Agriculture Reference
In-Depth Information
Effects of rootstock on tree size and leaf area per tree (m
)
and per unit of orchard land (LAI, m
leaf m
−
land), cv. 'Red
Delicious' apple, Penticton, BC, Canada
Table
.
Tree height
Number of
Leaf area
Rootstock
(m)
trees ha
−
(m
tree
−
)
LAI
Seedling
.
.
'M.
'
.
.
'M.
'
.
.
'M.
'
.
.
Calculated from data given by Heinicke (
).
autumnal senescence could be essentially stopped by transferring apple trees
to an
◦
C night temperature regime. This effect of temperature
provides an explanation for the failure of apple leaves to shed synchronously
in the tropics and the need for chemical or manual defoliation to release fruit
buds from correlative inhibition by leaves. In temperate climates, light frost
hastens the low-temperature induced abscission process (Larsen,
◦
Cday,
).
Neither light intensity nor daylength appears to have any effect on the
abscission process ( Jonkers,
).
Cultivars differ in their time of leaf shed within the overall constraints im-
posed by temperature. This characteristic is highly heritable, with some evi-
dence for major gene effects (Tydeman,
).
The rootstock can have a marked effect on the time of onset of leaf senes-
cence and this can be delayed by nitrogen fertilizer application (Heinicke,
). Senescing leaves export carbohydrates and also N, P, and K, but not
Ca, to the rest of the plant prior to shed (Mason and Whitfield,
).
Individual tree and orchard leaf area
The canopy size of the individual tree reflects the accumulated effects of its
genetic make-up, in terms of both scion and rootstock, of tree management
practices and of the external environment.
The rootstock has a very large effect on leaf area. Heinicke (
) found
the leaf area per tree of 'Red Delicious' apple on seedling rootstock to be
m
and on the dwarfing 'M.
m
when the trees
' rootstock to be only
were planted at the then typical spacings (Table
.
). The trees described in
Table
.
had much denser leaf canopies than those typical of more modern
orchards.
Giuliani
et al.
(
m
per tree (LAI,
) cited a leaf area of
.
.
) for heavily
trees ha
−
,
cropping 'Smoothee Golden Delicious'/'Pajam
' planted at
