Temperature affects growth and flowering of the balloon flower (Platycodon grandiflorus (Jacq.) A. DC. cv. Astra Blue).

摘要

The effects of temperatures of 14 to 29deg C on the growth and flowering of P. grandiflorus cv. Astra Blue are described. Under greenhouse conditions, seedlings flowered after 45 days (the earliest) when grown at 29degree C, compared with 108 days when grownat 14degree C. Height at flowering was greatest at 19degree C, and branch number was greatest (13/plant) at 22degree C. Fresh and dry mass, and leaf area at flowering, increased with decreasing temperature. Imbibing seeds at 4degree C prior to germination had no significant effecton the time to flowering, or on the number of nodes below the flowers. In a growth chamber experiment, apical dissections showed that flowers were initiated earlier at 20degree C than at 10degree C. It is suggested that the balloon flower is highly sensitive to temperature, and that cool temperatures delay the time to flower initiation or flowering.