ABSTRACT
Four- and 14-year-old Cabernet Franc, Cabernet Sauvignon, Pinot Meunier, Pinot noir, and 15-year-old Riesling vines located at Thirty Bench Vineyards in Beamsville, Ontario, were assessed in terms of vine age (2002 and 2003) and reflective mulch treatments (2003) with respect to berry, must, and wine composition as well as wine sensory attributes. In 2002, but not 2003, old vines had higher yields, clusters per vine, cluster weights, and berry weights than young vines. Berries from young vines tended to have higher Brix and lower titratable acidity (TA), pH, and total phenols than those from old vines in 2002; in 2003, age showed little impact on berry composition. Wines made from young vines in 2002 were higher in TA, and often lower in pH, color intensity, and anthocyanins than those from old vines, while in 2003, young vines produced wines with lower TA, and higher pH, intensity, and total phenols. Reflective mulch showed few effects on the berry, must, and wine composition of the red wine cultivars; however, mulch increased free and bound terpenes in the Riesling berries. Wines produced from young Cabernet Sauvignon and Cabernet Franc vines exhibited more intense vegetal aromas and flavors than those from old vines in 2002 but not in 2003. The red wines made from the mulched vines generally exhibited the least amount of vegetal aroma and flavor. Reflective mulch also led to less perceived acidity in Riesling wines.
INTRODUCTION
Wines produced from young vines allegedly lack the attributes and character of old vine wines. However, this commonly held assumption has yet to be widely validated scientifically, and no published data are available that comprehensively compare effects of vine age. CitationHeymann and Noble (1987) demonstrated a correlation between vine age and berry aroma and negative correlations between vine age and both green bean aroma and vegetative flavor in California Cabernet Sauvignon wines. The Niagara region in Ontario has experienced a large addition of newly planted vineyards, many of which have been designated by wineries for the production of premium wines. Many industry members are debating whether the young vines are capable of producing wines of high quality.
Increasing the penetration of sunlight into the canopy has been shown to enhance the final fruit composition (CitationSmart and Smith, 1988; CitationSmart and Robinson, 1991). In many vineyards, sun exposure into the canopy is increased by using viticultural practices such as shoot positioning, shoot removal, and leaf removal in the fruiting zone (CitationBledsoe et al., 1988; CitationReynolds and Wardle 1989; CitationReynolds et al., 1995). Reflective mulch is a new approach for increasing the amount of light into the fruiting zone of the grapevine canopy. It is believed that reflective surfaces, such as the white stones (galets) of the Chateauneuf-du-Pape, advance the maturity of the grapes and also add complexity to the resulting wine (CitationJohnson and Robinson, 2001). The addition of reflective mulch in a vineyard increases soil temperature (CitationBowen et al., 2004a) and directs more sunlight back up into the canopy where it will come in contact with the grape clusters and leaves of the canopy (CitationRazungles et al., 1996; CitationRobin et al., 1996). This can potentially improve the fruit composition and might improve the sensory attributes of the wines made from this fruit. If a reflective surface is applied to a vineyard where younger vines are planted, this may help in enhancing the fruit composition. Wines made from vegetative young vines with shaded fruit zones that are treated with a reflective surface may have sensory attributes that are superior or similar to wines made from old vines.
While the impacts of reflective soils and mulches have been studied to an extent throughout different areas of France (CitationRazungles et al., 1996; CitationRobin et al., 1996), there has been little research on their impacts on grape production, fruit composition, and wine sensory attributes. There has also been very little research on the relationship between grapevine age and both fruit composition and wine sensory attributes. The objectives of this trial were to investigate these factors and to provide information in relation to both. We hypothesized that the use of reflective mulch would enhance the light microclimate of the grapevine clusters, which would concomitantly optimize the berry composition (increasing Brix, anthocyanins, phenols, and monoterpenes; while decreasing the titratable acidity). We further hypothesized that young vines treated with reflective mulch would have berry composition and wine sensory quality equal or superior to that of old vines.
MATERIALS AND METHODS
Experimental Design
Two experimental plots located at Thirty Bench Vineyards in Beamsville, Ontario, were used for the vineyard trial. The vineyards were both located on Chinguacousy clay loam soil (gleyed brunisolic grey brown luvisol) (CitationKingston and Presant, 1989) and were separated by about 20 m. The plots were planted in 1990 (“old vines”) and in 1999 (“young vines”), respectively. All vines were grafted to C.3309 rootstock, trained on a Guyot system (head-trained, cane-pruned with two canes), and spaced 1.2 m × 2.4 m (vine × row) in north:south-oriented rows. Growing season canopy management consisted of vertical shoot positioning and basal leaf removal on the east side of the canopy at pea-size of berry development. In 2002, 25 vines each of five Vitis vinifera red wine cultivars in each of the 1990- and 1999-planted vineyard blocks were set aside for study. Block areas (ha; 1990- and 1999-planted) were: Cabernet Franc (0.4 and 1.2); Cabernet Sauvignon (0.2 and 3.3); Merlot (0.6 and 2.0); Pinot noir (0.1 and 1.3); and Pinot Meunier (0.1 and 0.5). Vines were selected along an “X-shaped” sampling grid superimposed upon each block. These vines were designated as experimental units and those from which all individual yield and fruit composition data were ultimately obtained. Experimental design was treated as a completely randomized design using (age x vine) as an estimate of error.
In 2003, red wine cultivars included Cabernet Franc, Cabernet Sauvignon, Pinot Meunier, and Pinot noir; winter injury prevented continued use of Merlot. A 9.4-ha block of Riesling planted in 1990 was also used in this study. Addition of a second experimental variable (reflective mulch) necessitated a reconfiguration of the experimental design; however, the same plots were used as in 2002. In each row used for the vineyard trial, several postlength panels (five vines each) were randomly selected as either “mulched” or “non-mulched.” Design was a randomized block with three replications (old vines) and four replications (young vines); the larger vineyard blocks (all > 0.5 ha) in the 1999-planted portions of the vineyard allowed for more replication. In mid-July, one-meter wide polypropylene aluminized mulch sheets (Phillips Farm Supplies, Brighton, ON) were placed underneath the selected grapevines to provide 0.5-m mulched strips on each side of the vine. Each section of reflective mulch had two other strips of reflective mulch laid in the adjacent rows. For each cultivar, each replicate section of reflective mulch was comprised of 25 vines (old) and 25 vines (young).
Widespread winter injury occurred throughout Niagara in the 2002–2003, 2003–2004, and 2004–2005 winters and also was observed at the experimental site. Although injury was relatively minor in the 2003 growing season, Merlot excepted, vine damage in subsequent seasons necessitated termination of the trial after 2003. Although the effects of vine age were studied for only two years and those of mulch for a single season, the fact that multiple cultivars were observed compensates for the lack of a multiple-year trial.
Light Measurements
From veraison to harvest 2003, three sets of light measurements on canopy microclimate and reflectance were taken with a LiCor 1800 radiospectrophotometer cosine integrator (Li-Cor, Lincoln, NB). Dates of data collection were: 27 July, 9 September, and 10 October 2003, and the light measurements were taken between 1100h and 1300h under clear sunny conditions. Measurements were taken in a single replicate of both the mulched and non-mulched treatments of Cabernet Franc vines in the old vineyard. Spectral radiation measurements ranged between wavelengths of 300 to 1100 nm in 1, 2, 5, and 10 nm intervals. The silicon detector on the radiospectrophotometer was capable of scanning 30 nm per second. Measurements were taken at six different aspects: within the canopy at cluster level facing up, perpendicular to the canopy, facing down, 45° facing up from the canopy, 45° facing down from the canopy, and upwards to open ambient light.
Harvest and Berry Sampling
Individual vines in each plot were harvested each season and data were collected for yield and clusters per vine. Cluster weights were calculated from these data. In 2002, 100-berry samples were collected randomly prior to harvest from each of the 25 vines in each of the old and young vineyard plots. Berry weights were determined from these samples; berries per cluster were estimated from berry weight and cluster weight data. Berry samples were stored at −25oC until analysis. In 2003, 100-berry samples were collected from each five-vine plot from the selected rows, for each red winegrape cultivar in all vine age × mulch combinations. Both 100- and 250-berry samples were also randomly collected from each of the mulched and non-mulched plots in the selected Riesling rows. Samples were collected either on or one day before the commercial harvest of the grapes between October and early November.
Winemaking
Fruit for winemaking was stored at 4°C overnight prior to processing. In 2002, replicate experimental wines were made from Cabernet Sauvignon, Merlot, Pinot Meunier, and Pinot noir wines according to vine age treatments. Additional commercial quantities of Cabernet Franc, Cabernet Sauvignon, Merlot, and Pinot noir wines were made in 2002 using identical standard protocols from all remaining fruit in each vineyard block and ultimately stored in two 220-L second-fill French oak barrels per treatment replicate for each cultivar. In 2003, Cabernet Franc, Cabernet Sauvignon, Pinot Meunier, and Pinot noir wines were vinified separately by vine age and mulch treatment. Each treatment replicate within each cultivar was fermented separately. For experimental wines in both seasons, the grapes were crushed and de-stemmed and sulfited to 40 mg L−1. Two 250-mL must samples were taken from each treatment replicate for must composition analysis (Brix, TA, pH, color, anthocyanins, and phenols) immediately before inoculation. Each treatment combination had three ca. 16-L replicate fermentations in 20-L food-grade plastic pails, inoculated with commercial yeast (Cabernet Franc and Cabernet Sauvignon inoculated with Saccharomyces cerevisiae D-254; Pinot Meunier and Pinot noir inoculated with S. cerevisiae RC-212) (Lallemand Inc., Montreal, QB). Each replicate was fermented covered at 25°C for approximately 21 days, until the caps fell, after which the wines were pressed in an Idropress basket/bladder press (Enoagricola Rossi, Calzolaro, Italy) with a maximum pressure of 2.0 bars. Each fermentation was punched down three times daily. Two 250-mL wine samples were taken from each treatment replicate for wine composition analysis (ethanol, TA, pH, color, anthocyanins, and phenols). The wines then underwent malo-lactic fermentation at 27°C, after which they were sulfited to 50 mg L−1, and cold stabilized at −2°C for ∼30 days. Filtration of wines was carried out using 0.5 μ pad filters (Scott Laboratories, Pickering, ON) in series with a 0.22 μ hydrophilic cartridge filter (Millipore, Bedford, MA) and immediately bottled. All wines were stored at 11°C until sensory analysis was conducted 7 to 9 months later. Commercial wines in 2002 were vinified using the same yeast strains and fermentation protocols as those used for the experimental wines.
The Riesling grapes were crushed and de-stemmed, sulfited to 50 mg L−1 and given skin contact for 24 hours at 4°C. The Riesling musts were then pressed in the aforementioned bladder press to 2.0 bars, and inoculated with S. cerevisiae VL-1 (Lallemand Inc., Montreal, QB) and fermented in 20-L glass carboys at 15°C. Upon completion of fermentation, Riesling wines were racked and sulfited to 50 mg L−1 and cold stabilized at −2°C for ∼30 days. Wines were then filtered and bottled using the same protocol as for the red wines.
Berry, Must, and Wine Analysis
Brix, TA, and pH
All berry samples were analyzed for percent soluble solids (Brix), titratable acidity (TA), and pH; red winegrape berry samples were also analyzed for color (A420 and A520), anthocyanins, and phenols according to standard methods (CitationZoecklein et al., 1995). At the time of analysis, berry samples were placed in 250-mL beakers, thawed at room temperature and then heated to 80°C in a Fisher Scientific Isotemp 228 water bath (Fisher Scientific, Mississauga, ON) and held at that temperature for one hour to dissolve precipitated tartrates. Samples were then cooled to ambient temperature, and the juice was extracted from the berries using an Omega 500 juicer. The Brix of the berry and must samples was measured using an Abbé refractometer (American Optical Corp., Buffalo, NY) with temperature correction. The pH of the berry, must, and wine samples was measured with a Fisher Scientific Accumet pH meter. The TA of a 5.0 mL portion of berry, must, or wine sample was measured by titration to an 8.2 pH endpoint using a PC Titrate automated titration system (Man-Tech Associates Inc., Guelph, ON) with a standardized 0.1 N NaOH solution.
Color, Anthocyanins, and Phenols
Berry and must samples of red winegrape cultivars were prepared as described previously for Brix, pH, and TA analysis. The samples were then centrifuged at 4500 rpm for 10 minutes in an IEC Centra CL2 centrifuge (International Equipment Co., Needham Heights, MA). The supernatant from each sample was filtered through a 0.45μ HV Durapore syringe membrane filter (Millipore Corp., Bedford, MA). Filtered wine samples were used for analysis without any further preparation. Color analyses were carried out using the method of CitationMazza et al. (1999). Absorbances at 420 and 520 nm were determined with the use of a 1-mm quartz cuvette and an Ultrospec 100E UV/VIS spectrophotometer (Pharmacia Biotech, Cambridge, UK; used for all spectrophotometric analyses), and hue and intensity were calculated from these data. Data were expressed as 10-mm equivalents. The following formulae were used to calculate color intensity and hue: Color intensity = A520 + A420; hue = A420/A520.
Anthocyanin concentrations in berries, musts, and wines were determined using the pH shift method described by CitationMetivier et al. (1980). A pH 1.0 buffer solution was prepared using 0.2M KCl and 0.2M HCl, and a pH 4.5 buffer was prepared using 1M sodium acetate, 1M HCl and distilled water. The samples were diluted tenfold using the 1.0 and 4.5 buffers and left in the dark for one hour, after which the absorbances were measured at 520 nm in a 10-mm quartz cuvette using a UV/VIS spectrophotometer. The total anthocyanin concentration was then calculated as malvidin-3-glucoside with the following formula: Total anthocyanins (mg L−1) = (pH 1.0 A520 − pH 4.5 A520) × 255.75.
The phenolic reduction method, using Folin-Ciocalteu reagent, was used to analyze the total phenols in the berry, must, and wine samples (CitationZoecklein et al., 1995). A calibration curve was constructed from the absorbance values determined from gallic acid calibration standards (0, 50, 100, 150, and 500 mg L-1), prepared by serial dilutions of a 5000 mg L-1 stock solution. For analysis, 1 mL of sample was diluted to 10 mL in distilled water. One mL from each diluted sample was placed in a 100-mL volumetric flask with 60 mL of distilled water, 5 mL of Folin-Ciocalteu reagent, and 15 mL of 2% sodium carbonate solution, brought up to volume, mixed thoroughly and left to stand at room temperature for 2 h. Absorbance was measured at 765 nm using 10-mm quartz cuvettes, and the concentrations of phenols in the samples were thereafter calculated by multiplying the sample absorbances by the dilution factor of 10, and using the equation developed by the calibration curve.
Monoterpenes (Riesling Berry Samples Only)
The 250-berry Riesling samples were used for the analysis of free volatile terpenes (FVT) and potentially volatile terpenes (PVT). The method for determining berry monoterpene concentrations was based on the steam distillation/colorimetric reaction method described by CitationReynolds and Wardle (1989), based upon the original method CitationDimitriadis and Williams (1984). The two salient components to this method were sample preparation/distillation and colorimetric analysis.
Sample preparation and distillation
The berry samples were allowed to thaw overnight at 4°C. Two 100-g replicate samples were homogenized in a Waring commercial laboratory blendor. The pH of the samples was adjusted to pH 6.6 to 6.7 with the addition of a 20% NaOH solution. The samples were then distilled and the FVT fraction was collected within 10 to 15 minutes in a 25-mL volumetric flask contained in an ice water bath. The pH of the distillate was then adjusted to ca. 2.0 by adding 10 mL of a 50% solution of H3PO4. The PVT fraction was thereafter collected within 15 to 20 minutes in a 50-mL volumetric flask immersed in an ice water bath. The FVT and PVT fractions were stored at 4°C.
Colorimetric analysis
Standard linalool solutions of 1.0, 2.0, 5.0, 10.0, 15.0, and 20.0 mg L−1 were prepared in 10-mL volumetric flasks. The linalool standards were analyzed for monoterpene concentration by adding 5 mL of 2% vanillin in concentrated H2SO4 to 10 mL of each linalool standard in ice water. The solutions were sealed, mixed and heated to 60°C for 20 minutes. The tubes were then removed and cooled at room temperature for 5 minutes. Absorbance of each solution was read at 608 nm on a UV/VIS spectrophotometer within 15 minutes. This produced a standard curve used to determine the concentration of monoterpenes in the berry samples.
Sensory Analysis
The wines underwent an organoleptic evaluation by a 12-member panel in the Cool Climate Oenology and Viticulture Institute. Prior to the evaluation the judges were trained in three sessions to ensure accuracy and reproducibility. During these sessions, the judges established descriptors (e.g., cherry, berry, tobacco, etc.) and also established orders of magnitude for these descriptors. These standards for Cabernet Franc, Cabernet Sauvignon, Merlot, Pinot Meunier, Pinot noir, and Riesling are shown in and . The age (2002) and mulch × vine age treatments (2003) were randomized before evaluation to ensure that no judge's samples were in the same order. The wines were evaluated for visual, aroma, retronasal aroma (flavor), and mouthfeel attributes. The evaluation was performed under controlled conditions including red light to minimize color bias. The visual evaluation was performed under natural light. Each approximately one-hour session used for evaluation of the 2002 wines consisted of five flights of two wines (one for each cultivar) in the morning and afternoon. The 2003 wines were evaluated using morning and afternoon sessions consisting of four flights of four wines each. The evaluation was performed using Compusense 5.0 software (Compusense Inc., Guelph, ON) by means of a 100-mm line scale. Sensory evaluation took place between March and May 2004, using commercial barrel samples (2002), and experimental wine samples from carboys (2003).
TABLE 1. Preparation of red wine standards for use in sensory evaluation of 2002 and 2003 Cabernet Franc, Cabernet Sauvignon, Pinot Meunier, and Pinot noir wines, Thirty Bench, Beamsville, ON. All standards were based upon 0.5 L of neutral red base wine
TABLE 2. Preparation of white wine standards for use in sensory evaluation of 2003 Riesling, Thirty Bench, Beamsville, ON. All standards were based upon 0.5 L of neutral base wine
Statistical Analysis
Statistical analysis was performed using SAS statistical software package (SAS Institute, Cary NC). In 2002, a completely randomized design was applied to each cultivar whereby age × vine was used as an estimate of error. In 2003, a split-plot design was applied, with age × vine used as an estimate of error for vine age and treatment × block used as the estimate of error for mulch effects. The general linear models procedure (PROC GLM) was used to demonstrate the significance among age and mulch treatments and their interactions for the berry, must, and wine composition. Principal components analysis (PCA) was performed on the sensory data to identify variation and attributes among treatments.
RESULTS AND DISCUSSION
Vine Age Effects, 2002
Yield Components
Yields of young Cabernet Sauvignon, Pinot Meunier, and Pinot noir vines were considerably less than those of old vines in 2002. Mean values of young vines ranged from 0.4 to 0.6 kg vine−1, or 0.9 to 1.6 t ha−1, compared to 1.9 to 2.5 kg vine−1 (4.7 to 6.1 t ha−1) in old vines (). Old vines of Cabernet Sauvignon and Pinot Meunier also had more clusters and heavier berries, while old Pinot noir vines had higher cluster weights and berries per cluster. Many of these differences were expected, since the young vines were in their third growing season and had therefore not reached their full yield potential.
TABLE 3. Impact of vine age on yield components of Cabernet Sauvignon, Merlot, Pinot Meunier, and Pinot noir, Thirty Bench Vineyards, Beamsville, ON, 2002
Berry and Must Composition
Two of four cultivars (Cabernet Sauvignon and Pinot Meunier) produced berries with lower Brix in old vines, while both Pinot Meunier and Pinot noir musts from old vines were lower as well (). Berries from old vines of all four cultivars had higher TA, as did the musts of three of four cultivars (Merlot was the only exception). Berry pH was highest in old vines in Merlot and Pinot noir, but musts from two cultivars (Cabernet Sauvignon and Pinot noir) had lower pH from old vines. Hue values were not consistent across vine age treatment; berries and musts of Pinot noir were higher from old vines, while Merlot berry hue and Cabernet Sauvignon must hue were higher in young vines. Intensity data were likewise inconsistent; berry intensity in Merlot and must intensity in Pinot Meunier were highest in old vines, but values from Pinot Meunier berries and Pinot noir musts were highest in young vines. Similarly, total anthocyanins were higher in berries from old vines in Merlot, but berries and musts from young Pinot noir vines, as well as Merlot musts, were higher. These trends tended to be consistent with those seen in intensity values. Total phenols were also not necessarily associated with a specific vine age treatment; phenols were higher in Merlot and Pinot noir berries from old vines, but Pinot Meunier berries, as well as musts from three of four cultivars were highest in young vines.
TABLE 4. Impact of vine age on berry and must composition of Cabernet Sauvignon, Merlot, Pinot Meunier, and Pinot noir, Thirty Bench Vineyards, Beamsville, ON, 2002
There is a paucity of literature addressing berry, must, and wine composition differences between young and old vines. This appears to be the first investigating color and phenolic analytes. Many individuals contend that old vines with a significant proportion of perennial wood have the potential to produce better wines than young vines (CitationKoblet and Perret, 1982, Citation1985). Additional perennial wood supplied by high trunks was credited as the reason for yield increases and enhanced fruit maturity in those treatments (CitationKonlechner, 1961; CitationWeaver and Kasimatis, 1975; CitationStoev and Dobreva, 1976; CitationMihailov, 1980). Augmentation to perennial wood of Müller-Thurgau and Pinot noir vines in Switzerland led to enhanced yields and higher cluster weights without significant changes in berry composition (CitationKoblet and Perret, 1982, Citation1985). Moreover, CitationReynolds et al. (1994) observed that Riesling vines of the same age but trained to old cordons had highest yield, cluster weights, TA, FVT, and PVT. More recently, CitationConsidine (2004) showed that vine age in Zante Currant was inversely proportional to weight of cane prunings and berries per cluster but not related to yield per vine or berry composition.
Wine Composition
TA of experimental wines from all four cultivars was lowest in old vine treatments, as it was in two of four cultivars in the commercial wines (). Commercial Cabernet Sauvignon wines from old vines had slightly higher TA. Experimental wine pH was highest in old vine treatments in three of four cultivars (Pinot noir excepted), but in only two of four of the commercial wines (Cabernet Franc and Cabernet Sauvignon displayed opposite trends). Hue was higher in young vine treatments in two of four cultivars (experimental wines) and three of four cultivars (commercial wines), while intensity was higher in old vine treatments in two of four cultivars (experimental wines; Pinot Meunier and Pinot noir displayed opposite trends) but only one of four (Cabernet Sauvignon) in the commercial wines. Two of four cultivars also displayed higher anthocyanins in the experimental wines from old vines (Pinot Meunier showed an opposing trend), whereas two of four cultivars displayed higher anthocyanins in the commercial wines from old vines. Finally, total phenols were higher in experimental wines from old Cabernet Sauvignon vines only and were not different amongst treatments in the commercial wines.
TABLE 5. Impact of vine age on experimental wine composition of Cabernet Sauvignon, Merlot, Pinot Meunier, and Pinot noir, and on commercial wines of Cabernet Franc, Cabernet Sauvignon, Merlot, and Pinot noir, Thirty Bench Vineyards, Beamsville, ON, 2002. Pinot Meunier was not kept separated for commercial wines in 2002
Sensory Attributes
The intensities of most of the aroma and flavor sensory descriptors did not differ between vine age treatments in Cabernet Franc (). Wines from young vines were more intense in herbaceous, tobacco, and vegetable aromas, as well as herbaceous and vegetable flavors. Color was more intense in wines from old vines. In Cabernet Sauvignon wines, treatments differed only in terms of vegetable aroma and color (young vines were higher). With Merlot, wines from young vines had more intense color, but less body, than those from old vines. In Pinot noir, treatments differed only in terms of color (old vines were higher).
Table 6. Sensory attributes of commercial wines of four Vitis vinifera cultivars as impacted by vine age, Thirty Bench Vineyards, Beamsville, ON, 2002. Values are based on a scale from 0 to 100 points
No study thus far has comprehensively examined vine age relative to wine composition or sensory attributes in red wine cultivars. CitationHeymann and Noble (1987) showed that Cabernet Sauvignon wines from young vineyards in California were lower in berry aroma and higher in green bean aroma and vegetative flavor. In white wines, CitationReynolds et al. (1994)showed that Riesling vines with old cordons produced wines that were slightly higher in TA and lower in pH than treatments with younger cordons. Moreover, their wines were higher in candy and fruity aromas and flavors, and lower in grassy aromas and flavors.
Vine Age and Mulch Effects, 2003
Reflectance
Higher reflectance in the 300 to 1100 nm wavelength range was measured in the reflective mulch treatment on 25 July, whereby ∼40% of photosynthetically active radiation was reflected back into the canopy in mulched plots, compared to ∼10% in non-mulched plots (CitationCoventry et al., 2005; data not shown). This is in accordance with results attained by CitationRobin et al. (1996) that also showed that there was an apparent effect on percent reflectance on an aluminized reflective surface compared to that of a control (soil) and a black polyethylene film. The light measurements for the reflected mulch taken on 10 October also showed higher percent reflectance from 300 to 1100 nm. However, levels were slightly lower than the 25 July measurements, likely because the reflective surface was oxidizing and/or was dirty. This deteriorating reflective surface was becoming less effective in reflecting sunlight back into the canopy to enhance the light microclimate around the grape clusters and basal leaves. Magnitude of difference in reflectance between mulched and non-mulched treatments increased with increasing wavelength, particularly in the 720 to 1100 nm range. CitationRobin et al. (1996) also showed a trend where the difference in reflectance between mulched and non-mulched plots increased with increasing wavelength.
Yield Components and Berry Composition
There were differences in 2003 amongst the vine age treatments for yield in Cabernet Franc only, with older vines having a greater crop size than young vines (). TA of berries was lower in the old vines compared to the young vines; however color intensity was greater in the old vines. Total anthocyanins also tended to be higher for the older vines. There were little differences amongst the mulch treatments in terms of yield, berry weight, Brix, TA, pH, hue, color intensity, and total phenols for Cabernet Franc vines in 2003, and age × mulch interactions were not significant. There was a trend towards slightly higher yield, and higher color intensity and total anthocyanins in berries sampled from young Cabernet Sauvignon vines (). There were few differences between the mulch treatments and vine age on yield, berry weight, Brix, TA, pH, hue, intensity, total anthocyanins, and total phenols for Cabernet Sauvignon berries, and no age × mulch interactions.
TABLE 7. Impact of vine age and mulch treatment on yield components and berry composition of Cabernet Franc, Cabernet Sauvignon, Pinot Meunier, and Pinot noir, Thirty Bench Vineyards, Beamsville, ON, 2003
Berries from the young Pinot Meunier vines had a greater concentration of anthocyanins compared to the old berries, while the old Pinot Meunier berries were more intense in color (). The reflective mulch treatments had no effects on berry composition of Pinot Meunier and there were no age × mulch interactions. Berries from the young Pinot noir vines were more intense in color and less concentrated in phenols compared to those from the old Pinot noir vines (). Berry weight and TA was increased in old vines; however young vines showed a tendency of increased Brix. Vine age showed little impact on yield, pH, hue, and anthocyanins for Pinot noir berries. The reflective mulch treatments had no effects on the Pinot noir berry composition, and there were no age × mulch interactions.
Research by CitationKoblet and Perret (1982, Citation1985) showed that vines with a significant volume of “old wood” had increased yields and slight improvements in berry composition compared to vines with less old wood. Similar trends were reported in vines trained to high trunks (CitationKonlechner, 1961; CitationWeaver and Kasimatis, 1975; CitationStoev and Dobreva, 1976; CitationMihailov, 1980). These results are consistent with the Pinot noir and Cabernet Franc data in our study. The improvements in fruit composition may be due to the fact that the older vines had a more established system of trunks, cordons, and other perennial parts; comparative trunk diameters were ∼2 cm and ∼8 cm for the young and old vines, respectively. However, berries from the Pinot Meunier young vines had a higher concentration of anthocyanins. This might be attributed to a trend towards lower yields and berry weights on the younger vines, therefore allowing a greater concentration of anthocyanins and other compounds in the berry.
Overall, the mulch treatments had no effect on berry composition in the red wine cultivars. Similarly, CitationStevenson et al. (1986) investigated the effects of woven plastic mulch on irrigated Marechal Foch grapevines and found no effects on berry soluble solids. CitationBowen et al. (2004b) also found no impact of polyethylene mulch on Merlot yield components and berry composition.
There were no differences in yield, berry weight, Brix, TA, and pH between the mulched and non-mulched Riesling treatments (). However the mulched treatment resulted in higher FVT and PVT compared to the non-mulched treatment. This might have been due to increased light penetration into the fruiting zone of the Riesling vines, which would have caused warming of the clusters. Similar results were shown by CitationReynolds et al. (1996), whereby improved light penetration into the fruiting zone through canopy division, basal leaf removal, and increased vine spacing increased FVT and PVT concentrations in Riesling fruit. This study suggested that improving light microclimate and fruiting zone temperature will increase berry monoterpenes, and the results from the present reflective mulch study are consistent with these results.
TABLE 8. Impact of reflective mulch on Riesling yield components and berry composition. Thirty Bench Vineyards, Beamsville, ON, 2003
Must Composition
Musts from young Cabernet Franc vines had higher pH and hue compared to old vines; while the old vines had higher TA and color intensity (). There were no vine age differences in Brix, anthocyanins, and phenols in Cabernet Franc musts. Musts from the non-mulched treatment had higher phenols and hue, and lower pH and intensity of color, compared to the mulched vines. There were no age × mulch interactions except for color intensity. Cabernet Sauvignon old vine musts had higher TA, pH, color intensity, total anthocyanins, and total phenols compared to those from young vines (). In the non-mulched treatment, color intensity and concentration of phenols were higher compared to the mulched treatment; this is consistent with data of CitationBergqvist et al. (2001) who reported reduced concentrations of anthocyanins and phenols in fully exposed Cabernet Sauvignon and Grenache berries. Vine age × mulch interactions existed for pH, hue, intensity, anthocyanins, and phenols. The non-mulched young vines exhibited the lowest pH. The young mulched vines had highest hue compared to the rest of the treatments; whereas the old vine treatments had highest color intensity. The old mulched vines exhibited higher anthocyanins and phenols compared to the rest of the treatments.
TABLE 9. Impact of vine age and mulch treatment on must composition of Cabernet Franc, Cabernet Sauvignon, Pinot Meunier, and Pinot noir, Thirty Bench Vineyards, Beamsville, ON, 2003
Musts from the old Pinot Meunier vines had higher TA, color intensity, and phenols than young vines, but there were no differences in hue or anthocyanins (). In the mulched treatments there were no differences for Brix, TA, pH, anthocyanins, and phenols. The mulched treatment had higher color intensity and a lower hue value. Vine age × mulch interactions existed for Brix, pH, and hue. The young non-mulched vines had higher Brix and hue compared to the older vines. The musts from older vines had higher TA than those from the younger vines. There was also increased TA in old vine Pinot noir musts and in non-mulched treatments (). Young vines, however, had higher Brix, pH, and color intensity compared to old vine musts. Must hue and anthocyanins were not affected by vine age, and Brix, pH, and anthocyanins displayed few differences between mulch treatments. Vine age × mulch interactions existed for TA, hue, and color intensity. The young vines had a much lower TA compared to the old vine treatments. The old non-mulched vines had the highest hue along with the lowest color intensity compared to the other treatments.
Overall, the musts from older Cabernet Sauvignon, Pinot Meunier, and Pinot noir vines had higher concentrations of anthocyanins and phenols. The mulch treatment showed more differences in the must samples compared to the berry samples. This could be due to the fact that the must samples represented a greater percentage of the population of clusters on the vines. Older Cabernet Sauvignon mulched vines exhibited the highest color intensity, anthocyanins, and phenols in comparison to the rest of the Cabernet Sauvignon treatment combinations. The young Pinot Meunier non-mulched vines produced the highest Brix and hue of all the other treatments. The young Pinot noir mulch and non-mulch exhibited the lowest TA and highest intensity of color. The color enhancement might have been due to the high skin-to-juice ratio of the grapes, since the younger vines tended to produce smaller berries.
Wine Composition
Differences in TA, pH, hue, intensity, total anthocyanins, and phenols for vine age were observed in Cabernet Franc wines (). Old vines had higher TA with a corresponding lower pH, as well as lower hue and total phenols than young vines but increased color intensity and anthocyanins. Mulch treatments showed no difference in TA, pH, hue, intensity, anthocyanins, or phenols. Age × mulch interactions existed for intensity of color and total phenols. The old vine treatments exhibited greater color intensity in comparison to the young vines. The young mulched vines had the highest concentration of phenols compared to the old mulched treatments in which phenol concentration was lowest. For Cabernet Sauvignon wines, vine age had an impact on TA, pH, hue, intensity, and phenols (). Vine age had no effects on anthocyanins. The mulch treatment appeared to have little effect on wine composition for TA, pH, hue, intensity, anthocyanins, and phenols. Mulch × vine interactions existed for TA, pH, and hue but not intensity, anthocyanins, and phenols. The young mulch treatments contained the lowest TA; also the young mulch and non-mulched vines had the lowest pH. The old mulch and non-mulched vine treatments had higher hue values compared to the young treatments.
TABLE 10. Impact of vine age and mulch on wine composition of Cabernet Franc, Cabernet Sauvignon, Pinot Meunier, and Pinot noir, Thirty Bench Vineyards, Beamsville, ON, 2003
Wines from young Pinot Meunier vines had higher phenols and greater hue compared to the old vines (). Wines from young vines also showed lower TA and pH compared to wines from the old vines. No differences were observed for TA, pH, intensity, total anthocyanins, and phenols from the mulch treatment. There were vine age x mulch interactions for TA, pH, and hue but not for intensity, anthocyanins, and phenols. The old mulch and non-mulched treatments exhibited a higher TA and lower pH compared to the young mulched and non-mulched treatments. The young mulched and non-mulched vines exhibited a greater hue in comparison to the old treatments. For Pinot noir wines, vine age had little effect on total phenols and hue. The wine from the young vines had higher color intensity and anthocyanins compared to the old vine wines (). The wines from the old vines had a higher TA and pH compared to the young vine wine. No differences for pH, intensity, total anthocyanins, or phenols were observed for the mulch treatment. The young non-mulched and mulched treatments had the lowest TA compared to the old mulched and non-mulched vine treatments. The young mulched and the non-mulched had the highest concentration of anthocyanins whereas the old non-mulched treatment had the lowest concentration of anthocyanins.
Riesling wines did not differ in terms of composition; non-mulch and mulch values were: ethanol (12.9 and 12.3 % v/v); TA (8.2 and 8.9 g L−1); pH (3.25 for both); FVT (0.46 and 0.53 mg L−1); PVT (1.17 and 1.34 mg L−1).
In many cases the red wines from young vines had higher concentrations of phenols (three of four cultivars) and anthocyanins (one of four cultivars) compared to the old vines. This is a desirable trait in red wines, which could result in improved color and improved mouthfeel. The wines from the Cabernet Franc young vine mulched treatment exhibited the lowest color intensity and the highest phenols compared to the rest of the treatments. In Pinot Meunier, wines from the young mulched and non-mulched vines exhibited the lowest TA while containing a greater pH and hue compared to the rest of the treatments. With Pinot noir wines from old mulched and non-mulched vines displayed a higher TA and lower anthocyanins compared to the young Pinot noir treatments. These results could reflect the slightly lower berry skin-to-juice ratio in young vines. Overall, as with berry composition, mulch treatments had little effect on wine composition. The lack of mulching effects may be a result of the degradation and oxidation of the exposed mulch, which reduced its ability to reflect sunlight into the canopy (CitationCoventry et al., 2005). It is also possible that the mulch was applied too late for maximum efficacy; CitationKeller and Hrazdina (1998) found flavonols in Cabernet Sauvignon began to accumulate at berry set. The slightly mounded surface immediately below the vines might also have played a role, causing light to reflect into adjacent rows rather than into the canopy above. If the mulch were capable of heating and retaining heat in the soil beneath the vine this might have increased heat conductance to the vines, especially in the evening. Below-surface temperature measurements did, in fact, have an ameliorating effect of day-night temperature differences, which were significantly less in mulched soils (Coventry and Strommer, unpublished).
Wine Sensory Attributes
Cabernet Franc wines from the vine age treatments did not differ with the exception of more intense color and less intense vegetable aromas in young vine wines (). Cabernet Franc wines also showed no differences between mulched and non-mulched treatments, except that the non-mulched wines had a higher vegetable aroma compared to the wines from the mulched vines. Cabernet Sauvignon wines similarly showed no differences between vine age treatments for most sensory attributes; although wines from the young vines had greater cherry aroma, berry flavor, and astringency, while wine from the old vines had higher herbaceous and vegetable aromas. The Cabernet Sauvignon wines also were not different between mulched and non-mulched treatments for most sensory attributes, but non-mulched wines had higher color intensity and vegetable aroma compared to the mulched wines.
TABLE 11. Sensory attributes of commercial wines of four Vitis vinifera cultivars as impacted by vine age and mulch, Thirty Bench Vineyards, Beamsville, ON, 2003
The Pinot Meunier wines did not differ between young and old vines for most sensory attributes; however, wines from the old vines exhibited stronger berry aromas and cherry flavors compared to the wines from the young vines, along with reduced astringency, body, and aftertaste. Pinot Meunier wines also showed few differences between mulched and non-mulched treatments for most sensory attributes, although the non-mulched wines exhibited more intense vegetable flavors compared to the wines from the mulched vines. The Pinot noir wines showed no differences between vine age treatments for most sensory attributes; however, wines from young vines exhibited more intense chocolate aromas along with greater body and color compared to the wines from old vines. Pinot noir wines showed few differences between the mulch treatments for most sensory attributes; although mulched wines exhibited more intense plum aroma, currant flavor, and color and less herbaceous aromas compared to the wines from the non-mulched vines.
PCA was not successful in segregating groups of vine age or mulch treatments across red wine cultivars. However, certain cultivars could be characterized through PCA. For instance, Cabernet Franc wines were characterized by plum and chocolate (aromas and flavors) along with acidic and astringent attributes (). Cabernet Sauvignon wines were best described by bell pepper, herbaceous, tobacco, and currant (aroma and flavor) attributes. Pinot Meunier wines were characterized by berry and cherry aromas and flavors, while Pinot noir wines displayed similar attributes along with herbaceous aromas and flavors.
FIGURE 1. Principal components analysis of sensory descriptors of Cabernet Franc, Cabernet Sauvignon, Pinot Meunier, and Pinot noir wines, Thirty Bench Vineyards, Beamsville, ON, 2003. Legend: Cultivar designations: CF: Cabernet Franc; CS: Cabernet Sauvignon; PM: Pinot Meunier; PN: Pinot noir; Treatment designations: Age treatments: O: old; Y: young; Mulch treatments: M: mulched; no designation: non-mulched. A number “2” following a given cultivar-treatment combination indicates tasting replicate #2; otherwise replicate #1.
The Riesling wines from the mulched treatment showed lower color intensity (27 vs. 36 on a 100-point scale) and acidity (55 vs. 62) compared to the non-mulched wine. Floral, apple/pear, citrus, peach, melon, and vegetable aromas, citrus, apple/pear, peach, melon, and vegetable flavors, astringency, body, and finish were not different between mulched and non-mulched vines (data not shown).
As mentioned previously, the effect of vine age on wine sensory attributes has not been studied extensively studied. CitationReynolds et al. (1994) found that Riesling vines with old cordons produced wines with higher fruity aroma and flavor and the least grassy aroma and flavor. Little data are readily available on impact of vine age on red wine sensory quality except for those of CitationHeymann and Noble (1987), which indicated that Cabernet Sauvignon wines from young vineyards in California tended to be higher in green bean aroma and vegetative flavor. As to reflective mulch, a few studies (CitationRazungles et al., 1996; CitationRobin et al., 1996) have been performed on the effect of a reflective surface and the impact on the sensory attributes of the wine. These studies found that wines made from vines that were exposed to aluminum-covered soil were preferred. In the present study, Pinot noir wines made from the mulched vines had greater plum aroma, currant flavor, and color compared to the non-mulched wines. All the wines made from non-mulched vines exhibited more intense vegetable aromas and flavors along with herbaceous aromas.
CONCLUSIONS AND GROWER BENEFITS
Vine age had a substantial impact on berry, must, and wine composition of four red wine cultivars over a two-year period. Between vine age and reflective mulch treatments, vine age had the greater impact overall on berry, must, and wine composition of Cabernet Franc, Cabernet Sauvignon, Pinot Meunier, and Pinot noir. Vine age had a greater impact on must and wine composition compared to berry composition. The must and wines from young vines had more concentrated phenols and anthocyanins compared to the old vines. Sensorially, old vines did not necessarily produce superior wines, which is contrary to popular opinion. For example, the Cabernet Sauvignon and Cabernet Franc experimental wines produced from the old vines exhibited higher vegetable aromas and flavors in one season. Pinot noir and Pinot Meunier wines produced from the young vines contained stronger chocolate flavor and aroma and were fuller bodied than those from older vines.
Mulch treatments did not impact berry, must, and wine composition to the extent hypothesized. In many instances mulch treatment had no impact on berry, must, and wine composition. Mulch treatments showed some effects on color, which is consistent with data that showed reflection of light into the canopy. The mulch treatments also had an effect on must composition, although after vinification, differences were not as apparent. The mulch increased the concentrations of FVT and PVT in the Riesling berries, suggesting improved canopy microclimate as a result of the mulch. The non-mulched vines produced wines that exhibited stronger vegetable aromas and flavors. However, considering the relatively small benefits of this mulch product compared to the cost of application, removal, and disposal, along with its short effective lifespan, its use cannot be recommended. However, it is possible that other more robust mulch products may exist that could justify the cost of material plus that of application.
Acknowledgments
Authors wish to thank Yorgos Papageorgiou and Marek Maniecki, Thirty Bench Winery, for their cooperation. Financial assistance from the National Research Council of Canada is hereby acknowledged. Thanks also to Blake Hansler for assistance with mulch application. Efforts of the many sensory panelists are also acknowledged.
LITERATURE CITED
- Bergqvist , J. , Dokoozlian , N. and Ebisuda , N. 2001 . Sunlight exposure and temperature effects on berry growth and composition of Cabernet Sauvignon and Grenache in the central San Joaquin Valley of California . Amer. J. Enol. Viticult. , 52 : 1 – 7 .
- Bledsoe , A.M. , Kliewer , W.M. and Marois , J.J. 1988 . Effects of timing and severity of leaf removal on yield and fruit composition of Sauvignon blanc grapevines . Amer. J. Enol. Viticult. , 39 : 49 – 54 .
- Bowen , P.A. , Bogdanoff , C.P. and Estergaard , B. 2004a . Impacts of using polyethylene sleeves and wavelength-selective mulch in vineyards. I. Effects on air and soil temperatures and degree day accumulation . Can. J. Plant Sci. , 84 : 545 – 553 .
- Bowen , P.A. , Bogdanoff , C.P. and Estergaard , B. 2004b . Impacts of using polyethylene sleeves and wavelength-selective mulch in vineyards. II. Effects on growth, leaf gas exchange, yield components, and fruit quality in Vitis vinifera cv. Merlot . Can. J. Plant Sci. , 84 : 555 – 568 .
- Considine , J.A. 2004 . Grapevine productivity and yield components: A case study using field vines of Zante Currant . Austral. J. Grape and Wine Res. , 10 : 108 – 115 .
- Coventry , J.M. , Fisher , K.H. , Strommer , J.N. and Reynolds , A.G. 2005 . Reflective mulch to enhance berry quality in Ontario wine grapes . Acta Hort. , 689 : 95 – 102 .
- Dimitriadis , E. and Williams , P.J. 1984 . The development and use of a rapid analytical technique for estimation of free and potentially volatile monoterpene flavorants of grapes . Amer. J. Enol. Viticult. , 35 : 66 – 71 .
- Heymann , H. and Noble , A.C. 1987 . Descriptive analysis of commercial Cabernet Sauvignon wines from California . Amer. J. Enol. Viticult. , 38 : 41 – 44 .
- Johnson , H. and Robinson , J. 2001 . The World Atlas of Wine, , 5th , London : Octopus Publishing .
- Keller , M. and Hrazdina , G. 1998 . Interaction of nitrogen availability during bloom and light intensity during veraison. II. Effects on anthocyanin and phenolic development during grape ripening . Amer. J. Enol. Viticult. , 49 : 341 – 349 .
- Kingston , M.S. and Presant , E.W. 1989 . The soils of the Regional Municipality of Niagara , 2 : 131 Rept. No. 60 of the Ont. Institute of Pedology
- Koblet , W. and Perret , P. The role of old vine wood on yield and quality of grapes . Proc. Davis Grape & Wine Centennial Symp . Edited by: Webb , A.D. pp. 164 – 169 .
- Koblet , W. and Perret , P. 1985 . Die Bedeutung des alten Holzes für Ertrag und Qualität bei Reben . Wein-Wissenschaft , 40 : 228 – 237 .
- Konlechner , H. 1961 . Standraum und Qualität. . Der Deutsche Weinbau , 16 : 627 – 628 .
- Mazza , G. , Fukumoto , L. , Delaquis , P. , Girard , B. and Ewert , B. 1999 . Anthocyanins, phenolics, and color of Cabernet Franc, Merlot, and Pinot noir wines from British Columbia . J. Agric. Food Chem. , 47 : 4009 – 4017 .
- Metivier , R.P. , Francis , F.J. and Clydesdale , F.M. 1980 . Solvent extraction of anthocyanins from wine pomace . J. Fd. Sci. , 45 : 1099 – 1100 .
- Mihailov , A. 1980 . Influence of training system trunk formation of grapevine and their pruning treatment on the manifestations of growth and yield of the variety Rkatsiteli. Bulgarian . Gradinarska y Lozar. Nauka , 17 ( 1 ) : 82 – 89 .
- Razungles , A.J. , Baumes , R.L. , Robin , J.P. and Bayonove , C.L. Microclimatic influences in the vineyard on the flavor quality of grapes . Proc. 4th Int. Symp. on Cool Climate Viticult. and Enol . Edited by: Henick-Kling , T. pp. V49 – 53 .
- Reynolds , A.G. and Wardle , D.A. 1989 . Influence of fruit microclimate on monoterpene levels of Gewürztraminer . Amer. J. Enol. Viticult. , 40 : 149 – 154 .
- Reynolds , A.G. , Wardle , D.A. and Dever , M. 1994 . Shoot density effects on Riesling grapevines: Interactions with cordon age . Amer. J. Enol. Viticult. , 45 : 435 – 443 .
- Reynolds , A.G. , Wardle , D.A. , Hall , J.W. and Dever , M. 1995 . Fruit maturation of four Vitis vinifera cultivars in response to vineyard location and basal leaf removal . Amer. J. Enol. Viticult. , 46 : 542 – 558 .
- Reynolds , A.G. , Wardle , D.A. and Naylor , A.P. 1996 . Impact of training system, vine spacing, and basal leaf removal on Riesling. Vine performance, berry composition, canopy microclimate, and vineyard labor requirements . Am. J. Enol. Vitic. , 47 : 63 – 76 .
- Robin , J.P. , Sauvage , F.X. , Boulet , J.C. , Suard , B. and Flanzy , C. Repercussions on the must composition and on the wine quality . Proc. 4th Int. Symp. on Cool Climate Viticult. and Enol . Reinforcement of the radiative and thermic stresses of the grapevine in field conditions using a reflective soil cover , Edited by: Henick-Kling , T. pp. II-99 – 104 .
- Smart , R. and Robinson , M. 1991 . Sunlight into Wine , Underdale, , Australia : Winetitles .
- Smart , R.E. and Smith , S.M. Canopy management: Identifying the problems and practical solutions . Proc. 2nd Int. Symp. Cool Climate Viticulture and Oenology . Auckland. Edited by: Smart , R.E. , Thornton , R.J. , Rodriguez , S.B. and Young , J.E. pp. 109 – 115 . New Zealand Society for Viticulture and Oenology .
- Stevenson , D.S. , Neilsen , G.H. and Cornelsen , A.-M. 1986 . The effect of woven plastic mulch, herbicides, grass sod, and nitrogen on ‘Foch’ grapes under irrigation . HortScience , 21 : 439 – 441 .
- Stoev , K. and Dobreva , S. 1976 . Influence du mode de conduite de la vigne sur la photosynthèse et la distribution des substances elaborées . Connaissance Vigne Vin , 10 : 125 – 139 .
- Weaver , R.J. and Kasimatis , A.N. 1975 . Effect of trellis height with and without crossarms on yield of ‘Thompson Seedless’ grapes . J. Amer. Soc. Hortic. Sci. , 100 : 252 – 253 .
- Zoecklein , B.W. , Fugelsang , K.C. , Gump , B.H. and Nury , F.S. 1995 . Wine Analysis and Production , New York : Chapman & Hall .