Agriculture Reference
In-Depth Information
Table
.
Leaf nutrient concentrations in apple and pear
Apple
Pear
Nutrient element
Deficient
Normal
Deficient
Normal
N%
< .
.-.
< .
.-.
P%
< .
.-.
< .
.-.
K%
< .
.-.
< .
.-.
Ca%
< .
.-.
< .
.-.
Mg%
< .
.-.
< .
.-.
Mn ppm
<
-
<
-
Fe ppm
-?
-
B ppm
<
-
<
-
Cu ppm
<
-
<
-
Zn ppm
<
-
<
-
Mo ppm
< .
.-.
Apple leaves taken from the mid-portion of terminal shoots at about the
time of cessation of terminal growth ( July). Pear leaves are spur leaves
in August except for Zn for which samples were taken in September.
Mn concentrations of more than ppm in -year-old bark of apple
indicate toxicity but this critical level may vary depending on the level
of Ca, B and other elements.
Data from Shear and Faust (
).
data summarized by Shear and Faust (
), citing data for nutri-
ent levels in mid-extension shoots taken in late August, concluded that rather
higher levels of N and K (
). Rowe (
.
-
.
% and
.
-
.
%, respectively) are needed
to show sufficiency and that more than
ppm of Zn or Mn indicates toxic
levels.
The rootstock can influence the susceptibility of the tree to nutrient defi-
ciencies. Apple trees on 'MM.
' are highly susceptible to magnesium defi-
ciency, trees on 'M.
', 'M.
' and 'MM.
' are susceptible and those on 'M.
',
'MM.
). Pear trees on quince root-
stocks on alkaline (high pH) soils generally suffer from lime-induced chlorosis
resulting from iron deficiency (Lombard and Westwood,
' and 'M.
' are resistant (MAFF,
), although some
new quince selections are tolerant (Webster,
). Pear trees on Pyrus root-
stocks are generally tolerant.
Scion cultivars may have different nutrient requirements depending on the
quality characteristics required. High nitrogen concentrations promote dark
green skin colour, which is desirable for cultivars like 'Bramley's Seedling' but
not for cultivars like 'Worcester Pearmain'. Different cultivars also have large
differences in fruit acidity, which relates to potassium content so indicates likely
differences in K requirement.
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