•A wide range of temperature- based models were tested for the trait ‘temperature requirements to sugar ripeness’.•Six sugar concentrations were assessed as an objective measure of ripeness.•Two ...temperature-based models were successfully developed for the day of the year to reach the six sugar concentrations.•65 cultivars were characterised for different sugar targets using these models.•Cultivar confidence intervals were reported.
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 (t0) = 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 °C, start date (t0) = 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.
•A temperature based phenological model was calibrated for grapevine varieties.•95 and 105 varieties were characterized for flowering and veraison respectively.•Model efficiency was assessed for each ...variety for both stages.•Varietal confidence intervals were improved with more observations and sites.•We report a process that could be used to characterize phenology of other crops.
Understanding differences in phenology for varieties of a given species is important for making informed decisions on variety choice in the context of climate change and breeding new cultivars. Phenological models that incorporate temperature as a key environmental factor can be used to describe the differences in phenological timing between cultivars. This paper outlines a methodology, based on a phenological model, for classifying the timing of flowering and veraison for a substantial number of varieties of the grapevine (Vitis vinifera L.). 95 varieties were characterized for flowering and 104 varieties for veraison. Various statistical measures were used to assess the performance and predictions of the model at the varietal level: model efficiency, root mean squared error and confidence intervals. The methodology might be used to understand varietal differences for other species in future studies. Model outputs can be used in combination with predicted climate change scenarios to assess the suitability of varieties under climate conditions of the future.
Leaves of different
Vitis vinifera L. cultivars, susceptible or resistant to downy mildew, Chasselas, Solaris, IRAC 2091 (cvs. Gamaret x Bronner) and
Muscadinia rotundifolia were inoculated with
...Plasmopara viticola. Samples were then examined by scanning and transmission electron microscopy, by light microscopy and for their ability to synthesise stilbenes. These phytoalexins were strictly analysed at infection sites. In the susceptible Chasselas,
P. viticola colonises, at 72
h post-infection (hpi), all of the spongy mesophyll with functional haustoria and produces mainly the non toxic piceide. No necrotic zone was observed on Chasselas leaves. The ultrastructural response to downy mildew infection is different in each of the other three resistant grape cultivars. In Solaris, where leaf necrosis are rapidly induced, the infection is restricted to the upper part of the loose spongy mesophyll, and associated with a rapid cell wall disruption and the dispersion of cytoplasmic content along with the production of viniferins. In IRAC 2091, leaf necrosis are quite similar to those observed on Solaris but the infected plant cell, as well as the haustoria, show high electron dense cellular particles without any recognisable organelles, probably related to the effect of the toxic compound pterostilbene, which is synthesised in this grape cultivar. In
M. rotundifolia leaf necrosis are much more scarce and smaller than in other cultivars, but pathogen and plant cells are both strongly affected, with concomitant expulsion of cytoplasmic materials through the stomata after
P. viticola penetration. In this cultivar, the concentration of all identified stilbenes exceeds 1
×
10
3
μmol
mg
−1 FW. The critical role of stilbenes in the resistance of
Vitis spp. is discussed.
► Stilbens synthesis is the most effective way to stop downy mildew development in grapes. ► Resistant vines produce high concentrations of toxic stilbens at the sites of infection. ► Functional haustoria formation is not the key-step for the induction of stilbens synthesis. ► Stilben synthesis can occur in all species of the
Vitaceae family.
The heat waves of 2003 in Western Europe and 2010 in Russia, commonly labelled as rare climatic anomalies outside of previous experience, are often taken as harbingers of more frequent extremes in ...the global warming-influenced future. However, a recent reconstruction of spring–summer temperatures for WE resulted in the likelihood of significantly higher temperatures in 1540. In order to check the plausibility of this result we investigated the severity of the 1540 drought by putting forward the argument of the known soil desiccation-temperature feedback. Based on more than 300 first-hand documentary weather report sources originating from an area of 2 to 3 million km², we show that Europe was affected by an unprecedented 11-month-long Megadrought. The estimated number of precipitation days and precipitation amount for Central and Western Europe in 1540 is significantly lower than the 100-year minima of the instrumental measurement period for spring, summer and autumn. This result is supported by independent documentary evidence about extremely low river flows and Europe-wide wild-, forest- and settlement fires. We found that an event of this severity cannot be simulated by state-of-the-art climate models.
Nitrogen deficit affects both crop production and composition, particularly in crops requiring an optimal fruit N content for aroma development. The adaptation of cultural practices to improve N use ...efficiency (NUE) (i.e. N uptake, assimilation and partitioning) is a priority for the sustainable production of high-quality crops. A trial was set on potted grapevines (Vitis vinifera L. cv. Chasselas) to investigate the potential of crop limitation (via bunch thinning) to control plant NUE and ultimately fruit N composition at harvest. A large crop load gradient was imposed by bunch thinning (0.5-2.5 kg m-2) and N traceability in the plant was realised with an isotope-labelling method (10 atom % 15N foliar urea). The results indicate that the mobilisation of root reserves plays a major role in the balance of fruit N content. Fertiliser N uptake and assimilation appeared to be strongly stimulated by high-yielding conditions. Fertilisation largely contributed to fulfilling the high fruit N demand while limiting the mobilisation of root reserves under high yield conditions. Plants were able to modulate root N reserve mobilisation and fertiliser N uptake in function of the crop load, thus maintaining a uniform N concentration in fruits. However, the fruit free amino N profile was modified, which potentially altered the fruit aromas. These findings highlight the great capacity of plants to adapt their N metabolism to constraints, crop thinning in this case. This confirms the possibility of monitoring NUE by adapting cultural practices.
Interest in
(
)
is growing in the world of winemaking.
is used both to protect musts from microbial spoilage and to modulate the aromatic profile of wines. Here, we describe the isolation, ...characterization, and use of an autochthonous strain of
in the vinification of Chasselas musts from the 2022 vintage.
was used in co-fermentation with
at both laboratory and experimental cellar scales. Our results showed that
does not ferment sugars but has high metabolic activity, as detected by flow cytometry. Furthermore, sensory analysis showed that
contributed slightly to the aromatic profile when compared to the control vinifications. The overall results suggest that our bioprospecting strategy can guide the selection of microorganisms that can be effectively used in the winemaking process.
Grapevine red blotch virus (GRBV) is a recently identified virus that infects grapevine and has a severe impact on the grape industry in North America. Since the first description of the virus 8 ...years ago, clear progress has been made regarding our understanding of the GRBV pathosystem. However, questions remain regarding the origin of this pathogen and its spread outside North America, especially in Europe. In this study, we present the results of a large-scale GRBV survey in two European repositories; we targeted
Vitis
spp. accessions with diverse geographical origins. Of 816 accessions from different origins (50 different countries around the world), six accessions were infected by GRBV, all of which originated from the United States. We investigated the DNA virome of 155 grapevine accessions from the Swiss grapevine collection using high-throughput sequencing. We observed that virome of the Swiss grapevine collection was composed of several RNA viruses. In contrast, we did not detect any DNA viruses in the 155 Swiss grapevine accessions. This finding suggests that the abundance of DNA viruses infecting grapevines in Switzerland is either very low or non-existent. Our results and the findings of studies published since 2008 show that GRBV most likely originated in North America and subsequently spread to other viticultural areas in the world via unintentional movement of infected cuttings. According to our data, the most plausible scenario for the origin of GRBV is that the virus evolved from non-
Vitis vinifera
hosts and underwent a host jump to
Vitis vinifera
after its introduction to North America in the 1600s.
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