Abstract

In order to achieve the mature stage, the growth time of Hylocereus undatus (Haw.) Britt. and Rose vegetative buds is about 3-4 months. The changes in the sugar, starch contents and C/N ratio of branches and their relationship with flowers-bud initiation were studied. The total sugar and starch contents increase during branches's growth. The starch level in mature shoot apices is about 3% fresh weight. The nitrogen content is high in juvenile branches and reduces when shoot tips do not lengthen. Its low ratio (0,98-1,09) in mature shoot apices leads to the C/N propotrion increase. The higher total sugar, starch reserve and C/N ratio in the reproductive branches play an impotrant role in flower-bud initiation. The accumulation of these compounds may create a favourable condition for the synthesis and action of the responsible substances for flower induction.