Influence of IAA upon the longitudinal and tangential movement of labelled sugars in the phloem of Willow.

Using a bark abrasion technique, the influence of IAA upon patterns of sugar translocation in isolated stem segments of Willow (Salix viminalis L.) has been studied. IAA was found to exert a considerable influence over translocation in both a longidutinal and tangential direction. Studies on longitudinal movement have led to the postulation of two possible effects of IAA on this system. Firstly a stimulation of sugar loading from the storage parenchyma into the sieve elements as described by Lepp and Peel (1970), and secondly a direct effect upon, the longitudinal transport process. The situation with regard to the tangential transport system is not as clear in all its aspects, though once again it is postulated that IAA may have a direct effect upon the movement of sugars in the tangential transport system.