Agriculture Reference
In-Depth Information
percentage of cuttings rooted and the number of roots per cutting (Howard,
cm wide
black adhesive tape to a de-leafed node just behind the shoot tip greatly in-
creased rooting of cuttings subsequently taken in winter with blanched bases,
the rooting percentage of these blanched distal winter cuttings being
). Blanching 'MM.
' rootstock shoots by application of a
.
%
compared with
% for unblanched distal and
% for unblanched basal cut-
tings (Heighton and Howard,
). In these studies IBA was applied to the
cut surfaces of the cuttings as is conventional for summer and winter cuttings.
The 'pre-etiolation' effect can, however, be demonstrated in the absence of
IBA treatment. Harrison-Murray
et al.
(
) found that etiolation of sucker
shoots of 'M.
% rooting of summer cuttings even without IBA
application. Banding also induces root primordia emergence both on young
apple stems still on the stock plant (Gardner,
' resulted in
), and on much more mature
rootstock stems below the graft union during their maiden year in the nurs-
ery (Harrison-Murray
et al.
,
). In the latter case the
portion of rootstock stem which had been banded while above ground in the
nursery gave rise to a new root system when deep-planted in the orchard.
The rooting response to etiolation appears to be complex: the associated
effects range from changes in stem anatomy which are correlated with ease of
rooting to changes in the light control of auxin metabolism, factors affecting
the activity of IAA-O and in the activity of rooting co-factors (Maynard and
Bassuk,
; Jackson
et al.
,
).
In cool-winter climates such as that of the United Kingdom winter (hardwood)
cuttings of apple do not root adequately if planted directly in the field, so are
rooted in cutting bins with the benefit of base heat and transplanted after initi-
ation of rooting. A temperature of
◦
C at the cutting base has been found to
be suitable for rootstocks (Howard,
) and is generally used although higher
◦
C, are more effective especially with difficult-to-root
material such as 'Cox' apple scionwood cuttings (Fenlon,
temperatures, up to
). The period
of exposure to bottom heat is usually limited to about
weeks: longer periods
result in poor establishment, probably as a result of depletion of carbohydrates
(Howard,
◦
C (Howard,
)
and in countries with warm winters and relatively high soil temperatures in
the dormant season apple rootstock cuttings treated with IBA can be rooted
directly in the field.
). Appreciable rooting is stimulated at
!
Although winter cuttings of apple and quince are leafless their rooting is in-
fluenced by the relative humidity of their environment and the water content
of the rooting medium. The effect of relative humidity varies with time of
