Observation and modeling of climate at fine scales in wine-producing areas

The increasing interest in enhancing groundbreaking sensory profile of wines determined the need to select novel strains of lactic acid bacteria (LAB). Metabolic processes characterizing malolactic fermentation (MLF) lead to the production of several organic compounds that significantly impact the oenological and sensory characteristics of wines.

Typically, subjective, and visual methods are used by grape growers to assess harvest maturity. These methods may not accurately represent the maturity of an entire vineyard – especially if extensive and representative sampling was not used. New technologies have been investigated for improved harvest management decisions. Spectroscopy methods utilizing the near-infrared region of the light spectrum is one such technology investigated as an alternative to classic methods and particularly the application of hyperspectral imaging (HSI) has recently gained attention in research. HIS is a spectroscopic technique that obtains hundreds of images at different wavelengths collecting spectral data for each pixel in the sample i.e., providing both spectral and spatial data.

Modern agriculture employs large amounts of plastics, such as mulching and greenhouse films, thermal covers, plant protection tubes and tying tape. The latter two types are very common in viticulture. Guard tubes are employed to protect young vines from mechanic and atmospheric damage, whilst polymeric tying tape has replaced natural-origin materials to hold the canopy of vines. Both materials are made on synthetic polymers, which include a range of additives to improve their environmental stability remaining in the environment of vineyards for years. During this time, they are exposed to the range of pesticides (fungicides, insecticides and in a lesser extend herbicides) applied to vines.

Stomatal traits determine grapevine water use, carbon supply, and water stress, which directly impact yield and berry chemistry. Breeding for stomatal traits has the strong potential to improve grapevine performance under future, drier conditions, but the trait values that breeders should target are unknown. We used a functional-structural plant model developed for grapevine (HydroShoot) to determine how stomatal traits impact canopy gas exchange, water potential, and temperature under historical and future conditions in high-quality and hot-climate California wine regions (Napa and the Central Valley). Historical climate (1990-2010) was collected from weather stations and future climate (2079-99) was projected from 4 representative climate models for California, assuming medium- and high-emissions (RCP 4.5 and 8.5). Five trait parameterizations, representing mean and extreme values for the maximum stomatal conductance (gmax) and leaf water potential threshold for stomatal closure (Ψsc), were defined from meta-analyses. Compared to mean trait values, the water-spending extremes (highest gmax or most negative Ysc) had negligible benefits for carbon gain and canopy cooling, but exacerbated vine water use and stress, for both sites and climate scenarios. These traits increased cumulative transpiration by 8 – 17%, changed cumulative carbon gain by -4 – 3%, and reduced minimum water potentials by 10 – 18%. Conversely, the water-saving extremes (lowest gmax or least negative Ψsc) strongly reduced water use and stress, but potentially compromised the carbon supply for ripening. Under RCP 8.5 conditions, these traits reduced transpiration by 22 – 35% and carbon gain by 9 – 16% and increased minimum water potentials by 20 – 28%, compared to mean values. Overall, selecting for more water-saving stomatal traits could improve water-use efficiency and avoid the detrimental effects of highly negative canopy water potentials on yield and quality, but more work is needed to evaluate whether these benefits outweigh the consequences of minor declines in carbon gain for fruit production.

The Southern Oregon American Viticultural Area (AVA) consists of the Applegate Valley, Rogue Valley, Umpqua Valley, Elkton Oregon, and Red Hills of Douglas County sub-AVAs (Figure 1) that are some of the many winegrape producing regions found within the intermountain valleys along the west coast of the United States.