To sustainably adapt viticultural production to drought, the planting of rootstock genotypes adapted to a changing climate is a promising means. Rootstocks contribute to the regulation of scion vigor and water consumption, modulate scion phenological development and determine resource availability by root system architecture development. There is, however, a lack of knowledge on spatio-temporal root system development of rootstock genotypes and its interactions with environment and management that prevents efficient knowledge transfer into practice. Hence, winegrowers take only limited advantage of the large variability of existing rootstock genotypes. Models of vineyard water balance combined with root architectural models, using both static and dynamic representations of the root system, seem promising tools to match rootstock genotypes to frequently occurring future drought stress scenarios and address scientific knowledge gaps. In this perspective, we discuss how current developments in vineyard water balance modeling may provide the background for a better understanding of the interplay of rootstock genotypes, environment and management. We argue that root architecture traits are key drivers of this interplay, but our knowledge on rootstock architectures in the field remains limited both qualitatively and quantitatively. We propose phenotyping methods to help close current knowledge gaps and discuss approaches to integrate phenotyping data into different models to advance our understanding of rootstock x environment x management interactions and predict rootstock genotype performance in a changing climate. This could also provide a valuable basis for optimizing breeding efforts to develop new grapevine rootstock cultivars with optimal trait configurations for future growing conditions.

Interest in sustainability has increased significantly in the wine sector in the past few years, driven by customer interest, as well as the impact of global warming-intensified weather extremes on wine growers. For a sustainable future the wine industry must design its entire value chain in such ways that it conserves and regenerates the natural environment and at the same time promotes human rights, inclusion and equality. The current paper identified five key challenges which have to be overcome in order to reach this goal: (1) climate change impact and adaptation strategies, (2) the reduction of GHG emissions and creation of carbon sinks, (3) vineyard inputs, (4) packaging and (5) social and economic sustainability. For each of these five challenges research gaps and possible solutions are presented which enable a holistic improvement of the sustainability of the whole wine value chain from the vineyard to the consumers. Examples for this are strategies to reduce the use of pesticides in the vineyard as well as carbon insetting options in the vineyard. Additionally, it is of utmost importance that every educational institution integrates facts and vision into their teaching programs in a holistic manner. Together, these approaches form the basis for a realistic sustainability vision for the global wine industry.

Abstract. Extended periods without precipitation observed for example in Central Europe including Germany during the seasons from 2018 to 2020, can lead to water deficit and yield and quality losses for grape and wine production. However, irrigation infrastructure is largely non–existent. Regional climate models project changes of precipitation amounts and patterns, indicating an increase in frequency of occurrence of comparable situations in the future. In order to assess possible impacts of climate change on the water budget of grapevines, a water balance model was developed, which accounts for the large heterogeneity of vineyards with respect to their soil water storage capacity, evapotranspiration as a function of slope and aspect, and viticultural management practices. The model was fed with data from soil maps (soil type and plant available water capacity), a digital elevation model, the European Union (EU) vineyard–register, observed weather data and future weather data provided by regional climate models and a stochastic weather generator. This allowed conducting a risk assessment of the drought stress occurrence for the wine–producing regions Rheingau and Hessische Bergstraße in Germany on the scale of individual vineyard plots. The simulations showed that the risk for drought stress varies substantially between vineyard sites but might increase for steep–slope regions in the future. Possible adaptation measures depend highly on local conditions and to make targeted use of the resource water, an intense interplay of different wine-industry stakeholders, research, knowledge transfer, and local authorities will be required.

The evaluation of the current and future impact of climate change on viticulture requires an integrated view on a complex interacting system within the soil-plant-atmospheric continuum under continuous change. Aside of the globally observed increase in temperature in almost all viticulture regions for at least four decades, we observe several clear trends at the regional level in the ratio of precipitation to potential evapotranspiration. Additionally the recently published 6th assessment report of the IPCC (The physical science basis) shows case-dependent further expected shifts in climate patterns which will have substantial impacts on the way we will conduct viticulture in the decades to come.Looking beyond climate developments, we observe rising temperatures in the upper soil layers which will have an impact on the distribution of microbial populations, the decay rate of organic matter or the storage capacity for soil organic carbon (SOC). All this influences the emission of greenhouse gases (GHGs) and the viscosity of water in the soil-plant pathway, altering the transport of water. Interactions between micro-organisms in the rhizosphere, the grapevine root system, degradation and fixation processes of SOC are complex and poorly understood but respond to environmental factors (such as increased soil temperatures), the plant material (rootstock for instance), and the cultivation system (for example bio-organic versus conventional, cover crop use versus open tillage). Increasing SOC stocks is discussed as a measure to reduce soil GHG emissions with the potential to improve the balance between GHG emissions and carbon removal from the atmosphere. Yet it is difficult to deduct the impact of climatic changes and cultivation practices on patterns of carbon storage or losses from soils. This paper presents a first attempt to quantify these potential impacts on SOC for a vineyard location using the RothC-model (Coleman and Jenkinson, 2005) in combination with the Geisenheim long-term (> 100-year) soil temperature record and climate predictions by the STAR II-model of the Potsdam Institute of Climate Impact using a medium realization run (Orlowsky et al., 2008).It is shown that retaining pruning wood and using a full cover crop yielded a SOC increase of 16.2 t C ha-1 over time. However, CO2 emissions over the simulated time span were only slightly less than C-storage in the soil. It is concluded that cover crops in vineyards helps to achieve CO2-neutrality but additional measures are required to make vineyards a significant C-sink.

Viticulture is exposed and vulnerable to extreme weather and climate change. In Europe, owing to the high socio-economic value of the winemaking sector, the development of adaptation strategies to mitigate climate change impacts will be of foremost relevance for its future sustainability and competitiveness. Some guidelines on feasible short-term adaptation strategies are provided here (Figure 1), collected by the Clim4Vitis action (https://clim4vitis.eu/). Long-term adapation startegies are described in an accompanying technical review.

The image-forming methods copper chloride crystallization, capillary dynamolysis and circular chromatography are presented as an instrument for assessing wine quality. Wine quality of samples from a long-term field trial comparing integrated, organic and biodynamic management were investigated by using image-forming methods and sensory analysis. Concerning the image-forming methods copper chloride crystallization, capillary dynamolysis and circular chromatography, the images of encoded samples were (i) grouped into pairs with similar image features; (ii) characterized based on reference images (e. g. high–low resistance to degradation); (iii) ranked (according to the characterization), and (iv) assigned to the different production methods (classified). Wine samples from organic and biodynamic management needed less wine per sample for a similar expression of structural characteristics than wine samples from integrated cultivation. Organic and biodynamic samples also show structures that indicate less degeneration than integrated samples. Due to these properties, nine coded wine samples from 2010 could be (i) grouped, (ii) characterized, (iii) ranked and (iv) classified without errors, i.e., assigned to the cultivation methods of integrated, organic and biodynamic agriculture. In sensory analysis, the wine derived from biodynamic management had the highest aroma intensity. In the other parameters the differences were not significant. Analysis with the image-forming methods copper chloride crystallization, capillary dynamolysis and circular chromatography complements sensory analysis for a more complete description of the characteristic properties of wines originating from different management systems. If further studies confirm these results, the image-forming methods copper chloride crystallization, capillary dynamolysis and circular chromatography may be developed as a complementary tool to sensory and chemical analysis in assessing wine quality.

Climate change is a major challenge to viticulture worldwide. The adaptation potential of the different strategies to cope with climate change still embraces many uncertainties (e.g., unpredictable social-economic developments and land-use changes), particularly in the long-term. However, adaptation strategies adjusted to local terroirs and regional climate change projections will contribute to the sustainable development of the winemaking sector. The Clim4Vitis action (https://clim4vitis.eu/) recommends some guidelines for long-term adaptation (Figure 1).

Aim: The image forming methods biocrystallisation, capillary dynamolysis and circular chromatography are introduced as a complementary tool for grape quality assessment. These methods were used to investigate grape juice samples from a long-term field trial comparing integrated, organic and biodynamic viticultural practices.Methods and results: Characteristic changes in structures created by the reaction of metal salts with grape juice were evaluated using biocrystallisation, circular chromatography and capillary dynamolysis image forming methods. In particular, this study tested the effects of cultivation method, aging time and juice concentration on structure formation.To assess grape quality, the images of the encoded grape juice samples were: i) grouped into pairs with similar image features, ii) characterised based on reference images (e.g., high versus low resistance to degradation, or the amount of substance necessary for structure formation), iii) ranked according to structures associated with grape quality, and iv) assigned to the different production methods (classification). In order for similar structural features in the image forming methods to be expressed, all samples of grape juice harvested from integrated production over four years required higher juice concentrations than samples from organic and biodynamic origin. This was interpreted as the latter two production systems having higher structure formation efficacy. Furthermore, juices produced from the integrated management system exhibited more structures, indicative of a lower resistance to aging. In three out of four harvest years, the biodynamic samples exhibited the highest structure forming efficacy and resistance to aging.Conclusion: These findings are consistent with enhanced form maintenance and thus higher internal product quality of biodynamic and organic grapes compared to grapes from integrated farming.Significance and impact of the study: Image forming methods may serve as a valuable tool for grape juice and wine quality assessment to complement compound-specific chemical analyses.

Increasing temperatures due to climate change are leading to advances in grapevine phenology and sugar accumulation in grape berries. This study aims to (i) determine if a temperature-based model can predict the time to target sugar concentrations from 170 to 220 g/L for Vitis vinifera L., (ii) use the best model to characterise the time to the specified target sugar concentrations for a wide range of cultivars with statistical evaluation of each cultivar's parameterisation, and (iii) establish cultivar classifications based on these thermal times to the specified target sugar concentrations. The Day of the Year (DOY) to reach the specified target sugar concentrations (170, 180, 190, 200, 210 and 220 g/L) was determined from time series of sugar concentrations collected from research institutes, extension services and private companies. Models were fitted for the species Vitis vinifera L. The two best-fit models for the DOY to reach the target sugar concentrations were selected using the Akaike Criterion (AIC) (evaluates model complexity and goodness of fit within one criterion) and assessed for model efficiency (EF) and error of prediction (RMSE, root means squared error) followed by a sensitivity analysis and model validation. The models were then parameterised for individual cultivars. The best model across all target sugar concentrations was the non-linear best Sigmoid model "best SIG"' model (parameters: start date (t(0)) = 86, d = -0.1294, e = 14.87). The best linear (Growing Degree Days) model was also selected which represents the model that required the least parameters and therefore the simplest in application for winegrowers. This model was termed the "Grapevine Sugar Ripeness" model (GSR) (parameters: base temperature (Tb) = 0 degrees C, start date (t(0)) = 91 or 1 April, Northern Hemisphere). Both models performed better than the Winkler and Huglin growing degree day models. Sixty-five cultivars were classified for the thermal time to one or more of the six sugar targets using these two models. Fifty percent of all combinations of cultivar and time to target sugar concentrations had EF values greater than 0.5 and RMSE values less than seven days. Confidence intervals were calculated for cultivars where there was sufficient data for the thermal time to target sugar concentrations. The classifications generated from both models provides the opportunity to implement either model to support cultivar choice in response to concerns of climate change and may provide cultivar solutions to issues of harvesting grapes at high sugar concentrations with resultant higher alcohol wines.

The predicted developments in climate are region-specific and adaptation can only be successful considering the regional characteristics with its diverse technical, environmental, economic and social implications. One of the key concerns for many regions is the availability of water through precipitation, the distribution of precipitation throughout the year, and possible changes in evaporative demand of the atmosphere and thus water use. From rising temperatures it is mostly assumed that water holding capacity of the atmosphere will increase in the future as a function of the Clausius-Clapeyron law, which predicts an increase in the saturation vapour pressure of the atmosphere of 6–7% per degree Celsius. As a consequence, a simultaneous increase in potential evapotranspiration (ETp, the amount of water that could potentially be evaporated from soils and transpired by plants due to changes in climatic factors such as temperature, vapour pressure deficit, radiation and wind speed) is assumed in many cases, which would alter soil and plant water relations. However, the same underlying principles also predict an increase in precipitation by 1–2% per degree warming. Additionally, model predictions for many regions forecast altered precipitation patterns and thus in combination with the possibility of increased ETp, farmers around the world fear an increase in the likelyhood of water deficit and a reduction in the availability of water for irrigation. Contrary to expectations, there have been reports on a reduction in evaporative demand worldwide despite increasing temperatures. In many cases this has been related to a decrease in solar radiation observed for many areas on earth including wine growing regions in Europe until the beginning of the 80th (global dimming) of the last century. However, since then, solar radiation has increased again, but ETp did not always follow and a worldwide decrease in wind speed and pan evaporation has been observed. In order to evaluate different grape growing regions with respect to observed changes on precipitation patterns and ETp, the data of seven wine-growing areas in five countries in the Northern and Southern hemisphere across a large climatic trans-sect were analyzed (Rheingau, Germany, Burgundy, Rhone Valley, France, Napa Valley, USA, Adelaide Hills, Tasmania, Australia, Marlborough, New Zealand) were analyzed. Precipitation patterns differed vastly between locations and showed very different trends over observation periods ranging from 23 to 60 years. The ETp has increased continuously in only two of the seven wine growing areas (Rheingau and Marlborough). In most other areas, ETp has been stable during winter and summer for at least 22 years (Rhone Valley, Napa Valley, Tasmania), sometimes much longer (45 years Adelaide Hills), and has been declining in Burgundy after a period of strong increase for the last 13 years. The potential underlying factors are discussed in relation to observed shifts in precipitation patterns.

Grapevines are perennial plants that can display remarkable longevity. It is often thought that some of their characteristics evolve in a positive way as they grow older, such as having a higher tolerance to water deficit and an improved balance between vegetative and reproductive growth. However, only a few studies have been conducted so far on the possible effects of age on vine productivity and water status. An experimental vineyard was designed in the German Rheingau region to compare vines of identical planting material planted at three different times. The vineyard was established in 1971 with Vitis vinifera (L.) cv. Riesling vines (clone Gm 239-17) grafted on 5C Teleki and trained in double Guyot and cordon in alternating rows. In 1995 and 2012, rows of both training systems were uprooted and replanted with the same scion/rootstock combination. The aim of this study was to evaluate the impact of vine age on several physiological and reproductive parameters. Vines planted in 2012 were generally more sensitive to water deficit than vines planted in 1995 and 1971, although this depended on the amount of precipitations during the growing season. A supporting trial was carried to create more intense drought conditions by deploying a plastic mulch around selected vines during rain events. Young vines were most affected by the treatment, suggesting that their lower trolerance to water deficit might be due to a shallower root system. Vines planted in 1995 and 1971 displayed similar response to water deficit. Canopy architecture, cluster parameters and vine balance components including pruning weight and yield were different for the youngest vines until the fifth year after planting due to their lower cropping capacity. Even though the observed yield and pruning weight per meter were lower for grapevines planted in 1971 than those planted in 1995, these variables were similar across the two age groups when missing vines were taken into account. Wood diseases were identified as the main factor behind the decline of old vines. The study suggests that the management of wood diseases is a key component in improving vineyard longevity, and that the conservation of grape yield and technological maturity parameters for vineyards in similar environmental conditions is indeed possible over the long term.

Aim: The effects of integrated, organic and biodynamic management on soil quality and the growth and morphological development of Riesling grapevines were assessed during the first 4 years of a long-term field trial in Geisenheim, Germany. The overall aim was to understand the effects of these different viticultural practices on soil quality and plant morphology as the basis for product quality. Methods and results: As indicators of soil quality, earthworm abundance and the activity of selected enzymes were assessed. The vegetative and reproductive development of the grapevines, as well as their susceptibility to fungal diseases in the field, wood and grape composition, and grape yield, were investigated. Individual variables were subjected to analysis of variance. Additionally, all variables were subjected to multivariate principal component analysis. Compared with plots under integrated management, plots under the two biological treatments were characterized by higher soil quality and lower vegetative growth and grape yield, and therefore higher exposure of grapes and lower grape cluster compactness, and, probably as a result of these morphological differences, lower incidence of acetic acid rot. Principal component analysis clearly differentiated the three treatments, and showed that biodynamic management had more pronounced effects than organic management in terms of enhanced soil fertility and reduction of vegetative growth. Conclusions: In the present study, organic and especially biodynamic management resulted in a morphology favouring production of high-quality grapes. The treatments differed in terms of fertilization and plant protection methods as well as choice of cover crops. Therefore, further research is necessary with respect to root growth and the nitrogen and water uptake dynamics of vines and cover crops. The differences between grapes produced under organic and biodynamic management emphasize the need for more research on the mode of action of biodynamic preparations. Significance and impact of the study: In recent years, both winegrowers and consumers have expressed steadily growing interest in organic and especially biodynamic wine production. The present study contributes to a better understanding of the effects on grapevine growth and morphological development of shifting to these methods as a way to increase product quality.

The predicted developments in climate are region-specific and adaptation can only be successful considering the regional characteristics with its diverse technical, environmental, economic and social implications. Beyond some obvious adaptation strategies in response to emerging environmental constraints for example there are many more “basic” challenges below “the surface”. One of the key concerns for many regions is the availability of water and how increasing temperature will drive the evaporative demand of the atmosphere. For this, individual regions need to be analysed to quantify possible associated risks. This paper will address differences in regional water relations of grape growing areas in different parts of the world as a basis to address the points listed above.

How rootstocks contribute to the control of scion transpiration under drought is poorly understood. We investigated the role of root characteristics, hydraulic conductance and chemical signals (abscisic acid, ABA) in the response of stomatal conductance (gs) and transpiration (E) to drought in Cabernet Sauvignon (Vitis vinifera) grafted onto drought-sensitive (Vitis riparia) and drought-tolerant (Vitis berlandieri × Vitis rupestris 110R) rootstocks. All combinations showed a concomitant reduction in gs and E, and an increase in xylem sap ABA concentration during the drought cycle. Cabernet Sauvignon grafted onto 110R exhibited higher gs and E under well-watered and moderate water deficit, but all combinations converged as water deficit increased. These results were integrated into three permutations of a whole-plant transpiration model that couples both chemical (i.e., ABA) and hydraulic signals in the modelling of stomatal control. Model comparisons revealed that both hydraulic and chemical signals were important for rootstock-specific stomatal regulation. Moreover, model parameter comparison and sensitivity analysis highlighted two major parameters differentiating the rootstocks: (i) ABA biosynthetic activity and (ii) the hydraulic conductance between the rhizosphere and soil-root interface determined by root system architecture. These differences in root architecture, specifically a higher root length area in 110R, likely explain its higher E and gs observed at low and moderate water deficit.

The impact of environmental changes induced by climate modifications on grapevine growth and functioning is region-specific. Since grapevines are cultivated across a vast array of climate types the responses to climatic changes and the challenges resulting will vary. This chapter focuses on the problems induced by observed and predicted climate variability in summer rainfall temperate grape-growing regions on plant water relations, disease problems and their possible subsoil surface causes such as altered nitrogen mineralization rates. It stresses that changes observed and predicted during the growing season are important but developments during the 'off-season' need to be considered more. Finally, a literature comparison is presented on the effects of elevated CO2 as a major driver of climate change on grapevines as compared to other special crops such as fruits and vegetables.

Grapevines are cultivated on six out of seven continents, between latitudes 4 degrees and 51 degrees in the Northern Hemisphere and between latitudes 6 degrees and 45 degrees in the Southern Hemisphere across a large diversity of climates ( oceanic, warm oceanic, transition temperate, continental, cold continental, Mediterranean, subtropical, attenuated tropical, and arid climates). Accordingly, the range and magnitude of environmental factors differ considerably from region to region and so do the principal environmental constraints for grape production. The type, number, and magnitude of environmental constraints are currently undergoing changes due to shifts in climate patterns already observed for the past and predicted for the future. These changes are already affecting grape composition with observed changes in sugar and acidity concentrations. As with other components such as polyphenols or aroma compounds, their relationships to environmental changes are more difficult to quantify. In general, one can divide the expected climatic changes during the grape-ripening period into two scenarios: warmer and dryer and warmer and moister, with different responses for red and white grape varieties. The production challenges within this broad separation are vastly different, and the strategies to ensure a sustainable product need to be adapted accordingly. The economic impact of these changes is difficult to assess. An in-depth analysis is necessary to construct relevant scenarios and risk analysis for individual regions and to quantify the costs and/or benefits of regional climate developments. (JEL Classifications: Q1, Q54)

This article is based on a joint presentation given by the authors at the 9th International Cool Climate Symposium held in Brighton, England, on 26-28 May, 2016, for which they examined how climate change is influencing the cool climate limits to viticulture and wine production.

The photosynthetic activity (A) of leaves of different ages on primary and secondary shoots of Riesling and Chasselas vines was measured under field conditions in relation to photon flux density (PFD) at various leaf temperatures. The data sets from 4 years and two locations (Geisenheim, Germany; Changins, Switzerland) were analysed using non-linear regression models to determine possible genetic and/or climate-induced differences in the light and temperature response between different leaf ages, A non-rectangular hyperbola with physiologically meaningful parameters was found to adequately describe the response to photon flux density. For both varieties, maximum photosynthetic rates were observed on leaves of primary shoots, opposite to the clusters, at a leaf temperature of 27-32 degrees C and at light saturation. Young leaves showed a less pronounced temperature optimum. The light response curves of photosynthesis of the two cultivars were similar over a temperature range of 20-30 degrees C. Below this temperature, Riesling showed higher values of A than Chasselas in most Eases, whereas it was the reverse when leaf temperature exceeded 30 degrees C, This was particularly evident for leaves on secondary shoots and was related to differences in the photorespiration rate. Mature Riesling leaves had higher apparent quantum yields (alpha) and lower light saturation indices (I-s) than Chasselas at leaf temperatures below 30-35 degrees C. Dark respiration (R-D) and the light compensation point (I-c) responded strongly to temperature with differences between leaf ages but no consistent difference between varieties. Leaves on secondary shoots of both cultivars had the highest photosynthetic activity during the ripening period of the fruit.