Is it daylength or nightlength that induces flowering 16 Photoperiod Sd LD Light break(15 min)in dark SDP Cocklebur Length of (Xanthium) continuous dark period LDP IS Important Henbane LD SDPhotoperiod SDP Cocklebur (Xanthium) LDP Henbane SD LD Light break (15 min) in dark Length of continuous dark period is important SD LD Is it daylength or nightlength that induces flowering?