Preliminary Studies On Flowering Control By Means Of Photoperiod In Echinacea Purpurea 'White Swan'

Echinacea purpure 'White Swan' is one of the most excellent cut flower in garden.The color of petals is white and is frequently tinged with green.It has larger plant type.Flowering control is necessary to meet the floriculture and consumption,in which manipulating photoperiod is easy and whithout environmental pollution.A quantitative undersdanding of photoperiod on Echinacea purpure 'White Swan' could be directly used in guiding mass cultivation.The results are as follows:①Echinacea purpurea 'White Swan'is a short-long-day plant.The plant tended to have an uptight habit with incease in height and crown diameter under long days and a compact habit with low height under short days.But the plant flowering is earier under short days than the plant's under long days.Accordingly,long days is more important than short days for flowering of Echinacea purpurea 'White Swan'.②Transferring plants between SD and LD according to leaf number or growing weeks of seeding,it is concluded that the short days induced phase of Echinacea purpurea 'White Swan' ended at 10～11 leaf stage.The process study is simplified by light transferring resting on growing weeks of seeding,simultaneously,a reliable parameter for floriculture is provided by observation on leaf number.③The flower bud differentiation process of Echinacea purpurea 'White Swan' could be divided into 8 phases:Vegetative growth prophase,Vegetative growth anaphase, Inflorescence primordium differentiation phase,bract differentiation phase,Ligulate flower primordium differentiation phase,Tubular flower primordium differentiation phase,Tubular flower stamen primordium differentiation phase,Tubular flower pistil primordium differentiation phase.The reponse of flower bud differentiation of Echinacea purpurea 'White Swan' to photoperiod started at 8 leaf stage,which is at Inflorescence primordium differentiation phase.The end of the short days induced is at 10～11 leaf stage,which is at Lingulate flower primordirum differentiation phase.④Significant linear relationships existed between growing weeks of seedling,leaf number and crown diameter of Echinacea purpurea 'White Swan' and its flower bud differentiation phase,the regression equations are as follows:y=0.5393x-2.9482 (growing weeks of seeding;R~2=0.9441),y=0.6966x-2.4063(leaf number;R~2=0.908), y=0.2362x-0.9063(crown diameter;R~2=0.7466)。It indicates that the more sensitive of growth characteristics to photoperiod,the more significant relationship between growth characteristics and flower bud differentiation phase.It could be drawn that it was from Inflorescence primordirum differentiation phase to Tubular flower primordirum differentiation phase that Echinacea purpurea 'White Swan' accepted the floral induction by short days;and it was from Tubular flower primordirum differentiation phase to Pistil of thbular flower primordirum differentiation phase accepted the floral induction by long days.