SEARCH

SEARCH BY CITATION

Keywords:

  • Deficit irrigation;
  • grapevines;
  • production;
  • vigour;
  • water-use efficiency

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. Acknowledgements
  9. References

Grapevine irrigation is becoming an important practice to guarantee wine quality or even plant survival in regions affected by seasonal drought. Nevertheless, irrigation has to be controlled to optimise source to sink balance and avoid excessive vigour. The results we present here in two grapevine varieties (Moscatel and Castelão) during 3 years, indicate that we can decrease the amount of water applied by 50% (as in deficit irrigation, DI, and in partial root drying, PRD) in relation to full crop’s evapotranspiration (ETc) [full irrigated (FI) vines] with no negative effects on production and even get some gains of quality (in the case of PRD). We report that in non-irrigated and in several cases in PRD vines exhibit higher concentrations of berry skin anthocyanins and total phenols than those presented by DI and FI vines. We showed that these effects on quality were mediated by a reduction in vigour, leading to an increase on light interception in the cluster zone. Because plant water status during most of the dates along the season was not significantly different between PRD and DI, and when different, PRD even exhibited a higher leaf water potential than DI vines, we conclude that growth inhibition in PRD was not a result of a hydraulic control. The gain in crop water use in DI and PRD was accompanied by an increase of the δ13C values in the berries in DI and PRD as compared to FI, suggesting that we can use this methodology to assess the integrated water-use efficiency over the growing season.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. Acknowledgements
  9. References

A large proportion of vineyards are located in regions with seasonal drought (e.g. climate of the Mediterranean type) where soil and atmospheric water deficits, together with high temperatures, exert large constraints in yield and quality. In recent years, the number of dry days per year has increased in southern Europe (Luterbacher et al., 2006), and this trend is likely to increase in the future, according to global change scenarios (Petit et al., 1999; Miranda et al., 2006). This will have an impact in viticulture (Schultz, 2000), with viticulturists in these regions having to rely more and more on irrigation to stabilise yield and improve wine quality. However, there is still some controversy concerning the positive and negative effects of grapevine irrigation practice in traditional viticulture because if water is applied in excess it can reduce colour and sugar content and produce acidity imbalances in the wine (Bravdo et al., 1985; Matthews et al., 1990; Esteban et al., 2001). On the contrary, a small water supplement can increase grape yield, maintaining or even improving quality (Reynolds & Naylor, 1994; Ferreyra et al., 2003; Santos et al., 2003). The question of when and how much water should be applied in a given environment and variety is still standing.

A key to improve winegrape quality in irrigated vineyards is to achieve an appropriate balance between vegetative and reproductive development, as an excess of shoot vigour may have undesirable consequences for fruit composition (McCarthy, 1997). A mild water stress, maintained through partial irrigation, may reduce vine vigour and competition for carbohydrates by growing tips, as well as promoting a shift in the partition of photoassimilates towards reproductive tissues and secondary metabolites. These changes in plant metabolism by mild water stress may increase the quality of the fruit and wine produced (Matthews & Anderson, 1988, 1989).

With enhanced pressure on water resources, the increasing demand for vineyard irrigation will only be met if there is an improvement in the efficiency of water use (Davies et al., 2002; Chaves & Oliveira, 2004; Flexas et al., 2004; Cifre et al., 2005; Souza et al., 2005a). New approaches for irrigation management will have to reduce both water consumption and the detrimental environmental effects of current agricultural practices. This goal may be achieved in several ways, deficit drip irrigation being a widely used practice with the aim of saving water and simultaneously improving wine quality. Currently, the two most important irrigation tools, based on physiological knowledge of grapevine and other crops response to water stress, are regulated deficit irrigation (RDI) and partial root-zone drying (PRD).

In RDI water input is removed or reduced for specific periods during the crop cycle, improving control of vegetative vigour, to optimise fruit size, fruitfulness and fruit quality (Chalmers et al., 1986; Alegre et al., 1999; Dry et al., 2001). RDI has been used successfully with several crops, reducing water use in crops, such as olive trees (Alegre et al., 1999; Goldhamer, 1999; Wahbi et al., 2005), peaches (Mitchell & Chalmers, 1982; Li et al., 1989; Boland et al., 1993), pears (Mitchell et al., 1989; Caspari et al., 1994; Marsal et al., 2002) and grapevines (Goodwin & Macrae, 1990; Battilani, 2000). However, this technique needs control of water application, which is difficult to achieve in practice.

In vineyards under Mediterranean conditions it has been a common practice to manage the water deficit during the final phases of grape development (Williams & Matthews, 1990). However, in Australia, for example, the most common practice is to apply less water early in the season (McCarthy et al., 2000). Both of these practices have shown to benefit wine, in one case reducing the grape size by limiting available water and in the other one by limiting the potential for grape growth. Flavour compounds, which determine wine quality, are located principally in the berry skin; therefore a smaller size in the grape berries improves fruit quality as a result of the increase in skin to flesh ratio (McCarthy, 1997). Yet, crops such as apple trees are negatively influenced by the latter (Leib et al., 2006).

Partial root-zone drying is a new irrigation technique that requires approximately half of the root system to be maintained in a drying state while the remainder of the root system is irrigated. Theoretically, roots of the watered side maintain a favourable plant water status, while dehydrating roots will synthesise chemical signals, which are transported to the leaves in the transpiration stream, leading to the reduction of stomatal conductance and/or growth and bringing about an increase in water-use efficiency (WUE) (Loveys, 1984; Davies & Zhang, 1991; Dodd et al., 1996; Dry et al., 1996; Davies et al., 2000; Loveys et al., 2000; Stoll et al., 2000; Liu et al., 2001; Souza et al., 2003; Antolín et al., 2006). There is also the indication that PRD irrigation may have impact on root growth leading to an increased root development in the deeper layers as shown by Dry et al. (2000) and Santos T.P., Lopes C.M., Rodrigues M.L., Souza C.R., Maroco J.P., Pereira J.S., Silva J.R., Chaves M.M. (submitted) in grapevine or in the overall root system, as shown in tomato by Mingo et al. (2003). It has also been reported that, as a result of drying roots in PRD, non-hydraulic signalling could occur, leading to increases in abcisic acid (ABA) production and in xylem pH (Davies & Zhang, 1991; Dry et al., 1996; Dry & Loveys, 1999; Stoll et al., 2000) as well as a reduction of cytokinins (Stoll et al., 2000; Davies et al., 2005).

The frequency of switching irrigation between rows in PRD will have to be determined according to the soil type and other factors such as rainfall, temperature and evaporative demand, but in most of the published data in grapevines, the PRD cycles were around 10–15 days (Davies et al., 2000; Stoll et al., 2000; Santos et al., 2003). The agronomic and physiological effects of the PRD technique have been tested on several horticultural crops and fruit trees, in studies carried out either in pot or field conditions. These include apple (Gowing et al., 1990), citrus (Hutton, 2000), almond (Heilmeier et al., 1990), pear (Kang et al., 2002, 2003), olive (Wahbi et al., 2005), tomato (Davies et al., 2000; Mingo et al., 2003), soybean (Bahrun, 2003) and recently common bean (Wakrim et al., 2005). The results are variable as a consequence of species differences and the characteristics of each experiment: soils, climate and agronomic practices. The debate in the literature over the effects and underlying causes of PRD functioning is still very intense. For example, according to Bravdo (2005), an absolute control of root drying is not possible under field conditions and also hydraulic redistribution from deeper to shallower roots may prevent that the clear results obtained in potted plants, are achieved under field conditions. Other authors, e.g. Gu et al. (2004), argue that the amount of water used rather than the application system explains the effects of PRD.

We studied the effects of different irrigation regimes in physiology and production of two grapevine varieties (Moscatel and Castelão), during 3 years, under the framework of the EU project IRRISPLIT. The treatments applied were full irrigation for minimum water deficit (FI, 100% of the ETc), deficit irrigated (DI, 50% of the ETc, half of water supplied to each side of the row), partial root drying (PRD, 50% of ETc periodically supplied in alternation, to only one side of the root system whereas the other one was allowed to dry) and rain fed, non-irrigated grapevines (NI). In the present paper we review the most important results obtained, illustrating them with data obtained in the two cultivars, during the 3 years of experiments.

Material and methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. Acknowledgements
  9. References

Experimental conditions

Our research was conducted during three seasons (2000–2002) in a commercial vineyard at the Centro Experimental de Pegões, southern Portugal (70 km east of Lisbon). The climate is of the Mediterranean type, with hot and dry summers and mild and rainy winters. Long-term (1976–2005) mean annual rainfall is 550 mm year−1, with 400 mm falling during winter months (INMG, 1991). The mean annual air temperature is 16°C. Fig. 1 shows the monthly rainfall and the mean air temperature at the experimental site during the 3 years of the experiment and the average values of 30 years (1976–2005). The soil is derived from podzols, with a sandy surface layer (0.6–1.0 m) and clay at 1 m depth. Two cultivars of Vitis vinifera L. were studied, cv. Moscatel (syn. Muscat of Alexandria), a white variety (used for wine and table grapes) and cv. Castelão, a red wine variety, both grafted on 1103 Paulsen rootstock in 1997 and 1996, respectively. We have chosen the two varieties because, in addition of producing different wine types (white versus red), they are the most important varieties in the wine region (98%), and they are contrasting in precocity (Castelão starting vegetation earlier than Moscatel) and in resistance to drought (Moscatel tends to resist better than Castelão). The vines were spur pruned on a bilateral Royat Cordon system (∼16 buds per vine) using a vertical shoot positioning with a pair of movable wires. Shoots were trimmed at about 30 cm above the higher fixed wire, two to three times between bloom and véraison. The vineyard has a planting density of 4000 vines h−1, the vines being spaced 2.5 m between and 1.0 m along rows.

image

Figure 1. Total rainfall (bars) and monthly mean air temperature (lines) at the experimental site during 2000, 2001 and 2002 season and average values of 30 years (1976–2005).

Download figure to PowerPoint

Irrigation water was applied with drip emitters (4 L h−1 for FI and PRD and 2 L h−1 for DI), two per vine, positioned 30 cm from the vine trunk (out to both sides of the rows) and distributed on both sides of the root system. The water was supplied according to the crop evapotranspiration (ETc = ET0 × Kc) calculated from the evaporation of a Class A pan (ET0), corrected with the crop coefficient (Kc), We used the most suitable Kc for our conditions, according to Prichard (1992) and Allen et al. (1999). This Kc was 0.6 in June and 0.7 in July and August. The irrigation treatments were: rain fed, NI; PRD (50% of the ETc was supplied to only one side of the root system, alternating sides each 15 days approximately); deficit irrigation (50% of the ETc was supplied to both sides of the vine, 25% in each side); full irrigation (FI, 100% of the ETc was supplied to both the sides of the root system, 50% in each side). Water was supplied twice per week from the beginning of berry development (June) until harvest (September). Cumulative rainfall during the experimental period (mid-June until the end of August) was 19.4 mm in 2000, 6.3 mm in 2001 and 0.5 mm in 2002 growing season (the driest year). The total amount of water supplied to FI, PRD and DI vines are shown in Table 5. During the growing season, mean soil moisture was on average 125% higher in FI and 65% in DI and PRD when compared to NI (see Santos et al., 2005 for more details). In PRD the right side of the root zone, the first one to be irrigated, had soil moisture values around twice (95 mm) those of the left side (40 mm). The reverse occurred when the irrigation side was switched.

Table 5.  Yield components, berry composition and irrigation amount at harvest in Moscatel and Castelão grapevines for four water treatments (NI, PRD, DI, FI) in 2000, 2001 and 2002.
 200020012002
NIPRDDIFILSDNIPRDDIFILSDNIPRDDIFILSD
  1. d.f., degrees of freedom; LSD, least significant difference; DI, deficit irrigation; NI, non-irrigated; FI, full irrigated; PRD, partial root drying; TPI, total phenols index.

Moscatel
 Parameter
  Yield components
   Mean cluster number per vine15.615.015.815.31.19 (6)18.218.520.019.61.32 (6)27.428.728.828.72.22 (6)
   Mean cluster weight (g)475.9515.9502.0592.855.65 (6)472.2506.0473.4502.526.67 (6)377.5407.0398.0395.33.86 (6)
   Yield (ton ha−1)28.930.931.636.03.87 (6)s33.236.436.838.82.40 (6)36.745.846.145.824.42 (6)
  Berry composition
   Total soluble solids (°Brix)21.021.820.620.61.03 (7)17.718.617.918.41.69 (7)15.817.015.915.61.70 (7)
   Anthocyanins (mg L−1 must)nananana nananana nananana 
   TPI15.615.813.012.81.73 (7)17.616.817.216.91.02 (7)8.78.78.07.70.68 (7)
   Titratable acidity (g L−1)3.53.63.83.90.26 (7)4.04.04.04.20.33 (7)3.43.43.53.80.29 (7)
   pH4.074.073.993.970.04 (7)3.953.953.913.900.14 (7)3.813.843.843.780.14 (7)
  Irrigation amount (L vine−1)0183.0183.0366.1 0210.7210.7421.4 0246.5246.5493.0 
Castelão
 Parameter
  Yield components
   Mean cluster number per vine15.515.617.216.22.19 (6)19.918.819.921.53.72 (6)21.723.923.124.93.47 (6)
   Mean cluster weight (g)114.9141.1122.3151.518.32 (6)203.9245.8236.2236.232.85 (6)188.0260.8275.9254.24.25 (6)
   Yield (ton ha−1)7.28.88.410.01.76 (6)16.218.518.820.34.27 (6)16.124.625.3254.226.93 (6)
  Berry composition
   Total soluble solids (°Brix)23.424.123.523.10.98 (7)22.422.323.022.20.97 (7)19.019.718.718.92.37 (7)
   Anthocyanins (mg L−1must)646.4490.2453.7351.272.25 (7)703.6445.2438.4364.0148.71 (7)799.1820.6682.2646.4158.61 (7)
   TPI21.817.015.912.22.67 (7)14.213.610.411.42.44 (7)20.623.219.218.92.52 (7)
   Titratable acidity (g L−1)3.483.904.084.480.28 (7)3.34.34.13.90.27 (7)3.93.94.34.80.76 (7)
   pH4.224.224.164.070.10 (7)4.214.134.224.160.05 (7)3.923.883.813.820.20 (7)
  Irrigation amount (L vine−1)0183.0183.0366.1 0210.7210.7421.4 0246.5246.5493.0 

The experimental design was a latin square with four treatments and four replications per treatment. Each replicate (plot) had 20 vines.

Vegetative growth

Leaf area per shoot (eight shoots per treatment) was assessed periodically in shoot counts from bud break onwards in a non-destructive way, using the methodologies proposed by Lopes & Pinto (2000). In these methodologies primary leaf area was estimated using a mathematical model with four variables: shoot length, leaf number and area of the largest and the smallest leaf. Lateral leaf area estimation was performed by another model that uses the same variables with the exception of lateral shoot length. The area of single leaves was estimated using an empirical model based on the relationship between the length of the two main lateral leaf veins and leaf area on 1645 leaves of all sizes, using a leaf area meter (LI-3000; LI-COR Lincoln, NB, USA). Leaf area per plant was calculated multiplying the average leaf area per shoot by the mean shoot number.

At winter pruning, shoot number and pruning weight were recorded and shoot weight and crop load (yield/pruning weight) were calculated.

Light at the cluster zone was measured on sunny days at mid-day using a Sunflek Ceptometer (model SF-40; Delta T Devices Ltd, Cambridge, UK) inserted horizontally at cluster zone along the row. The values of incident photosynthetic photon flux density (PPFD) were expressed in percentage of a reference PPFD, measured over the canopy top.

Water relations and gas exchange

Pre-dawn (Ψpd) leaf water potential was measured weekly with a Scholander-type pressure chamber (Model 1000; PMS Instrument Co., Corvallis, OR, USA), from the beginning of berry development until harvest. The measurements were carried out in six fully expanded leaves per treatment in five dates from June to August, just before the irrigation.

Net CO2 assimilation rate (A) and stomatal conductance (gs) were measured on sun-exposed fully mature leaves (from primary shoots) using a portable Li-6400 IRGA (LI-COR, Lincoln, NB, USA). All measurements were replicated 4–8 times. A and gs values were used to calculate the instantaneous intrinsic WUE (A/gs). The relative stomatal limitation (RSL) was estimated from (A/Ci) response curve, as described in Souza et al. (2005a). The maximum ratio of Rubisco carboxylation (Vcmax) and maximum electron transport capacity at saturating light (Jmax) were obtained by fitting the model of Farquhar et al. (1980) with modifications by Sharkey (1985) to A/Ci response curves as described by Maroco et al. (2002).

Carbon isotope composition

Samples to determine carbon isotope composition of mature leaves were collected in primary shoots from six plants per treatment, at harvest. Berry samples consisted of 30 berries per replicate (six replicates per treatment) taken randomly from exposed clusters. We measured whole berries in the 3 years of study, and in 2001 and 2002 the pulp berry also. The dried leaves and berry samples were ground into a fine homogeneous powder and 1 mg subsamples were analysed for δ13C using an Europa Scientific ANCA-SL Stable Isotope Analysis System (Europa Scientific Ltd., Crewe, UK). Carbon isotopic composition was expressed as δ13C = [(Rs − Rb)/Rb] × 1000, where Rs is the ratio 13C/12C of the sample and Rb is the 13C/12C of the PDB (Pee Dee Belemnite) standard.

Yield and fruit quality

Berry composition was studied at harvest. Sampling was carried out by collecting cluster fractions using a 200 berries sample per plot, collected in all vines (3–4 berries per cluster) and representative of all positions within the clusters (Carbonneau, 1991). Subsamples per plot were used for fresh berry analysis of weight and volume, pH, soluble solids (°Brix) by refractometry and titratable acidity by titration with NaOH as recommended by OIV (OIV, 1990). Another subsample of berries per plot was frozen at −30°C for anthocyanin and total phenolic compounds analysis. Total phenols were determined by spectrophotometry, by measuring ultraviolet absorption at 280 nm (Total Phenol Index, TPI) (OIV, 1990). Anthocyanins were measured by the sodium bisulphite discolouration method (Ribereau-Gayon & Stonestreet, 1965). At harvest, yield components were assessed, following manual harvesting and weighing the production on-site. Cluster number and yield per vine were recorded for all vines on each plot.

Statistical analyses

Factorial analyses of variance (ANOVA), with year, sampling time and/or treatments as main factors, were used to test the main effects and factor interactions on the physiological, biochemical and growth parameters evaluated. For multiple comparisons of treatments, we report also the SE and Fisher least significant differences (LSD). Statistically, significant differences were assumed for P < 0.05 and statistical data analysis were performed with Statistica (v5, Statsoft, Tulsa, OK, USA).

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. Acknowledgements
  9. References

Leaf water status, vegetative growth and canopy microclimate

In both varieties we observed that FI vines maintained a high Ψpd throughout the growing season (values for 2002 in Fig. 2). The minimum Ψpd was measured in middle August in 2002 (the driest year), attaining −0.22 MPa for Moscatel and −0.26 MPa Castelão (Table 1) On the contrary, NI vines showed a progressive decline in Ψpd from July onwards and the two deficit irrigation treatments (PRD and DI) had Ψpd values intermediate between FI and NI (Fig. 2). In Castelão, Ψpd of PRD vines was significantly higher than in DI. The Ψpd of Castelão NI vines at middle August reached lower values (∼−0.78 MPa) than those of NI in Moscatel (−0.64 MPa).

image

Figure 2. Seasonal evolution of pre-dawn leaf water potential for all water treatments (•, NI, ○, PRD, ▾, DI, ▵, FI), in Moscatel (A) and Castelão (B) during 2002 growing season. Each point represents the average of eight measurements with SE. Bars not visible indicate SE smaller than symbol. Least significant difference (LSD) bars and d.f. (degrees of freedom) are given for comparisons proposes. DI, deficit irrigation; NI, non-irrigated; FI, full irrigated; PRD, partial root drying.

Download figure to PowerPoint

Table 1.  Pre-dawn leaf water potential and stomatal conductance measured at mid-day in the middle of August in Castelão and Moscatel grapevines for the four water treatments (NI, PRD, DI, NI) and the 3 years 2000, 2001 and 2002.
 200020012002
ψpd (MPa)gs (mol m−2s−1)ψpd (MPa)gs (mol m−2s−1)ψpd (MPa)gs (mol m−2s−1)
  1. d.f., degrees of freedom; LSD, least significant difference; DI, deficit irrigation; NI, non-irrigated; FI, full irrigated; PRD, partial root drying.

Moscatel
 NI−0.580.10−0.390.13−0.640.13
 PRD−0.230.23−0.290.15−0.420.19
 DI−0.340.27−0.190.20−0.440.22
 FI−0.150.29−0.110.25−0.220.23
 LSD (d.f.)0.04 (4)0.11 (3)0.12 (4)0.05 (3)0.12 (4)0.10 (3)
Castelão
 NI−0.680.15−0.510.05−0.780.05
 PRD−0.370.20−0.300.15−0.430.08
 DI−0.400.20−0.280.23−0.460.08
 FI−0.280.30−0.150.30−0.260.11
 LSD (d.f.)0.06 (4)0.04 (3)0.13 (4)0.04 (3)0.08 (4)0.05 (3)

Water availability affected vine growth: the average weight per shoot measured during the winter pruning and the total pruning weight per vine were significantly lower in NI (and in PRD in the variety Castelão) than in FI and DI in the 3 years of studies (Table 2). Similar differences were observed in the percentage of water shoots (epicormic shoots grown from the old woody stem), with NI and PRD showing values significantly lower than FI and DI (Table 2). Total leaf area per vine at véraison presented, in both varieties, significantly higher values (P < 0.05) in FI than in NI and PRD vines; DI plants had intermediate values (Table 2). The differences of total leaf area observed between treatments were mainly because of differences in the lateral shoot leaf area as in some cases (Moscatel 2000, Castelão 2002) primary shoot leaf area was similar in the different watering treatments.

Table 2.  Vigour parameters measured at pruning time or at véraison (the case of leaf parameters) in Castelão and Moscatel grapevines for the four water treatments (NI, PRD, DI, FI) in 2000, 2001 and 2002.
 200020012002
NIPRDDIFILSDNIPRDDIFILSDNIPRDDIFILSD
  1. d.f., degrees of freedom; LSD, least significant difference; DI, deficit irrigation; NI, non-irrigated; FI, full irrigated; PRD, partial root drying.

Moscatel
 Shoot
  Shoot number per vine1111991.06 (6)131213120.78 (6)161718170.03 (6)
  Pruning weight (kg/vine−1)0.520.560.570.640.08 (6)0.460.510.520.580.05 (6)0.450.480.520.540.67 (6)
  Shoot weight (g)49.053.464.369.08.23 (6)36.441.242.650.84.37 (6)29.228.831.133.42.16 (6)
  Water shoots (%)nananana 8.09.412.712.92.01 (6)9.512.016.917.71.65 (6)
 Leaf
  Leaf layer number (véraison)2.63.23.83.80.30 (6)2.42.73.63.80.29 (6)2.12.23.23.60.25 (6)
  Main leaf area (m2 vine−1)2.01.92.11.90.55 (6)Nananana 2.53.13.44.00.80 (6)
  Lateral leaf area (m2  vine−1)1.62.42.84.41.29 (6)Nananana 1.91.71.83.71.22 (6)
  Total leaf area (m2  vine−1)3.64.34.96.31.24 (6)Nananana 4.34.95.27.61.60 (6)
Castelão
 Shoot
  Shoot number per vine141616171.32 (6)161820191.78 (6)191921202.20 (6)
  Pruning weight (kg vine−1)1.11.41.61.80.19 (6)1.11.21.51.50.22 (6)0.91.11.51.50.22 (6)
  Shoot weight (g)70.189.8102.5105.811.72 (6)64.967.876.877.810.54 (6)47.956.176.274.911.42 (6)
  Water shoots (%)nananana 11.214.021.520.82.82 (6)13.615.225.923.24.12 (6)
 Leaf
  Leaf layer number (véraison)2.32.63.43.40.28 (6)2.42.63.43.60.25 (6)1.62.33.33.70.24 (6)
  Main leaf area (m2  vine−1)2.63.23.43.60.73 (6)Nananana 4.44.65.56.20.73 (6)
  Lateral leaf area (m2  vine−1)0.81.31.32.51.14 (6)Nananana 0.81.01.51.51.14 (6)
  Total leaf area (m2  vine−1)3.44.54.76.01.55 (6)Nananana 5.25.67.07.71.55 (6)

The reduction in vegetative growth observed in NI and in many instances in PRD resulted in a more open canopy as indicated by the significant increase in the PPFD received by the clusters in these treatments when compared to DI and FI (Fig. 3).

image

Figure 3. Incident photosynthetic photon flux density (PPFD) at the cluster zone expressed as a percentage of a reference (PPFD at the top of the canopy) in Castelão and Moscatel grapevines under four water treatments (•, NI, ○, PRD, ▾, DI, ▵, FI) during the 2002 growing season. Values shown represent the mean of 80 measurements with SE. Least significant difference (LSD) bars and d.f. are given for comparisons proposes. DI, deficit irrigation; NI, non-irrigated; FI, full irrigated; PRD, partial root drying.

Download figure to PowerPoint

Photosynthetic performance and water-use efficiency

Diurnal time courses of gas exchange and intrinsic WUE in a typical day in August of 2002 are shown in Fig. 4. A and gs decreased throughout the day, with differences between treatments being more marked in the late afternoon and in the variety Castelão as compared with Moscatel. NI vines showed the lowest A and gs. Although most differences between PRD and DI were not statistically significant, the values of gs in PRD were closer to NI than to DI vines. Midday gs values recorded in mid-August for the two varieties and the 3 years are shown in Table 1. Because they represent the lowest attained stomatal conductances, we conclude that only in NI treatments gs reached values close to or lower than 0.1 mol m−2 s−1.

image

Figure 4. Diurnal course of photosynthesis (A), stomatal conductance (gs), intrinsic water use efficiency (A/gs) and photosynthetic photon flux density (PPFD) in cultivars Moscatel (A) and Castelão (B) measured, respectively on 5 and 8 of August 2002 for all water treatments (•, NI, ○, PRD, ▾, DI, ▵, FI). Values are the means ± SE. Least significant difference (LSD) bars and d.f. (degrees of freedom) are given for comparisons proposes. DI, deficit irrigation; NI, non-irrigated; FI, full irrigated; PRD, partial root drying.

Download figure to PowerPoint

A/gs (2002 values) did not show significant differences among treatments in Moscatel, except in the afternoon (16.00 h), where FI exhibit lower A/gs than the other treatments (Fig. 4). In Castelão, the highest values in A/gs throughout the day were observed in NI.

Stomatal limitation of gas exchange (RSL) of Moscatel NI vines was significantly higher than of FI and DI vines in two out of the three years studied (2000 and 2002, Table 3). PRD was not significantly different either from NI or from FI and DI. In Castelão (only measured in 2002) RSL of NI vines was significantly higher than of FI, DI and PRD vines (Table 3).

Table 3.  Estimated model parameters (Vcmax and Jmax) and relative stomatal limitations (RSL) for the irrigation treatments in Moscatel during years 2000, 2001 and 2002, and in Castelão during 2002.
TreatmentVCmax (μmol m−2 s−1)Jmax (μmol m−2 s−1)RSL (%)
  1. d.f., degrees of freedom; LSD, least significant difference; DI, deficit irrigation; NI, non-irrigated; FI, full irrigated; PRD, partial root drying.

Moscatel
 2000
  NI45.68130.0835.75
  PRD46.10149.9932.49
  DI47.56153.6323.77
  FI55.84170.6423.24
  LSD (d.f.)16.54 (3)21.41 (3)7.68 (3)
 2001
  NI44.89154.4137.33
  PRD54.14186.1431.33
  DI49.23177.2224.65
  FI53.42206.4325.75
  LSD (d.f.)12.14 (3)23.34 (3)9.92 (3)
 2002
  NI44.96127.5037.14
  PRD42.88219.1627.68
  DI44.35203.1318.88
  FI53.99235.1119.77
  LSD (d.f.)10.30 (3)28.44 (3)13.54 (3)
Castelão
 2002
  NI53.81217.9738.96
  PRD50.24196.4925.75
  DI48.82193.9025.47
  FI61.65220.3326.69
  LSD (d.f.)13.07 (3)34.44 (3)8.36 (3)

The estimated maximal velocity of carboxylation (Vcmax) was not significantly different between treatments in the variety Moscatel, in any of the years of study (Table 3). The same result was obtained for Castelão, in measurements made in 2002.

However, in the variety Moscatel, the rate of electron transport (Jmax) was lower in NI than in FI in the 3 years, with PRD being closer to NI and DI closer to FI in 2000. In Castelão no differences between treatments were observed (Table 3).

Carbon isotopic composition (δ13C)

The effects of the treatments on the δ13C values of bulk leaf tissue (primary and lateral leaves), whole berry and pulp berry are shown in Table 4 for the two varieties, and, in the case of Moscatel, for the 3 years. The tissues of NI plants were less depleted in 13C (higher δ13C, lowest discrimination against 13C) than the other treatments, and FI vines showed the lowest δ13C (higher discrimination against 13C). Deficit irrigation treatments (PRD and DI) showed intermediate values. In general, significant differences between NI and FI were observed in berries and pulp where a substantial enrichment of 13C is apparent as compared with the other tissues. The highest values of δ13C were shown in berry pulp as compared to leaves. A good relationship was established between pulp δ13C and intrinsic WUE (Fig. 5). This is not the case between A/gs and δ13C in leaves.

Table 4.  Carbon isotope composition (δ13C) in leaves, whole berries and pulp of grape subjected to different water treatments.
δ13C
TreatmentLeavesBerriesPulp
  1. d.f., degrees of freedom; LSD, least significant difference; DI, deficit irrigation; na, not analyzed; NI, non-irrigated; FI, full irrigated; PRD, partial root drying.

Moscatel
 2000
  NI−25.75−24.33na
  PRD−26.63−25.43na
  DI−26.67−25.88na
  FI−27.26−26.34na
  LSD (d.f.)0.55 (3)0.47 (3) 
 2001
  NI−26.83−25.02−24.61
  PRD−27.08−25.37−25.14
  DI−26.82−25.41−25.30
  FI−26.91−25.71−25.54
  LSD (d.f.)0.49 (3)0.20 (3)0.18 (3)
 2002
  NI−26.23−24.68−24.43
  PRD−26.77−25.18−25.22
  DI−26.72−25.45−25.31
  FI−27.03−25.86−25.79
  LSD (d.f.)0.32 (3)0.45 (3)0.38 (3)
Castelão
 2002
  NI−26.83−24.04−23.23
  PRD−27.53−25.72−24.89
  DI−28.08−25.43−25.22
  FI−28.34−26.61−26.04
  LSD (d.f.)0.43 (3)0.74 (3)0.62 (3)
image

Figure 5. Relationship of δ13C with intrinsic water use efficiency (A/gs) in leaves and berry pulp of Moscatel, respectively, (y = 26.37 + 0.002x, R2 = 0.01 (A); y = 27.42 − 0.04x, R2 = 0.60** (C)) and in leaves an pulp of Castelão (y = 27.81 − 0.02x, R2 = 0.26 (B); y = 28.47 − 0.04x, R2 = 0.70** (D)). Each point represents one replicate of the water treatments. The measurements of A/gs were made in August 2002.** indicates significant difference at level of 0.01. DI, deficit irrigation; NI, non-irrigated; FI, full irrigated; PRD, partial root drying.

Download figure to PowerPoint

Yield and fruit composition

As for the yield components, the number of clusters per vine was independent of soil water availability. However, cluster weight was significantly lower in NI than in FI (except in Moscatel in 2001) resulting in a significant yield decrease in the former. The three irrigated treatments showed no significant differences among them in 2001 and 2002 (Table 5).

Berry composition at harvest changed with treatments. In Castelão, skin anthocyanins accumulation was higher in NI and PRD (only significantly different in 2002) grapevines as compared to DI and FI. NI and PRD presented the highest total phenols when compared with the other treatments, and FI and DI the lowest (except in 2001 in Moscatel when no differences between treatments were observed) (Table 5). Irrigation had no significant effect on berry total soluble solids (°Brix) and pH. However, must titratable acidity increased significantly in FI as related to NI, in both varieties and in 2 years (2000 and 2002). PRD and DI also presented higher must titratable acidity than NI in the variety Castelão in 2000 and 2001 (Table 5).

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. Acknowledgements
  9. References

Our results show the potential to utilise deficit irrigation, particularly PRD, to control the redistribution of photoassimilates, through a reduction in vigour, with a positive effect on light interception in the cluster zone and in the berry composition. We showed also that the pattern of physiological responses to water deficits was identical in both varieties, but most of the effects of deficit irrigation are more pronounced in the variety Castelão than in Moscatel. This can be explained by the low sensitivity to water stress in Moscatel plants (Regina & Carbonneau, 1996). By irrigating PRD and DI grapevines with 50% of ETc, we imposed a mild water deficit that led to leaf pre-dawn water potentials at the end of the season, which were intermediate (−0.2 to −0.4 MPa in both treatments and the two varieties) between FI (−0.1 to −0.3 MPa) and NI vines (−0.6 to −0.8 MPa) (Table 1). In July 2002, we observed that PRD vines exhibited slightly higher ψpd than in DI (Fig. 2), which might be explained by the tendency for some stomatal closure (lower gs) during the afternoon in PRD, as shown in Fig. 4. Another evidence for the mild water deficits induced in PRD and DI vines was that the estimated RSL of photosynthesis in PRD and DI was not significantly higher than in FI (Table 3).

Crop ***WUE (amount of fruit produced per unit of water applied) in PRD and DI was twice that in FI, as a result of these plants (PRD and DI) having utilised half of the irrigation water for a similar yield in FI (Table 5). However, the intrinsic WUE estimated throughout the day or as an integral along the season (Souza et al., 2005b) was not significantly different in the three irrigated treatments (PRD, DI and FI). These results might be explained by the fact that flowering buds are preset and half water supply was enough to maintain a ‘normal’ sink supply and because the effects of water deficits on stomata and photosynthesis were proportional, as it seems to be the case in both varieties (Fig. 4).

Interestingly, δ13C values in the berries of DI and PRD vines were intermediate between FI and NI (Table 4 and Fig. 5), suggesting a higher integrated WUE over the season in DI and PRD than in FI. This might be the result of stomata of DI and PRD remaining closed for more hours in the day than in FI along the growing season. The correlation between δ13C and WUE has been well documented in several crops (Farquhar & Richards, 1984), including grapevines (Gaudillère et al., 2002; Souza et al., 2005b). The results that we obtained point out to the interest of using integrated measures of physiological performance in order to evaluate long-term responses of plants to the environment and to agricultural practices.

The higher δ13C values found in berries as compared to leaves may have two explanations, (1) the fact that berry filling results from current photosynthates, which were produced during the summer, reflecting the effects of mild water stress on stomatal closure as compared to the spring when leaves were formed; (2) the δ13C of leaves may be more depleted than that of berries because there are more post-photosynthetic fractionation processes (namely respiration) in berries, which might result in differences in the carbon isotope composition of the two organs (Badeck et al., 2005).

When comparing the two deficit irrigation treatments, one of the striking observations made in the three years of the study was the reduction in vigour observed in PRD as compared to FI, which did not occur in DI vines (Table 2). As stated above, this effect was more marked in variety Castelão than in Moscatel. Because plant water status during most of the dates along the season was not significantly different between the two treatments, and when different, PRD even exhibited a higher leaf water potential than DI vines, we conclude that these effects are not a result of an hydraulic control, but rather support the hypothesis of a long distance signalling originated in dehydrating roots. Indeed, in recent years strong evidence has accumulated suggesting that stomatal closure and growth slow-down observed in the early stages of soil water deficits (Hsiao, 1973; Kramer, 1983) may be mediated by chemical signals produced in drying roots, namely ABA or cytokinins and transported to the shoot in the transpiration stream (Wilkinson & Davies, 2002). Even though some studies reported an increase in xylem ABA concentration in PRD plants (Stoll et al., 2000), which we did not find in the present study (Rodrigues M.L., Santos T., Rodrigues A., Souza C.R., Lopes C., Maroco J., Pereira J.S., Chaves M.M., unpublished data), we think that other chemical signals, such as cytokinins, ethylene, alterations in ion contents of the xylem sap or changes in apoplastic pH in the leaves might be involved in that regulation (Wilkinson & Davies, 2002; Sobeih et al., 2004).

We cannot discard the interpretation that applying the water only in one side of the plant may affect plant water status as a result of alterations in the dimension and architecture of the root system. In fact, we observed some changes in the pattern of root distribution, PRD vines showing a tendency for producing more roots in the deeper layers than the other treatments (Santos T.P., Lopes C.M., Rodrigues M.L., Souza C.R., Maroco J.P., Pereira J.S., Silva J.R., Chaves M.M., submitted). Effects of PRD in the root system were also reported by Dry et al. (2000) in grapevines and by Mingo et al. (2003) showing an overall increase in root biomass in potted tomato plants growing under PRD.

Taken together our results showed that the effects of PRD are dependent on the variety studied and the climatic conditions during the growing season (see also Santos et al., 2003, 2005; Souza et al., 2003, 2005a,b). This is consistent with the knowledge that environmental factors (such as PPFD, temperature or VPD) that influence shoot physiological processes will interact with factors that affect the rhizosphere, determining the final nature and intensity of chemical signalling (Wilkinson, 2004). As a consequence, plant WUE will reflect the multiple environmental stimuli perceived and the ability of the particular genotype to sense the onset of changes in moisture availability and therefore fine-tune its water status in response to the environment. This complexity of responses to the environment together with the difficulty in maintaining an effective partial root drying under field conditions as a result of root hydraulic redistribution (Smart et al., 2005), as it was pointed out by Bravdo (2005), makes the impact of PRD not so clear as under controlled conditions. Soil type may also play a role in the intensity of the response to PRD. Sandy-type soils, as the one in our experiment, may produce effects closer to controlled conditions because lateral diffusion of irrigation water is lower than under clay-type soils (data not shown from an ongoing experiment).

Finally, our results also indicate that, for the region where our study took place (moderately subjected to water deficits), the differences in yield between irrigated (FI, PRD and DI) and rainfed vines (NI) only occurred in the driest year (2002). As for fruit quality, NI and PRD tended to exhibit higher concentrations of berry skin anthocyanins and total phenols than those presented by DI and FI vines. This suggests that the main impact of the type of irrigation was produced via the effect of vigour on the light interception and the overall microclimate in the cluster zone (Williams & Matthews, 1990).

Irrigation did not significantly affect berry sugar accumulation and pH. These results are in contrast with those obtained by other authors who observed either an increase (Schultz, 1996; Lopes et al., 2001) or a decrease (Jordão et al., 1998; Pire & Ojeda, 1999) in berry sugars induced by high soil water availability. So in our experiment berries acted as a preferential sink for carbohydrates under the moderate water deficits (as occurred in DI and PRD) and even under full irrigation conditions as observed in FI vines.

Conclusions

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. Acknowledgements
  9. References

It was demonstrated that large fluxes of water are not essential to optimal plant performance for agricultural purposes and that moderate water deficits, induced under deficit irrigation practices, might be used successfully in grapevine production to control sink–source relationships, maintaining or ameliorating fruit quality, while improving WUE in relation to full irrigated crops. Our data point out to subtle physiological differences between PRD receiving 50% of ETc (given in alternation to each side of the root system) and DI (the deficit irrigation receiving equal amount of water as PRD, but distributed by the two sides of the root system). These differences include slight reductions of stomatal aperture in PRD as compared to DI, recorded at some dates, but a clear depression of vegetative growth in PRD. Growth inhibition occurs in spite of similar or even better plant water status in PRD plants, suggesting a non-hydraulic regulation mechanism. On the other hand, no significant differences in photosynthetic rates, chlorophyll fluorescence parameters and WUE were observed between DI and PRD. Growth inhibition in PRD as compared to DI led to an increase in cluster exposure to solar radiation, with some potential to improve fruit quality. In fact, we report that NI and in several instances in PRD, vines exhibit higher concentrations of berry skin anthocyanins and total phenols than those presented by DI and FI vines. We have also observed that plant responses to deficit irrigation are dependent on the variety and the environmental conditions during the growing season.

Acknowledgements

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. Acknowledgements
  9. References

Financial support is acknowledged to the EU Projects IRRISPLIT ICA3-CT-1999-00008 and WATERWEB FP6-2002-INCO-WBC–509163 and the FCT Project POCI/AGR/59079/2004. M.F. Ortuño was a recipient of a Postdoctoral research fellowship from M.E.C. of Spain.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Material and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. Acknowledgements
  9. References
  • Alegre S., Girona J., Marsal J., Arbones A., Mata M., Montagut D., Teixido F., Motilva M.J., Romero M.P. (1999) Regulated deficit irrigation in olive trees. Acta Horticulturae, 474, 373376.
  • Allen R.G., Pereira L.S., Raes D., Smith M. (1999) Crop Evapotranspiration. Guidelines for Computing Crop Water Requirements. FAO Irrigation and Drainage Paper No. 56. Rome, Italy: United Nations – FAO. 300 pp.
  • Antolín M.C., Ayari M., Sanchez-Diaz M. (2006) Effects of rootzone drying on yield, ripening and berry ABA in potted tempranillo grapevines with split roots. Australian Journal of Grape and Wine Research, 12, 1320.
  • Badeck F., Tcherkez G., Nogués S., Piel C., Ghashghaie J. (2005) Post-photosynthetic fractionation of stable carbon isotopes between plant organs – a widespread phenomenon. Rapid Communications in Mass Spectrometry: RCM, 19, 13811391.
  • Bahrun A. (2003) Improving water-use efficiency of field-grown soybean (Glycine max L. cv. Bromo) by partial zone irrigation. In Journal of Experimental Botany, 54: 6-6, Special Issue: International Conference on Watersaving Agriculture and Sustainable Use of Water and Land Resources (ICWSAWLR), 26–29 October 2003, Yangling, Shaanxi, PR China. Elsevier.
  • Battilani A. (2000) Application of the regulated deficit irrigation to grapevines (Vitis vinifera) in a sub-humid area. Acta Horticulturae, 537, 887893.
  • Boland A.M., Mitchell P.D., Jerie P.H., Goodwin I. (1993) The effect of regulated deficit irrigation on tree water use and growth of peach. Journal of Horticultural Science, 68, 261274.
  • Bravdo B.A. (2005) Physiological mechanisms involved in the production of non-hydraulic root signals by partial rootzone drying – a review. In ISHS Acta Horiculturae. Volume 689: VII International Symposium on Grapevine Physiology and Biotechnology, 21–25 June 2004, pp. 267276. Ed. L.E.Williams. California: Davis.
  • Bravdo B.A., Hepner Y., Loinger C., Cohen S., Tabacmen H. (1985) Effect of irrigation and crop level on growth, yield and wine quality of Cabernet Sauvignon. American Journal of Enology and Viticulture, 36, 132139.
  • Carbonneau A. (1991) Observation sur vigne: codification des donnés agronomiques. Rivista di Viticoltura e di Enologia, 4, 3745.
  • Caspari H.W., Behboudian M.H., Chalmers D.J. (1994) Water use, growth and fruit yield of ‘Hosui’ Asian pears under deficit irrigation. Journal of the American Society for Horticultural Science, 119, 383388.
  • Chalmers D.J., Burge G., Jerie P.H., Mitchell P.D. (1986) The mechanism of regulation of ‘Bartlett’ pear fruit and vegetative growth by irrigation withholding and regulated deficit irrigation. Journal of American the Society for Horticultural Science, 111, 904907.
  • Chaves M.M., Oliveira M.M. (2004) Mechanisms underlying plant resilience to water deficits: prospects for water-saving agriculture. Journal of Experimental Botany, 55, 23652384.
  • Cifre J., Bota J., Escalona J.M., Medrano H., Flexas J. (2005) Physiological tools for irrigation scheduling in grapevine (Vitis vinifera L.). An open gate to improve water-use efficiency? Agriculture, Ecosystems and Environment, 106, 159170.
  • Davies W.J., Zhang J.H. (1991) Root signals and the regulation of growth and development of plants in drying soil. Annual Review of Plant Physiology and Plant Molecular Biology, 42, 5576.
  • Davies W.J., Bacon M.A., Thompson D.S., Sobeih W., Rodriguez L.G. (2000) Regulation of leaf and fruit growth in plants growing in drying soil: exploitation of the plant’s chemical signalling system and hydraulic architecture to increase the efficiency of water use in agriculture. Journal of Experimental Botany, 51, 16171626.
  • Davies W.J., Wilkinson S., Loveys B. (2002) Stomatal control by chemical signalling and the exploitation of this mechanism to increase water use efficiency in agriculture. New Phytologist, 153, 449460.
  • Davies W.J., Kudoyarova G., Hartung W. (2005) Long-distance ABA signaling and its relation to other signaling pathways in the detection of soil drying and the mediation of the plant’s response to drought. Journal of Plant Growth Regulation, 24, 285295.
  • Dodd I.C., Stikic R., Davies W.J. (1996) Chemical regulations of gas exchange and growth of plants in drying soil in the field. Journal of Experimental Botany, 47, 14751490.
  • Dry P.R., Loveys B.R. (1999) Grapevine shoot growth and stomatal conductance are reduced when part of the root system is dried. Vitis, 38, 151156.
  • Dry P.R., Loveys B.R., Botting D., Düring H. (1996) Effect of partial root-zone drying on grapevine vigour, yield, composition of fruit and use of water. In Proceedings of the Ninth Australian Wine Industry Technical Conference, pp. 128131. Eds C.Stockeley, A.Sas, R.Johnstone and T.Lee. Adelaide: Winetitles.
  • Dry P.R., Loveys B.R., Düring H. (2000) Partial drying of the rootzone of grape. II. Changes in the pattern of root development. Vitis, 39, 912.
  • Dry P.R., Loveys B.R., McCarthy M.G., Stoll M. (2001) Strategic irrigation management in Australian vineyards. Journal International des Science de la Vigne et du Vin, 35, 129139.
  • Esteban M.A., Villanueva M.J., Lissarrague J.R. (2001) Effect of irrigation on changes in the anthocyanin composition of the skin of cv Tempranillo (Vitis vinifera L.) grape berries during ripening. Journal of the Science of Food and Agriculture, 81, 409420.
  • Farquhar G.D., Richards R.A. (1984) Isotopic composition of plant carbon correlates with water use efficiency of wheat genotypes. Australian Journal of Plant Physiology, 11, 539552.
  • Farquhar G.D., Von Caemmerer S., Berry J.A. (1980) A biochemical model of photosynthetic CO2 assimilation in leaves of C3 species. Planta, 149, 7890.
  • Ferreyra E.R., Sellés G., Ruiz S.R., Sellés M.I. (2003) Efecto del estrés hídrico aplicado en distintos períodos de desarrollo de la vid cv. Chardonnay en la producción y calidad del vino. Agricultura Técnica (Chile), 63, 277286.
  • Flexas J., Bota J., Cifre J., Escalona J.M., Galmés J., Gulías J., Lefi E.-K., Martínez-Canellas S.F., Moreno M.T., Ribas-Carbó M., Riera D., Sampor B., Medrano H. (2004) Understanding down-regulation of photosynthesis under water stress: future prospects and searching for physiological tools for irrigation management. Annals of Applied Biology, 144, 273284.
  • Gaudillère J.P., Van Leeuwen C., Ollat N. (2002) Carbon isotope composition of sugars in grapevines, an integrated indicator of vineyard water status. Journal of Experimental Botany, 369, 757763.
  • Goldhamer D.A. (1999) Regulated deficit irrigation for California canning olives. Acta Horticulturae, 474, 369372.
  • Goodwin I., Macrae I. (1990) Regulated deficit irrigation of Cabernet Sauvignon grapevines. Australian and New Zealand Wine Industry Journal, 5, 131133.
  • Gowing D.J.G., Davies W.J., Jones H.G. (1990) A positive root-source signal as an indicator of soil drying in apple Malus × domestica Borkh. Journal of Experimental Botany, 41, 15351540.
  • Gu S.L., Du G.Q., Zoldoske D., Hakim A., Cochran R., Fugelsang K., Jorgensen G. (2004) Effects of irrigation amount on water relations, vegetative growth, yield and fruit composition of Sauvignon blanc grapevines under partial root zone drying and conventional irrigation in the San Joaquin Valley of California, USA. Journal of Horticultural Science and Biotechnology, 79, 2633.
  • Heilmeier H., Wartinger A., Hartung W. (1990) The relationship between abcisic acid concentration of xylem sap and leaf conductance in almond trees [Prunus dulcis (Miller) D.A. Webb]. In Importance of Root to Shoot Communication in the Responses to Environmental Stress. Monograph 21. pp. 217219. Eds W.J.Davies and B.Jeffcoat. Bristol: British Society for Plant Growth Regulation.
  • Hsiao T.C. (1973) Plant responses to water stress. Annual Review of Plant Physiology, 24, 519570.
  • Hutton R. (2000) Improving the water use efficiency of citrus at Yanco Agricultural Institute. Farmers’ Newsletter Horticulture, 184, 4749.
  • Instituto Nacional de Meteorologia e Geofísica (INMG). (1991) O Clima de Portugal – Fascículo XLIX - volume 3-3a Região, Normais Climatológicas da Região de “Trás-os-Montes, Alto Douro e Beira Interior”, correspondentes a 1951–1980. Lisboa.
  • Jordão A.M., Ricardo-da-Silva J.M., Laureano O. (1998) Influence of irrigation on phenolic composition of Touriga Francesa (Vitis vinifera L.). Ciencia y Tecnologia de los Alimentos, 2, 6073.
  • Kang S.Z., Hu X.T., Goodwin I., Jerie P. (2002) Soil water distribution, water use, and yield response to partial root zone drying under a shallow groundwater table condition in a pear orchard. Scientia Horticulturae, 92, 277291.
  • Kang S.Z., Hu X.T., Du T.S., Zhang H.H., Jerie P. (2003) Transpiration coefficient and ratio of transpiration to evapotranspiration of pear tree (Pyrus communis L.) under alternative partial root-zone drying conditions. Hydrological Processes, 17, 11651176.
  • Kramer P.J. (1983) Water Relations of Plants. London: Academic Press, Inc.
  • Leib B.G., Caspari H.W., Redulla C.A., Andrews P.K., Jabro J.J. (2006) Partial rootzone drying and deficit irrigation of ‘Fuji’ apples in a semi-arid climate. Irrigation Science, 24, 8599.
  • Li S.H., Huguet J.G., Schoch P.G., Orlando P. (1989) Response of peach tree growth and cropping to soil water deficit at various phenological stages of fruit development. Journal of Horticultural Science, 64, 541552.
  • Liu L., McDonald A.J.S., Stadenberg I., Davies W.J. (2001) Stomatal and leaf growth responses to partial drying of root tips in willow. Tree Physiology, 21, 765770.
  • Lopes C., Pinto P.A. (2000) Estimation de la surface foliaire principale et secondaire d‘un sarment de vigne. Progrès Agricole et Viticole, 117, 160166.
  • Lopes C., Vicente-Paulo J., Santos T., Rodrigues M.L., Barroso J., Chaves M.M. (2001) An attempt to quantify grapevine water stress in a mediterranean environment. Proceedings XIIémes Journées GESCO, AGRO Montpellier, Montpellier, 1, 4348.
  • Loveys B.R. (1984) Diurnal changes in water relations and abscisic acid in field grown Vitis vinifera cultivars. III. The influence of xylem-derived abscisic acid on leaf gas exchange. New Phytologist, 98, 563573.
  • Loveys B.R., Dry P.R., Stoll M., McCarthy M.G. (2000) Using plant physiology to improve the water efficiency of horticultural crops. Acta Horticulturae, 537, 187197.
  • Luterbacher J., Xoplaki E., Casty C., Wanner H., Pauling A., Kuettel M., Rutishauser T., Broennimann S., Fischer E., Fleitmann D., Gonzalez-Rouco J.E., García-Herrera R., Barriendos M., Rodrigo F.S., Gonzalez-Hidalgo J.C., Saz M.A., Gimeno L., Ribera P., Brunet M., Paeth H., Rimbu N., Felis T., Jacobeit J., Duenkeloh A., Zorita E., Guiot J., Turkes M., Alcoforado M.J., Trigo R., Wheeler D., Tett S.F.B., Mann M.E., Touchan R., Shindell D.T., Silenzi S., Montagna P., Camuffo D., Mariotti A., Nanni T., Brunetti M., Maugeri M., Zerefos C., De Zolt S., Lionello P., Nunes M.F., Rath V., Beltrami H., Garnier E., Le Roy Ladurie E. (2006) Mediterranean climate variability over the last centuries, a review. In The Mediterranean Climate: An Overview of the Main Characteristics and Issues, pp. 27148. Eds P.Lionello, P.Malanotte-Rizzoli and R.Boscolo. Amsterdam: Mediterranean Climate Variability, Elsevier.
  • Maroco J.P., Rodrigues M.L., Lopes C., Chaves M.M. (2002) Limitations to leaf photosynthesis in field-grown grapevine under drought – metabolic and modelling approaches. Functional Plant Biology, 29, 451459.
  • Marsal J., Gelly M., Mata M., Rabones A., Rufat J., Girona J. (2002) Phenology and drought affects the relationship between daily trunk shrinkage and midday stem water potential of peach trees. Journal of Horticultural Science and Biotechnology, 77, 411417.
  • Matthews M.A., Anderson M.M. (1988) Fruit ripening in grapes (Vitis vinifera L.): responses to seasonal water deficits. American Journal of Enology and Viticulture, 39, 313320.
  • Matthews M.A., Anderson M.M. (1989) Reproductive development in grape (Vitis vinifera L.): responses to seasonal water deficits. American Journal of Enology and Viticulture, 40, 5260.
  • Matthews M.A., Ishii R., Anderson M.M., O’Mahomy M. (1990) Dependence of wine sensory attributes on vine water status. Journal of Science of Food and Agriculture, 51, 321335.
  • McCarthy M.G. (1997) The effect of transient water deficit on berry development of cv Shiraz (Vitis vinifera L.). Australian Journal of Grape and Wine Research, 3, 102108.
  • McCarthy M.G., Loveys B.R., Dry P.R. (2000) Regulated Deficit Irrigation and Partial Rootzone Drying as Irrigation Practices – Water Reports 22. Rome: FAO.
  • Mingo D.M., Bacon M.A., Davies W.J. (2003) Non-hydraulic regulation of fruit growth in tomato plants (Lycopersicon esculentum cv Solairo) growing in drying soil. Journal of Experimental Botany, 54, 12051212.
  • Miranda P.M.A., Valente M.A., Tomé A.R., Trigo R., Coelho M.F.E.S., Aguiar A., Azevedo E.B. (2006) O clima de Portugal nos séculos XX e XXI. In Alterações Climáticas em Portugal. Cenários, Impactes e Medidas de Adaptação, pp. 45113. Eds F.D.Santos and P.Miranda. Lisboa: Gradiva.
  • Mitchell P.D., Chalmers D.J. (1982) The effect of reduced water supply on peach tree growth and yields. Journal of the American Society for Horticultural Science, 107, 853856.
  • Mitchell P.D., Van Den Ende B., Jerie P.H., Chalmers D.J. (1989) Response of ‘Bartlett’ pear to withholding irrigation, regulated deficit irrigation, and tree spacing. Journal of the American Society for Horticultural Science, 114, 1519.
  • Office Internationale de la Vigne et du Vin (OIV). (1990) Recueil des Methodes Internationales d’Analyses des Vins et des Moûts. Paris: OIV.
  • Petit J.R., Jouzel J., Raynaud D., Barkov N.I., Barnola J.M., Basile I., Bender M., Chappellaz J., Davis M., Delaygue G., Delmotte M., Kotlyakov V.M., Legrand M., Lipenkov V.Y., Lorius C., Pepin L., Ritz C., Saltzman E., Stievenard M. (1999) Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica. Nature, 399, 429436.
  • Pire R., Ojeda M. (1999) Vegetative growth and quality of grapevine ‘Chenin blanc’ irrigated under three pan evaporation coefficients. Fruits, 54, 135139.
  • Prichard T.L. (1992) A volume balance approach to quality wine grape irrigation. In Viticultural Practices, pp. 1223. Eds M.A.Walker and W.M.Kliewer. Davis: University of California.
  • Regina M.A., Carbonneau A. (1996) Trocas gasosas em Vitis vinifera sob regime de estresse hídrico. I Caracterização do comportamento varietal. Pesquisa Agropecuaria Brasileira, 31, 869876.
  • Reynolds A.G., Naylor A.P. (1994) “Pinot noir” and “Riesling” grapevines respond to water stress duration and soil water-holding capacity. HortScience, 29, 15051510.
  • Ribereau-Gayon J., Stonestreet E. (1965) Le dosage des anthocyanes dans le vin rouge. Bulletin des Sociétés Chimiques Belges, 9, 26492652.
  • Santos T.P., Lopes C.M., Rodrigues M.L., Souza C.R., Maroco J.P., Pereira J.S., Silva J.R., Chaves M.M. (2003) Partial rootzone drying: effects on growth, and fruit quality of field-grown grapevines (Vitis vinifera L.). Functional Plant Biology, 30, 663671.
  • Santos T.P., Lopes C.M., Rodrigues M.L., De Souza C.R., Ricardo-Da-Silva J.M., Maroco J.P., Pereira J.S., Chaves M.M. (2005) Effects of partial root-zone drying irrigation on cluster microclimate and fruit composition of field-grow Castelão grapevines. Vitis, 44, 117125.
  • Schultz H.R. (1996) Water relations and photosynthetic responses of two grapevine varieties of different geographical origin during water stress. Acta Horticulturae, 427, 251266.
  • Schultz H.R. (2000) Climate change and viticulture: a European perspective on climatology, carbon dioxide and UV B effects. Australian Journal of Grape and Wine Research, 6, 212.
  • Sharkey T.D. (1985) Photosynthesis in intact leaves of C-3 plants: physics, physiology and rate limitations. Botanical Review, 51, 53105.
  • Smart D.R., Carlisle E., Goebel M., Nuñez B.A. (2005) Transverse hydraulic redistribution by a grapevine. Plant, Cell and Environment, 28, 157166.
  • Sobeih W., Dodd I.C., Bacon M.A., Grierson D.C., Davies W.J. (2004) Long-distance signals regulating stomatal conductance and leaf growth in tomato (Lycopersicon esculentum) plants subjected to partial rootzone drying. Journal of Experimental Botany, 55, 23532363.
  • Souza C.R., Maroco J.P., Santos T., Rodrigues M.L., Lopes C., Pereira J.S., Chaves M.M. (2003) Partial rootzone-drying: regulation of stomatal aperture and carbon assimilation in field grown grapevines (Vitis vinifera cv. Moscatel). Functional Plant Biology, 30, 653662.
  • Souza C.R., Maroco J., Santos T., Rodrigues M.L., Lopes C., Pereira J.S., Chaves M.M. (2005a) Control of stomatal aperture and carbon uptake by deficit irrigation in two grapevine cultivars. Agriculture, Ecosystems and Environment, 106, 261274.
  • Souza C.R., Maroco J., Santos T., Rodrigues M.L., Lopes C.M., Pereira J.S., Chaves M.M. (2005b) Impact of deficit irrigation on water use efficiency and carbon isotope composition (δ13C) of field-grown grapevines under Mediterranean climate. Journal of Experimental Botany, 56, 21632172.
  • Stoll M., Loveys B.R., Dry P.R. (2000) Hormonal changes induced by partial rootzone drying of irrigated grapevine. Journal of Experimental Botany, 51, 16271634.
  • Wahbi S., Wakrim B., Aganchich B., Tahi H., Serraj R. (2005) Effects of partial rootzone drying (PRD) on adult olive tree (Olea europea) in field conditions under arid climate. I. Physiological and agronomic responses. Agriculture, Ecosystems and Environment, 106, 289301.
  • Wakrim R., Wahbi S., Tahi H., Aganchich B., Serraj R. (2005) Comparative effects of partial root drying (PRD) on water relations and water use efficiency in common bean (Phaseolus vulgaris L.). Agriculture, Ecosystems and Environment, 106, 275287.
  • Wilkinson S. (2004) Water use efficiency and chemical signalling. In Water use Efficiency in Plant Biology, pp. 75112. Ed M.Bacon. Oxford: Blackwell Publishing.
  • Wilkinson S., Davies W.J. (2002) ABA-based chemical signalling: the co-ordination of responses to stress in plants. Plant, Cell and Environment, 25, 195210.
  • Williams L.E., Matthews M.A. (1990) Grapevine. In Irrigation of Agricultural Crops. Series of Agronomy, pp. 10191055. Madison, Wisconsin, USA.