Influences of different day and night temperatures on growth of plug seedlings and flowering of Zinnia hybrida

摘要

The effect of 16 different day and night temperatures during the growth of plug seedlings on stem elongation of Zinnia hybrida was investigated. The plug seedlings grown in various temperatures were transplanted to larger pots to determine how the temperatures during plug raising period affect the flowering in natural growing condition. The plug seedlings grown in high day temperature had greater plant height and internode length than those in high night or average daily tem?perature. However, thenumber of nodes and unfolding rate of leaves increased as average daily temperature was increased. Suppressed stem lengths of plug seedlings grown in low day temperature were increased more after transplanting in natural condition. Flower initiation wasmuch stimulated in 20/24 (DT/NT, deg C) showing the least node number at flowering. Also the number of ray petal was negatively associated with the time of flower initiation. The results indicate that the differences in day and night temperature in plugsystem affect not only stem elongation but also flower initiation of the seedling and number of ray petals.