Sectorial Patterns in Leaves on Fruit Tree Shoots Produced by Radioactive Assimilates and Solutions

In vigorously growing shoots of apple and plum 14C-assimilates were translocated from a ‘fed’ leaf to particular sectors of other leaves in a distribution pattern associated with the phyllotaxis; the same sectorial and distribution patterns were produced by 32P phosphate solution taken into the shoot through a cut petiole. The frequency with which a given sectorial pattern occurred at a particular position on the phyllotactic spiral was ascertained. Such patterns were not observed above the third rolled leaf in the apple shoot apex. Killing the phloem in the petiole prevented egress of labelled assimilate but not of 32P solution. Barkringing above the source leaf reduced, but did not completely prevent, assimilate movement up the stem, suggesting some translocation in the xylem. Distribution of label from 45CaCl2, 86RbCl and [3H]asparagine, incorporated through cut petioles, did not follow the same pattern as label from 32P solutions.