The Rules Of Flower Formation And Regulation Mechanism In 'Siji Hua' Longan (Euphoria Longana)

1.When a tree is＞4 years old,it flowered yearly for 4 time.Trees from 4 to 8 years old,the older one took more chances to flowering for its shoots.Moreover,winter shoots inclined to form floral differentiation.2.The diameter of bearing-base-shoot is a critical factor,shoots with 0.46 cm～0.51 cm in diameter can form flower in its first growth season,and that with 0.39cm～0.42 cm can not.3.For the summer shoot,leaf colour is an exterior indicator to evaluate floral differentiation, if the colour turned from light-green to yellowish,it would form flower undoubtedly. However,shoots developed in other season usually lack obvious change in leaf colour.4.Practices,e.g.spaying PP₃₃₃ on leaves,ring girdling at main branches and topping new shoot can promote floral bud differentition by 48.3%,18.7%and 8.5%,respectively, compared with that of CK.Of which,spaying PP₃₃₃ received extra advantages,e.g.it enlarged the bearing-base-shoot and increased the number of flowers and female flowers.5.In the natural floral differentiation process,ABA content is lower in the stages of before the flower formation,the differentiation phase of inflorescences primordium and the differentiation phase of first order inflorescences than the stages of the differentiation phase of lateral inflorescence and floral organ or the differentiation phase of the stamens and the pistils.ABA content were always higher than that of GA₃,ZR_S and IAA in each natural floral differentiation.6.Spaying PP₃₃₃ declined GA₃ content but increased that of ABA and ZR_S,which making a further effect of decreasing the IAA content in three stages of before the flower formation, the differentiation phase of inflorescences primordium and the differentiation phase of first order inflorescences,and resulting to higher values of ZR_S/GA₃,ABA/IAA,ZR_S/IAA and ABA/GA₃,and finally,accelerating flowering.7.Ring girdling at main branches enhanced the ABA content.At the same time,it,as well as topping new shoot,raised ZRs content gradually and brought IAA down content to a level lower than that showed in natural floral formation.These conditions in turn induced floral differentiation.