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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Research Unit » Research » Publications at this Location » Publication #344716
Title: Vineyard floor management and cluster thinning inconsistently affect ‘Pinot noir’ crop load, berry composition, and wine quality

Author
item REEVE, ALISON - Oregon State University
item SKINKIS, PATRICIA - Oregon State University
item VANCE, AMANDA - Oregon State University
item MCLAUGHLIN, KATHERINE - Oregon State University
item TOMASINO, ELIZABETH - Oregon State University
item Lee, Jungmin
item TARARA, JULIE - Ste Michelle Estates

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2017
Publication Date: 3/21/2018
Citation: Reeve, A.L., Skinkis, P.A., Vance, A.J., McLaughlin, K.R., Tomasino, E., Lee, J., Tarara, J.M. 2018. Vineyard floor management and cluster thinning inconsistently affect ‘Pinot noir’ crop load, berry composition, and wine quality. HortScience. 53(3):318-328. https://doi.org/10.21273/HORTSCI12682-17.
DOI: https://doi.org/10.21273/HORTSCI12682-17

Interpretive Summary: Top quality Oregon ‘Pinot noir’ winegrape vineyards commonly reduce yield by cluster thinning; the objective being increased fruit quality by reducing the burden upon the vines. A 3-year field study was conducted to determine relationships between crop load metrics and berry composition for ‘Pinot noir’ through the manipulation of vegetative growth (vine vigor) and fruit yield using competitive cover cropping and cluster thinning. Vine vigor was altered by perennial red fescue grown in both (Grass), one (Alternate), or none (Tilled) of the alleyways flanking the vine row. Cluster thinning was performed on half of the vines in each vineyard floor treatment, retaining one cluster per shoot (Half Crop), while the other vines had no clusters removed (Full Crop). The use of floor management treatments altered both canopy size and yield, due to altered nitrogen (N) status. However, crop load was considered to be altered when the yield/pruning weight ratio (Y:PW), rather than leaf area/yield ratio (LA:Y) was used. Sugar levels reached a maximum at similar LA:Y after two years, but achieving this canopy to yield ratio did not always result in desirable sugar levels. Yield had the greatest influence on pH and total anthocyanin concentration, during the coldest and highest yielding year. Wine sensory evaluation revealed no differences in quality for 2011 or 2012 produced wines. However, sensory panelists ranked 2013 wines from the Alternate-Half and -Full Crop treatments as high quality, and they rated wines from the Tilled-Half and -Full Crop treatments as low quality. Using crop load metrics to achieve acceptable sugar levels were unreliable in this study, although the relationships between other berry components and crop load could be explained by tissue N, photosynthetic photon flux, or yield. Cluster thinning to adjust yields may not alter source/sink relationships or crop load enough to overcome ripening limitations of cool climates, which may limit the benefit to subjective wine qualities.

Technical Abstract: A 3-year field study was developed to determine relationships between crop load metrics and berry composition for ‘Pinot noir’ in a cool-climate through the manipulation of vegetative growth and fruit yield using competitive cover cropping and cluster thinning, respectively. To alter vine vigor, perennial red fescue (Festuca rubra L.) was grown in both (Grass), one (Alternate), or none (Tilled) of the alleyways flanking the vine row while the remaining alleyways were cultivated. Cluster thinning was performed on half of the vines in each vineyard floor treatment, retaining one cluster per shoot (Half Crop), while the other vines had no clusters removed (Full Crop). The use of floor management treatments altered both canopy size and yield, due to altered nitrogen (N) status. However, crop load was considered to be altered when the yield:pruning weight ratio (Y:PW), rather than leaf area to yield ratio (LA:Y) was used. TSS reached a maximum at similar LA:Y in two years, but achieving this canopy to yield ratio did not always result in desirable TSS. Yield had the greatest influence on pH and total anthocyanin in the highest yielding, coolest year. Sensory evaluation revealed no differences in wine quality for wines produced in 2011 or 2012. However, 2013 wines made from both Alternate-Half and -Full Crop treatments were ranked as high quality and wines from both Tilled-Half and -Full Crop treatments were ranked low quality by consumers and winemaker panelists. Using crop load metrics to achieve acceptable TSS was unreliable in the varied seasons experienced in this study and the relationships between other berry components and crop load could be explained by tissue N, photosynthetic photon flux, and/or yield. Cluster thinning to adjust yields may not alter source:sink relationships or crop load enough to overcome ripening limitations of cool climates and may have limited impact on wine sensory.