Abstract: The effect of Kinetin(KT) on organ differentiation incucumber cotyledons was studied with the provision of KT stages at the beginning of culture .The results showed that:1) Provision of KT caused a desending rooting,had almost no effect on vegetable bud differentiation ,and was utterly essential to the flower bud formation.2)Provision of Kt caused the content of Putrescine(Put) to the change greatly. It had two peak values,one occurred on the 2nd day,the other on the 6th day,but on the 4th day its content decreased sharply.3) Provision of KT caused the contents of IAA and ABA to decrease significantly on the 2nd day and to rise sharply on teh 4th day for IAA. Based on these results,we discuss the relationship between these physiological changes and flower differentiation.

Key words: Kinetin, Cucumber cotyledon, Organ differentiation, Polyamines, Endogenous