Agriculture Reference
In-Depth Information
the growingseason. Newly rootedhardwood cuttingsestablish justas well if the
roots are removed before planting as if the roots are retained (Howard,
).
Rooting during orchard establishment
A rootstock planted in winter in a nursery is usually budded in the following
summer, when in rapid growth, and the bud remains dormant until the fol-
lowing spring. If the rootstock is grafted with dormant scionwood this is done
in the second spring after planting. The rootstock shoot above the bud or graft
is removed, temporarily increasing the root to shoot ratio, but the balance is
restored by rapid growth of the scion in the nursery. It is reduced again by the
process of lifting trees from the nursery, transporting and transplanting them.
This is done during the winter prior to budbreak.
Hatton
et al.
(
) reported on a number of studies involving excavation
of apple root systems within
years of planting. They commented that their
results 'confirmed, in a modified form, the oft-repeated assertion that, after
removal from the nursery and replanting, the young tree has practically to
start afresh in its root-making'.
Tamasi (
years after planting apple trees
on seedling rootstocks, new roots grew almost exclusively from thick 'skeletal'
roots cut back at planting and after
) reported that during the first
years roots began to develop from the
rootstock neck.
Abod and Webster (
) assessed the mortality of the transplanted root sys-
tems of one-year-old transplanted trees of 'Spartan' on 'MM.
'
rootstocks by measuring total 'old' root length on trees at the date of plant-
ing and at excavation at
' and 'M.
-day intervals after this. This length of 'old' roots
declined to
%,
%,
% and
% of the initial length at
,
,
and
days after planting, respectively. No new roots were regenerated in the first
days from planting but by
days the trees on 'M.
' had
m of new roots
and those on 'MM.
' had
m. By
days they had
m and
m,
respectively. Fifty-eight per cent of the new 'M.
' roots originated directly from
the rootstock stem,
% from old coarse roots (
>
mm diameter) and
%
from old fine roots. For 'MM.
' the corresponding figures were
%,
%
and
%.
This rapid root regeneration can lead to excellent new root systems being
produced within
years even when all existing roots are trimmed off at the
time of planting into the orchard (Hatton
et al.
,
). This new
root establishment is, however, accompanied by a severe check to shoot growth
(Hatton
et al.
,
; Figure
.
). The practice of
root pruning before planting to enable cheap and rapid planting into holes
drilled into the ground (called Stringfellowing after its originator) is therefore
not widely employed. A secondary problem is that the mechanical drilling of
; Preston,
; Young and Werner,
