Influences of day and night temperatures on the growth of plug seedlings and their flowering responses after transplanting in Torenia fournieri

摘要

Sixteen different day (DT) and night temperature (NT) combinations were given to plug seedlings of Torenia founieri to define optimum day and night-temperatures for its growth and development. Torenia had less tolerance to the low temperatures (below 16 deg C) than other bedding plants, such as Impatiens and Zinnia. Best results were obtained when the growing temperature was kept above DT/NT=16 deg C/20 deg C or 20 deg C/16 deg C for the production of healthy plug seedlings. The internode elongation was greatly affected by increasing day temperature rather than night temperature. High correlation was observed between average daily temperature and leaf unfolding rate, and between +DIF and chlorophyll content. After transplanting, height of plug seedlings grown in a -DIF condition increased more rapidly than that of plants grown in a +DIF condition. Branch number increased as night temperature increased during the plug production period. However, number of flowers was limited at an early floweringcondition (DT/NT=24 deg C/16 deg C). Depending on day and night temperatures during seedling production, flowering time differed maximum 15 days among treatments.