The induction and differentiation of 8-year-old Alphonse Lavallee and Sultana grape vines were studied.
Defoliation methods enabled us to determine the induction time in grape vines as in other fruit species.
- Induction and differentiation in the tested varieties were not connected with temporary growth cessation; on the contrary, process took place during the most intensive growth.
- A correlation was found between the number of leaves and induction period. 18-21 leaves above the examined buds were needed in bot-h varieties to complete the induction.
- The leaf area needed for induction in a bud of Sultana was lYe times larger than that needed for Alphonse. The efficiency of the leaves of Alphonse to induce differentiation was thus greater.
- The primordia ,development from induction to detection under the microscope (differentiation) was connected with a constant vegetative development. The time needed for this development was determined by the growth rate of the variety (18
days in Sultana, 14 days in Alphonse).
- The translocation of materials inducing differentiation from the base of the shoot upwar,ds has not been proved in our work.
- In Alphonse a lag period of two days was found for the differentiation of each bud along the cane.