ADVENTITIOUS ROOT INITIATION IN RECIPROCALLY GRAFTED LEAF CUTTINGS FROM THE JUVENILE AND MATURE PHASE OF HEDERA-HELIX L

Reciprocal grafts involving leaf petioles and lamina of the juvenile and mature phase of Hedera helix were prepared to determine the relative importance of petiole and lamina on root initiation in leaf cuttings. The results indicated that root initiation was mainly a function of the potential of cells in the petiole to respond in a specific morphogenetic pattern. Initially, root initiation was unaffected by the type of lamina. However, over time, a factor translocated from the juvenile lamina promoted root initiation in the mature petiole. This factor decreased the time taken for root initiation and increased the number of roots per mature petiole. There was no evidence for an inhibitor from the mature lamina affecting root initiation in the juvenile petiole.