Abstract: The induction of vascular tissues in graft unions by IAA zeatin (ZT) was studied by using explanted internode autografting of cucumber(Cucumis sativus) cultured in vitro. Exogenous hormones were the limiting and controlling factors for vascular bundle regeneration in the graft unions. Vascular development ,such as formation time and total amount of vascular bridges as well as tracheary elements(TE) between stocks and scions,depended on the concentrations and the kinds of exogenous homones. Explanted internode autografting is one of ideal systems for studying the vascular tissue differentiation.

Key words: Plant hormones, Vascular tissue, differentiation, Explanted internode grafting , Cucumber