The Control of Flowering in Lilium longiflorum Thunb. cv. Nellie White by Cyclic or Continuous Light Treatments1

Abstract

Abstract Flowering was accelerated by incandescent light day extensions of 3 minutes of light and 27 minutes of dark or longer light cycles and by 15 minutes of light and 15 minutes of dark cycles when BCJ-ruby incandescent light was given to young shoots from non-vernalized bulbs. If bulbs were vernalized for 3 weeks, cool white fluorescent light accelerated flowering as a day extension. As a night interruption, incandescent, fluorescent or BCJ-ruby incandescent cyclic light treatments accelerated flowering of shoots from vernalized or non-vernalized bulbs. Day extensions of cyclic fluorescent or BCJ-ruby light treatments of 6 minutes on and 24 off or 3 minutes on and 27 off did not mediate a phytochrome controlled flowering response and along with the fact that there was no photoreversibility between day extensions of incandescent, fluorescent or BCJ-ruby incandescent light, indicate a high energy reaction involvement in the flowering of the lily. As a night interruption treatment, a phytochrome mediated flowering response was observed with 3 minutes of light on and 27 off or 6 minutes on and 24 off cyclics of fluorescent or BCJ-ruby incandescent light treatments. However, as the light period increased to 15 minutes on and 15 off or under a continuous light cycle, there were no differences in the flowering response between fluorescent or BCJ-ruby incandescent. As night interruptions there was a reversibility response by R — FR, but not by FR — R. This indicated the simultaneous operation of the phytochrome and the high energy reaction.