Relationship between viticultural climatic indices and grape maturity in Australia

Impact of climate change on grape berry ripening: An assessment of adaptation strategies for the Australian vineyard

Compressed vintages, high alcohol and low wine acidity are but a few repercussions of climate change effects on Australian viticulture. While warm and cool growing regions may have different practical concerns related to climate change, they both experience altered berry and must composition and potentially reduced desirable wine characteristics and market value. Storms, drought and uncertain water supplies combined with excessive heat not only depress vine productivity through altered physiology but can have direct consequences on the fruit. Sunburn, shrivelling and altered sugar-flavour-aroma balance are becoming more prevalent while bushfires can result in smoke taint. Moreover, distorted pest and disease cycles and changes in pathogen geographical distribution have altered biotic stress dynamics that require novel management strategies. A multipronged approach to address these challenges may include alternative cultivars and rootstocks or changing geographic location. In addition, modifying and incorporating novel irrigation regimes, vine architecture and canopy manipulation, vineyard floor management, soil amendments and foliar products such as antitranspirants and other film-forming barriers are potential levers that can be used to manage the effects of climate change. The adoption of technology into the vineyard including weather, plant and soil sensors are giving viticulturists extra tools to make quick decisions, while satellite and airborne remote sensing allow the adoption of precision farming. A coherent and comprehensive approach to climate risk management, with consideration of the environment, ensures that optimum production and exceptional fruit quality is maintained. We review the preliminary findings and feasibility of these new strategies in the Australian context.

GABA shunt contribution to flavonoid biosynthesis and metabolism in tea plants (Camellia sinensis)

γ-Aminobutyric acid (GABA), a signal molecule, is regarded as the intersection node of carbon and nitrogen metabolism, and its contributions to flavonoid metabolism in tea plant growth and development remain unclear. The correlation between the GABA shunt and flavonoid metabolism in tea plants is worth to explore. Secondary metabolites and their correlations with the taste of tea soup made from tea plants (Camellia sinensis) during different seasons were investigated. Related secondary metabolites and transcript profiles of genes encoding enzymes in the GABA shunt, flavonoid pathway and polyamine biosynthesis were measured throughout the tea plant growth seasons and after exogenous GABA applications. In addition, the abundance of differentially expressed proteins was quantified after treatments with or without exogenous GABA. The tea leaves showed the highest metabolite concentrations in spring season. CsGAD, CsGABAT, CsSPMS, CsODC, CsF3H and CsCHS were found to be important genes in the GABA and anthocyanin biosynthesis pathways. GABA and anthocyanin concentrations showed a positive correlation, to some extent, CsF3H and CsCHS played important roles in the GABA and anthocyanin biosynthesis.

Accuracy of Interpolated Versus In-Vineyard Sensor Climate Data for Heat Accumulation Modelling of Phenology

BACKGROUND AND AIMS

In response to global heating, accurate climate data are required to calculate climatic indices for long-term decisions about vineyard management, vineyard site selection, varieties planted and to predict phenological development. The availability of spatially interpolated climate data has the potential to make viticultural climate analyses possible at specific sites without the expense and uncertainty of collecting climate data within vineyards. The aim of this study was to compare the accuracy and precision of climatic indices calculated using an on-site climate sensor and an interpolated climate dataset to assess whether the effect of spatial variability in climate at this fine spatial scale significantly affects phonological modelling outcomes.

METHODS AND RESULTS

Four sites comprising two topographically homogenous vineyards and two topographically diverse vineyards in three wine regions in Victoria (Australia) were studied across four growing seasons. A freely available database of interpolated Australian climate data based on government climate station records (Scientific Information for Land Owners, SILO) provided temperature data for grid cells containing the sites (resolution 0.05° latitude by 0.05° longitude, approximately 5 km × 5 km). In-vineyard data loggers collected temperature data for the same time period. The results indicated that the only significant difference between the two climate data sources was the minimum temperatures in the topographically varied vineyards where night-time thermal layering is likely to occur.

CONCLUSION

The interpolated climate data closely matched the in-vineyard recorded maximum temperatures in all cases and minimum temperatures for the topographically homogeneous vineyards. However, minimum temperatures were not as accurately predicted by the interpolated data for the topographically complex sites. Therefore, this specific interpolated dataset was a reasonable substitute for in-vineyard collected data only for vineyard sites that are unlikely to experience night-time thermal layering.

SIGNIFICANCE OF THE STUDY

Access to accurate climate data from a free interpolation service, such as SILO provides a valuable tool tomanage blocks or sections within vineyards more precisely for vineyards that do not have a weather station on site. Care, nevertheless, is required to account for minimum temperature discrepancies in topographically varied vineyards, due to the potential for cool air pooling at night, that may not be reflected in interpolated climate data.

Microcliamte changes caused by black inter-row mulch decrease flavonoids concentrations in grapes and wines under semi-arid climate

In this study, black geotextile inter-row mulch, a weed control practice, was applied under a semi-arid climate to attenuate solar reflection in 2015-2017, and it concurrently increased soil temperature and fruit-zone high temperature duration and decreased low temperature duration. Inter-row mulch decreased anthocyanins concentrations in grapes in 2015-2016, and consistently inhibited flavonols accumulation in 2015-2017. Correlation analysis between microclimate parameters and flavonoids concentrations reflected the importance of solar reflection, fruit-zone high and low temperature duration, heat accumulation and soil temperature to flavonoids accumulation. Basal leaf removal, a widely applied practice to increase fruit-zone light exposure, was applied to mulch-treated grapevines to investigate if increasing incident light could mitigate the impact of inter-row mulch on flavonoids, and it had limited influence on anthocyanins whereas compensated the loss of flavonols in grapes caused by inter-row mulch. Notably, inter-row mulch wines showed less red and more yellow color than controls because of lower anthocyanins concentrations.

Climate Vulnerability and Adaptation Challenges in Szekszárd Wine Region, Hungary

Wine producers face several challenges regarding climate change, which will affect this industry both in the present and the future. Vulnerability assessments are at the forefront of current climate research, therefore, the present paper has two main aims. First, to assess two components of climate vulnerability regarding the Szekszárd wine region, Hungary; second, to collect and analyze adaptation farming techniques in terms of environmental sustainability aspects. Exposure analyses revealed that the study area will face several challenges regarding intensive drought periods in the future. Sensitivity indicators show the climate-related characteristics of the most popular grapevines and their relatively high level of susceptibility regarding changing climatic patterns. Since both external and intrinsic factors of vulnerability show deteriorating trends, the development of adaptation actions is needed. Adaptation interventions often provide unsustainable solutions or entail maladaptation issues, therefore, an environmental-focused sustainability assessment of collected interventions was performed to avoid long-term negative path dependencies. The applied evaluation methodology pointed out that nature-based adaptation actions are preferred in comparison to using additional machines or resource-intensive solutions. This study can fill the scientific gap by analyzing this wine region for the first time, via performing an ex-ante lock-in analysis of available and widely used adaptation interventions in the viticulture sector.

Spatial distribution of Crimean agroecological resources as a factor of variability of the main and secondary metabolites of grapes

The work is aimed at identifying the relationship between agroecological conditions and the formation of carbohydrate-acid and phenolic grape complexes. The agro-climatic parameters of 14 cv. ‘Cabernet Sauvignon’ industrial vineyards located in five wine-growing regions of Crimea have been determined using the methods of geoinformation and mathematical modeling. According to the similarity of 9 agro-climatic characteristics, the vineyards are united into 6 clusters, significantly different from each other. The dispersion of the main and secondary metabolites of grapes, as well as technological indicators based on them in the harvest from the selected clusters, has been established. According to the combined mass concentration of anthocyanins in berries, potential amount of extractable anthocyanins, anthocyanin extractability, monophenolmonooxygenase activity, glucoacidimetric index and grape ripeness index the selected vineyard clusters are discriminated with Wilks L. = 0.09 at α<0.00001. Sugar content, active acidity index, glucoacidimetric index, and grape ripeness index were found to correlate inversely with the amount of precipitation during the growing season; anthocyanin extractability correlates directly with the Huglin and Winkler indices; monophenolmonooxygenase activity with the sum of active temperatures above 10 °C, Huglin index, total precipitation per year and growing season.

Dataset of concentrations of free terpenes at different phenological stages in Vitis vinifera L. Shiraz, Cabernet Sauvignon, Riesling, Chardonnay and Pinot Gris

Five Vitis vinifera L. cultivars Shiraz, Cabernet Sauvignon, Riesling, Chardonnay and Pinot Gris at different E-L development stages were harvested in two experimental vintages. Temperature and rainfall data of the growing period were obtained from the Australian Government Bureau of Meteorology. Free terpene concentrations of all harvested grape samples were analysed using HS-SPME-GC-MS. One-way ANNOVA was performed to evaluate the significance of changes in terpene concentrations at different maturation stages. More analysis of the data is provided in “Free terpene evolution during the berry maturation of five Vitis vinifera L. cultivars” [1].