terclim by ICS banner
IVES 9 IVES Conference Series 9 Updating the Winkler index: An analysis of Cabernet sauvignon in Napa Valley’s varied and changing climate

Updating the Winkler index: An analysis of Cabernet sauvignon in Napa Valley’s varied and changing climate

Abstract

This study aims to create an updated, agile viticultural climate index (similar to the Winkler Index) by performing in-depth analyses of current and historical data from industry partners in several major winegrowing regions. The Winkler Index was developed in the early twentieth century based on analysis of various grape-growing regions in California. The index uses heat accumulation (i.e. Growing Degree Days) throughout the growing season to determine which grape varieties are best suited to each region. As viticultural regions are increasingly subject to the complexity and uncertainty of a changing climate, a more rigorous, agile model is needed to aid grape growers in determining which cultivars to plant where. For the first phase of this study, 21 industry partners throughout Napa Valley shared historical phenology, harvest, viticultural practice, and weather data related to their Cabernet sauvignon vineyard blocks. To complement this data, berry samples were collected throughout the 2021 growing season from 50 vineyard blocks located throughout 16 American Viticultural Areas that were then analyzed for basic berry chemistry and phenolics. These blocks have been mapped using a Geographic Information System (GIS), enabling analysis of altitude, vineyard row orientation, slope, and remotely sensed climate data. Sampling sites were also chosen based on their proximity to a weather station. By analyzing historical data from industry partners and data specifically collected for this study, it is possible to identify key parameters for further analysis. Initial results indicate extreme variability at a high spatial resolution not currently accounted for in modern viticultural climate indices and suggest that viticultural practices play a major role. Using the structure of data collection and analyses developed for the first phase, this project will soon be expanded to other wine regions globally, while continuing data collection in Napa Valley.

DOI:

Publication date: May 31, 2022

Issue: Terclim 2022

Type: Poster

Authors

Paige Breen, James Campbell, Kayla Elmendorf, Seth Frey and Elisabeth Forrestel 

Department of Viticulture and Enology, University of California, Davis, USA

Contact the author

Keywords

climate index, climate science, Growing Degree Days, Napa Valley, viticulture

Tags

IVES Conference Series | Terclim 2022

Citation

Related articles…

Understanding wine as a sensory, emotional, and cognitive experience to promote and communicate conscious consumption

In the complex scenario that the wine industry and its promotion are currently facing, this research proposes a theoretical expansion of the traditional model used to understand the wine experience, namely the classic sensory, emotional and cognitive triad, moving toward a multidimensional approach that also incorporates cultural, symbolic and contextual dimensions in order to comprehend the conscious experience.

Read More

Microwave-assisted maceration and stems addition in Bonarda grapes: effects on wine chemical composition and sensory properties over two vintages

AIM: Bonarda, the second red grape variety in Argentina, produces high yields per hectare generating, in several cases, wines with low levels of quality compounds.

Read More

OPTIMIZATION, VALIDATION AND APPLICATION OF THE EPR SPIN-TRAPPING TECHNIQUE TO THE DETECTION OF FREE RADICALS IN CHARDONNAY WINES

The aging potential of Burgundy chardonnay wines is considered as quality indicator. However, some of them exhibit higher oxidative sensitivity and premature oxidative aging symptoms, which are potentially induced by no-enzymatic oxidation such as Fenton-type reaction (Danilewicz, 2003). This chemical mechanism involves the action of transition metal, native phenolic compounds and oxygen which promote the generation of highly reactive oxygen species (ROS) such as hydroxyl radicals (OH) or 1-hydroxyethyl radicals (1-HER) from oxidation of ethanol. Such mechanism is involved in the radical oxidation occurring during bottle aging. According to Elias et al.,(2009a), the 1-HER is the most abundant radical in forced oxidation treated wines. Consequently, understanding its evolution kinetic in dry white wines is of great importance.

Read More

Transcriptomic and metabolomic responses to wounding and grafting in grapevine

Grafting plants uses intrinsic healing processes to join two different plants together to create one functional organism. To further our understanding of the molecular changes occurring during graft union formation in grapevine, we characterized the metabolome and transcriptome of intact and wounded cuttings (with and without buds to represent scions and rootstocks respectively), and homo- and heterografts at 0 and 14 days after wounding/grafting. As over-wintering, dormant plant material was grafted, we also characterized the gene expression changes in the wood during bud burst and spring activation of growth. We observed an asymmetrical pattern of gene expression between above and below the graft interface, auxin and sugar related genes were up-regulated above the graft interface, while genes involved in stress responses were up-regulated below the graft interface.

Read More

Development of spectral indices to monitoring non-destructive of ripeness for water stressed grapevine (Vitis vinifera L.) using contour map optimization

Accurate and non-destructive monitoring of grape ripening is essential for optimising harvest decisions, particularly under water stress conditions.

Read More