Abstract
Twenty Pinot noir clonal selections were evaluated for viticultural characteristics in a vineyard managed for production of sparkling wine in the Los Carneros American Viticultural Area, Sonoma County, CA. Eight clones were of California origin from Foundation Plant Services (FPS), University of California, Davis: 2A, 4, 13, 17, 22, 31, 32, and 33. Twelve clones were of French (Champagne) origin: 389, 521, 665, 666, 668, 743, 779, 780, 870, 871, 872, and 927. Vine yield, yield components, fruit composition (soluble solids, pH, and titratable acidity), and vegetative growth were measured over three growing seasons, 1999 through 2001. Clones were harvested at similar soluble solids levels. Yield and all yield components differed significantly among clones. FPS 33 and clones 389 and 666 had significantly highest yields while FPS 13 and 22 and clone 870 had the lowest yields. Yield differences were primarily due to number of berries per cluster and number of clusters per shoot. Juice pH and titratable acidity differed significantly among clones, although the range for both measurements was small. Clones 521 and 870 had the highest pruning weights while clones 780, 668, and 665 and FPS 31 had the lowest pruning weights. Ravaz index values were high (>12) for 780, 668, and FPS 31, while values were lowest (~5) for clones 870, 521, and FPS 17.
Pinot noir (Vitis vinifera L.) is an important winegrape used for the production of high-quality table wines and sparkling wines. It is widely grown in France, Germany, Italy, Australia, South Africa, and South America. Pinot noir is also one of few varieties grown across North America, with plantings in the northeastern United States, in Oregon, Washington, and California, and in British Columbia and Ontario, Canada. In 2005, there were 9900 hectares of Pinot noir planted in California, more than triple the area only a decade earlier and making it, by planted area, the fourth-ranked red winegrape in the state (CASS 2006).
Pinot noir was first mentioned by name in the late 14th century in documents relating to Burgundian wine (Bernard 1986, Galet 1998). As a long-cultivated variety, an exceptionally high number of Pinot noir clones have been identified, some of which differ considerably in growth habit, cluster morphology and number, leaf morphology, and berry color density (Bernard 1995, Wolpert 1995). As would be expected for a widely planted cultivar with multiple clones, Pinot noir clonal evaluations have been reported throughout the wine-producing world, by research teams in Burgundy (Bernard 1986), Champagne (Barillere et al. 1995), Australia (Cirami et al. 1984), Canada (Reynolds et al. 2004), New York (Pool et al. 1995), Oregon (Price and Watson 1995), and California (Mercado-Martín et al. 2006). Local studies are valued because of concern that clonal performance differs in different locations (Cirami and Ewart 1995), presumably affected by mesoclimates and/or soils.
Clonal trial results must also be interpreted in light of different wine styles and production goals. In France, clonal selection of Pinot noir for sparkling wines has been conducted independently from clonal research on Pinot noir for table wine (Barillere et al. 1995). Sparkling wine producers typically look for Pinot noir clones with higher acidity, higher yield, and lower anthocyanin and tannin content than their table wine counterparts (Barillere et al. 1995, Bernard 1986, Pool et al. 1995).
An initial experiment investigated performance of 11 Pinot noir clones and two field selections for sparkling wine production (Mercado-Martín et al. 2006), primarily involving selections that had largely been used for table wine production in California. Significant differences were found in virtually all vegetative and yield components measured. The study reported here is part of continuing efforts to characterize certified clones from Foundation Plant Services (FPS) at the University of California, Davis (UC Davis). Previous work investigated clones of Chardonnay (Wolpert et al. 1994), Cabernet Sauvignon (Wolpert et al. 1995), Zinfandel (Wolpert 1996), and Merlot (Benz et al. 2006). The purpose here was to evaluate the viticultural characteristics of 12 imported Pinot noir clones, specifically selected for sparkling wine production in Champagne, France (Nelson-Kluk 2003). They were compared to eight California clones, five of which had been included in the original Pinot noir evaluation (Mercado-Martín et al. 2006).
Materials and Methods
Twenty Pinot noir clones were evaluated for viticultural performance (Table 1⇓). Eight were of California origin from FPS, UC Davis: 2A, 4, 13, 17, 22, 31, 32, and 33. Twelve were of French (Champagne) origin: 389, 521, 665, 666, 668, 743, 779, 780, 870, 871, 872, and 927.
Authenticated French winegrape clones became available in about 2002 to U.S. growers through ENTAV International, a program that distributes ENTAV-INRA selections. The French clones of Champagne origin used in this study arrived in California before the establishment of that program and therefore carry the designation “reported to be” as a way to distinguish them from authenticated clones that arrived through the trademarked program (Nelson-Kluk 2003). All clones are currently available from FPS except FPS 33.
The experiment was established in 1993 at Gloria Ferrer Champagne Caves in the Los Carneros American Viticultural Area (AVA), in southern Sonoma County. The soil was a Diablo clay loam (Miller 1972). Dormant Teleki 5C rootstocks (Vitis berlandieri x V. riparia) were planted in spring 1993 and clones were fall-budded that year. Vine spacing was 1.5 m x 3.0 m, vine by row, equivalent to a vine density of 2,222 vines/ha. Row orientation was east-west. Vines were head-trained, cane-pruned, and trained to a vertical shoot-positioned trellis system. The trellis consisted of a fruiting wire at 90 cm and two pair of movable shoot-positioning wires above the fruiting wire.
Mature vines were cane-pruned to two 12-bud canes with four two-bud renewal spurs. In addition to pruning, shoot number was controlled through spring shoot thinning. Applied water was delivered by drip irrigation. Cultural practices were typical for sparkling wine Pinot noir vineyards in the Los Carneros AVA.
Data collection began in 1999, when the vines were seven years old, and continued through 2001. Clones were harvested on a soluble solids basis, with a target of 20 Brix. At harvest, clusters were counted and crop weights measured for all data vines. Yield, cluster number, and berry weight data were used to calculate average cluster weight, average berry weight, and number of berries per cluster. Prior to harvest, a 100-berry sample was taken per treatment-replicate. Samples were processed in the laboratory where berries were weighed to determine average berry weight, then berries were crushed and juice was filtered through cheesecloth. Soluble solids were measured as Brix with a hand-held, temperature-compensating refractometer. Juice pH was measured with an electronic pH meter, and juice samples were titrated with 0.1 N NaOH to pH 8.2 endpoint to determine titratable acidity (TA).
During the dormant season, shoots on each vine were counted and weight of dormant prunings recorded. These data were used to calculate the average weight per shoot and the Ravaz index (RI; yield to pruning weight ratio) (Ravaz 1911).
The experiment was a vineyard block 22 rows wide and 54 vines long. The two outside rows and two vines at both ends of each row were nondata vines, leaving an experimental area of 20 rows and 50 vines. The 20 rows were divided into five blocks of four rows each and the 50 vines were divided into five groups of 10 adjacent vines. Each 10-vine group comprised an experimental unit and clone treatments were randomly assigned within each block, creating a randomized complete block design. For statistical analysis purposes, the experiment was treated as a split-plot design where clones were main plots and years were subplots. Data were subjected to analysis of variance (ANOVA), with mean separation by Duncan’s multiple range test.
Results
Yield and yield components.
Yield and all yield components differed significantly among clones (Table 2⇓). FPS 33 and clone 666 had the highest average yields, 8.7 and 8.5 kg/vine, respectively. FPS 2A and clone 389 also had high yields, averaging 7.9 and 8.0 kg/vine, respectively. FPS 13 and clone 870 had the lowest yields, averaging 5.3 and 5.4 kg/vine, respectively. Other low-yielding clones were FPS 22 and FPS 4 at 6 kg/vine. Overall yield increased significantly each of the three years from 6.3 kg/vine in 1999 to 7.6 kg/vine in 2001.
Berries per cluster were highest for clone 743, which averaged 135 berries per cluster, followed by clone 872 and FPS 33. FPS 13 had the fewest berries per cluster (78), followed by FPS 4 and clone 870.
While berry size differed significantly among clones, the range was small, only a 0.2 g difference between the smallest, clone 872, and largest, FPS 17 (Table 2⇑). Yearly difference in berry size was also small, although the average berry weight was significantly different in each year studied. Because of the relative lack of difference in berry weight, cluster weight was most closely correlated to berries per cluster (data not shown). Clone 743 had the heaviest cluster by a wide margin (190 g), 20% heavier than clone 872, which had the second heaviest cluster, and was 40% larger than clones FPS 13 and FPS 4, which had the smallest clusters.
Average number of clusters per shoot differed significantly, with clone 743 and FPS 22 having the fewest average clusters per shoot and clone 927 the most. Clones 666 and FPS 2A also produced, on average, over two clusters per shoot. The number of shoots per vine was controlled through dormant pruning and in-season shoot thinning, so differences in shoot numbers were small (data not shown). Therefore, number of clusters per vine closely followed the pattern of differences in clusters per shoot (Table 2⇑).
Fruit composition.
Clones were intended to be harvested at the same Brix level, but that was not precisely achieved. Clones differed significantly from a low of 19.8 Brix for FPS 2A and 4 to a high of 20.9 Brix for clone 872 (Table 3⇓). Ranges in pH and TA values were statistically significant but small. Harvest date was delayed, on average, by 15 days from first to last clone harvested and ranged from 17 days in 1999 (7 to 24 Sept), to 20 days in 2000 (19 Aug to 8 Sept) and 11 days in 2001 (20 to 31 Aug). The number of days of delay was better related with yield: prunings ratio (r2 = 0.46) (Figure 1⇓) than with yield (r2 = 0.42) or pruning wt (r2 = 0.36) (data not shown).
Vegetative growth.
Clones 521 and 870 had the greatest average pruning weight (both 1.4 kg/vine) and heaviest shoots, averaging 51 and 47 g, respectively (Table 4⇓). FPS 13 also had high pruning weight at 1.3 kg/vine. All three clones, as a result of large pruning weight and moderate or low yield, had the lowest RI values (≤ 5.0). In contrast, FPS 31, 668, and 780 had low pruning weight (≤ 0.7 kg per vine) and moderate yields, resulting in RI values above 12. Vegetative growth decreased over the three years of data, from 1.07 kg/vine in 1999 to 0.75 kg in 2001. Given the decrease in pruning weight and increase in crop, RI values, averaged over all treatments, increased from 6.8 in 1999 to 12.4 in 2001.
Discussion
Yield and yield components.
Yield and yield components differed widely among clones (Table 2⇑), consistent with other Pinot noir clonal evaluations (Barillere et al. 1995, Cirami and Ewart 1995, Price and Watson 1995, Whiting and Hardie 1990). According to a French evaluation of Champagne clones, clone 388 was high yielding in multiple research plots (Barillere et al. 1995), consistent with its performance here. Clone 389, the second highest producer in the French study, was the third highest producer here, and clone 666, second highest yielding clone in this study, was also relatively high yielding in the French study. However, the French evaluation also found clones 665, 668, and 743 to yield heavy crops, whereas they bore moderate crops in this study. Low yield of clone 870 agreed with the French study (Barillere et al. 1995), but that study also found clones 779 and 927 to be low yielding, while they were moderate producers here.
Another study reported that FPS 2A had average to low yield (Price and Watson 1995), whereas it had high yield here. An Australian study found that FPS 13 had greater yield than FPS 2A (Cirami et al. 1984), which is the opposite of the pattern we found. These comparisons point out that clones perform differently under different conditions, and whether that is due to climate, soil, rootstock choice, or cultural practices cannot be determined.
In a study of Oregon Pinot noir, the authors noted that the “small clustered clones had low yields while the large clustered clones had high yields” and that “no clones departed from this general trend” (Price et al. 1988). Such was not the case in this evaluation, where clones 743 and 872 both had very high cluster weights, but moderate yields because of their low number of clusters per shoot, and the converse was seen for clone 927, where clusters were small but yield was moderate because the cluster number per shoot was the highest at 2.2.
The range of berry size was relatively small (Table 2⇑), and few clones stood out as having either small or large berries. Smaller berries are valued in red wines for having a high skin-to-pulp ratio and increased wine color and phenolic concentration (Gladstone 1992, Singleton 1972). However, in the case of sparkling wine, light color and low phenolic extraction are desirable (Barillere et al. 1995, Ewart and Sitters 1986, Pool et al. 1995), thus berry size may be relatively unimportant for Pinot noir clones chosen for sparkling wine. Ewart and Sitters (1986) suggested that Pinot noir clones selected in Champagne have large berries while clones selected in Burgundy have small berries. However, in this evaluation, none of the clones had particularly large berries and Champagne clone 872 had the smallest berries.
Fruit composition.
Grapes for sparkling wine are typically harvested at lower sugar levels than grapes for table wines, and the target here was 20 Brix. The range in soluble solids was 1.1 Brix, 19.8 to 20.9 for all clones (Table 3⇑). Juice pH and TA did not differ widely among clones. Clones with higher yield to pruning ratio took longer to ripen than clones with less yield (Figure 1⇑). In sparkling wine production areas of northern California, grapes reach appropriate sugar levels sufficiently early every year (late August to early September) so that ripening periods of 20 additional days would not be a concern.
Vegetative growth.
Vegetative growth, measured as pruning weight, differed more than 2-fold among clones (0.6 to 1.4 kg/vine; Table 4⇑). Because shoot number was held to a relatively small range (27 to 30 per vine, data not shown), differences in pruning weight were reflected in average weight per shoot, which more than doubled from 22 g (clone 780) to 51 g (clone 521). High vegetative growth was not a vine compensatory response to low yield, as is illustrated by clones 780, 870, and 521. All three had moderate to low yield (<7 kg/vine). However, clone 780 had the lowest pruning weight, 872 had moderate, and 521 had high.
Half of the clones tested had an average Ravaz index over 8, and seven clones had RI values over 10. The latter is considered high (Smart and Robinson 1991) and could indicate that vines in this study were overcropped and that yields should be limited through crop removal. However, regarding yield and quality in sparkling wine, tasting preference has been correlated to clonal yield, where the lowest yielding clones were the most preferred (Barillere et al. 1995). Conversely, another study reported that high yields can be consistent with high quality sparkling wine (Pool et al. 1995). Pruning weight decreased over the course of our experiment (1999 to 2001) (Table 4⇑), while the yield increased. This strong yearly effect is possibly due to climatic differences, but no observations or data give any explanation for a cause.
Conclusions
Selections recently imported from the Champagne region of France, studied for the first time in the United States, performed similarly to studies in France where French data were available but some exceptions were seen. Relatively different performance between the study reported here and others from Australia, France, and Oregon indicate the value of local research. Pinot noir clones differed significantly in most reproductive and vegetative measures. Because of differences in yield and pruning weight, Ravaz index values ranged from very low to very high. Those planting Pinot noir clones with RI values below 5 (FPS 13 and clone 870) should take care to control vegetative growth by choosing a rootstock that imparts lower vigor to the scion. Conversely, those planting Pinot clones with RI values above 10 (FPS 2A, 31, and 33 and clones 389, 665, 668, 780, and 871) should consider using a rootstock that imparts increased vigor to the scion. While all clones, including those with both low and high RI values, reached desired maturity levels, current viticultural principles suggest that deviation from accepted RI values may result in vineyards that are less sustainable than those managed at recommended values.
Footnotes
Acknowledgments: Research funding from the American Vineyard Foundation.
The authors thank Michael Crumly and Robert Iantosca of Gloria Ferrer Champagne Caves for superb cooperation, M. Jason Benz for data analyses, and G. Stanley Howell for critical comments on the manuscript.
- Received January 2007.
- Revision received April 2008.
- Revision received February 2008.
- Copyright © 2008 by the American Society for Enology and Viticulture