Abstract
Day length plays an essential role in the transition from vegetative phase to reproductive phase in long-day (LD) plants (LDP) and short day (SD) plants (SDP). Inductive LD or SD signal induces the differentiation from shoot apical meristem to floral meristem. Chrysanthemum is a typical SDP and responds to shorting of day length in the phase transition. Night break (NB) treatment is sufficient for the repression of flowering in SDP and commonly applied to manipulate the production of chrysanthemum. After short day signal induced floral meristem identity in chrysanthemum, their development was inhibited by NB. The length of SD exposure was sufficient for the activation of floral activator gene homologues and repression of floral repressor gene homologues in dosage manner. Therefore, continuous SD signal can be sufficient for the development of floral organs in chrysanthemum.
