Abstract
To elucidate the role of light signaling on photoperiodic flowering in Chrysanthemum, flowering response under various photoperiodic treatments were tested with different light qualities. When white light was given during the main photoperiod, short irradiation (Night Break; NB) with red light has the strongest effect on inhibition of flowering, whereas NB with blue (NB-B) or far-red light has little inhibitory effect. However, with main photoperiod of blue light, NB-B strongly suppressed flowering. This inhibitory effect of NB-B was cancelled when red light was supplemented with blue light during the main photoperiod. These results suggest that phytochrome(s) play a major role in NB-induced inhibition of flowering, and the light quality during main photoperiod affect the sensitivity to light irradiation at middle of the flower-inductive dark period.
