CARBOHYDRATES AND THEIR EFFECTS ON THE GROWTH AND ESTABLISHMENT OF TILIA AND BETULA .2. THE EARLY SEASON MOVEMENT OF CARBOHYDRATES BETWEEN SHOOTS AND ROOTS

C-14 applied as labelled CO(2)-C-14 was shown to move from leaves and shoots to roots of young Betula transplants as early as two weeks after budburst, approximately one week before the first visible signs of new root growth. Similar translocation in young transplanted Tilia was not noted until four weeks after budburst, again about one week before the onset of new root growth, which begins later after budburst in this species. The maintenance of a basal stem girdle over the period between planting and approximately eight weeks after budburst severly inhibited new root growth in both genera and also reduced individual leaf area and extension shoot growth. Carbohydrate content within the roots of both species declined in the first month after budburst. Girdling had no effect upon Tilia root carbohydrate content but severely reduced that of Betula. Total carbohydrate content of Betula shoots and leaves increased in the month following budburst, whereas that of Tilia declined slightly. Defoliation one month after budburst also reduced new root growth of both species in the subsequent month; shoot growth of Tilia, but not Betula, was reduced by defoliation. The results are discussed in relation to transplanting success with Tilia and Betula.