Effects of cultivars and ambient environments on in vitro flowering in Kalanchoe blossfeldiana Poellniz

Abstract

The effects of temperature, day-length, photosynthetic photon flux density(PPFD), and ventilation of vessel (number of air exchanges per hour) on the growth and flowering of Kalanchoe blossfeldiana in vitro were examined. The variations in time of differentiation and developmental processes of flower buds between in vitro and in vivo cultured plants are also discussed. 1. Among 7 cultivars (cvs.) tested, in vitro flowering occurred in 5 cultivars of the early- and mid-season flowering types under a short-day condition. However, 'Sensation' and 'Rose Crown', two late flowering cvs., produced no flower buds within 25 weeks. The early flowering 'Singapore' and 'Adagio' also flowered early in vitro, followed by 'Oukan', 'Houkan' and 'Fortyniner' which are mid-season flowering cvs. In response to ambient temperature, the above 5 cvs. produced flower buds at 20 °C, whereas only 'Oukan' produced flower buds at both 20 °C and 25 °C in vitro. 2. 'Singapore' flowered in vitro under 20 °C and short- days. In vitro flowering occurred at 40 μ mol · m-2 · s-1 PPFD, whereas at 10 and 30 μ mol · m-2 · s-1 PPFD, the above plants failed to produce flower buds in vitro. 3. Controlling ventilation within the culture vessels using aluminum foil closure with 0.03 air exchange per hour failed to produce flower buds, whereas an air permeable closure and a silicon rubber stopper, with 3.40 and 3.75 air exchanges per hour, respectively, allowed flower bud differentiation and development. 4. Under our environmental conditions, 35 days from the flower bud differentiation stage to the visible flower bud stage were required. The rate of flower bud development was nearly equal in both in vitro and in vivo cultured plants.