Abstract: Physiological and chemical variation and construction of floral buds of cotyledons of Cucuibita pepo L . induced by kinetin are reported in the present paper . The results domonestrated that differentiation in floral bud of the cotyledons which cultured on MS mixed with kinetin 1 . 0 mg·L- 1 accounted for 45% of the total, whereas only reached 5% in the control . During construction of the floral buds , the endogenous soluble protein , soluble suger , RNA and POD activity of the cotyledons apparent exceeded
those of the control ; the ratio between Spd and Put (Spd􊄯Put ) is two times more than that of the control ; the content of starch and DNA are not quite different from the control , but DAP and Cad apparently decreased. It is easy to come to a conclusion that the varition of physiological and chemical induces in the cotyledons in vitro induced by kinetin promoted the construction of floral buds .

Key words: Cucuibita pepo