Agriculture Reference
In-Depth Information
The conventional production of clonal apple rootstocks is by the stoolbed tech-
nique in which one-year-old rooted shoots are planted in rows and established
for one season before being cut close to ground level (stooled). Shoots are pro-
duced from the stumps and encouraged to root during summer by mounding
soil around them. The rooted shoots are then removed by cutting below the
new root system during the following winter. This stooling process is repeated
annually with each new flush of shoots. Howard (
) found that the use of
good quality shoots (
cm in length) to establish the stoolbeds led to larger
permanent root systems and many more rooted shoots (liners) being produced
each year with the difficult-to-root 'M.
>
a' rootstock, although effects on the
easy-rooting 'MM.
' were slight.
Where propagation is by winter cuttings (hardwood cuttings), as with the
easy-to-root 'M.
' apple rootstock, the cuttings taken at the base of the ann-
ual shoot root most readily. After the removal of the winter cuttings it is
important to prune the framework shoots of the hedges to three or four buds.
This stimulates the production of shoots with a high rooting potential com-
pared with shoots from un-pruned or lightly pruned bushes (Howard,
;
Table
).
For quince, better rooting of winter cuttings is achieved if they have a
'heel' of older wood, with pre-formed root initials, retained at the base of the
cutting.
Leafy summer cuttings (softwood cuttings) are not generally used to pro-
duce apple and pear rootstocks. Their small size at rooting, and the need for
mist to prevent them from desiccating, results in them being much more ex-
pensive than winter hardwood cuttings to grow to a size suitable for budding
or grafting. They can, however, be used when very rapid multiplication is re-
quired. Cuttings are generally taken from the tips of shoots, which probably
have more cells capable of becoming meristematic and less sclerified tissue
than older shoots. Lateral shoots, about
.
cm) in length and not in
active growth, are preferred. They are best obtained from bushy stock plants
established in pots and brought into a warm house in late winter. These pro-
vide excellent cuttings in May and early June which can quickly be induced to
root and are fit to be transferred to open ground by early July (Garner
inches (
.
,
).
!
The rooting potential of apple cuttings is at a peak in late winter and early
spring (Table
). These changes in rooting potential are associated with
changes in rooting co-factor activity (Bassuk and Howard,
.
). Rootstocks
of quince, which leaf out early in spring, are best propagated in autumn when
their buds are fully dormant (Table
.
).
