CLIMATE AS A TERROIR COMPONENT

Congress on climate and viticulture, Zaragoza, 10-14 April 2007. 1

CLIMATE AS A TERROIR COMPONENT

Van LEEUWEN Cornelis1*, BOIS Benjamin1+2, PIERI Philippe2 and GAUDILLÈRE Jean-Pierre2

1ENITA de Bordeaux, ECAV - ISVV, UMR Écophysiologie et Génomique Fonctionnelle de la Vigne n° 1287,

1 cours du Général de Gaulle, CS 40201, 33175 Gradignan cedex, France 2INRA, ECAV - ISVV,

UMR Écophysiologie et Génomique Fonctionnelle de la Vigne n° 1287, BP 81, 33883 Villenave d’Ornon cedex, France

*Corresponding author : [email protected]

Abstract: Terroir is an important concept in viticulture because it relates the sensory attributes of wine to the environmental conditions in which the grapes are grown. Quality hierarchy and wine style may, to a considerable extent, be explained by terroir. However, terroir is difficult to study on a scientific basis because many factors are involved, including climate, soil, cultivar and human practices, and these factors interact. All over the world, great wines are grown in a variety of climatic conditions and it is not possible to define the ideal climate for grape growing by assessment of climatic parameters alone. The impact of climate on vine physiology can best be described by the sum of active temperatures (influence on vine phenology) and water balance (influence on water deficit stress experienced by the vines). The best expression of terroir is achieved when the precocity of the grapevine variety is suited to the local climatic conditions (sum of active temperatures) in such a way that full ripeness is attained by the end of the growing season. For the production of high quality red wines, environmental conditions should induce moderate vine vigour, generally through moderate water deficit stress (negative water balance). These conditions are most frequently met in moderately dry climates. Climate varies in time and in space. Yearly variations in climatic conditions are well known in viticulture as the vintage effect. In Bordeaux, the quality of the vintage depends mainly on the water balance (the more negative the water balance, the better the vintage). Spatial variations in climate can be studied at various scales, ranging from macro-climate to micro-climate. At the meso-climate scale, topography has a great influence on climatic parameters. Soil type and canopy management are crucial factors at the micro-climate scale. Great changes in climate are predicted by climatologists during the 21st century due to greenhouse effect induced by human activities. Adaptation to these changes is a major challenge for viticulturists worldwide for the next decades.

Key words: terroir, vine, climate, temperature, water balance, phenology, climate change


Introduction

Terroir is concerned with the relationship between the characteristics of an agricultural product (quality, taste, style) and its geographic origin, which might influence these characteristics. The concept of terroir is frequently used to explain the hierarchy of high-quality wines. It can be defined as an interactive ecosystem, in a given place, including climate, soil and the vine (Seguin, 1988). To understand the way terroir functions, it is essential to take into account the interactions among the factors that contribute to terroir. Climate is considered as a highly important factor in terroir expression (van Leeuwen et al., 2004a; van Leeuwen et al., 2004b). While very high quality wines are grown in various climates, it is impossible to define the ideal climate for fine wines in terms of temperature, rainfall (amount and distribution), or solar radiation. Each of the factors of the natural environment contributing to terroir expression, including climate, have to be considered in terms of their interaction with the vine. The climate influences vine physiology through temperatures, rainfall, Vapor Pressure Deficit (VPD), Potential Evapo-Tranpiration (PET), sunshine hours and wind. Agro-climatic indices are useful to account for the influence of climate on vine development and grape ripening. Vine phenology can be modelled by means of the sum of active temperatures (Winkler et al., 1974; Huglin and Schneider, 1998). Evolution of vine water deficit stress over the season can be monitored by a water balance model (Lebon et al., 2003), which takes into account the effects of climatic parameters like rainfall, PET and active temperatures. Some authors also consider the effect of minimal temperatures during the ripening period as a critical climatic parameter (Tonietto and Carbonneau, 2000; Tonietto and Carbonneau, 2004). Climate varies in time and space. Yearly variations in climatic conditions are well known in viticulture as the vintage effect. Variations in vine behaviour and grape ripening from one year to the other on a given plot reflect the effect of climate alone, because soil type and plant material can be considered constant (van Leeuwen et al., 2004a). Climate varies in space at various scales: from one region to the other (macro-climatic scale), inside a given wine growing region (meso-climatic scale), with topography (topo-climatic scale), inside a plot or inside the canopy of a given vine (micro-climatic scale). Great changes in climate are predicted by climatologists during the 21st century due to greenhouse effect induced by human activities (IPCC, 2001). Adaptation to these changes is a major challenge for viticulturists worldwide for the next decades.

To achieve terroir expression, the precocity of the grapevine variety has to match local climatic conditions

The vine is a perennial plant adapted to a wide range of climatic conditions. The main cultivated vine species for quality wine making is Vitis vinifera, which can survive temperatures as low as –15 ºC to –20 °C (depending on the cultivar) in winter. The heat load needed for grapes to attain full ripeness is highly variable among cultivars. At least, 1,200 degree days base of 10 ºC are necessary for the earliest ripening cultivars, which is another limitation on vine cultivation at high latitudes. In equatorial regions, vine vegetation is continuous and all the reproductive stages exist simultaneously in the same plot. Although viticulture is possible in equatorial regions, especially for table grape production, fruit grown under these conditions does not have a high enological potential. Taking into account these limitations, it appears that the zone most suited to growing high-quality grapes is between the 35th and the 50th parallel latitude, on both the Northern and Southern hemisphere. In some cases, high altitude can compensate for low latitude.

In this large range of latitude, climatic conditions are highly variable. It is not possible to define the ideal climatic conditions to produce high quality wines, because great wines are


produced within this range of latitude in cool conditions in the Rhine Valley, Burgundy and New Zealand, in temperate conditions in Bordeaux, Tuscany and Rioja, but also in warm conditions in Languedoc-Roussillon, Alicante, South Australia and the Napa Valley. To define more precisely the effect of climatic conditions on wine quality, interactions between climate and grapevine variety have to be taken into account.

Precocity for fruit ripening is a genetically determined property that is highly variable from one cultivar to another. In the ampelographic collection of the École Nationale Supérieure d’Agronomie de Montpellier (ENSAM), where several hundred cultivars are grown in the same vineyard, it is common to observe a two-month time lag between the moment of ripeness of the earliest and the latest ripening varieties. In traditional wine-growing regions in Europe, growers have used this property to adapt the vines to local climatic conditions. At high latitudes, the limiting factor for producing high-quality wines is the level of ripeness of the grapes. Unripe grapes give green, acidic wines, with low alcohol levels, as a result of insufficient sugar accumulation in the fruit. For this reason, early ripening varieties such as Pinot noir, Chardonnay and Gew rztraminer are grown at high latitudes, to optimise the chances of attaining correct ripeness. At lower latitudes, where the climate is warmer, grapes might attain ripeness early in the summer. Quick ripening of the grapes reduces aromatic expression in the wines produced. This was already observed by Ribéreau-Gayon and Peynaud (1960), who wrote that « the best wines are produced with cultivars that just achieve ripeness under the local climatic conditions, as if quick ripening of the grapes burned the essences that makes the finesse of great wines ». According to this empirical knowledge, growers have planted late-ripening varieties such as Grenache, Carignan and Mourvèdre (called Monastrel in Spain) in warmer climates at low latitudes. As a result, in traditional wine-growing regions in Europe, grape picking generally takes place between 10 September and 10 October, despite huge climatic differences between, for example, the Mosel in Germany and Alicante in Spain. This type of viticulture is also called « cool climate viticulture », not necessarily because the climate is particularly cool, but because the ripening of the grapes occurs in cool conditions, at the end of the summer or in the early autumn (Happ, 1999; Happ, 2000). When the precocity of the grapevine variety is matched to the local climatic conditions in this way, high terroir expression is obtained in the produced wines. These conditions are not necessarily met for the production of varietal wines, for which early ripening varieties are often planted in warm climates, resulting in harvest in August on the Northern hemisphere or January/February on the Southern hemisphere.

Agro-climatic indices are necessary to assess the impact of climatic conditions on wine production

Weather stations register a great range of climatic parameters: temperatures (minimum, maximum, mean), rainfall, Vapor Pressure Deficit (VPD), sunshine hours and wind speed and direction. These parameters can be averaged or summed at various time scales: per hour, per day, per decade, per month, per year or over pluri-annual periods. These averages are not always relevant indicators to describe vine development. Vine phenology is essentially determined by the sum of active temperatures (Winkler, 1974). Although the « zero of vegetation » is dependant upon the grapevine variety, most authors admit that vine development starts at approximately 10 °C. Vine phenology can thus be accurately modelled by the daily sum of temperatures base of 10 °C (Winkler et al., 1974). Huglin (1978) proposes another model, based on both average and maximum temperatures, and day length, to model grape maturity. Many papers relate on the role of moderate water deficits in vine vigour and yield reduction and quality potential enhancement (Duteau et al., 1981; Matthews and Anderson, 1988; van Leeuwen and Seguin, 1994; Tregoat et al., 2002; van Leeuwen et al.,


2004a; Coipel et al., 2006). The sum of rainfall is not an accurate parameter to describe the level of water deficit experienced by the vine, because the latter also depends on Potential Evapo-Transpiration (PET) and the distribution of the rainfall. A water balance model (Riou and Lebon, 2000 ; Lebon et al., 2003) allows representing the daily changes in water availability to the vine. Hence, it is a relevant agro-climatic index to assess the influence of water deficits on vine development. Although not confirmed by abundant scientific literature, empirical knowledge supports the idea that low minimum temperatures during the ripening period positively influences secondary metabolite accumulation in grapes and enhances grape quality potential. Hence, Tonietto and Carbonneau (2004) include the average minimum temperature of September (Northern hemisphere) or March (Southern hemisphere) in their Géoviticulture Multicriteria Climatic Classification System (MGC System) to account for this possible effect.

Climatic conditions vary from year to year: the vintage effect

Vine behaviour (phenology, yield, grape quality potential) varies from one year to another. This variability is the result of changing climatic conditions and is known in viticulture as the vintage effect. Variations in wine quality depending on the vintage have a huge effect on wine prices, especially in the Bordeaux region. In exceptional vintages, like 2005, prices of great Bordeaux wines can increase three fold in comparison to prices of less reputed vintages. For this reason, vintage quality has since long been registered by brokers in this region. When the ratings of Bordeaux wine brookers « Tasted and Lawton » are compared with agro-climatic indices, it appears that the intensity of water deficit stress is highly related to vintage quality.

To assess the water uptake conditions of 32 vintages in Bordeaux (1974 – 2005), average Water Deficit Stress Index (WDSI) between veraison and ripeness was calculated by the model published by Pieri and Gaudillère (2005). A Total Transpirable Soil Water (TTSW) Content at field capacity of 200 mm was used, which corresponds to an average value for Bordeaux soils. The WDSI calculated by the model ranges between 0 (severe water deficit stress, stomata permanently closed) and 1 (no water deficit stress, no stomatal regulation). A correlation between WDSI values and vintage quality ratings by Bordeaux wine brokers Tastet and Lawton shows that more than 45 % (significant at = 0.001 ; n = 32) of the quality of red Bordeaux vintages is explained by the intensity of the water deficit stress (Figure 1). Thus, vine water status can be considered as an important quality factor for red wine vintage quality in Bordeaux. Poor quality vintages are without exception wet vintages: 1974, WDSI = 0.85; 1977, WDSI = 0.97; 1984, WDSI = 0.91; 1992, WDSI = 0.99. Vintages where the vines were subjected to a serious water deficit correspond without exception to very good or great vintages: 1990, WDSI = 0.42; 1995, WDSI = 0.35; 1998: WDSI = 0.18; 2000, WDSI = 0.31; 2001, WDSI = 0.19; 2003, WDSI = 0.39; 2005, WDSI = 0.05. In not one vintage during the last 32 years, the overall quality suffered from excessive water deficit stress in Bordeaux, even if, during a dry summer, excessive water deficit stress might occur on some blocks with negative consequences on the wine quality (particularly in blocks with young vines, with a superficial root system). However, a few wet vintages produced outstanding wines, like 1982. During the period 1974 - 2005, vintage ratings are only poorly correlated to the sum of active temperatures (R2 = 0.20, data not shown). Although some very warm vintages produced high quality red Bordeaux wines (1989, 1990, 2003, 2005), other warm vintages were not outstanding (1994, 1997). Some cool vintages (1978, 1985, 1988, 1996) were among the finest over the last three decades. Temperature is a less decisive quality factor in Bordeaux than water deficit stress, although these factors are not completely independent: high temperatures generate high Potential Evaporation rates and increases water deficit stress, independently of the amount of rainfall.


The vintage effect is also a manner to study the impact of climate on vine development and fruit ripening in comparison to other parameters of the terroir effect. In an eight year study (1996-2003), phenology, vine development and grape composition of Vitis vinifera L. cv. Merlot, Cabernet franc and Cabernet-Sauvignon, were compared on three soils of the Saint-Émilion region (Bordeaux, France). By means of a three factor ANOVA, the contribution of soil, grapevine variety and climate (vintage effect) to the total variability has been measured. Most of the considered variables are significantly influenced by the climate of the vintage, the soil and the cultivar. The percentage of variance explained by each parameter is given in table 1.

A - Precociousness, vine vigour and yield The date of budbreak, flowering and veraison were very much influenced by the climatic conditions of the vintage (respectively 71 %, 87 % and 88 % of the total variance). The span between veraison in the most precocious vintage (1997) and the latest vintage (2001) of this series is 20 days (table 2). Differences among cultivars are small (8 % of the total variance), but remain highly significant. Merlot is the most precocious among the studied cultivars. Veraison occurs later for Cabernet franc than for Cabernet-Sauvignon, although Cabernet-Sauvignon reaches ripeness after Cabernet franc because of a much lower ripening speed. Differences in veraison among soils are very small (one day later on S compared to G and C), but significant.

Total shoot length and growth cessation are highly influenced by the vintage (respectively 26 % and 74 % of the total variance) and the soil type (52 % and 15 %), and much less so by the cultivar. Growth cessation is precocious in dry vintages (1998, 2000 and 2003) and on soils subjected to water stress (G and C). The span between growth cessation in a dry vintage (2003) and a wet vintage (1999) reaches as much as 81 days. The difference between the clayey soil (C) and the sandy soil (S) is 25 days. Berry weight depends on the soil type (32 %), the climate (25 %) and the cultivar (19 %). Berry weight is high on the sandy soil S (high water supply to the vines) and low on the gravelly soil (G) and the clayey soil (C). Berry weight is low for Cabernet-Sauvignon, medium for Cabernet franc and high for Merlot. Berry weight was high in 1997 and 2002 (wet vintages), but differences in berry weight among the other vintages were small and not always easy to explain.


B - Berry pulp constitution at ripeness Berry sugar content is explained by the cultivar (37 % of the total variance), the soil type (35 %) and the vintage (13 %). Merlot produces grapes with more sugar compared to Cabernet-Sauvignon. Cabernet franc berry sugar content is average, but closer to Merlot than Cabernet-Sauvignon. The clayey soil (C) is characterized by very high berry sugar content at ripeness. Sugar content is high in good vintages and low in poor vintages. The difference between the 2000 vintage (very good), and the 1997 vintage (poor) reaches in average 20 g/L. The berry sugar content at ripeness is related to the ripening speed (r = 0.64, n = 72, p 0.001). Grape juice acidity is mainly determined by the vintage. The vintage explains 66 % and 62 % of the total variance of respectively total acidity and pH. For tartaric acid, some variations exist among vintages (45 % of the total variance); 1998 is characterized by a low berry tartrate content. Grape juice tartaric acid content does not vary to a considerable extent depending on soil (only 4 % of the total variance) and cultivar (2 %). Berry malic acid content varies also depending on the vintage (60 % of the total variance), 1996 being characterized by very high concentrations and 1998 and 2003 by very low concentrations. The effect of the cultivar on malic acid (21 % of the total variance) is also highly significant: Cabernet-Sauvignon contains in average 70 % more malate than Cabernet franc and Merlot. Variation depending on soil is significant (more malate in grapes on the sandy soil), but not very big (5 % of the total variance). Total acidity is closely related to malic acid content (r = 0.92, n = 72, p 0.001), but not to tartaric acid content (r = 0.05, n = 72, n.s.)

C - Berry anthocyanin content Berry anthocyanin content, expressed in mg/kg of grapes, is surprisingly not very much influenced by the cultivar (11 % of the total variance). The effect of vintage (52 %) is higher than that of soil type (14 %). 2000, which is a very good vintage, produced grapes with high anthocyanin content, but so did 1996, which was an average vintage. Anthocyanin content is low in 1997. Among soils, the gravelly soil (G) and the clayey soil (C) produce grapes with a high anthocyanin content, unlike the sandy soil (S).

D - Vine water status Vine water status is assessed in this study by means of pre-dawn leaf water potential ( d). Minimum pre-dawn leaf water potential before veraison can be considered as an indicator of early water deficit stress and minimum pre-dawn leaf water potential between veraison and harvest as an indicator of late water deficit stress. The lowest pre-dawn leaf water values have been reached every year between veraison and harvest.

Vintage effect on vine water status was greatest in this study (42 % of the total variance). In 1998, 2000, 2001 and 2003, which were dry vintages, vines were subject to marked water stress. In these vintages, vines showed a beginning of defoliation after veraison on the gravely soil. Water stress occurred very early in the season in 1998. Only small water deficit was shown in 1996, 1997 and 2002. In 1996 and 2002, water deficit was greater than in 1997 at veraison (respectively d = -0.17, 0.19 and -0.10 Mpa), but the period veraison until harvest was wet in 1996 and 2002 and water deficit did not increase. In 1997, no water deficit occurred before veraison, because of heavy rains in June, but September was dry and a slight water deficit was registered just prior to harvest ( d = -0.24).

A highly significant effect of soil on vine water status is shown (39 % of the total variance). On the sandy soil (S), where the vine roots meet a water table, d remains close to zero, which indicates no water deficit. On the clayey soil (C), water deficit occurs early in the season (lower d pre-veraison compared to the gravelly soil), but the intensity of water stress


between veraison and harvest is greater on gravelly soil (G). Therefore, vines are subjected to moderate water deficits for a longer period on C, compared to G.

A small, but significant effect of the cultivar on vine water status is shown: d is less negative for Cabernet-Sauvignon. This variety had in average less leaf area, which can explain that it consumed less water.

Carbon isotope discrimination measured on grape sugar at ripeness ( 13C) indicates similar tendencies. 13C values are well correlated with the lowest pre-dawn leaf water potential values obtained between veraison and harvest (r = -0.79, n = 72, p 0.001).

These results show that climate (here assessed through climatic variations from year to year) is a major factor in terroir expression. In 16 out of the 22 measured variables, climate explained the largest part of the total variance. Among the variables that are mainly explained by the climate: precociousness of budbreak (71 % of the total variance), flowering (87 %) and veraison (88%), date of shoot growth cessation (74 %), total acidity (66 %), pH (62 %), malic acid (60 %) and anthocyanin (52 %).

Climatic conditions vary in space at various scales

Climatic conditions vary from one wine region to another (macro-climate scale). This effect is very difficult to study on a scientific basis, because soil also varies among wine growing regions, making it impossible to assess the effect of climatic differences alone. However, it is generally admitted that climate is a highly important feature of the typicity of wines from various vinegrowing regions. Regional climatic differences are accurately described by the Geoviticulture MGC System developed by Tonietto and Carbonneau (2004).

Climate can also account for differences in wine quality and style inside a vinegrowing region (meso-climate scale). This effect has been studied in Alsace (France) by Dumas et al. (1997), in Bordeaux by Bois (2002), in Tuscany (Italy) by Bindi and Maselli (2001) and in Oregon (USA) by Jones at al. (2004). Regional differences in active temperature sums and water balance can be the result of topography (topo-climatic scale) or land use features. Topography influences climatic parameters through altitude, aspect and slope. In altitude, temperature decreases by 0.6 °C per 100 m. Altitude fixes the limit of vinegrowing in regions like Chianti Classico (Italy), where no quality wines can be produced at altitudes higher than 600 m because the main variety (Vitis vinifera L. cv. Sangiovese) does not attain full ripeness. Heat balance is modified by aspect : vineyard blocks located on slopes exposed to the South receive more insolation, resulting in higher temperatures. Blocks on slopes exposed to the North are cooler. This effect increases with the percentage of the slope. Digital Elevation Models can be used to model the effect of aspect and slope on the amount of solar radiation received on a bare soil block. Figure 2 shows the impact of aspect and slope on the percentage of incident radiation received on the soil in the vinegrowing region of Saint-Émilion (France). Water run-off from the surface might occur during intense rainfall episodes. Hence, it modifies the amount of water infiltrating the soil and thus water balance. The higher the percentage of the slope, the greater the amount of water running off from the surface.


Figure 2 - Variation in clear sky irradiation (% of horizontal clear sky irradiation) in Saint-Émilion (France), in September.

Other geographic features like cities, forests or water masses influence climatic parameters. In the Médoc (Bordeaux, France), temperatures are influenced by the proximity of the Gironde estuary. Close to the river, minimum temperatures are higher (Figure 3a) and maximum temperatures slightly lower (Figure 3b). This temperature gradient results in a gradient of precociousness in flowering and veraison: these phenological stages are about one week delayed in blocks located at 10 km from the Gironde, compared to blocks located close to the river (Figure 3c).

Figure 3a and 3b - Gradient in minimum (left) and maximum (right) annual temperatures in the Haut-Médoc in a range from 1 to 9 kilometers from the Gironde estuary

(period 1994-2003; data from 10 climate stations).

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from 1 to 9 kilometers from the Gironde estuary. At a micro-climatic scale, climatic parameters are influenced by soil type and canopy management. Soil temperature is closely related to the amount of water in the soil. Wet soils warm up slowly in the spring, resulting in delayed phenology (Barbeau et al., 1998a et b). Canopy management has a major influence on the amount of sunlight received by the leaves and clusters (Smart and Robinson, 1991). Hence, leaf and berry temperature are greatly modified by canopy management practices, like shoot positioning, trimming or leaf removal (Pieri and Fermaud, 2005).

Adaptation to climate change: a major challenge for viticulturists in the 21st century

Climatologists predict an increase in average temperatures ranging from 2 to 5 °C over the 21st century due to the greenhouse effect induced by human activities (IPCC, 2001). In Western Europe, climate is likely to become also dryer in summer time (Moisselin et Dubuisson, 2007). Given the major impact of temperatures and water balance on vine behaviour, these huge climate changes are a major challenge for viticulturists. Viticultural practices will have to be adapted in order to continue to grow high quality wines.

An increase in temperatures will speed up grape ripening. In many European grapegrowing regions, grapes will no longer attain ripeness at the end of September, but in August. Grape ripening in the warmest part of the summer is not favourable to wine quality (van Leeuwen and Seguin, 2006). Viticultural practices have to be adapted to delay ripeness. Ripeness can be delayed by approximately one week by the grafting on certain rootstocks (like 420A, 41B). Ripening can also be delayed a few days by the use of late ripening clones. Certain viticultural practices, like leaf removal, will have to be abandoned. Altogether, ripeness can approximately be delayed by two weeks in this way. This will not be enough if the most pessimistic predictions (5 °C temperature increase) will come true. If so, a change in grapevine varieties will become inevitable. In some regions, like Bordeaux, internal resources do exist. Today, the majority of the Bordeaux area is planted with the early ripening Vitis

vinifera L. cv Merlot variety. The late ripening Vitis vinifera L. cv Cabernet-Sauvignon is

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only planted in early ripening locations, like blocks with gravelly soils. To adapt viticulture in Bordeaux to climate change, higher proportions of Vitis vinifera L. cv Cabernet-Sauvignon should be planted. In other vinegrowing regions, like Burgundy, such internal resources do not exist, because Vitis vinifera L. cv Pinot noir is the only red variety used for high quality wines and Vitis vinifera L. cv Chardonnay for high quality white wines. Later ripening varieties could be imported from other regions, like Vitis vinifera L. cv Merlot, Cabernet franc or Syrah, but this will completely change the typicity of the produced wines.

Higher temperatures will induce an increase in grape sugar content, resulting in the production of unbalanced wines with a high alcohol content. Grape sugar content can be reduced by the implementation of viticultural practices delaying ripeness. Cellar techniques, like reverse osmosis, can also be implemented reduce alcohol content in wine.

To obtain high quality potential red grapes, mild water deficit stress is necessary. A dryer climate will result in better wines in many red wine-producing regions. In dry regions, high quality wines can also be produced in dry farmed vineyards, but only at low yields. Less rainfall in these regions will mean lower yields, making wine production less profitable. Vitis

vinifera is a very drought resistant species. Drought resistance can be enhanced by viticultural techniques. The choice of a drought resistant rootstock (110R, 140Ru or other Vitis

berlandieri * Vitis rupestris crossings) is one of them. Vine water consumption can be reduced by limiting leaf area. However, grape yield should be reduced in the same proportion to maintain a favourable leaf area / fruit weight ratio. Mediterranean gobelet bush vine plantations are a good example of water use efficient vineyard design. This type of vineyard, low production costs, compensates partly for low yield, making grape production at an acceptable price per ton of grapes possible. If water is available, irrigation is also a possible way of avoiding excessive water deficit stress. Irrigation is a yield increasing technique, but production costs are also increased. To assess the opportunity to irrigate vines in a given region (beside quality implications) production costs between irrigated and non-irrigated vines should be compared at a per ton basis. Irrigation is not a sustainable way of producing grapes, especially in a context where water resources become scarcer. Hence, irrigation of vines should not be generalized and limited to situations where no other alternatives are available.

Conclusion

Climate is a major factor in terroir expression. Climate varies in space. Each wine-growing region is characterized by its average climatic conditions. Highest terroir expression is obtained in a given region with a Vitis vinifera cultivar that reaches ripeness at the end of September, or early October (on the Northern hemisphere). Inside a vinegrowing region, climatic variability is linked to topography or other geographic features. At the plot scale, soil type and canopy management influence microclimate in the fruit zone. Climate varies in time. Yearly variations in climate account for the vintage effect. Due to the greenhouse effect, climate will become warmer and probably dryer during the summer in Western Europe. Adaptation to these changes is a major challenge for viticulture in the 21st century.

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clim

ate

ps

oil

pcu

ltivarp

clim

at*s

oil

pclim

ate

*cu

ltivarp

co

il*cu

ltivarp

resid

ual

Pre

co

ucio

usn

ess, v

igo

ur

NS

: p >

0,0

5

Budbre

ak (5

0%

)71

***1

***23

***2

***2

**0

NS

1* : p

< 0

,05

Flo

werin

g (5

0%

)87

***0

*7

***1

NS

2*

0N

S2

** : p <

0,0

1

Vera

ison (5

0%

)88

***1

***8

***0

NS

2**

0N

S1

*** : p <

0,0

01

Pru

nin

g w

eig

ht (g

/vin

e)

30

***25

***15

***5

NS

12

NS

12

***10

Rip

enin

g s

peed

30

***8

***48

***3

NS

5N

S1

NS

5

Tota

l shoot le

ngth

(cm

)26

***52

***2

***9

***3

*5

***3

Shoot g

row

th c

essatio

n (D

ay O

f the Y

ear)

74

***15

***0

***8

***2

***1

***1

Leaf A

rea In

dex (m

2/m2)

37

***22

***21

***6

*4

NS

5**

5

Yie

ld c

om

po

ne

nts

Yie

ld (k

g/v

ine)

25

***31

***3

**7

*17

***11

***5

Berry

weig

ht (g

)25

***32

***19

***7

NS

7*

4**

7

Berry

an

d g

rap

e m

ust c

om

po

sitio

n a

t ripen

ess

Sugar (g

/L)

13

***35

***37

***4

**4

***2

***2

Tartra

te (m

eq/L

)45

***4

**2

*13

**28

***1

NS

7

Mala

te (m

eq/L

)60

***5

***21

***2

NS

6**

3**

3

Tota

l acid

ity (m

eq/L

)66

***4

***22

***1

NS

4**

0N

S3

Pota

ssiu

m (m

eq/L

)32

***0

NS

13

***9

NS

30

***6

**10

pH

62

***6

***15

***4

**8

***1

*3

Anth

ocyanin

(mg/L

)52

***14

***11

***7

NS

8N

S2

NS

12

Botry

tis in

tensity

(%)

27

**6

NS

7*

18

*23

*4

NS

14

Assim

ilable

nitro

gen (m

g N

/L)

9***

60

***12

***9

**4

NS

3N

S4

Vin

e w

ate

r sta

tus

Min

imum

pre

-daw

n le

af w

ate

r pote

ntia

l befo

re v

era

ison (M

Pa)

41

***34

***3

***17

***1

NS

1**

2

Min

imum

pre

-daw

n le

af w

ate

r pote

ntia

l afte

r vera

ison (M

Pa)

42

***39

***3

***14

***0

NS

1*

2

Carb

on is

oto

pe d

iscrim

inatio

n o

n g

rape s

ugar (

13C

/ 12C

)44

***47

***1

***5

***2

**0

NS

1

Tab

le 1

- 3 w

ay

an

aly

sis

of v

aria

nc

e : p

erc

en

tag

e o

f va

rian

ce

attrib

uta

ble

to c

lima

te (v

inta

ge

effe

ct), s

oil, c

ultiv

ar a

nd

the

ir

inte

rac

tion

s

Congre

ss o

n c

limate

and v

iticultu

re

Zarra

goza, 1

0-1

4 a

vril 2

007

1996

1997

1998

1999

2000

2001

2002

2003

Gra

vel

Sand

Cla

yM

erlo

t C

ab. F

ranc

Cab. S

auvig

non

Pre

co

cio

us

ne

ss

an

d v

ine

vig

or

Budbre

ak (5

0%

)

102

a

77g

89

de

91c

98b

86f

87e

89d

89c

91a

90b

85c

89b

95a

Flo

werin

g (5

0%

)

157

a

141f

155

b

151

d

153

c

154

b

155

b

147

e

151

b

152

a

152

ab

150

c

152

b

154

a

Vera

ison (5

0%

)

221

b

204f

220

c

217

d

217

d

224

a

222

b

208

e

216

b

217

a

216

b

215

c

219

a

216

b

Pru

nin

g w

eig

ht (g

/vin

e)

328

cd

410

b

350

bcd

298

d

354

bcd

385

bc

307

d

475

a

358

b

427

a

306

c

354

b

414

a

322

c

Rip

enin

g s

peed

0,9

2

de

0,8

5

e

1,2

5

b

1,0

5

cd

1,1

0

bc

1,1

4

bc

1,0

2

cd

1,5

3

a

1,1

3

b

0,9

7

c

1,2

2

a

1,3

3

a

1,2

4

b

0,7

6

c

Tota

l shoot le

ngth

(cm

)

347

cd

409

b

256f

477

a

308

e

319

de

378

c

366

c

321

b

480

a

271

c

378

a

360

a

334

b

Sh

oo

t gro

wth

cessatio

n (D

ay O

f the

Ye

ar)

275

b

269

c

240f

283

a

231

g

249

e

261

d

202

h

244

b

267

a

242

b

248

b

252

a

253

a

Leaf A

rea In

dex (m

2/m2)

1,2d

2,1

6

a

1,8

1

b

1,4

8

c

1,4

1

c

1,5

5

c

1,5

6

c

1,4

7

b

1,9

0

a

1,4

1

b

1,8

6

a

1,5

9

b

1,3

3

b

Yie

ld

Yie

ld (k

g/v

ine)

1,0

2

bc

0,9

2

c

1,2

9

a

1,4

2

a

1,1

2

b

1,1

1

b

0,7

7

d

0,8

5

c

1,3

8

a

1,0

5

b

1,0

9

ab

1,1

8

a

1,0

1

b

Berry

weig

ht (g

)

1,2

3

bc

1,3

9

a

1,2

6

b

1,1

8

bc

1,2

8

b

1,2

7

b

1,4

2

a

1,1

4

c

1,2

1

b

1,4

1

a

1,1

9

b

1,3

8

a

1,2

4

b

1,1

9

b

Berr y

an

d g

rap

e m

us

t co

mp

os

ition

at rip

en

ess

Sugar (g

/L)

206

c

200

d

209

c

206

c

220

a

216

ab

215

ab

213

b

203

b

204

b

225

a

223

a

212

b

196

c

Tartra

te (m

eq

/L)

81

ab

77

bc

67d

84a

82a

68d

75c

82a

80a

76b

76b

79a

78a

75b

Mala

te (m

eq/L

)

53a

22d

12e

28c

28c

33c

38b

16e

28b

33a

25b

22c

25b

39a

Tota

l Acid

ity (m

eq

/L)

102

a

67d

60e

69d

75c

74c

88b

60e

73b

79a

72b

67c

71b

85a

Po

tassiu

m (m

eq

/L)

51a

48

ab

46

cd

49

ad

45

cd

44d

43d

47

bc

47

NS

46

NS

47

NS

49a

45c

46b

pH

3,2

4

e

3,4

9

b

3,6

1

a

3,4

6

bc

3,5b

3,4

4

c

3,3

1

d

3,5

8

a

3,5

1

a

3,4

2

b

3,4

4

b

3,5

3

a

3,4

3

b

3,4

0

b

Anth

ocyanin

(g/k

g)

1,0

0

a

0,6

6

d

0,8

8

bc

0,8

6

c

0,9

6

ab

0,8

7

bc

0,8

3

c

0,8

5

c

0,9b

0,7

2

c

0,9

8

a

0,8

4

b

0,8

4

b

0,9

1

a

Bo

trytis

inte

nsity

(%)

1,5

6

a

0,0

2

b

0,2

2

b

1,8

2

a

0,1

5

b

1,2

0,7

50,3

10,5

9

b

0,3

7

b

1,3

1

a

Assim

ilable

Nitro

gen (m

g N

/L)

146

c

183

ab

160

bc

158

bc

206

a

248

a

145

b

119

c

199

a

139

c

174

b

Vin

e w

ate

r sta

tus

Min

imum

pre

-daw

n le

af w

ate

r pote

ntia

l befo

re v

era

ison (M

Pa

)

-0,1

7

bc

-0,1

1

a

-0,3

6

e

-0,1

5

b

-0,2

2

d

-0,1

5

bc

-0,1

9

c

-0,1

6

bc

-0,2

1

b

-0,1

0

a

-0,2

6

c

-0,1

9

b

-0,2

1

c

-0,1

6

a

Min

imum

pre

-daw

n le

af w

ate

r pote

ntia

l afte

r vera

ison (M

Pa)

-0,1

7

a

-0,2

4

bc

-0,5

4

f

-0,2

7

c

-0,4

3

e

-0,4

4

e

-0,2

1

b

-0,3

9

d

-0,4

5

c

-0,1

7

a

-0,3

9

b

-0,3

5

b

-0,3

7

b

-0,2

9

a

Carb

on is

oto

pe d

iscrim

inatio

n o

n g

rap

e s

ug

ar (

13C

/ 12C

)

-24

,1

cd

-22,2

a

-24,1

c

-23,2

b

-24c

-25

,6

e

-24,3

7

e

-22

,6

a

-25

,0

c

-24

,3

b

-24

,1

b

-23,8

a

-23,9

a

VIN

TA

GE

(CL

IMA

TE

EF

FE

CT

)S

OIL

CU

LT

IVA

R

Tab

le 2

- 3 w

ay a

naly

sis

of v

aria

nce

of th

e e

ffect o

f clim

ate

, so

il an

d c

ultiv

ar o

n p

reco

cio

usn

ess, v

igo

ur, y

ield

, berry

co

mp

ositio

n a

nd

vin

e w

ate

r sta

tus. L

ette

rs in

dic

ate

ho

mo

gen

eo

us g

rou

ps o

bta

ined

by N

ew

man

-Keu

ls te

st (p

< 5

%)

Congre

ss o

n c

limate

and v

iticultu

re

Zarra

goza, 1

0-1

4 a

vril 2

007

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