要

Corms of Freesia hybrida cv. Cote d'Azur averaging 6.7 g, which had been stored at 30oC for 10 weeks, were potted, exposed to seven temperature regimes from 3 to 21oC for 6 weeks and then transferred to 23oC. Flower buds were observed microscopically at the end of exposure to 6, 9, 12, 15 and 18oC. The developmental stage of flower buds was most advanced at 12 and 15oC; however, the flower buds initiated at 12, 15 and 18oC failed to develop floral parts, and the elongation of the flower stalks wasgreatly suppressed upon transfer to 23oC. Whereas plants exposed to 9oC for 6 weeks subsequently flowered at 23oC, those exposed to 6oC developed malformed inflorescences having abnormally elongated bracts and lacking floral organs. At 23oC, the apical meristems of plants exposed to 3oC continued to initiate leaf primordia, while those exposed to 21oC formed bract-like organs. Daughter corm formation 10 weeks after transferring plants to 23oC was most advanced in plants previously exposed to 12oC for 6weeks.