1. FACTORS DETERMING GRAPE
POTENTIAL AND THEIR CONTROL
Professor Cornelis van Leeuwen
ENITA Bordeaux Agricultural
University
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

2. Plan
• Definition of grape potential
• Factors determing grape potential :
– Absence of grape diseases
– Vine vigor
– Berry weight
– Leaf / fruit weight ratio
• Terroir: effects of climate, soil and grapevine variety
• Role of vine water status
• Examples of grape potential management in various
conditions of soil and climate
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

3. How can grape potential be defined?
• A grape with a high enological potential :
– Is healthy
– Contains an optimum amount of sugar (variable
depending on the type of wine)
– Contains an optimum acidity (variable depending
on the type of wine)
– Presents a good ability to ferment
• Ideal grape composition is highly variable depending
on wine type and color
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

4. Grape potential for the production of high
quality red wine
+ Small berries
+ High phenolic content in the skins (tannins,
anthocyanin)
+ Phenolic ripeness
+ Ripe pips
+ Varietal aromas
- Vegetatif aromas under the perception treshold
- Low malic acid content 2004, Grapes, wine and
Van Leeuwen,
environment, Roanoke (Virginia)

5. Grape potential for the production of high
quality white wine
+ Optimum acidity (variable depending on climatic zone)
+ Fruity aromas
+ High glutathione content
- Vegetatif aromas under the perception treshold
- Low phenolic content in the skins
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

6. High potential grapes are
healthy
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

7. It is not possible to make good wines with
disease affected grapes
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

8. Effects of vine vigor on grape
potential
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

9. Vine vigor can be highly
variable from one plot to
another
Medium to high vigor Medium to low vigor Very low vigor
Merlot / 420A, plantation 1984-86, densité 4348 (AOC Buzet)
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

10. How can vine vigor be estimated?
• Individual vigor of a vine
– Number and diameter of shoots
– Secondary leaf area / primary leaf area
ratio
• Vigor of a plot of vines
– Pruning weight (kg/ha)
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

11. Excessive vigor
• Delays shoot growth cessation
– Competition for carbohydrates between grapes
and shoots
• Great development of laterals and suckers
– Competition apex / grapes
– Dense canopy
– Negative canopy micro climate implications:
→ temperature (lower malic acid degradation)
→ low light (less anthocyanin, more IBMP)
→ humidity (diseases)
• Increases berry Van Leeuwen, 2004, Grapes, wine and
weight
environment, Roanoke (Virginia)

12. Which parameters determine
vine vigor ?
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

13. Effect of environmental ressources on vine vigor
Apparent photosynthesis
(µmol CO2 . m-² . s-1
• Soil (especially soil depth)
– Mineral elements (N, K, pH…)
– water (water holding capacity)
• Climate (effect on photosynthesis)
– temperature
– light
– water (rainfall and ETo)
Leaf temperature (°C)
Van Leeuwen, 2004, Grapes, wine and
(in : Zufferey, 2000)
environment, Roanoke (Virginia)

14. Effect of plant material on vine vigor
• Rootstock
– Highly dominant effect
1 2 3 4 5
Riparia 101-14 Mgt Gravesac SO 4 ; 1103 P ;
Gloire de (-) ; (-) ; 41 B ; 110 R 5 BB ;
Montpellier 3309 C ; Fercal 140 Ru ;
420 A ; 161- 99 R
49 C
• Grapevine variety
– difficult to use
• Clone
– interesting aspect,
Van Leeuwen, 2004, Grapes, wine and
insufficiently used
environment, Roanoke (Virginia)

15. Effect of training system on vine vigor
• Training system
80
determines exposed
75 h = 1.2m
leaf area
70 h = 1m – Light interception
– Crop evapo-transpiration
% intercepted
65
radiation
60 (ETC)
55 • Wich parameters
50 determine exposed leaf
45 area ?
40
1 1.2 1.4 1.6 1.8 2 2.2
– Foliage height
– Density and particularly
Row spacing (m)
row spacing
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

16. Effect of berry weight on grape
potential
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

17. Relationship berry weight / grape potential
70 y = -2,7084x + 113,09 • Small berries contain
Weight of 50 berries (g)
2
65 R = 0,7157 higher sugar levels
60
55
• Small berries have
50
higher concentrations
45
in phenolics
40
18 19 20 21 22 23
°Brix
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

18. Which parameters determine berry weight?
Berry weight (g)
• Genetic potential
2,00 (grapevine variety, clone)
1,80 • Number of seeds
1,60 • Vine water status
1,40 • Vine nitrogen status
y = -0,2167x - 3,5687
1,20
R = -0,83
1,00
-25 -24 -23 -22 -21
Carbon isotope discrimination (deltaC13)
Measured on grape sugar at ripeness
Van Leeuwen, 2004, Grapes, wine and
(in : Trégoat et al., 2003) environment, Roanoke (Virginia)

19. Effect of leaf area / fruit weight
ratio on grape potential
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

20. Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

21. Which parameters determine leaf area /
fruit weight ratio?
• Leaf area → limited by
– Training system
– water ressources
– nitrogen ressources
• Fruit load
– Fertility (cultivar, vigor)
– Number of budds / ha
– Number of berries /
cluster
– Berry weight
(in : Huglin, 1958) Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

22. The terroir effect on grape
potential
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

23. The « terroir » effect combines many
factors
• Environmental factors
– Soil (type, depth)
– Climate (temperatures, rainfall, sunshine hours)
– Topography (altitude, slope, exposition)
• Biological factors
– Grapevine variety
– Rootstock
– Vine age
• Human factors
– Viticultural and enological practices
– Historical factors
– Economical factors
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

24. All these factors interact
• It is not possible to define the ideal climate for
vine growing
• Great wines are produced on various soil
types
• Terroir can be defined as « an ecosystem,
managed by man, in which the vine interacts
with environmental factors (soil, climate) »
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

25. Hierarchy of factors in the
terroir effect
• Climate, soil and grapevine variety play
a major role in the terroir effect
• What is the hierarchy between these
three factors?
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

26. Experimental set-up
• Three red grapevine varieties: Cabernet-Sauvignon,
Cabernet franc and Merlot
• Planted on three soils: Sand, Gravel and heavy Clay
• Where studied during eight vintages (variations in
climate)
• 37 variables were registered
• 3 factor analyses of variance were carried out to
compare the role of climate, soil and cultivar in the
terroir effect
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

27. The soils
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

28. Eight vintages with specific climatic conditions
1996: Temperatures and rainfall in Saint-Emilion; 1997
comparison with mean values
200 25
200 25
180 180
160 20 160 20
140
Temperatures (°C)
Temperatures (°C)
140
Rainfall (mm)
Rainfall (mm)
120 15 120 15
100 100
80 10 80 10
60 60
40 5 40 5
20 20
0 0 0 0
April May June July August September April May June July August September
1998 1999
200 25 200 25
180 180
160 20 160 20
140
Temperatures (°C)
Temperatures (°C)
140 Rainfall
Rainfall (mm)
Rainfall (mm)
120 15 120 Mean rainfall 15
100
Temperatures
100
Mean temperatures
80 10 80 10
60 60
40 5 40 5
20 20
0 0 0 0
April May June July
Van Leeuwen, 2004, Grapes, wine and
August September April May June July August September
environment, Roanoke (Virginia)

29. 2000: Temperatures and rainfall in Saint-Emilion; 2001
comparison with mean values
200 25
200 25
180 180
160 20 160 20
140
Temperatures (°C)
Temperatures (°C)
140
Rainfall (mm)
Rainfall (mm)
120 15 120 15
100 100
80 10 80 10
60 60
40 5 40 5
20 20
0 0 0 0
April May June July August September April May June July August September
2002 2003
200 25 200 25
180 180
160 20 160 20
Rainfall
140 140
Temperatures (°C)
Temperatures (°C)
Mean rainfall
Rainfall (mm)
Rainfall (mm)
120 15 120 Temperatures 15
100 100 Mean temperatures
80 10 80 10
60 60
40 5 40 5
20 20
0 0 0 0
April May June July August September April May June July August September
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

30. Water balance in the Bordeaux area for the vintages Water balance in the Bordeaux area for the vintages
1996, 1997, 1998 and 1999 2000, 2001, 2002 and 2003
Date Date
1/4 1/5 31/5 30/6 30/7 29/8 28/9 1/4 1/5 31/5 30/6 30/7 29/8 28/9
0 0
Water balance (rainfall - ETc)
-50
Water balance (rainfall - ETc)
-50
1997 2002
-100 -100
1999
in m m
in mm
-150 -150
Water balance 1996 Water balance 2000 2001
-200 -200
Water balance 1997 Water balance 2001
-250 Water balance 1998 -250 Water balance 2002
1996 2003
Water balance 1999 1998 Water balance 2003 2000
-300 -300
1996: cool and relatively rainy
1997: warm and rainy
1998: temperate and dry
1999: warm and relatively rainy
2000: warm and dry
2001: cool and relatively dry
2002: cool and wet
2003: hot and dry Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

31. Vine vigor
• One of the variables related to vine vigor is
the precociousness of shoot growth cessation
• Depending on the vintage and the soil type,
shoot growth cessation can be delayed to
over two monthes
• Delayed shoot growth cessation creates
competition between shoot growth and berry
ripening
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

32. Effect of climate, soil and cultivar on
precociousness of growth cessation
Precociousness of growth cessation: vintage effect
Effect of climate, soil and cultivar on
300
precociousness of growthe cessation
b c f280 a g d h Vintage effect: 75%
Day of the year
260 of total variance
240
220
200
180
bb 1996 1997 1998 1999 2000 2001 2002 2003
bb a a a a Vintage
Precociousness of growth Precociousness of growth
cessation: soil effect cessation: cultivar effect
300 300
b a b
Day of the ye ar
280 280
Day of the ye ar
Soil effect: 15% 260 260 b a a Cultivar effect: <1%
of total variance 240 240 of total variance
220
220
200
200
180
180
Merlot Cabernet Cabernet-
Gravel Sand Clay franc Sauvignon
Grapevine variety
Soil type
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

33. Precociousness of
phenological stages
• Depending on climate, soil and cultivar
berries can reach ripeness more or less early
in the season
• Too late ripening: lack of maturity, green and
acid wines
• Too early ripening: wines lacking aroma and
« finesse »
• Among phenological stages, veraison is most
appropriate to define objectively the
precociousness
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

34. Effect of climate, soil and cultivar on
precociousness of veraison
Precociousness of veraison: vintage effect
230
b f c d d a b e Vintage effect: 88%
Day of the year
220
of total variance
210
200
190
1996 1997 1998 1999 2000 2001 2002 2003
Vintage
Precociousness of veraison: Precociousness of veraison:
soil effect cultivar effect
230 230
Soil effect: 1% c a b
Day of the ye ar
b a b Cultivar effect: 8%
Day of the ye ar
220 220
of total variance of total variance
210
210
200
200
190
190 Merlot Cabernet Cabernet-
Gravel Sand Clay franc Sauvignon
Grapevine variety
Van Leeuwen, 2004, Grapes, wine and
Soil type
environment, Roanoke (Virginia)

35. Yield components
• Yield is determined by:
– Number of vines per hectare (density)
– Number of shoots per vine
– Number of clusters per shoot (bud fertility)
– Number of berries per cluster
– Berry weight at harvest
• Among yield components, berry weight is
also directly related to grape potential:
– Small berries have higher potential for making
quality red wines
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

36. Effect of climate, soil and cultivar on
berry weight
Berry weight: vintage effect
1,5
bc a b bc b b a c
Berry weight (g)
1,4
Vintage effect: 25%
1,3
of total variance
1,2
1,1
1,0
1996 1997 1998 1999 2000 2001 2002 2003
Vintage
Berry weight: Berry weight: cultivar effect
soil effect
1,5
a b b
Be rry w e ight (g)
1,5 1,4
b a b
Be rry w e ight (g)
1,4
1,3
Soil effect: 32% 1,3 Cultivar effect: 19%
1,2
of total variance 1,2 of total variance
1,1
1,1
1,0
1,0 Merlot Cabernet Cabernet-
Gravel Sand Clay franc Sauvignon
Grapevine variety
Soil type
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

37. Grape sugar
• Among variables indicating ripeness,
grape sugar is most universally used
• However, it cannot be used alone to
define grape potential
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

38. Effect of climate, soil and cultivar on
grape sugar content
Grape sugar content at ripeness: vintage effect
225
c d c c a ab ab b
220
215 Vintage effect: 13%
Sugar (g/L)
210 of total variance
205
200
195
190
1996 1997 1998 1999 2000 2001 2002 2003
Vintage
Grape sugar content at ripeness: Grape sugar content at
soil effect ripeness: cultivar effect
a a
225 225
220 220
b
Sugar (g/L)
Soil effect: 35% 215
Sugar (g/L)
215
210 b b 210 Cultivar effect: 37%
of total variance 205
c
205
200
of total variance
200 195
195 190
190 Merlot Cabernet Cabernet-
Gravel Sand Clay franc Sauvignon
Grapevine variety
Soil type
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

39. Acidity
• Grape acidity can be expressed by:
– Total acidity
– pH
– Tataric acid content
– Malic acid content
• Tartaric acid is the dominant organic acid in grapes,
but its level shows little variations
• Malic acid is another important organic acid in
grapes; its level is highly variable
• -> Variations in grape acidity are generally well
correlated with variations in grape malic acid content
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

40. Effect of climate, soil and cultivar on
grape malic acid content
Malic acid content at ripeness: vintage effect
60
a d e c c c c e
Malic acid (meq/L)
50
Vintage effect: 60%
40
of total variance
30
20
10
0
1996 1997 1998 1999 2000 2001 2002 2003
Vintage
Malic acid content at ripeness: Malic acid content at ripeness:
soil effect cultivar effect
60 60
M alic acid (m e q/L)
M alic acid (m e /L)
50 50
Soil effect: 5% b a b c b a
40 40
Cultivar effect: 21%
of total variance 30 30
of total variance
20
20
10
10
0
0
Merlot Cabernet Cabernet-
Gravel Sand Clay franc Sauvignon
Grapevine variety
Soil type
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

41. Skin phenolic content
• Red wine quality is highly dependant on
the abundance of grape skin phenolics
• Anthocyanin content is highly correlated
to tannin content
• Anthocyanin measurements are more
reproductable than tannin
measurements
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

42. Effect of climate, soil and cultivar on
grape anthocyanin content
Anthocyanin content at ripeness: vintage effect
1,2
Anthocyanin (g/kg)
1,0
a d bc c ab bc c c Vintage effect: 31%
of total variance
0,8
0,6
0,4
1996 1997 1998 1999 2000 2001 2002 2003
Vintage
Anthocyanin content at ripeness: Anthocyanin content at
soil effect ripeness: cultivar effect
Anthocyanin (g/k g)
Anthocyanin (g/k g)
1,0 b c a 1,0 b b a
Soil effect: 39% Cultivar effect: 4%
0,8 0,8
of total variance of total variance
0,6
0,6
0,4
0,4
Merlot Cabernet Cabernet-
Gravel Sand Clay franc Sauvignon
Grapevine variety
Soil type
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

43. Vine water status
• Climate and soil act on vine water
status
• Vine water status can be assessed by
measuring leaf or stem water potential
• The more negative the values, the more
the vine are subject to water deficit
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

44. Effect of climate, soil and cultivar on
minimum pre-dawn leaf water potential
Minimum pre-dawn leaf water potential: vintage effect
1996 1997 1998 1999 2000 2001 2002 2003
0,0
Vintage effect: 42%
Pre-dawn leaf water
-0,1
potential (Mpa)
-0,2
of total variance
-0,3
-0,4
-0,5
-0,6 a bc f c e e b d
Vintage
Minimum pre-dawn leaf water Minimum pre-dawn leaf water
potential: soil effect potential: cultivar effect
Cabernet-
Gravel Sand Clay M erlot Cabernet franc Sauvignon
0,0 0,0
Soil effect: 39%
Pre -daw n le af w ate r
Pre -daw n le af w ate r
-0,1 -0,1
Cultivar effect: 3%
pote ntial (M pa)
pote ntial (M pa)
of total variance -0,2 -0,2
of total variance
-0,3 -0,3
-0,4 -0,4
-0,5 -0,5 b b a
-0,6 c a b -0,6
Soil type Grapevine variety
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

45. Correlation between vine water status and
precociousness of shoot growth cessation
Correlation between shoot growth cessation and
minimum pre-dawn leaf water potential (Merlot,
Cabernet franc, Cabernet-Sauvignon, 1996-2003)
300
cessation (day of the
2
R = 0,4477
280
Shoot growth
260
3 cultivars, 8 vintages
year)
240
220
200
-1,0 -0,8 -0,6 -0,4 -0,2 0,0
Pre-dawn leaf water potential (MPa)
Correlation between shoot growth cessation and minimum pre-
dawn leaf water potential (Merlot, 1996-2003)
300
Shoot growth cessation
R2 = 0,3862
(day of the year)
280
260 1 cultivar, 8 vintages
240
220
200
-1,0 -0,8 -0,6 -0,4 -0,2 0,0
Pre-dawn leaf water potential (MPa)
Correlation between shoot growth cessation and minimum
stem water potential (Merlot, 2000)
300
Shoot growth cessation
2
R = 0,6986
(day of the year)
280
260
1 cultivar, 1 vintage 240
220
200
-2,0 -1,5 -1,0 -0,5 0,0
Van Leeuwen, 2004, Grapes, wine and Stem water potential (MPa)
environment, Roanoke (Virginia)

46. Correlation between vine water status and
precociousness of veraison
Correlation between precociousness of veraison and
minimum pre-dawn leaf water potential (Merlot, Cabernet
franc, Cabernet-Sauvignon, 1996-2003)
230
3 cultivars, 8 vintages
Date of veraison
(day of the year)
220
210
200
190
-1,0 -0,8 -0,6 -0,4 -0,2 0,0
Pre-dawn leaf water potential (MPa)
Correlation between precociousness of veraison and minimum
pre-dawn leaf water potential (Merlot, 1996-2003)
230
Date of veraison
(day of the year)
220
1 cultivar, 8 vintages 210
200
190
-1,0 -0,8 -0,6 -0,4 -0,2 0,0
Van Leeuwen, 2004, Grapes,Pre-dawn leaf water potential (MPa)
wine and
environment, Roanoke (Virginia)

47. Correlation between vine water status and
berry weight
Correlation between berry weight and minimum
pre-dawn leaf water potential (Merlot, Cabernet
franc, Cabernet-Sauvignon 1996-2003)
1,6
3 cultivars, 8 vintages
Berry weight (g)
R2 = 0,2023
1,4
1,2
1,0
0,8
-1,0 -0,8 -0,6 -0,4 -0,2 0,0
Pre-dawn leaf water potential (MPa) Correlation between berry weight and minimum pre-dawn leaf
water potential (Merlot, 1996-2003)
1,6
R2 = 0,482
1 cultivar, 8 vintages
Berry weight (g)
1,4
1,2
1,0
0,8
-1,0 -0,8 -0,6 -0,4 -0,2 0,0
Pre-dawn leaf water potential (MPa)
Correlation between berry weight and minimum stem water
potential (Merlot, 2000)
2,0
2
R = 0,7578
1,8
Berry weight (g)
1,6
1 cultivar, 1 vintage 1,4
1,2
1,0
-2,0 -1,5 -1,0 -0,5 0,0
Van Leeuwen, 2004, Grapes, wine and Stem water potential (MPa)
environment, Roanoke (Virginia)

48. Correlation between vine water status and
grape sugar content
Correlation between berry sugar content and minimum pre-
dawn leaf water potential (Merlot, Canbernet franc, Cabernet-
Sauvignon, 1996-2003)
Berry sugar content (g)
2 250
R = 0,2997 240
230
220
3 cultivars, 8 vintages
210
200
190
180
-1,0 -0,8 -0,6 -0,4 -0,2 0,0
Pre-dawn leaf water potential (MPa)
Correlation between berry sugar content and minimum pre-
dawn leaf water potential (Merlot, 1996-2003)
250
Berry sugar content (g)
2
R = 0,5527
240
230
1 cultivar, 8 vintages
220
210
200
190
180
-1,0 -0,8 -0,6 -0,4 -0,2 0,0
Pre-dawn leaf water potential (MPa)
Correlation between berry sugar content and minimum stem
water potential (Merlot, 2000)
270
Berry sugar content (g)
2
R = 0,7132
260
250
1 cultivar, 1 vintage 240
230
220
210
-2,0 -1,5 -1,0 -0,5 0,0
Van Leeuwen, 2004, Grapes, wine and Stem water potential (MPa)
environment, Roanoke (Virginia)

49. Correlation between vine water status and
grape malic acid content
Correlation between berry malic acid content and minimum pre-
dawn leaf water potential (Merlot, Cabernet franc, Cabernet-
Sauvignon, 1996-2003)
60
3 cultivars, 8 vintages
Malic acid (meq/L)
2
R = 0,214
50
40
30
20
10
0
-1,0 -0,8 -0,6 -0,4 -0,2 0,0
Pre-dawn leaf water potential (MPa)
Correlation between berry malic acid content and minimum pre-
dawn leaf water potential (Merlot, 1996-2003)
50 1 cultivar, 8 vintages
Malic acid (meq/L)
R2 = 0,165
40
30
20
10
0
-1,0 -0,8 -0,6 -0,4 -0,2 0,0
Pre-dawn leaf water potential (MPa) Correlation between berry malic acid content and minimum
stem water potential (Merlot, 2000)
50
Malic acid (meq/L)
R2 = 0,5248
40
30
1 cultivar, 1 vintage 20
10
0
-2,0 -1,5 -1,0 -0,5 0,0
Van Leeuwen, 2004, Grapes, wine and Stem water potential (MPa)
environment, Roanoke (Virginia)

50. Correlation between vine water status and
grape tartaric acid content
Correlation between berry tartrate content and minimum pre-
dawn leaf water potential (Merlot, Cabernet franc, Cabernet-
Sauvignon, 1996-2003)
100 3 cultivars, 8 vintages
Tartrate (meq/L)
90
80
70
60
50
-1,0 -0,8 -0,6 -0,4 -0,2 0,0
Pre-dawn leaf water potential (MPa)
Correlation between berry tartrate content and minimum pre-
dawn leaf water potential (Merlot, 1996-2003)
100
Tartrate (meq/L)
90
80
1 cultivar, 8 vintages
70
60
50
-1,0 -0,8 -0,6 -0,4 -0,2 0,0
Pre-dawn leaf water potential (MPa)
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

51. Correlation between vine water status and
grape anthocyanin content
Correlation between berry anthocyanin content and minimum
pre-dawn leaf water potential (Merlot, Cabernet-franc,
Cabernet-Sauvignon, 1996-2003)
2 1,20
Anthocyanin (g/kg)
R = 0,2246
1,10
1,00 3 cultivars, 8 vintages
0,90
0,80
0,70
0,60
-1,0 -0,8 -0,6 -0,4 -0,2 0,0
Pre-dawn leaf water potential (MPa) Correlation between berry anthocyanin content and minimum
pre-dawn leaf water potential (Merlot, 1996-2003)
1,20
R2 = 0,4865 1 cultivar, 8 vintages
Anthocyanin (g/kg)
1,10
1,00
0,90
0,80
0,70
0,60
-1,0 -0,8 -0,6 -0,4 -0,2 0,0
Pre-dawn leaf water potential (MPa) Correlation between berry anthocyanin content and minimum
stem water potential (Merlot, 2000)
2
2600
R = 0,7799
Anthocyanin (g/kg)
2400
2200
2000
1 cultivar, 1 vintage 1800
1600
1400
1200
-2,0 -1,5 -1,0 -0,5 0,0
Van Leeuwen, 2004, Grapes, wine and Stem water potential (MPa)
environment, Roanoke (Virginia)

52. Among other factors , low nitrogen
supply increases grape potential for
red wine making
Low N High N
N-tester values 446 525
Assimilable must nitrogen (mg N/L) 63 134
Shoot growth cessation (day of the year) 260 269
Yield (kg/vine) 1.8 2.2
Berry weight (g) 1.67 1.84
Grape sugar (g/L) 247 227
Anthocyanin (mg/L) 1490 1250
Total Phenolics Index 54 43
Total acidity (g tartrate/L) 4.7 5.4
Malic acid (g/L) 2.0 2.4
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

53. However, nitrogen deficiency
decreases grape potential for white
wine making
0N 60 N
P-4MMP (ng eq/L) 405 (a) 715 (b)
P-4MMPOH (ng eq/L) 760 (a) 2059 (b)
P-3MH (ng eq/L) 3358 (a) 14812 (b)
Must total tannin content 0.28 (a) 0.21 (b)
Glutathione mg/L 18 (a) 120 (b)
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

54. Terroir effect
• On most of the variables, the effect of climate > soil >
cultivar
• Terroir effect is largely mediated through vine water
status, which depends on climate (rainfall, ET0) and
soil (water holding capacity)
• Shoot growth and berry size are reduced in water
stressed vines
• Malic acid is reduced and anthocyanin is increased in
water stressed vines
• Grape sugar content is optimum when water deficit is
mild
• Precociousness of veraison and tartaric acid are not
related to vine water status
• Low nitrogen supply increases red grape potential
Van Leeuwen, 2004, Grapes, wine and
and decreases white grape potential
environment, Roanoke (Virginia)

55. Control of grape potential
• Examples in three different
climatic zones
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

56. 1 – Dry meditteranean climate, production of vin
red wine
• Warm and dry climate:
– Sufficient heat
degree days to
obtain good ripeness
– Irregular rainfall
• Shallow soil
– Limited water
holding capacity
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

57. Consequences of climate and soil
• Sum degree days allows to bring most varieties to complete
ripeness
– Choice of late ripening varieties : Grenache, Syrah, Mourvèdre,
petit Verdot
• Vines subject to water dificit
• A) When irrigation is not allowed or not possible
– Drought resistant rootstock (110 Richter)
– Limited leaf area
– Limited yield to maintail favorable leaf area / fruit weight
ratio
• B) When irrigation allowed and possible
- Apply deficit irrigation
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

58. Drought resitant rootstocks…
• …tend to be vigourous and so vines tend to develop
great leaf area in spring
• Leaf area has to be controlled to avoid water losses
(in non irrigated vineyards)
– « Gobelet » training system is well adapted
– Average vine density (3500 à 4000 pieds / ha)
– Limit nitrogen supply to the vines
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

59. Production costs are low
• Little canopy management
• Few problems with vine diseases
• Low cost/ha (approximately 3000 € / ha) but
limited production (5 T/ha)
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

60. 2 – Atlantic climate, red wine production
• Climate :
– Average sum of
degree days
– Weak or moderate
water deficit
• Deep soil :
– Not limiting water
and mineral supply
to the vines
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

61. Consequences of climate and soil
• Choice of grapevine variety dependant
on sum of degree days
• Low vigor rootstock
• Great leaf area
– Vine density > 5000 vines/ha
– Foliage height / row spacing = 0,8
– ->Exposed leaf area = 18 000 m2/ha
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

62. Yield should be limited
To limit yield (in order to respect a leaf
area / fruit weight ratio of 1.5)
– Spur pruning
– Inter row grassing
– Bunch thinning
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

63. In this production system :
• Vine vigor tends to be excessif
• It should be controlled by
– The use of low vigor rootstocks
– Limitation of nitrogen fertilisation
– The use of inter row grassing
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

64. Effects on production costs
• Elaborated canopy management
– desuckering
– Leaf removal
– Elimination of laterals
• Intensive pest control
– Downy mildew
– Botrytis
– Powdery mildew
• High production costs (5000€/ha)
• Yield should be a function of exposed leaf
area Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

65. 3 – Cool climate viticulture, white
wine production
• Climate
– Low sum of degree
days
– Little or no limitation
in vine water supply
• Soil
– Medium water
holding capacity and
mineral supply
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

66. Consequences of climate and soil
• Coice of grapevine varieties limited by the sum of
degree days (mainly white varieties)
• Low or medium vigor rootstock (depending on soil
lime content)
• Water supply allows great leaf area : > 5000 vines/ha
possible
• When exposed leaf area / fruit weight ratio >1.5, a
yield of 12T/ha is possible
• Limiting factor not desirable
– Nitrogen fertilisation
– No inter row grassing
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

67. Pest controll is a major issue
• Look for cluster aeration
• When inter row spacing is limited, cumulated row
length per hectare is optimized.
– Ideal density is 10 000 vines/ha
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

68. Effects on production costs
• Elaborated canopy management
– desuckering
– Leaf removal
– Elimination of laterals
• Intensive pest control
– Downy mildew
– Botrytis
– Powdery mildew
• High density
• High production costs (11 000 €/ha)
• Yield of 12T/ha possible
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)

69. Conclusion
• In viticulture grape potential is a major issue
• Viticultural practices should be adapted to maximize
grape potential (role of limiting factor)
• Grape potential is highly dependant on environmental
factors (soil, climate)
• Viticultural practices should be adapted to
environmental conditions (climate and soil)
• Production cost should be controlled. However, they
can be highly variable depending on the viticultural
practices (factor 1 à 4)
Van Leeuwen, 2004, Grapes, wine and
environment, Roanoke (Virginia)