Do lower yields on the vine always make for better wine?

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1 Grape and wine quality Increasing quality Do lower yields on the vine always make for better wine? Nick Dokoozlian Viticulture, & Enology E&J Gallo ry Do lower yields on the vine always make for better wine? Outline Vineyard metrics -How do we express vineyard yield? Grape and wine quality metrics -How do we express quality? Linking fruit and wine quality using vine balance -Yield -Canopy characteristics Summary Yield vs. Quality Traditional View Increasing yield Yield per acre WAWGG Annual Meeting

2 Grape and wine quality Increasing quality Yield vs. Quality Traditional View Non-certified plant materials Conventional vineyard design and trellis Non-irrigated Increasing yield Yield per acre Integrated Production Management Site Selection Sunlight Temperature Rainfall Wind Topography Soil texture and depth Soil chemistry Management Cultivar Rootstock Plant density Vineyard design Row orientation Training & trellis systems Basal leaf removal Shoot positioning Hedging Crop load management Irrigation Floor management Pre-plant soil preparation Fertility management Anthocyanins (mg/g) Merlot - Lodi r = Yield (tons per acre) WAWGG Annual Meeting

3 Fruit and wine composition Why consider vine balance? Canopy size Fruit yield Canopy size or capacity Fruit yield Accounts for differences in vineyard design, plant density, vine vigor and site capacity Additional leaf area has little impact on fruit composition Leaf area is limiting to fruit quality - cm leaf area per g fruit weight Leaf area (cm ) / fruit weight (g) WAWGG Annual Meeting

4 Y = x r =.9 6 cm leaf area per gram fruit 8 From: Kliewer & Weaver, AJEV : 7-77 (97). WAWGG Annual Meeting

5 Fruit and wine composition Mythbusting /8/ Pruning wt (lbs/vine) 8 6 g or lb pruning weight = m leaf area r = Total leaf area per vine (m ) Vegetative growth adequate for optimum quality to kg fruit per kg pruning weight Leaf area limiting to fruit quality Yield:Pruning Weight Ratio.6 Anthocyanins (mg/g) R =.699 Merlot Lodi R r = Yield: Pruning weight WAWGG Annual Meeting

6 Fruit and wine composition Vegetative growth adequate for optimum quality to kg fruit per kg pruning weight Leaf area limiting to fruit quality This relationship is consistent for sugar and color, but is this true for other grape Yield:Pruning and wine Weight compositional Ratio parameters? Soluble solids (Brix) Balance - cropped vines Yield = 7 tons per acre Yield pruning weigh ratio = 8 Under-cropped vines Yield = tons per acre Yield pruning weigh ratio = September October November Time Over - cropped vines Yield = tons per hectare Yield pruning weigh ratio = 6 -damascenone Odor Activity Value Balanced Cropped = 8: Under Cropped = : Over Cropped = : 6 8 Soluble solids (Brix) WAWGG Annual Meeting 6

7 -damascenone Odor Activity Value Sugar accumulation rate ( o Brix) Ratio of dark fruit to green aromas 6 Balanced-cropped 8: TT Threshold Over-cropped : 6 8 Soluble solids (Brix) Under-cropped : Uncoupled ripening Summary Uncoupling of sugar and impact aroma compounds in grapes What does this mean to the interpretation of earlier crop load experiments? Harvesting all the treatments on the same day is misleading Harvesting all treatments at the same Brix is also misleading How does ripening rate affect berry aroma at maturity? How important is sugar accumulation rate to: Fruit aroma, color accumulation? High LA:FW (Under cropped) Low LA:FA (Over cropped) Green aroma degradation? C partitioning in berry? Veraison Harvest ripening (time) WAWGG Annual Meeting 7

8 Fruit and wine composition Quality Optimum crop Undercropped Overcropped 6 8 Soluble solids (%) Vine balance and ripening rate Vine yield Pruning weight < 8 > Expected ripening rate Too little crop = rapid Balanced = optimum Too much crop = slow Vegetative growth adequate for optimum quality to kg fruit per kg pruning weight Leaf area limiting to fruit quality Is this relationship consistent among grape and wine quality parameters? How does this relationship change among cultivars? How do Pruning canopy characteristics Weight:Yield influence Ratio this relationship? WAWGG Annual Meeting 8

9 Variety Materials and Methods Relative sensitivity to crop load Mean Leaf area per vine (m ) Exterior leaves (%) Pinot noir High. Zinfandel High to Moderate 6. Cabernet Sauvignon Moderate 7. Chardonnay Moderate to Low 8.6 Materials and Methods Trials conducted in Sonoma County Mature vines planted on P rootstock FPS Clone 8 Cabernet Sauv FPS Clone 6 Zinfandel FPS Clone Pinot noir FPS Clone Chardonnay Bilateral cordon trained, spur pruned, VSP trellis Randomized complete block; large plots for destructive cluster sampling as needed Yield:Pruning Weight ratio manipulated following fruit set by thinning whole clusters and portions of clusters. Pruning performed at dormancy. Grape to Quality Metrics Positive Aromas -damasecenone -ionone Benzyl alcohol Phenethyl alcohol Linalool Eucalyptol Mouthfeel Negative Aromas Methoxypyrazine C6 compounds Hexenal Hexenol Hexadienal Color Polymeric tannins Quercetin glycosides Hydroxycinnamates Total anthocyanins Hunter color WAWGG Annual Meeting 9

10 Aroma chemistry Mouthfeel chemistry Odor and Mouthfeel Activity Values (OAV and MAV) Odor (or Mouthfeel) Activity Value Example: Odor (or Mouthfeel) Activity Value = = Measured concentration Concentration threshold ppt in grapes ppt threshold = Combine values for multiple quality traits in each bucket Grape to Aroma Dark fruit aroma chemistry (Combined odor activity values) Aroma intensity via sensory (-) Grape to Mouthfeel Mouthfeel activity (Combined mouthfeel activity values) Mouthfeel intensity via sensory (-) WAWGG Annual Meeting

11 Aroma chemistry Zinfandel Grape to Aroma Aroma chemistry (Combined mouthfeel activity values) 6 Zinfandel Aroma intensity via sensory (-) Zinfandel Grape to Mouthfeel Mouthfeel chemistry (Combined mouthfeel activity values) Zinfandel Mouthfeel intensity via sensory (-) Pinot noir Grape to Aroma Red fruit aroma compounds (Combined odor activity values) Pinot noir Aroma intensity via sensory (-) WAWGG Annual Meeting

12 Mouthfeel chemistry (Combined mouthfeel activity values) Aroma chemistry Mouthfeel Aroma chemistry (Combined mouthfeel activity values) Mouthfeel intensity via sensory (-) Mouthfeel activity values Pinot noir Grape to Mouthfeel Pinot noir Mouthfeel intensity via sensory (-) Chardonnay Grape to Aroma Red fruit aroma compounds (Combined odor activity values) Pinot noir Chardonnay Aroma intensity via sensory (-) Chardonnay Grape to Mouthfeel Red fruit aroma compounds (Combined odor activity values) Pinot noir Chardonnay Aroma intensity via sensory (-) WAWGG Annual Meeting

13 Harvest Brix to reach chemistry thresholds Soluble solids required to reach threshold aroma or mouthfeel chemistry values for harvest ( o Brix) 8 6 ~ week delay in harvest date Aroma Mouthfeel > failed to reach minimum mouthfeel chemistry > failed to reach minimum aroma chemistry 6 8 Yield:Pruning Weight Thresholds Variety Aroma Mouthfeel Comments Pinot noir > > Zinfandel >7 > Aroma and mouthfeel are very sensitive Mouthfeel most sensitive Cabernet Sauvignon < >7 >7 Mouthfeel most sensitive Chardonnay > > Aroma and mouthfeel relatively insensitive Vineyard performance metrics Metrics Fruit yield Pruning weight Exposed leaf area Total leaf area Exposed clusters Total clusters Measures Production efficiency Canopy efficiency Fruit microclimate WAWGG Annual Meeting

14 Total Soluble Solids ( o Brix) Leaf Area / Crop Weight Ratio (m /kg) From Kliewer and Dokoozlian - CHENIN BLANC TRELLIS TRIAL, DAVIS, CA Vertical GDC Lyre % Exposed LA 7% Exposed LA % Exposed LA 6% Exposed LA WAWGG Annual Meeting

15 Mouthfeel chemistry Variety Leaf area reduction compared to the control Light in fruit zone at mid-day (Ambient %) Exterior leaves (%) Control -.6 a a Lateral shoot thin Ver = % Harv = 7%. a 8 b Aroma chemistry (Combined mouthfeel activity values) 6 Control Zinfandel Laterals removed Aroma intensity via sensory (-) Mouthfeel activity (Combined mouthfeel activity values) Control Laterals removed Mouthfeel intensity via sensory (-) WAWGG Annual Meeting

16 Improved grape quality measures and metrics are critical to advance our understanding of crop load varieties and quality attributes vary significantly in their response to crop load The portion of total leaf area exposed to sunlight also plays a major role in vine response to crop load Systems biology is needed to help us better understand carbon partitioning in the berry Real-time measures of crop load are needed 7 WAWGG Annual Meeting 6