Agriculture Reference
In-Depth Information
(a)
Tip
(b)
1
2
4
6
3
8
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7
Select petiole opposite either
of the basal clusters during full bloom.
Collect blades taken from the most
recently developed, full-sized leaf.
Figure 3.9 (A) Position of leaves to be sampled for tissue analysis (petioles) at flowering
(bloom). (B) Sampling blades from mature leaves. (Christensen et al., 1978; reprinted with
permission of the Division of Agriculture and Natural Resources, University of California.)
Table 3.5 An Example of Changes in the Concentration of Some Mobile Nutrients in Petioles
over Time
Date of sampling a
November 9, 2012
(End of flowering)
November 14, 2012
(Fruit set)
February 7, 2013
(Postveraison)
N concentration (%)
2.2
2.0
0.54
P concentration (%)
0.86
0.69
0.62
K concentration (%)
1.9
1.2
0.53
S concentration (%)
0.26
0.24
0.15
a ForShirazvinesinavineyardintheYarraValleyregion,Victoria,Australia.
sampled at full flowering or bloom when the leaf is more sensitive to the external
nutrient supply than at later stages (box 3.5). The argument for even earlier sam-
pling is that a grower has more time to respond with a remedial fertilizer treat-
ment, but the disadvantage is that concentrations are changing more rapidly then.
The exact time of sampling is not so critical if a regular sampling program (every
year or second year) is followed (as discussed in “Interpreting Plant Analyses”).
For troubleshooting, or trying to confirm a deficiency or toxicity indicated
by visual symptoms, leaves may be collected at any time. Leaves are best sampled
early in the day when they are least likely to suffer water stress and must not be
sampled soon after a foliar spray has been applied.
 
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