Abstract
Eleven clones and two field selections of Pinot noir (Vitis vinifera L.) were evaluated for three years, 1992 through 1994, for viticulture characteristics in a vineyard managed for sparkling wine production. Clones from Foundation Plant Services (FPS), University of California, Davis, included Pinot noir FPS 1, 2A, 13, 23, 29, 31, 32, and 33. Also evaluated were three clones sourced from a plant importation program at Oregon State University, Espiguette 236, Espiguette 374, and Colmar 538, as were two field selections referred to locally in California as Wente and Gamay Beaujolais. The trial was established in 1988 in the Los Carneros American Viticultural Area in Sonoma County, California. Great variation among the clones was seen in vegetative growth and yield parameters. Pruning weight varied by a factor of 2 and yield by a factor of 1.5. Yield was influenced by cluster number, berries per cluster, and berry weight. There was a range of 4 Brix at harvest across all treatments in all three years and Brix was closely correlated with vine yield.
Pinot noir (Vitis vinifera L.) is an important winegrape variety used in production of dry table wines and sparkling wines. It is particularly well adapted to cool growing areas and can be grown at the highest latitudes where viticulture is practiced, such as Reims, Champagne, France (lat. 49°N). Generally, Pinot noir has a prostrate growth habit, small, tight clusters, and low yield, but it is known for wide phenotypic variation, (Bernard 1995, Bernard and Leguay 1986). There may be as many as 300 registered Pi-not noir clones in the world. There are more than 75 certified clones at Foundation Plant Services, University of California, Davis (FPS, UC Davis) (FPS 2003).
Many Pinot noir clones grown in California originated from French clonal selection programs. A major selection criterion for Pinot noir is low crop levels because short growing seasons limit sugar accumulation in Burgundy and Champagne, the two main Pinot noir production areas in France. High crop level in Pinot noir is perceived to result in low-quality grapes with delayed sugar accumulation and reduced varietal character and, consequently, low-quality wine. One study reported that wine production greater than 60 hL/ha (9.6 t/ha) is excessive for Pinot noir (Bernard and Leguay 1984).
Several studies have investigated variability in Pinot noir clones, including an 8-year study of 20 clones of Pi-not noir in the Finger Lakes region of New York (Pool et al. 1995). Clones recommended for red table wine included FPS 29 and selections referred to as Mariafeld and Pernand. Those Pinot selections tended to produce the more preferred wines during the course of the study, and they had better winter hardiness and less Botrytis bunch rot, two important criteria for successful winegrape production in New York.
In Germany, four clones of Pinot noir were studied for their yield, wine quality, and sensitivity to Botrytis bunch rot infection (Becker et al. 1988). The clone with best resistance to Botrytis was identified as Mariafeld, characterized as having a long rachis and a loose cluster. The exact relationship of Mariafeld used in Germany to New York Mariafeld and to clone FPS 23, also known as Mariafeld, is unclear. Yield was largely influenced by cluster number and berry size (Becker et al. 1988). Clones that had the lowest yields also had the most intense color and highest sugar, with the exception of the Mariafeld clone, which had an intense color despite large berry size and relatively high yield.
In Burgundy, among seven Pinot noir clones, Espiguette 236 was described as a fructiferous (fruitful) clone, being vigorous and susceptible to Botrytis bunch rot, although its behavior was variable depending on the vintage (Bernard et al. 1983). Acid levels of Espiguette 236 were high, leading to its recommendation for the production of sparkling or rosé wines (Bernard et al. 1983).
In Australia, five selections of Pinot noir were compared during three growing seasons for productivity and chemical composition (Whiting and Hardie 1990). Yield was positively correlated with number of clusters per vine in all three years and with cluster weight in two years. Berry weight did not have any influence on yield. All selections were harvested on the same day, and significant differences were observed in Brix, titratable acidity (TA), and pH. In another Australian study, nine clones of Pinot noir ranged in yield from 5.9 to 9.4 kg/vine on vines pruned to the same bud number (Cirami et al. 1984). Levels of color density, total anthocyanins, ionized anthocyanins, and total phenols were not correlated with fruit yield. Lack of a relationship between yield and color led the authors to conclude that color differences were due to clone. The authors suggested that lesser pigmented clones may be more suitable for production of sparkling wine and more pigmented clones better suited for red wine styles.
The studies described indicate that Pinot noir clones exhibit a wide range of differences in vegetative and reproductive characteristics. Comparing the relative performance of specific clones in different countries is made more difficult because the studies rarely have more than a few clones in common, a particular problem with Pinot noir because of the prodigious number of clones available for testing. While many of the studies focused on table-wine production, understanding these characters in clones for sparkling wine is also important.
Clones of Pinot noir in the FPS collection at UC Davis have not been scientifically evaluated. The trial was established at a time when accessions were arriving from France, directly to California and indirectly from Oregon. The California winegrape industry expressed interest in seeing how they would perform in California. The experiment is the first report of viticultural characteristics of Pi-not noir clones managed for sparkling wine production.
Materials and Methods
The experiment was conducted over a 3-year period at Gloria Ferrer Champagne Caves located in Sonoma County within the Los Carneros American Viticultural Area (AVA). The site was characterized as a region I with ~1,390 degree days of heat summation (above 10°C). The Pacific Ocean exerts strong influence on the Carneros area, resulting in a cool maritime climate. Early morning fog and afternoon winds are common during the summer months. The fog typically dissipates around midmorning and temperature increases thereafter until cooling winds develop in the early afternoon. The soil type was Clear Lake clay (Miller 1972), pH 6.0 to 7.0, with an effective root depth of 60 to 75 cm.
Eleven clones and two field selections of Pinot noir (Vitis vinifera L.) were evaluated (Table 1⇓). Eight clones were selected from FPS, UC Davis: FPS 1, 2A, 13, 23, 29, 31, 32, and 33. Three clones were obtained from Oregon State University: Espiguette (ESP) 236 and 374 and Colmar (COL) 538. In addition, two field selections of Pinot noir, locally known as Wente (WEN) and Gamay Beaujolais (GB), both provided by Gloria Ferrer, were included in the trial because they were extensively planted in Carneros and elsewhere in northern California for sparkling wine use. The Gamay Beaujolais clone of Pinot noir had been misidentified as a variety for many years in California. It is not related to true Gamay noir of Beaujolais, France. FPS 31 and ESP 236 have the same French clonal identification number, that is, they are, theoretically, the same material. However, because they were obtained from different sources, they were treated as separate clones throughout this study.
Fifty vines of each clone or field selection were grafted onto AXR#1 rootstock (V. vinifera L. Aramon x V. rupestris Ganzin #1), and planted in July 1988. Vines were spaced at 1.5 m x 3.0 m, equivalent to a density of 2,160 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, one wire at 115 cm for protection against wind damage, two pair of movable shoot-positioning wires at 120 and 150 cm, and a single fixed foliage wire at 180 cm. The experiment was designed as a randomized complete block, consisting of 10 vines of each clone per block, replicated five times. The experiment was established as a separate block in the vineyard, and guard vines were employed to separate the data vines from edge effects. Two rows at each side of the vineyard block and six vines at both ends of each row were planted to a single clone.
Vines were pruned by the Gloria Ferrer’s vineyard staff, and the number of buds retained was set in accordance with common practice for the observed vine growth. This corresponded to an average bud count of between 28 and 34 buds per vine over the three years that data were collected. A cover crop of vetch, peas, and oats was planted each fall, with the primary purpose of improving soil organic matter. Interrow spaces were cultivated during the growing season while weeds were controlled under vine rows by application of herbicides. The trial was drip-irrigated, and water was applied according to gypsum block readings. The average irrigation was about 90 L per vine on 3-week intervals, with approximately four irrigations per season. The plot did not experience any major pest or disease problems and very little incidence of Botrytis bunch rot was observed before harvest. No shoot thinning or leaf removal was performed in the plot. All other cultural practices were those of a typical Carneros Pinot noir vineyard for sparkling wine production.
The number of shoots and weight of one-year-old cane prunings was recorded on a per-vine basis in the dormant season. In the fall, each vine was harvested individually and yield and cluster number recorded. Individual vine data were averaged to give a single value per experimental unit for statistical analysis.
Fruit from each clone was harvested on a maturity basis with a target of 19 Brix. Frequent sampling was done to predict fruit maturity. One day before harvest of the first clone, a 100-berry sample was collected per 10-vine experimental unit. Each berry sample was weighed and pressed, and the juice analyzed for soluble solids (Brix), titratable acidity (TA), and pH by a previously described method (Wolpert et al. 19940. Berry weight for 1992 and 1993 are not presented here because in those two years, berry samples were not collected for each experimental unit on the harvest date of each clone. Berry weight would likely have continued to increase for later harvested clones. Comparing berry weight at a given date would not be indicative of final weight, nor could a one-time measure be used to accurately calculate berries per cluster in the normal manner (Wolpert et al. 1994). In 1994, in addition to the same-day berry sample just before harvest of the first clone, a replicated 100-berry sample was taken on the harvest date of each clone. Berry weight and cluster weight on the day of harvest were used to calculate berries per cluster for 1994 data.
Multiyear data were subjected to analysis of variance (ANOVA) using a split-plot model (repeated measures). All possible two-way interactions were included in the model.
Results
Vegetative growth components.
The average pruning weight of all clones varied from 1.6 kg/vine in 1992 to 2.0 kg/vine in 1994 (equivalent to 1.1 to 1.3 kg/m of row, respectively) (Table 2⇓). The 3-year average weight of cane prunings varied two-fold, from a high of 2.6 kg/vine for FPS 13 to a low of 1.2 kg/vine for ESP 236, equivalent to 1.6 to 0.8 kg/m of row, respectively. FPS clones 1 and 32 also produced relatively high pruning weights of 2.3 to 2.4 kg/vine, respectively; while FPS clones 2A and 31, ESP 374, COL 538, and WEN were relatively low at 1.5 to 1.7 kg/vine.
Average shoots per vine varied from 27 to 32. Variation was due to a difference in bud number retained at pruning and to the numbers of buds that did not produce a shoot (blind buds). In addition, basal shoots which developed from buds at the base of canes and renewal spurs were not removed by shoot thinning and were observed to contribute significantly to shoot count. However, blind buds and shoots from basal positions were not separately recorded. Basal shoots are typically removed by hand in Pinot noir vineyards intended for table wine; however, it is not a common practice in sparkling winegrape production. Average shoot weight varied nearly two-fold and showed the same pattern as pruning weight, with FPS 13 having the heaviest (89 g) and ESP 236 having the lightest (45 g) shoot weights (Table 2⇑).
Yield components.
Yield averaged across all treatments varied from 9.5 kg/vine in 1992 to 7.7 kg/vine in 1994 (Table 2⇑), a pattern inversely related to changes in average pruning weight. Poor fruit set in 1993, presumably because of inclement weather at bloom, resulted in an experiment-wide average cluster weight of only 108 g, versus 148 g and 123 g in 1992 and 1994, respectively (Table 2⇑).
High-yielding clones averaged 9 to 10 kg/vine and included FPS 23, 31, and 33, ESP 236, and WEN, while the lowest yielding clones were FPS 1, 13, and 29, which averaged between 6.5 and 7.0 kg/vine. Yield differences were due to both clusters per vine and cluster weight. FPS 2A and 33 had greater than 70 clusters per vine while FPS 1, FPS 29, and ESP 374 had less than 60 clusters per vine. FPS 23 and 31 had the heaviest clusters at 147 g and 151 g, respectively, while FPS 13 and 29 had the lightest at 112 g and 115 g, respectively. Mean yield was positively correlated with mean cluster weight (r = 0.79, p < 0.05) (Figure 1⇓). However, vines with similar yields had significantly different cluster weight values, indicating other yield components had significant effect. For example, FPS 2A and 23, with similar 3-year average yields of 8.8 and 9.0 kg/vine, respectively, had the opposite pattern of cluster number and cluster weight, with FPS 2A having more (72) and lighter (122 g) clusters while FPS 23 had fewer (61) and heavier (147 g) clusters.
The combination of lower yield and greater vegetative growth resulted in a range of average yield:pruning (Y:P) ratios from a high of 6.2 in 1992 to just over 4 in 1993 and 1994. Individual selections varied widely in average Y:P ratios from a low of 2.7 for FPS 13 to a high of 7.9 for ESP 236. The Y:P ratio was negatively correlated with the average shoot weight (r = −0.83) (Figure 2⇓).
Fruit maturity
Before the beginning of harvest, a berry sample established the relative sugar maturity levels of the 13 treatments. Because of its importance as a harvest criterion for sparkling winegrapes, Brix data are presented for individual years as well as for the 3-year mean. FPS 1 was the first clone to reach the target maturity of 19 Brix in all three years. The lowest Brix values were seen in FPS 31 and 33 and ESP 236. The difference between the earliest and latest ripening selections was 3.9 to 4.4 Brix over the three years (Table 3⇓). Mean Brix of the 13 treatments, on the harvest date of the first clone, showed a strong negative correlation to yield (r = −0.85) (Figure 3⇓).
Titratable acidity values were very high as is typical for grapes intended for sparkling wine use. The range was even greater given that the maturity comparisons were made at the very beginning of the harvest period, not at the final harvest sugar levels. There was no correlation between Brix and TA values (data not shown). As expected, early-ripening selections had lower TA levels, such as FPS 1 (18.9 Brix and 14.2 g/L TA), and later-ripening selections had higher TA levels, such as FPS 33 (15.6 Brix and 16.2 g/L TA). However the pattern did not hold for all treatments; for example, WEN had the lowest mean TA value (13.5 g/L) but the third highest mean Brix value (17.6). Values for pH ranged from 2.89 to 3.15 and were normal for maturity levels.
In 1994, berry samples at harvest permit a one-year examination of the contribution of berry weight and berries per cluster to yield differences (Table 4⇓). Berry weight varied by 20% from lowest to highest, with FPS 13 and WEN having the smallest berries (1.03 g and 1.06 g, respectively) and FPS 23 and 31 having the largest berries (1.29 g and 1.24 g, respectively). Numbers of berries per cluster also played a significant role in yield differences, varying by 55% from a low of 89 for FPS 1 to a high of 150 for FPS 31.
Discussion
Differences among Pinot noir clones and selections were significant, with vegetative growth varying more than two-fold and yield by 1.5-fold (Table 1⇑). Differences were greater than those reported for clones of Chardonnay (Wolpert et al. 1994), Cabernet Sauvignon (Wolpert et al. 1995), and Zinfandel (Wolpert 1996). For some clones, vegetative growth was excessive. Pruning weight of 2.4 to 2.6 kg/vine (1.6 to 1.7 kg/m) for FPS 32 and 13, respectively, exceeded the recommended upper level of 1.0 kg/m (Smart and Robinson 1991). This propensity for strong vegetative growth was exacerbated by low yield, largely because of small clusters. Increasing shoot number to increase yield is not a reasonable strategy because shoot numbers were already high at ~30/vine (20/m). A more appropriate strategy for balancing small-clustered Pinot noir clones would be to reduce vine growth, such as by selecting a less vigorous rootstock. The goal would be to decrease shoot weight from excessive levels, 75 to 89 g for FPS 1, 13, and 32, to moderate levels 50 to 60 g (Figure 3⇑).
Conversely, ESP 236 had the least growth (1.2 kg/vine, 0.8 kg/m) and high yield (9.1 kg/vine), resulting in the highest Y:P ratio at 7.9. While the Y:P ratio is not high enough to cause concern, the resulting shoot weight of 45 g was the lowest of the clones and lower than recommended for adequate performance (Smart and Robinson 1991). One strategy to ensure shoot weight for high-yielding clones would be to reduce shoot number, but that would reduce yield per hectare, unless vine spacing was concomitantly reduced (Intrieri and Filippetti 2000).
As with other varieties in California (Wolpert 1996, Wolpert et al. 1994, 1995), and in Pinot noir in Oregon (Watson et al. 1988), differences in yield among Pinot noir selections were largely due to cluster weight (Table 2⇑). However, more so than for other varieties referenced, yield of Pinot noir was affected by cluster number (Table 2⇑), although it is not clear whether this difference was due to fruitfulness of nodes retained, as a function of clone, or differences in number of blind buds. These differences in crop load were significantly correlated with maturity level as evidenced by Brix values at harvest, for data averaged over three years (Figure 3⇑). This well-known relationship of yield and maturity suggests that clones are not “early ripening” or “late ripening,” as they are referred to in popular literature, but rather low yielding and high yielding.
However, performance of two clones in the Carneros study can be discussed relative to previous research. The German experience with Mariafeld as a clone with large crop and large berries (Becker et al. 1988) is similar to the performance of FPS 23, also known as Mariafeld (Tables 2⇑ and 4⇑). Characterization of ESP 236 as fruitful with a tendency to overcrop (Bernard et al. 1983) was supported in our study, as ESP 236 had the highest Y:P ratio.
Another confounding factor that often calls the comparison of clone performances into question is the inability to determine clone identity via DNA analysis (C. Meredith, personal communication, 1998). Thus, in the absence of a unique phenotypical characteristic that identifies a clone, “trueness to type” is entirely dependent on keeping accurate records during importation and propagation. The performance data of FPS 31 (reported to be Espiguette 236) and the Oregon State University selection of Espiguette 236 (Table 1⇑) would indicate that the two clones significantly differ in pruning weight, shoot weight, yield, Y:P ratio, cluster weight, and, in 1994, berry weight. One could reasonably conclude that they are not the same clone. This example highlights the importance of developing confidence of the clonal source and the fidelity of recordkeeping during propagation.
Conclusion
This study is the first report of performance of sparkling wine clones of French origin (FPS 31, 32, and 33, ESP 236 and 374, and COL 538) in California. Their performance indicates some have potential for high yield and others for excessive vegetative growth. Viticultural performance data should be helpful to viticulturists responsible for making rootstock, spacing, and trellis choices for vineyards intended for sparkling wine production.
Footnotes
↵4 current address: Newton Vineyards, 2555 Madrona Ave., St. Helena, CA 94574.
Acknowledgments: Research funding from the American Vineyard Foundation is gratefully acknowledged.
The cooperation of Michael Crumly and Robert Lantosca of Gloria Ferrer and Freixenet Sonoma Caves and Harry Hansen formerly of Freixenet are acknowledged. Thanks are also extended to Michael Anderson of UC Davis for technical support.
- Received October 2005.
- Revision received April 2006.
- Copyright © 2006 by the American Society for Enology and Viticulture