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					Introduction


   Wine is far older than recorded history. Since the ancient world, the vine and the wine
have played a significant role in almost all civilizations. "Fruit of the vine and the work of the
Man” make an alliance of the flavorful and nutritional fruit with a privileged drink extracted
from it. Replete of symbology and full of religiosity and mysticism, the wine appears very
early in our literature, thus becoming a source for legends and myths inspiration. The
expressions "The Gift of Gods", "The Blood of Christ", and "The Essence of proper life"
attributed to this product support the role of the wine on the cultural slope as well as its
importance in our civilization (IVV, 2006).
       The vine was introduced in Portugal many years ago and nowadays is found from
North to South from the Coast to the Inland giving origin to fruits and wines of high quality
recognized world-wide, being the wine sector one of the most competitive on the international
level. The plantation of the vine in Portugal emerges from the Roman period (Almeida &
Chinelo, 1995), as the traces of that time document, namely the grape pips discovered in the
São Cucufate ruins, near Vidigueira, and some Roman wine ‘cuviers’ (IVV, 1998). Some
authors affirm that it was probably in Alentejo where the first vineyard was installed in
Portugal (Gonçalves, 1983).
   When the king D. Afonso Henriques attributed the first charter of the Palmela village, the
vineyard and the wine were already well known in the region, which confirms its wine-
growing tradition. It is known that Phoenicians and Greeks brought from the Near East a lot
of grape varieties and planted themes on the Peninsula of Setúbal since they considered its
mild climate, the hillsides lands of Arrábida and the marginal zone of the Tejo river, goods for
the vine plantation (IVV, 1998). In 1831, England imports wine from Portugal and the king
Richard II mentions the importation of wine from the Setúbal village. In 1868, in an
ampelographic (science that describes vineyards) research made in the Azeitão region, there
where described 19 white grape varieties and 10 red varieties for the wine production. On the
9th of September, 1875, Ferreira Lapa on his 6th wine conference refers to "a notable and
important viticultural district of Setúbal, the privileged region of moscatel, with a national and
European reputation". The Peninsula of Setúbal is, therefore, a pioneering region in the
elaboration of wine-growing products of well known quality, in the case of the Moscatel of
Setúbal, a rich wine whose productive area is well known delimited since 1907, in spite of the
fact that its production began rather earlier.
    In Palmela, the Castelão («Periquita») variety represents more than 95% of the planted red
varieties, while Fernão Pires and Moscatel of Setúbal are the majority of the planted white
varieties.
    The soils of Palmela are derived from podzols, mostly sandy soils with a low alkalinity.
The climate is of the Mediterranean type with low thermal range, having an average annual
rainfall of 400-500 mm (IVV, 1998). The frequent water scarcity observed during the spring
and summer, have been affected the berry ripening and grapevine yields.
    The climatic changes that occurred during the last years are the subject of the innumerable
discussions, such as their effect on the agriculture, the impact on the plants behavior, the
future plant water needs, which will the species and varieties better adapted and their
consequences on yield and quality. It is quite difficult to predict these climatic changes thanks
to the global greenhouse effect, even so the rise of the CO2 concentration in the atmosphere is
expected to be duplicated during the next century (Schultz, 2000), as well as the increased
level of the global radiation and sever changes in the hydrologic cycle with remarkable effects
on the actual agroclimatic conditions (Jones et al., 2005).
    In Europe the Mediterranean regions are particularly sensitive to dryness and potentially
very vulnerable to the expected climatic changes. Even if the rainfall levels are held the same,
the risks of severe dryness will increase due to the rise of the evaporative atmospheric
demand as a result of the global warming (Rizza et al., 2004).
    It should be take a special attention, all over the world, to the irrigation and to the use of
species and varieties well adapted to the new climatic conditions (Schultz, 2000; Chaves &
Oliveira, 2004), as the environmental global changes cause the expansion of the dry areas
(IPCC, 2001; Ragab & Prudhomme, 2002). To Jones et al. (2005), during the next fifty years
the global average temperature will increase approximately by 2 Cº and rich up to 4,5 Cº at
the end of the century, depending on the future industrial emissions (IPCC, 2001). This rise of
temperature associated with the foreseen changes in the precipitation standards, which can be
seen in the strong decrease on the rainfall values during summer, in some cases up to 50%
(Hulme et al. 1992), makes the correct water use in agriculture the main theme for the
survivals of some species and varieties, as water will become a limited source (Schultz,
2000). In the last years the number of the rainless days has increased dramatically in the
South of Europe (Luterbacher et al., 2006) and this tendency is expected to continue during
the next years (Miranda et al., 2006).
    The importance of the study and understanding of the climate changes impacts in the
agriculture is especially evident on the viticulture (Jones & Davies, 2000). The standard
climatic conditions of a specific region determine the success of some grapevine varieties, as
well as the wines characteristics produced from it, whereas the annual climate variability
determines the differences among the vintages of different years (Jones & Helman, 2003).
   The recent studies, based on the global climate models, show that the global warming will
severely penalize some viticulture regions, known for they high quality wines, since the
expected mean temperatures will be quite high for a good grape ripening. Other regions,
especially in the North of Europe, where nowadays the mean temperatures and the rainfall
levels are not so good for the grapevines, will on the contrary, benefit by the global warming
(Jones, 2005; Stock et al., 2005).
   The increase of the temperatures, the UV radiation levels and the CO2 concentration will
affect the grapevines physiological activity (Seguin & Cortazar, 2005). Many agricultural
models show that an increase on the CO2 concentration in the atmosphere will imply an
increase on the photosynthetic rates, vegetative growth, and water use efficiency, thus leading
to higher yields (Butterfield et al., 2000; Bindi et al., 2001). However, the changes in the
berry quality are more complex due to the interaction of different factors such as temperature
and the soil water availability (Schultz, 2000).
   The air temperature increase will accelerate the grapevine phenology, leading to a
reduction of the vegetative and reproductive period (Seguin & Cortazar, 2005). In some cases
it will be able to anticipate the berries ripening in about three weeks (Lebon, 2002) and to
increase the risk of the berries sunburn, causing changes in the berry quality (Schultz, 2000;
Tate 2001; Stock et al., 2005). Besides that, the sea levels are also predicted to be changed,
which will influence the climate of the coastal regions and promote the diseases appearance
due to the mild winters and springs (Salinari et al. 2006).
   The water use efficiency will become a key factor for the sustainability of many species,
as water will become scarce in most of the Mediterranean regions (Al-Kaisi & Yin, 2003).
With the gradual increase of the air temperature and with a reduction of soil water content, the
grapevine irrigation will become essential to guarantee the quality of wines and in extreme
cases the vines survival. Thus, it became essential the study of the irrigation effects on the
agronomic and physiologic grapevine responses.




   Effects of water availability on grapevine physiology
    In the Mediterranean climate, when the vines are planted without irrigation a strong water
stress is normally observed. These situations are more frequent, especially in summer and
appear as a consequence of the low soil water content, due to the low rainfall and the elevated
gradients of the water vapor pressure between the leaves and the air (Flexas, 2000; Silvestroni
et al., 2005).
    As water stress is one of the environmental factors that regulate the vegetative growth, the
photosynthesis and the yield at a global scale (Hsiao, 1973; McDonalds & Davies, 1996;
Chaves et al., 2002), particularly in zones with Mediterranean climate, water is the most
important factor of the plants productive activity (Kang & Zhang, 2004).
    The grapevine is a typically Mediterranean plant, well adapted to drought due to its deep
rootsystem, to the efficient reduction of the stomatal conductance and the high capacity of
osmotic adjustment (Rodrigues et al., 1993, Patakas & Noitsakis, 2001). Although, strong
water stresses lead to important decreases in yield and berry quality (Jackson & Lombard,
1993). The use of drip-irrigation on vineyards as increased during the last decades and is
study has been indicating important increases in the photosynthetic activity and yield
(Bravdo, 2005).
    The grapevine vegetative cycle is strongly influenced by the climate and the soil water
availability (Calò et al., 2002). Depending on the intensity of water stress and of the
vegetative cycle period where this occurs, thus will be the effect in the grapevine, which can
goes from the shoot growth stopping (Smart & Coombe, 1983; Mathews et al. 1987) until an
high leaf senescence (Lopes et al., 2001), which increases the risks of berry sunburn (Kliewer
et al., 1983; Smart & Robinson, 1991). The leaf area is particularly affected by water stress
due to the great sensitivity of the cellular growth to the dryness (Ginestar et al., 1988; Schultz
& Matthews, 1988; Lebon et al., 2006). When the water stress occurs at the beginning of the
vegetative development, we observe a reduction of the leaves size and a decrease of the shoot
elongation as in the number of lateral shoots (Williams & Matthews, 1990).
    With the irrigation we can induce the shoot growth rates (Bravdo & Naor, 1996;
Tandonnet et al., 1999) and promote increases in the leaf area (Carboneau & Casteran, 1979;
Bartolomé, 1993). However, exaggerated water amounts origin denser canopies that can have
a negative effect in the berry quality due to the decrease of the radiation levels and airing
inside of the canopy, leading to a deficient berry ripening and an increase of the risk of
plagues and diseases (Smart, 1994; Keller & Hrazdina, 1998). The regulation of the water
administration will thus allow a better balance between the vegetative and reproductive
development (Matthews et al., 1987).
    The deficit irrigation is defended by the majority of the authors as the best strategy to
control water stress (Ciphers et al., 2005) and the grapevines vigour (Stoll et al., 2000; Dry et
al., 2001; Kang & Zhang, 2004; Bravdo, 2005). The development of new methodologies of
deficit irrigation, such as Regulated deficit irrigation (RDI) and Partial Rootzone Drying
(PRD), had as main objective the increase of the plant water use efficiency (Goodwin et al.
1992; Boland et al., 1993; Loveys et al. 1997; Dry et al., 2001; Maroco et al., 2002; Flexas et
al., 2004; Gu et al., 2004; Souza et al., 2005) leading to important reductions of the water use
in agriculture (Stikic et al., 2003).
    In the RDI technique, the irrigation is interrupted in some critical periods of the vegetative
and reproductive growth (McCarthy, 1997; Dry et al., 2001) to induce mild stress on the
grapevines permitting improvements in some berry quality parameters without breakings in
the yield (Chalmers et al. 1986; Poni et al., 2005). In the vine, Dry & Loveys (1998) consider
that it is between the berry set and the veraison where we can have a better control of plant
vigour, since a moderate water stress after veraison has a little effect in the shoot growth
(Naor et al., 1993; Poni et al., 1994). RDI allows an efficient reduction in the grapevine
vigour, improving the wine quality (Jacckson & Lombard, 1993). RDI has been used
successfully with a number of crops, reaching a good balance between the vegetative and
reproductive growth and reducing water use in several crops such as olive trees (Fernández et
al., 2006), pears (Goodwing & Boland, 2002) and peaches (Boland et al., 1993, Naor, 2006).
    In PRD technique we irrigate half of the root system whereas the other half is kept in
contact with the dry soil, alternating the side of the irrigation every two weeks approximately
(Dry & Loveys, 1999). The great objective of the PRD is the manipulation of the grapevine
physiology through the reduction of the stomatal conductance (gs). The stomatal closure is
promoted by chemical/hormonal signals (ABA and cytokinins) produced by the dry roots and
sanded to the leaves through the xylem sap (Zhang and Davies 1989a,b; Gowing et al. 1990;
Tardieu et al. 1992; Croker et al. 1998; Loveys et al., 2004; Fuentes et al., 2005), whereas the
watered roots allow the plant to keep a good water status (Loveys, 1984; Davies & Zhang,
1991; Dry et al., 1996; Davies et al., 2000; Liu et al., 2001; Wakrim et al., 2005). The
physiological effects of the chemical signalling are reached through a time and space variation
of the soil moisture standards next to the rootzone (Fuentes et al., 2004).
    As related, the sending of chemical signals from the dehydrated roots to the leaves lead to
a reduction in the vegetative growth and of the stomatal conductance determining an increase
of the water use efficiency (WUE) (During et al., 1996; Dodd et al., 1996; Dry & Loveys,
1998; Loveys et al., 2000; Stoll et al., 2000; Souza et al., 2003; Kang & Zhang, 2004; Antolín
et al., 2006). The increase of the ABA concentration and the pH of the xylem are the main
agents of chemical signalling (Davies & Zhang, 1991; Davies et al. 1994; Dry et al., 1996;
During et al., 1996; Dry & Loveys, 1999; Sobeih et al. 2004) as well as the reduction of the
cytokinins concentration in the xylem (Stoll et al., 2000; Davies et al., 2005) which increase
the stomatal sensitivity to the ABA (Sauter et al., 2001; Fusseder et al., 1992). Other authors
defend that the stomatal regulation is influenced by other factors, such as the ethylene and
ionic changes in the xylem sap flow (Lösch & Schulze, 1994; Gollan et al., 1992; Wilkinson
& Davies, 2002; Sobeih et al., 2004).
   Some works with PRD relate that one of the advantages of this methodology is to
stimulate the root growth in depth, allowing to the plant to explore other water reserves and
nutrients throughout the soil profile (Dry et al., 2000; Kang et al., 2002, Mingo et al. 2003),
contrasting with other irrigation methods where the root system becomes more superficial
(Proffitt et al., 1985, Carmi et al., 1992). Some studies in faba bean (Husain et al., 1990) and
in maize (Schmidhalter et al., 1998) had significant increases in the root length, root density
and root biomass in drought conditions comparatively to well watered roots. In water stress
conditions is common to verify an increase of the plant relation roots/aerial part, since the root
growth is less affected by the water stress than the shoot growth (Wu & Cosgrove, 2000).
This lesser sensitivity of the roots results from the ABA accumulation in the dehydrated roots
that affect the ethylene production which is known for inhibiting the growth (Sharp et al.,
2000, Sharp & of Noble, 2002). Also the fast osmotic adjustment of the roots, that it allows
the root water absorption (Hsiao and Xu, 2000; Sharp et al., 2004) and the increase of the
cellular walls extensibility in the apical rootzone, as a consequence of the higher expansin
activity, determines the lesser root growth sensitivity to drying soils (Wu & Cosgrove, 2000).




   Influence of soil water content in the yield and quality


   As previously cited, the plant water status affect the vegetative growth and the gas
exchanges, being therefore one of the most important factors to guarantee a good yield with
high quality.
   The irrigation was installed whole over the world as a consequence of the decrease of the
soil water content, of the higher temperatures and the deficit of water vapour pressure of air
(Chaves & Rodrigues 1987; Schultz 1996) leading to great yield increases (Yuste et al., 1996;
Esteban et al., 1999) reaching 131% in some studies (Bartolomé, 1993). The gradual
generalization of the irrigation took to the accomplishment of many scientific works for one
correct evaluation of the effect of the total or partial reduction of the soil water deficit in the
yield and grape quality, having itself verified in almost all them an increase in the yield
components (Lopes, 1994; Flexas, 2000; Santos, 2000). This increase is mainly due to the
higher weight and number of the berries (Kliewer et al., 1983; Rodrigues, 1987; Pire &
Ojeda, 1999) and can in such a way be bigger depending if we irrigate, or not, in determined
critical periods of the berry development (Hardie & Considine, 1976; McCarthy et al., 1992).
After berry set, the berry growth can be represented by a double sigmoidal curve with two
phases of rapidly growth, separate for a platform that occurs next to the veraison (Coombe &
McCarthy, 2000). After the berry set, the berry growth results from the pericarp cell division
and of the existing cell expansion (McCarthy et al., 2002). Thus, this is the most sensitive
phase of the berry growth to water stress (Smart et al., 1974; Van Zyl, 1984; Matthews &
Anderson, 1989). During berry ripening the berry growth it is a consequence of the water
accumulation and cellular expansion (Coombe, 1992; Ojeda et al., 1999).
   The effect of irrigation in berry quality has generated much controversy because of the
great variability in the results. Depending on the irrigation water amounts, the irrigation
periods, the varieties, ambient conditions and of cultural practical, thus the gotten results had
been positive (Reynolds & Naylor, 1994; Schultz, 1996; Ferreyra et al., 2003; Escalona et al.,
2003) or negative (Bravdo et al., 1985; Hepner et al., 1985; Matthews et al., 1990; Williams,
1996). Whereas in some irrigation assays were observed increases in the sugar and
anthocyanins concentration (Garcia-Escudero et al., 1994; Bartolomé et al., 1995; Nadal &
Arola, 1995; Esteban et al., 1999), in others were verified decreases in these same quality
berry parameters (Van Leeuwen & Seguin, 1994; Pire & Ojeda, 1999). This discrepancy can
be explained by the effect of irrigation on the berry size. As related before, after the berry set
the water stress has a negative effect in the cellular division reducing its final size, increasing
the anthocyanins concentration as a consequence of the higher reason skin/pulp (Coombe &
MacCarthy, 2000; McCarthy et al., 2002). Another strategy to decrease the berry size is to
stop the irrigation during the ripening period that will affect the cellular expansion (Ojeda et
al., 1999) and the berry water accumulation (Williams & Matthews, 1990). However this is
not the best option, since during this phase there is a big flavour compounds accumulation in
the berries, being it’s very sensible to water stress (Coombe & MacCarthy, 2000).
   The deficit irrigation allows to improve the clusters microclimate (Bravdo, 2005)
increasing the berry quality (Dry et al., 2001). In almost all the studies where the deficit
irrigation treatments were compared to the full irrigated one, were observed increases in the
total sugar concentration (Lopes et al., 2001; Schultz, 1996), anthocyanins concentration
(Matthews et al., 1990; Hamman & Dami, 2000; Dry et al., 2001), phenols concentration
(Matthews & Anderson, 1988; Dry et al., 2001; Peterlunger et al., 2005) and in the berries
skin/pulp reason (Roby et al., 2004).




   Use of infrared thermography for water stress detection


   In the majority of the species the stomatal conductance is a very sensible parameter to
water stress, showing to be an excellent pointer of the plant water status (Jones, 2004).
Although this parameter is one of most used in several works to evaluate the plant water
needs, it demands an intensive work and it is not possible to be automatized.
   The recognition of that the leaf temperature tends to increase with the water stress, as a
consequence of the stomata closure (Raschke, 1960; Fuchs, 1990), led to the development of
new thermal sensorial methods for water stress detection, such as the infrared thermometry
(Anconelli & Battilani, 2000; Jones & Leinonen, 2003). These methods are very fast and
practical, having the advantage not to require the direct contact with the leaves, what it
preserves the stomatal response (Garcia et al., 2000). The infrared thermometry conjugated
with the digital image processing is an excellent tool for the fast detection of water stress,
becoming very useful in the irrigation programming (Giuliani & Flore, 2000). It was
developed an protocol of irrigation programming in U.S.A. called ‘BIOTIC’ (Biologically
Identified Optimal Temperature Interactive Console) that it compares continuous
measurements of the plant canopy temperature with the estimated ideal biological
temperature. Every time that the canopy temperature exceeds the ideal biological temperature
is considered that the plant is in a water stress condition (Mahan et al., 2000). Idso et al.
(1981) had developed a crop water stress indices (CWSI – ‘Crop Water Stress Index) being
based on the linear relation between the vapour pressure deficit and the difference between
the plant canopy and the air temperature, varying this index enters 0 (high soil water
availability) and 1 (in stress conditions) (Anconelli & Battilani, 2000).
   The infrared thermography is a methodology that measures the mean temperature of plant
canopy avoiding the inclusion of non-leaf material in the analysis of the images. In this way,
this technique becomes more efficient for the measurement of the grapevine water status that
the infrared thermometry (Jones et al., 2002). This last one only measures the value of one
target, enclosing possible non-leaf material (trunk, soil) (Moran et al., 1994). However, in
both methods canopy temperature is affected by environmental conditions as well as by
stomatal aperture, so needs calibration (Jones, 2004).
    More recently, approaches have been developed in attempts to improve the sensitivity of
infrared estimation of crop stress indices, by the use of either dry (Qiu et al. 1996) or wet and
dry (Jones et al., 1997) references surfaces. These indices have a very good correlation with
the stomatal conductance (Jones, 1999) and they present a powerful estimating capacity than
the one developed by Idso et al. (1981).




    Objectives


    The increase of the mean air temperatures and the reduction of the rainfall values for the
next decades will have consequences in all World-wide grape growing and special in the
regions with a mediterranean climate. With this work it was intended to evaluate the
grapevine responses submitted to two different water deficit irrigation strategies with 50% of
ETc. In the DI the water was uniformly applied to all the rootsystem and in PRD the water
was supplied to only one side of the root system while the other one was allowed to dry,
alternating periodically the watered side each 15 days. Our trial had also included a full
irrigated treatment with 100% ETc (FI) and a situation without irrigation (NI). The study was
conducted during three years (2000-2002) in an experimental field trial in an adult vine
located in the Experimental Center of Pegões. The two studied varieties of Vitis vinifera L
were Moscatel (syn. Muscat of Alexandria), a white variety (used for wine and table grapes)
and Castelão, a red wine variety, both grafted on 1103 Paulsen rootstock in 1997 and 1996
respectively.
    Having in account the previous considerations we are able to define the following
objectives for this thesis:
    1. To characterize the plant water status throughout the vegetative growth period, in view
        of supplying to the soil, in the most appropriate times, the necessary water amounts in
        order to assure the plant water needs (chapters II, III, IV).
    2. To characterize the vegetative growth, plant canopy and the microclimate at the cluster
        zone in the different irrigated treatments (chapters II, III, IV, V).
    3. To quantify the effect of different strategies and water amounts of irrigation in the
        yield components (chapters II, III, IV, V).
4. To evaluate the effect of different irrigation treatments in the berry composition
   (chapters II, III, IV, V) as well as in the aroma precursors, that determine the wine
   quality (chapter IV).
5. Application of infrared thermography, to be used by farmers in future irrigation
   programming systems in order to quantify the stomata closure (chapter VI).

				
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