The effect of day/night temperature on Pharbitis nil Chois. flowering

The interaction between day/night temperature (DT/NT) and irradiance during the photoperiod prior to the inductive night on Pharbitis nil (L.) cv. Violet flower induction was studied. Plants exposed to 12 or 18 degrees C NT did not flower regardless of DT. When NT was 24 or 30 degrees C, percent flowering plants increased progressively as DT increased from 12 to 30 degrees C. Percent flowering plants and total flower bud number per plant was greatest when seedlings were induced with a 24 or 30 degrees C DT/30 degrees C NT regime. DT/NT did not affect the node number to first flower. Irradiance did not affect flowering. Temperature effects on P. nil flowering could be described as a function of average daily temperature, where flowering increased as temperature rose from 22 to 30 degrees C.