Download - Vine grape potential byvanleeuwen

Van Leeuwen, 2004, Grapes, wine andenvironment, Roanoke (Virginia)

FACTORS DETERMING GRAPE POTENTIAL AND THEIR CONTROL

Professor Cornelis van Leeuwen

ENITA Bordeaux Agricultural

University


Plan

• Definition of grape potential

• Terroir: effects of climate, soil and grapevine variety

• Role of vine water status

• Examples of grape potential management in variousconditions of soil and climate

• Factors determing grape potential :

– Absence of grape diseases

– Vine vigor

– Berry weight

– Leaf / fruit weight ratio


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 dependingon the type of wine)

– Presents a good ability to ferment

• Ideal grape composition is highly variable dependingon wine type and color


Grape potential for the production of high

quality red wine

+ Small berries

+ High phenolic content in the skins (tannins, anthocyanin)

+ Phenolic ripeness

+ Ripe pips

- Vegetatif aromas under the perception treshold

- Low malic acid content

+ Varietal aromas


Grape potential for the production of high

quality white wine

+ Optimum acidity (variable depending on climatic zone)

- Low phenolic content in the skins

- Vegetatif aromas under the perception treshold

+ Fruity aromas

+ High glutathione content


High potential grapes are healthy


It is not possible to make good wines with

disease affected grapes


Effects of vine vigor on grapepotential


Vine vigor can be highlyvariable from one plot to

another

Merlot / 420A, plantation 1984-86, densité 4348 (AOC Buzet)

Medium to high vigor Medium to low vigor Very low vigor


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)


Excessive vigor

• Delays shoot growth cessation

– Competition for carbohydrates between grapesand shoots

• Increases berry weight

• 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)


Which parameters determinevine vigor ?


Effect of environmental ressources on vine vigor

• Soil (especially soil depth)

– Mineral elements (N, K, pH…)

– water (water holding capacity)

• Climate (effect on photosynthesis)

– temperature

– light

– water (rainfall and ETo)

(in : Zufferey, 2000)

Leaf temperature (°C)

Apparent photosynthesis

(µmol CO2 . m-² . s-1


Effect of plant material on vine vigor

• Rootstock

– Highly dominant effect

1 2 3 4 5

RipariaGloire de Montpellier

101-14 Mgt (-) ; 3309 C ;

420 A ; 161-49 C

Gravesac(-) ; 41 B ; Fercal

SO 4 ; 110 R

1103 P ; 5 BB ; 140 Ru ;

99 R

• Grapevine variety

– difficult to use

• Clone

– interesting aspect, insufficiently used


Effect of training system on vine vigor

• Training system determines exposedleaf area– Light interception

– Crop evapo-transpiration(ETC)

• Wich parametersdetermine exposed leafarea ?– Foliage height

– Density and particularlyrow spacing

40

45

50

55

60

65

70

75

80

1 1.2 1.4 1.6 1.8 2 2.2

Row spacing (m)

% i

nte

rce

pte

dra

dia

tio

n

h = 1.2m

h = 1m


Effect of berry weight on grapepotential


Relationship berry weight / grape potential

• Small berries containhigher sugar levels

• Small berries have higher concentrations in phenolics

y = -2,7084x + 113,09

R2 = 0,7157

40

45

50

55

60

65

70

18 19 20 21 22 23

°Brix

We

igh

t o

f 5

0 b

err

ies

(g

)


Which parameters determine berry weight?

• Genetic potential(grapevine variety, clone)

• Number of seeds

• Vine water status

• Vine nitrogen status

y = -0,2167x - 3,5687

R = -0,83

1,00

1,20

1,40

1,60

1,80

2,00

-25 -24 -23 -22 -21

Carbon isotope discrimination (deltaC13)

Berry weight (g)

Measured on grape sugar at ripeness

(in : Trégoat et al., 2003)


Effect of leaf area / fruit weightratio on grape potential


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)


The terroir effect on grapepotential


• 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

The « terroir » effect combines manyfactors


• 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) »

All these factors interact


• Climate, soil and grapevine variety playa major role in the terroir effect

• What is the hierarchy between thesethree factors?

Hierarchy of factors in theterroir effect


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 theterroir effect


The soils


Eight vintages with specific climatic conditions

1996: Temperatures and rainfall in Saint-Emilion;

comparison with mean values

0

20

40

60

80

100

120

140

160

180

200

April May June July August September

Ra

infa

ll (

mm

)

0

5

10

15

20

25

Te

mp

era

ture

s (

°C)

1997

0

20

40

60

80

100

120

140

160

180

200


Ra

infa

ll (

mm

)

0

5

10

15

20

25

Te

mp

era

ture

s (

°C)

1998

0

20

40

60

80

100

120

140

160

180

200


Ra

infa

ll (

mm

)

0

5

10

15

20

25

Te

mp

era

ture

s (

°C)

1999

0

20

40

60

80

100

120

140

160

180

200


Ra

infa

ll (

mm

)

0

5

10

15

20

25

Te

mp

era

ture

s (

°C)

Rainfall

Mean rainfall

Temperatures

Mean temperatures


2000: Temperatures and rainfall in Saint-Emilion;

comparison with mean values

0

20

40

60

80

100

120

140

160

180

200


Ra

infa

ll (

mm

)

0

5

10

15

20

25

Te

mp

era

ture

s (

°C)

2001

0

20

40

60

80

100

120

140

160

180

200


Ra

infa

ll (

mm

)

0

5

10

15

20

25

Te

mp

era

ture

s (

°C)

2002

0

20

40

60

80

100

120

140

160

180

200


Ra

infa

ll (

mm

)

0

5

10

15

20

25

Te

mp

era

ture

s (

°C)

2003

0

20

40

60

80

100

120

140

160

180

200


Ra

infa

ll (

mm

)

0

5

10

15

20

25

Te

mp

era

ture

s (

°C)

Rainfall

Mean rainfall

Temperatures

Mean temperatures


Water balance in the Bordeaux area for the vintages

1996, 1997, 1998 and 1999

-300

-250

-200

-150

-100

-50

0

1/4 1/5 31/5 30/6 30/7 29/8 28/9

Date

Wate

r b

ala

nc

e (

rain

fall -

ET

c)

in m

m

Water balance 1996

Water balance 1997

Water balance 1998

Water balance 1999

1997

1999

19961998

Water balance in the Bordeaux area for the vintages

2000, 2001, 2002 and 2003

-300

-250

-200

-150

-100

-50

0

1/4 1/5 31/5 30/6 30/7 29/8 28/9

Date

Wate

r b

ala

nce

(ra

infa

ll -

ET

c)

in m

m

Water balance 2000

Water balance 2001

Water balance 2002

Water balance 20032003

2000

2001

2002

1996: cool and relatively rainy1997: warm and rainy1998: temperate and dry1999: warm and relatively rainy2000: warm and dry2001: cool and relatively dry2002: cool and wet2003: hot and dry


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


Effect of climate, soil and cultivar onprecociousness of growth cessation

bb a abb a a

Precociousness of growth cessation: vintage effect

180

200

220

240

260

280

300

1996 1997 1998 1999 2000 2001 2002 2003

Vintage

Da

y o

f th

e y

ea

r

Precociousness of growth

cessation: soil effect

180

200

220

240

260

280

300

Gravel Sand Clay

Soil type

Da

y o

f th

e y

ea

r

Precociousness of growth

cessation: cultivar effect

180

200

220

240

260

280

300

Merlot Cabernet

franc

Cabernet-

Sauvignon

Grapevine variety

Da

y o

f th

e y

ea

r

b c f a g e d h

b a bb a a

Vintage effect: 75%of total variance

Cultivar effect: <1%of total variance

Soil effect: 15%of total variance

Effect of climate, soil and cultivar onprecociousness of growth cessation


Precociousness of phenological stages

• Depending on climate, soil and cultivar berries can reach ripeness more or less earlyin the season

• Too late ripening: lack of maturity, green andacid wines

• Too early ripening: wines lacking aroma and« finesse »

• Among phenological stages, veraison is mostappropriate to define objectively theprecociousness


Effect of climate, soil and cultivar onprecociousness of veraison

Precociousness of veraison: vintage effect

190

200

210

220

230

1996 1997 1998 1999 2000 2001 2002 2003

Vintage

Da

y o

f th

e y

ea

r

Precociousness of veraison:

soil effect

190

200

210

220

230

Gravel Sand Clay

Soil type

Da

y o

f th

e y

ea

r

Precociousness of veraison:

cultivar effect

190

200

210

220

230

Merlot Cabernet

franc

Cabernet-

Sauvignon

Grapevine variety

Da

y o

f th

e y

ea

r

b f c d da b e

b a b c a b


Cultivar effect: 8%of total variance



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 isalso directly related to grape potential:– Small berries have higher potential for making

quality red wines


Berry weight: vintage effect

1,0

1,1

1,2

1,3

1,4

1,5

1996 1997 1998 1999 2000 2001 2002 2003

Vintage

Be

rry w

eig

ht

(g)

Berry weight:

soil effect

1,0

1,1

1,2

1,3

1,4

1,5

Gravel Sand Clay

Soil type

Be

rry

we

igh

t (g

)

Berry weight: cultivar effect

1,0

1,1

1,2

1,3

1,4

1,5

Merlot Cabernet

franc

Cabernet-

Sauvignon

Grapevine variety

Be

rry

we

igh

t (g

)

Effect of climate, soil and cultivar onberry weight




bc a b bc b ba

c

b a ba b b


Grape sugar

• Among variables indicating ripeness, grape sugar is most universally used

• However, it cannot be used alone to define grape potential


Grape sugar content at ripeness: vintage effect

190

195

200

205

210

215

220

225

1996 1997 1998 1999 2000 2001 2002 2003

Vintage

Su

ga

r (g

/L)

ccdc bababa

Grape sugar content at ripeness:

soil effect

190

195

200

205

210

215

220

225

Gravel Sand Clay

Soil type

Su

ga

r (g

/L)

Grape sugar content at

ripeness: cultivar effect

190195200205

210215220225

Merlot Cabernet

franc

Cabernet-

Sauvignon

Grapevine variety

Su

ga

r (g

/L)

Effect of climate, soil and cultivar ongrape sugar content




b b

a a

b

c


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 wellcorrelated with variations in grape malic acid content


Malic acid content at ripeness: vintage effect

0

10

20

30

40

50

60

1996 1997 1998 1999 2000 2001 2002 2003

Vintage

Ma

lic

ac

id (

me

q/L

)

Malic acid content at ripeness:

soil effect

0

10

20

30

40

50

60

Gravel Sand Clay

Soil type

Ma

lic

ac

id (

me

/L)

Malic acid content at ripeness:

cultivar effect

0

10

20

30

40

50

60

Merlot Cabernet

franc

Cabernet-

Sauvignon

Grapevine variety

Ma

lic

ac

id (

me

q/L

)

Effect of climate, soil and cultivar ongrape malic acid content




a d e c c c c e

b a b c b a


Skin phenolic content

• Red wine quality is highly dependant on the abundance of grape skin phenolics

• Anthocyanin content is highly correlatedto tannin content

• Anthocyanin measurements are more reproductable than tannin measurements


Anthocyanin content at ripeness: vintage effect

0,4

0,6

0,8

1,0

1,2

1996 1997 1998 1999 2000 2001 2002 2003

Vintage

An

tho

cya

nin

(g

/kg

)

Anthocyanin content at ripeness:

soil effect

0,4

0,6

0,8

1,0

Gravel Sand Clay

Soil type

An

tho

cy

an

in (

g/k

g)

Anthocyanin content at

ripeness: cultivar effect

0,4

0,6

0,8

1,0

Merlot Cabernet

franc

Cabernet-

Sauvignon

Grapevine variety

An

tho

cy

an

in (

g/k

g)

Effect of climate, soil and cultivar ongrape anthocyanin content




a d bc c ab bc c c

b c a b b a


Vine water status

• Climate and soil act on vine waterstatus

• 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


Minimum pre-dawn leaf water potential: vintage effect

-0,6

-0,5

-0,4

-0,3

-0,2

-0,1

0,0

1996 1997 1998 1999 2000 2001 2002 2003

Vintage

Pre

-da

wn

le

af

wa

ter

po

ten

tia

l (M

pa

)

Minimum pre-dawn leaf water

potential: soil effect

-0,6

-0,5

-0,4

-0,3

-0,2

-0,1

0,0Gravel Sand Clay

Soil type

Pre

-da

wn

le

af

wa

ter

po

ten

tia

l (M

pa

)

Minimum pre-dawn leaf water

potential: cultivar effect

-0,6

-0,5

-0,4

-0,3

-0,2

-0,1

0,0M erlot Cabernet f ranc

Cabernet-

Sauvignon

Grapevine variety

Pre

-da

wn

le

af

wa

ter

po

ten

tia

l (M

pa

)




Effect of climate, soil and cultivar onminimum pre-dawn leaf water potential

a bc f c e e b d

c a b

b b a


Correlation between shoot growth cessation and

minimum pre-dawn leaf water potential (Merlot,

Cabernet franc, Cabernet-Sauvignon, 1996-2003)

R2 = 0,4477

200

220

240

260

280

300

-1,0 -0,8 -0,6 -0,4 -0,2 0,0

Pre-dawn leaf water potential (MPa)

Sh

oo

t g

row

th

ce

ssati

on

(d

ay

of

the

year)

Correlation between shoot growth cessation and minimum pre-

dawn leaf water potential (Merlot, 1996-2003)

R2 = 0,3862

200

220

240

260

280

300

-1,0 -0,8 -0,6 -0,4 -0,2 0,0


Sh

oo

t g

row

th c

essati

on

(day

of

the

ye

ar)

Correlation between shoot growth cessation and minimum

stem water potential (Merlot, 2000)

R2 = 0,6986

200

220

240

260

280

300

-2,0 -1,5 -1,0 -0,5 0,0

Stem water potential (MPa)

Sh

oo

t g

row

th c

essati

on

(day

of

the

ye

ar)

3 cultivars, 8 vintages

1 cultivar, 8 vintages

1 cultivar, 1 vintage

Correlation between vine water status andprecociousness of shoot growth cessation


Correlation between precociousness of veraison and

minimum pre-dawn leaf water potential (Merlot, Cabernet

franc, Cabernet-Sauvignon, 1996-2003)

190

200

210

220

230

-1,0 -0,8 -0,6 -0,4 -0,2 0,0


Date

of

ve

rais

on

(d

ay

of

the

ye

ar)

Correlation between precociousness of veraison and minimum

pre-dawn leaf water potential (Merlot, 1996-2003)

190

200

210

220

230

-1,0 -0,8 -0,6 -0,4 -0,2 0,0


Date

of

ve

rais

on

(d

ay

of

the

ye

ar)

Correlation between vine water status andprecociousness of veraison




Correlation between berry weight and minimum

pre-dawn leaf water potential (Merlot, Cabernet

franc, Cabernet-Sauvignon 1996-2003)

R2 = 0,2023

0,8

1,0

1,2

1,4

1,6

-1,0 -0,8 -0,6 -0,4 -0,2 0,0


Be

rry

we

igh

t (g

)

Correlation between berry weight and minimum pre-dawn leaf

water potential (Merlot, 1996-2003)

R2 = 0,482

0,8

1,0

1,2

1,4

1,6

-1,0 -0,8 -0,6 -0,4 -0,2 0,0


Be

rry

we

igh

t (g

)

Correlation between berry weight and minimum stem water

potential (Merlot, 2000)

R2 = 0,7578

1,0

1,2

1,4

1,6

1,8

2,0

-2,0 -1,5 -1,0 -0,5 0,0


Be

rry

we

igh

t (g

)

Correlation between vine water status andberry weight





Correlation between berry sugar content and minimum pre-

dawn leaf water potential (Merlot, Canbernet franc, Cabernet-

Sauvignon, 1996-2003)

R2 = 0,2997

180

190

200

210

220

230

240

250

-1,0 -0,8 -0,6 -0,4 -0,2 0,0


Be

rry

su

gar

co

nte

nt

(g)

Correlation between berry sugar content and minimum pre-


R2 = 0,5527

180

190

200

210

220

230

240

250

-1,0 -0,8 -0,6 -0,4 -0,2 0,0


Be

rry

su

gar

co

nte

nt

(g)

Correlation between berry sugar content and minimum stem

water potential (Merlot, 2000)

R2 = 0,7132

210

220

230

240

250

260

270

-2,0 -1,5 -1,0 -0,5 0,0


Be

rry

su

gar

co

nte

nt

(g)

Correlation between vine water status andgrape sugar content





Correlation between berry malic acid content and minimum pre-

dawn leaf water potential (Merlot, Cabernet franc, Cabernet-


R2 = 0,214

0

10

20

30

40

50

60

-1,0 -0,8 -0,6 -0,4 -0,2 0,0


Malic a

cid

(m

eq

/L)

Correlation between berry malic acid content and minimum pre-


R2 = 0,165

0

10

20

30

40

50

-1,0 -0,8 -0,6 -0,4 -0,2 0,0


Malic a

cid

(m

eq

/L)

Correlation between berry malic acid content and minimum


R2 = 0,5248

0

10

20

30

40

50

-2,0 -1,5 -1,0 -0,5 0,0


Malic a

cid

(m

eq

/L)

Correlation between vine water status andgrape malic acid content





Correlation between berry tartrate content and minimum pre-

dawn leaf water potential (Merlot, Cabernet franc, Cabernet-


50

60

70

80

90

100

-1,0 -0,8 -0,6 -0,4 -0,2 0,0


Tart

rate

(m

eq

/L)

Correlation between berry tartrate content and minimum pre-


50

60

70

80

90

100

-1,0 -0,8 -0,6 -0,4 -0,2 0,0


Tart

rate

(m

eq

/L)

Correlation between vine water status andgrape tartaric acid content




Correlation between berry anthocyanin content and minimum

pre-dawn leaf water potential (Merlot, Cabernet-franc,

Cabernet-Sauvignon, 1996-2003)

R2 = 0,2246

0,60

0,70

0,80

0,90

1,00

1,10

1,20

-1,0 -0,8 -0,6 -0,4 -0,2 0,0


An

tho

cya

nin

(g

/kg

)


pre-dawn leaf water potential (Merlot, 1996-2003)

R2 = 0,4865

0,60

0,70

0,80

0,90

1,00

1,10

1,20

-1,0 -0,8 -0,6 -0,4 -0,2 0,0


An

tho

cya

nin

(g

/kg

)



R2 = 0,7799

1200

1400

1600

1800

2000

2200

2400

2600

-2,0 -1,5 -1,0 -0,5 0,0


An

tho

cya

nin

(g

/kg

)

Correlation between vine water status andgrape anthocyanin content





Among other factors , low nitrogensupply increases grape potential for

red wine making

2.42.0Malic acid (g/L)

5.44.7Total acidity (g tartrate/L)

4354Total Phenolics Index

12501490Anthocyanin (mg/L)

227247Grape sugar (g/L)

1.841.67Berry weight (g)

2.21.8Yield (kg/vine)

269260Shoot growth cessation (day of the year)

13463Assimilable must nitrogen (mg N/L)

525446N-tester values

High NLow N


However, nitrogen deficiencydecreases grape potential for white

wine making

120 (b)18 (a)Glutathione mg/L

0.21 (b)0.28 (a)Must total tannin content

14812 (b)3358 (a)P-3MH (ng eq/L)

2059 (b)760 (a)P-4MMPOH (ng eq/L)

715 (b)405 (a)P-4MMP (ng eq/L)

60 N0 N


Terroir effect

• On most of the variables, the effect of climate > soil > cultivar

• Terroir effect is largely mediated through vine waterstatus, which depends on climate (rainfall, ET0) andsoil (water holding capacity)

• Shoot growth and berry size are reduced in waterstressed vines

• Malic acid is reduced and anthocyanin is increased in water stressed vines

• Grape sugar content is optimum when water deficit ismild

• Precociousness of veraison and tartaric acid are not related to vine water status

• Low nitrogen supply increases red grape potentialand decreases white grape potential


Control of grape potential

• Examples in three differentclimatic zones


1 – Dry meditteranean climate, production of vin

red wine

• Warm and dry climate:

– Sufficient heatdegree days to obtain good ripeness

– Irregular rainfall

• Shallow soil

– Limited waterholding capacity


Consequences of climate and soil

• Sum degree days allows to bring most varieties to completeripeness

– 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 weightratio

• B) When irrigation allowed and possible

- Apply deficit irrigation


Drought resitant rootstocks…

• …tend to be vigourous and so vines tend to developgreat 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


Production costs are low

• Little canopy management

• Few problems with vine diseases

• Low cost/ha (approximately 3000 € / ha) but

limited production (5 T/ha)


2 – Atlantic climate, red wine production

• Climate :

– Average sum of degree days

– Weak or moderatewater deficit

• Deep soil :

– Not limiting waterand mineral supplyto the vines



• Choice of grapevine variety dependanton 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


Yield should be limited

To limit yield (in order to respect a leafarea / fruit weight ratio of 1.5)

– Spur pruning

– Inter row grassing

– Bunch thinning


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


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 leafarea


3 – Cool climate viticulture, whitewine production

• Climate

– Low sum of degreedays

– Little or no limitation in vine water supply

• Soil

– Medium waterholding capacity andmineral supply



• Coice of grapevine varieties limited by the sum of degree days (mainly white varieties)

• Low or medium vigor rootstock (depending on soillime 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


Pest controll is a major issue

• Look for cluster aeration

• When inter row spacing is limited, cumulated rowlength per hectare is optimized.

– Ideal density is 10 000 vines/ha


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


Conclusion

• In viticulture grape potential is a major issue

• Viticultural practices should be adapted to maximizegrape potential (role of limiting factor)

• Grape potential is highly dependant on environmentalfactors (soil, climate)

• Viticultural practices should be adapted to environmental conditions (climate and soil)

• Production cost should be controlled. However, theycan be highly variable depending on the viticulturalpractices (factor 1 à 4)

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