LAUSR

Trials were set to assess low temperature effects on growth and development of Phalaenopsis. Different temperature treatment groups were set to maintain an average day/night temperature of 29/21, 26/20, 26/18(°C). Phalaenopsis Red Swan, Big Chili and Fuller's Sunset were all coordinated by the cold-induced release of reproductive bud dormancy. The morphological development of flower bud differentiation was similar in Phalaenopsis Big Chili and Sogo Yukidian: flower organ differentiation began with the formation of the outer tepal primordia, followed by the inner tetal primordia and finally, by the lip and column (stamen and carpel) primordia. The earlier the flower bud started differentiation, the earlier the flower bloomed. The inflorescence primordium differentiation started under 26/18 and 26/20 and no flower stalks emerged under 29/21 within 50 d. Different temperature treatments did not affect significantly the length of flower stalk. But temperature played a possible important role in leaf growth. High temperature (29/21) favored vegetative growth than 26/20 and 26/18. It was found ABA and GA3 levels in apical meristems of stalk increased before flower bud differentiation. High level of IAA decreased when the stalk began rapid elongation (longer than 5cm), and ZR levels at apical meristems were higher than at leaves.