Effect Of Girdling On Change Of Nutrition And Hormone In Leaves During Flower Bud Differentiation Of Moulmain Rhododendron

Rhododendron moulmainense Hook,an everygreen shrub or small arbor of Rhododendron genus in the Ericaceae family.The hight is 3 to 7 meter.The flower is big and colorful.It is a scarcity kind of Alpine Rhododendron.About 4000 Rhododendron moulmainense Hook. had lowest flowering rate.Adopting a proper regulating means had important theoretical and practical significance.The influence of one circle girdling and two circle girdling on growth,flowing rate and also soluble sugar,starch,total nitrogen,C/N,and endogenous hormone in leaves at the flower bud differentiation stages of Rhododendron moulmainense trees were studied.The effect on flowering rate of air-layering of Rhododendron moulmainense by girdling ,PP333 and Girdling matching to PP333 were searched.The main results were as following:1. Girdling inhibited the sprouting of spring shoot,and shortened the internode ,thereby restrained the growth of the spring flushes.Among the total treatments,two circle girdling had better containment. 2. Girdling increased the flowing rate,and two circle girdling had better effect than one circle one.3. Effects of shoot girdling on soluble sugar,starch,total nitrogen and C/N in leaves at the flower bud differentiation stages in Rhododendron moulmainense were investigated. The results showed that girdling significantly increased the soluble sugar and stach contents.Soluble sugar above one circle girdling shoots in leaves were similar to two circle one before the calyx primordium differentiation stage; however two circle girdling was higher than one circle after the stage.Girdling reduced the total nitrogen contents,and increased the C/N .Leaves above the two circle girdling shoots had lower nitrogen contents but more C/N.4. Effects of shoot girdling on endogenous hormone(abscisic acid (ABA), indole acetic acid (IAA),gibberellic acid (GA3) and zeatin riboside(ZR)) levels in leaves at the flower bud differentiation stages in Rhododendron moulmainense were determined. The results showed that girdling increased ZR and ABA content , however, reduced the IAA and GA3 content during the flower bud differentiation stages.At the same times,girdling changed the balance of endogenous hormone,which significantly increased the ratio of ZR to GA3,ABA to GA3 and ABA to IAA,while, reduced the ratio of ZR to ABA.5. The effect of girdling , PP333 spraying and girdling matching to PP333 on the flowing rate of air-layering of Rhododendron moulmainense.The result were that girdling matching to PP333 had high flowing rate than single girdling or single PP333 treatment.