The Effect of Photoperiod on Lateral Shoot Development in Dianthus caryophyllus L. cv. Improved White Sim1

Abstract

Abstract Long photoperiods (either naturally long days or 4-hour night interruptions with low intensity incandescent light) inhibited lateral shoot development and induced early flowering in perpetual flowering carnation (Dianthus caryophyllus). Short photoperiods delayed flowering but enhanced lateral shoot development only when shoots were vegetative. Once a shoot was induced, short photo periods had no influence on time to terminal shoot flower or on subtending vegetative lateral shoot development. Vegetative lateral shoot development was inhibited by night interruption lighting regardless of light source. These data indicate that high flower production in Spring and summer is due to lateral vegetative shoots which begin elongation and growth during the non-flower inductive short days of winter. At higher latitudes low production of flowers may not entirely be due to low photo-synthetic light but to the low number of lateral shoots. This low number of potential flowering shoots is due to highly inductive long days of summer which have caused shoots to flower before subtending lateral shoots can begin growth for future flower production.