Agriculture Reference
In-Depth Information
Other characteristics of
apple rootstocks
Resistance to temperature stresses
Soil temperatures above
◦
C may have adverse effects on the growth of
trees on most rootstocks. Nelson and Tukey (
) and Gur
et al
.(
) found
that 'M.
' and seedling rootstocks were relatively
resistant to high soil temperatures but 'M.
', 'M.
', 'M.
', 'MM.
', 'M.
', 'M.
' and 'MM.
' per-
◦
C and above. This is very important at
the macro-scale level of apple growing (Ferree and Carlson,
formed poorly at temperatures of
). Soil tem-
perature is closely related to air temperature, often being higher in the top few
centimetres. Diaz and Romo (
) showed that under Mexican conditions,
◦
C soil temperatures were about
◦
C at the
when air temperatures were
◦
Cat
◦
Cfrom
surface, about
cm and then about
to
cm depth.
◦
C soil temperatures were about
◦
Cat
When air temperatures were
◦
Cat
◦
Cat
the surface declining to around
cm and
cm. Since
most tree roots are located within the top
cm, or even the top
cm
(cf. Chapter
), high soil temperatures provide a major constraint on the use
of 'M.
' rootstock in warm-climate fruit-growing areas. It is likely that this
constraint will apply to many of the newer rootstocks with 'M.
' parentage.
Freezing soil temperatures, and in particular freezing air temperatures just
above the ground, can result in winter-freeze death of rootstocks and therefore
of trees. In regions prone to severe winter freezes, cold-hardy seedling root-
stocks, e.g. 'Antonovka Seedling' in Poland and 'Beautiful Arcade' in Canada,
were in general use. Trees on these were too vigorous to fit in with the evolving
systems of high-density planting, so the 'Malling' series of clonal rootstocks was
evaluated. When it became clear that although these showed a wide range of
cold tolerance 'M.
' was sensitive, there was considerable emphasis on the
breeding and selection of cold-tolerant dwarfing rootstocks. Some of these
proved very difficult to propagate so were used as dwarfing interstocks be-
tween a cold-resistant but vigorous rootstock and the scion cultivar which it
was desired to dwarf. Observations on cold-hardiness havegiven some variable
results, possibly because there are a number of different aspects to hardiness
(Ferree and Carlson,
). However, there is ample data that 'M.
' has poor
tolerance of winter-freezing conditions whereas 'M.
'are
as tolerant as, or more tolerant than, 'Beautiful Arcade' seedling rootstock
(Figure
' and 'MM.
.
, from Prive and Embree,
). Quamme and Brownlee (
)
also found 'M.
' to be sensitive to freezing injury in terms of both
field performance and exposure to different freezing temperatures, while 'J.
' and 'M.
'
was hardier than either and the equally dwarfing 'B.
' and 'P.
'wereashardy
as the vigorous Swedish 'Alnarp
'(Table
.
). In Poland, in a year without
−
◦
C at a depth of
snow cover with a soil temperature of
cm, only
-
%
