Introducing heterogeneity measurements in terroir studies. Application in the região demarcada do douro (n portugal)

In response to changes in their environment, grapevines regulate transpiration using various physiological mechanisms that alter conductance of water through the soil-plant-atmosphere continuum. Expressed as bulk stomatal conductance at the canopy scale, it varies diurnally in response to changes in vapor pressure deficit and net radiation, and over the season to changes in soil water deficits and hydraulic conductivity of both soil and plant. It is necessary to characterize the response of conductance to these variables to better model how vine transpiration also responds to these variables. Furthermore, to be relevant for vineyard-scale modeling, conductance is best characterized using data collected in a vineyard setting. Applying a crop canopy energy flux model developed by Shuttleworth and Wallace, bulk stomatal conductance was estimated using measurements of individual vine sap flow, temperature and humidity within the vine canopy, and estimates of net radiation absorbed by the vine canopy. These measurements were taken on several vines in a non-irrigated vineyard in Bordeaux France, using equipment that did not interfere with ongoing vineyard operations. An inverted Penman-Monteith equation was then used to calculate bulk stomatal conductance on 15-minute intervals from July to mid-September 2020. Time-series plots show significant diurnal variation and seasonal decreases in conductance, with overall values similar to those in the literature. Global sensitivity analysis using non-parametric regression found transpiration flux and vapor pressure deficit to be the most important input variables to the calculation of bulk stomatal conductance, with absorbed net radiation and bulk boundary layer conductance being much less important. Conversely, bulk stomatal conductance was one of the most important inputs when calculating vine transpiration, further emphasizing the need for characterizing its response to environmental changes for use in vineyard water use modeling.

Since the 1980s global regime shift, grape growers have been steadily adapting to a changing climate. These adaptations have preserved the region-climate-cultivar rapports that have established the global trade of wine with lucrative economic benefits since the middle of 17th century. The advent of using fractions of crop and actual evapotranspiration replacement in vineyards with the use of supplemental irrigation has furthered the adaptation of wine grape cultivation. The shift in trellis systems, as well as pruning methods from positioned shoot systems to sprawling canopies, as well as adapting the bearing surface from head-trained, cane-pruned to cordon-trained, spur-pruned systems have also aided in the adaptation of grapevine to warmer temperatures. In warm climates, the use of shade cloth or over-head shade films not only have aided in arresting the damage of heat waves, but also identified opportunities to reduce the evapotranspiration from vineyards, reducing environmental footprint of vineyard. Our increase in knowledge on how best to understand the response of grapevine to climate change was aided with the identification of solar radiation exposure biomarker that is now used for phenotyping cultivars in their adaptability to harsh environments. Using fruit-based metrics such as sugar-flavonoid relationships were shown to be better indicators of losses in berry integrity associated with a warming climate, rather than solely focusing on region-climate-cultivar rapports. The resilience of wine grape was further enhanced by exploitation of rootstock × scion combinations that can resist untoward droughts and warm temperatures by making more resilient grapevine combinations. Our understanding of soil-plant-atmosphere continuum in the vineyard has increased within the last 50 years in such a manner that growers are able to use no-till systems with the aid of arbuscular mycorrhiza fungi inoculation with permanent cover cropping making the vineyard more resilient to droughts and heat waves. In premium wine grape regions viticulture has successfully adapted to a rapidly changing climate thus far, but berry based metrics are raising a concern that we may be approaching a tipping point.

The development of fertigation could be a possible solution to adapt PGI Côtes de Gascogne (south-western France) wine production to climate change. The goal would be to limit the negative effects of water stress on yield performance expectation (around 15 tons per hectare) and to make the use of fertilizers more efficient. This study aimed to compare the effects of three strategies of water and minerals supply on grapes and wines qualities. Two fertigation practices were compared to a rainfed control which is the current standard of the local grape growing production. The fertilizers (nitrogen and potassium) were (i) fully brought by irrigation pipe during the season, (ii) partially brought by irrigation pipe and partially on the soil or (iii) fully brought on the soil at the beginning of the season for the non-irrigated control (local standard). The trial was run on cv. Colombard trained on spur pruned with vertical shoot positioning system on a sandy-silty-clay soil over the 2020 vintage which was particularly hot for the region. Moderate to strong water deficit appeared during the growing period of the berries and held on after veraison. Irrigation strategies allowed for maintaining grapevine without water deficit and being significantly different from the control water status. Grapevine with fully or partial fertigation strategies produced 25% more yield mainly due to the increase of the bunch weight. Also, the fully fertigation showed the best ratio between yield and maturity and brought 30% less of fertilizers (both nitrogen and potassium) than the two other strategies. Finally, the analysis of aromatic compounds in Colombard wines, varietal thiols family, showed the same level of concentrations for the 3 treatments, confirming that the yield performance did not impact the aromatic potential in this trial.

Anthocyanin potential of grape berries is an important quality factor in wine production. Anthocyanin concentration and profile differ among varieties but it also depends on the environmental conditions, which are expected to be greatly modified by climate change in the future. These modifications may significantly modify the biochemical composition of berries at harvest, and thus wine typicity. Among the diverse approaches proposed to reduce the potential negative effects that climate change may have on grape quality, genetic diversity among clones can represent a source of potential candidates to select better adapted plant material for future climatic conditions. The effects of individual and combined factors associated to climate change (increase of temperature, rise of air CO2 concentration and water deficit) on the anthocyanin profile of different clones of Tempranillo that differ in the length of their reproductive cycle were studied. The aim was to highlight those clones more adapted to maintain specific Tempranillo typicity in the future. Fruit-bearing cuttings were grown in controlled conditions under two temperatures (ambient temperature versus ambient temperature + 4ºC), two CO2 levels (400 ppm versus 700 ppm) and two water regimes (well-watered versus water deficit), both in combination or independently, in order to simulate future climate change scenarios. Elevated temperature increased anthocyanin acylation, whereas elevated CO2 and water deficit favoured the accumulation of malvidin derivatives, as well as the acylation and tri-hydroxylation level of anthocyanins. Although the changes in anthocyanin profile observed followed a common pattern among clones, such impact of environmental conditions was especially noticeable in one of the most widely distributed Tempranillo clones, the accession RJ43.

One of the biggest challenges of agriculture today is maintaining food safety and food quality while providing ecosystem services such as biodiversity conservation, pest and disease control, ensuring water quality and supply, and climate regulation. Organic farming was shown to promote biodiversity and carbon sequestration, and is therefore seen as one possibility of environmentally friendly production. Consumers expect organically grown crops to be free from chemical pesticides and mineral fertilizers and often presume that the quality of organically grown crops is different or higher compared to conventionally grown crops. Integrated, organic, and biodynamic viticulture were compared in a replicated field trial in Geisenheim, Germany (Vitis vinifera L. cv. Riesling). Amino acid profiles in juice, grape skin flavonoids, and hydroxycinnamic acids were monitored over three consecutive seasons beginning 7 years after conversion to organic and biodynamic viticulture, respectively. In addition, parameters such as soil nutrient status, yield, vigor, canopy temperature, and water stress were monitored to draw conclusions on reasons for the observed changes. Results revealed that the different sustainable management regimes highly differed in their amino acid profiles in juice and also in their skin flavonol content, whereas differences in the flavanol and hydroxycinnamic acid content were less pronounced. It is very likely that differences in nutrient status and yield determined amino acid profiles in juice, although all three systems showed similar amounts of mineralized nitrogen in the soil. Canopy structure and temperature in the bunch zone did not differ among treatments and therefore cannot account for the observed differences in favonols. A different light exposure of the bunches in the respective systems due to differences in vigor together with differences in berry size and a different water status of the vines might rather be responsible for the increase in flavonol content under organic and biodynamic viticulture.