Agriculture Reference
In-Depth Information
Mechanisms of rootstock and
interstock effects on scion
vigour
Introduction
The use of dwarfing rootstocks for the control of tree vigour is a dominant
feature of much of modern apple production and, to a lesser extent, pear
production. The mechanism of vigour control by rootstocks has been studied
for many years, partly in the hope that understanding the process will lead to
its more effective utilization.
The effects of the rootstocks and interstocks are manifold, interactive and
cumulative over years. Moreover, different mechanisms appear to be dominant
in different species and even in different stock/scion cultivar combinations
within a species. In practical terms the dwarfing effect of 'M.
' and its deriva-
tives on apple scions and of quince rootstocks on pear scions are probably
of the greatest importance so emphasis is given to these within the broader
context.
Mechanisms of rootstock and interstock
effects on vigour
The mechanisms of rootstock influence on tree vigour are best considered
within the concept that the vigour of the composite tree reflects in an additive
way the vigour of its components and that these interact. There is, as discussed
earlier, a tendency to attainment of a functional equilibrium between roots
and shoots. Roots supply shoots with nutrients and water, shoots supply roots
with assimilates, and the roots and shoots appear to have specific roles in the
productionoftheplantgrowthsubstancesthatcontrolandcoordinateactivities
in the plant. The graft union and the conducting tissues of the rootstock may
also influence growth through their effects on translocation from root to shoot
and from shoot to root.
