VIGOUR MECHANISMS IN DWARFING ROOTSTOCKS FOR TEMPERATE FRUIT TREES

Abstract

Dwarfing rootstocks have been widely used in the culture of apple and pear trees for a very long time. However, there is till almost no understanding of the plant mechanisms responsible for the dwarfing effect on the scion. The article first considers how the dwarfing effect is manifested in the scion’s growth. The relative importance of the rootstock roots, its stem piece (shank) and the graft union with the scion in the dwarfing effect are then discussed. Most of the article considers various theories concerning possible dwarfing mechanisms by the rootstock. These include effects on water and solute supply to the scion and the rootstock’s influence on the production and translocation of endogenous hormones (bioregulators) between scion and rootstock.