The influence of root pruning on subsequent root and shoot growth ofMalus, TiliaandBetula

Abstract

Different root types were removed at transplanting and the effects of these treatments on the subsequent root and shoot growth of one-year-old Malus pumila ‘Cox’s Orange Pippin’ / M.9 trees and of Tilia cordata and Betula pendula planting stocks examined. Removing all fine roots (2.0 mm diameter), primary roots, or for Malus, on that part of the rootstock stem beneath the soil surface. Whilst most new Tilia and Betula roots were produced on old, fine roots, the buried rootstock stem was the principal site of new root production on M.9. Removal of the old, coarse root had minimum influence on the total new root and shoot production of Tilia and Malus and on new root growth of Betula. This result occurred despite removing >50%, >70% and >90% of the original old, fine roots attached to coarse roots of Malus, Tilia and Betula respectively. Removal of old, coarse roots stimulated the growth of more new roots on Betula primary roots and also increased new root production per unit length intact old, fine root of all three genera.