Agriculture Reference
In-Depth Information
Macronutrient Concentrations (%) in Petioles for Assessing the Nutrient Status of Grapevines a
Table 5.3
Element
Very Deficient
Deficient
Low to Marginal
Adequate
High
Excessive
N (total)
0.7
0.7-0.84
0.85-1.2
1.2
P
0.15
0.15-0.19
0.2-0.29
0.3-0.5
0.5
P (Pinot Noir)
0.12
0.12-0.14
0.15-0.19
0.2-0.39
0.4
K (with adequate N)
1.0
1.0-1.7
1.8-2.0
2.1-4.4
4.5
K (vines on Ramsey
3.0
3-4.5
rootstock)
Ca
1.0
1.0-2.5
Mg
0.3
0.3-0.49
0.5-0.8
0.9
(mg/kg)
N as NO 3
50
350
350-600
601-1200
1200-2000
2000
a Source: Compiled from Kliewer (1991), Goldspink (1996), Robinson et al. (1997), and Jackson (2000)
Examples of Tissue-Testing Results
Critical values for each element are necessary to interpret tissue analyses. These
should be determined when no other nutrient is limiting growth and water sup-
ply is adequate. The critical values for plants under water stress tend to be lower
than for well-watered plants. If these conditions are met, the critical value should
be independent of soil type. Grapevine varieties differ to some extent in their up-
take of nutrients, which is also influenced by whether the variety is on its “own
roots” or a rootstock. However, because knowledge of the critical values for indi-
vidual varieties is incomplete, the examples given here are generalizations, based
on results for Thompson seedless grapes, unless otherwise stated. Tables 5.3 and
5.4 give petiole concentrations for some of the macronutrients and micronutri-
ents, respectively. The semiquantitative interpretations follow the principles of fig-
ure 5.2, that is, the critical value for the element is at the lower end of the opti-
mum range. In the case of nitrogen, analyses for NO 3 -N may also be used as an
indicator of the vine's N status.
5.2.3
Micronutrient Concentrations in Petioles for Assessing the Nutrient Status of Grapevines a
Table 5.4
Element
Deficient
Low to marginal
Adequate
High
Excessive
Fe
30
Cu
3
0
3-5
6-30
40 b
0
Zn
15
15-25
25-150
450 b
Mn
25
25-29
30-60
0
0
500
B
25
25-34
35-70
71-100
100
a Source: Compiled from Goldspink (1996), Robinson et al. (1997), and Jackson (2000)
b Possible contamination from fungicidal sprays
Note: All measurements in mg/kg.
 
 
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