Assessing the growth response of Vitis vinifera L. cv. Xynisteri, Maratheftiko, Shiraz and Sauvignon Blanc to different irrigation regimes.

The world’s changing climate is placing great pressure on the resources for sustainable viticulture. With this, it has become necessary to investigate grape varieties that are well adapted to hot climates. The aims of this study were to (1) assess the response of Xynisteri to different irrigation regimes, and (2) compare the performance of Xynisteri, Maratheftiko, Shiraz and Sauvignon Blanc grown in pots with different irrigation regimes. Trial one was established in a commercial Xynisteri vineyard in Cyprus under three different irrigation regimes - full, 50% and no irrigation in 2019. Trial two compared three irrigation regimes - full, 50% and 25% in a potted trial of Xynisteri and Sauvignon Blanc conducted in Cyprus in 2019. Trial three was a potted trial of Xynisteri, Sauvignon Blanc, Maratheftiko and Shiraz with the same three irrigation regimes conducted in Australia in 2020/21. Vine performance and physiology measurements were taken in both trials. Fruit composition analysis, yield (field trial only), shoot, trunk and root mass measurements were performed at the end of the season. Few differences between measures were found between irrigation regimes in the field trial. Fruit composition analysis revealed fructose to be lowest in the full irrigation group compared to deficit and no irrigation treatments. The potted trial in 2019 demonstrated that for all three irrigation regimes, Xynisteri had higher stem water potential, stomatal conductance and chlorophyll content than Sauvignon Blanc. Xynisteri produced greater end of season root, shoot and leaf mass than Sauvignon Blanc under all irrigation regimes. In 2020/21, Xynisteri had greater end of season root, shoot and leaf mass than Maratheftiko and Sauvignon Blanc with Shiraz the lowest. Few significant differences in stem water potential were observed in the early stages of the trial. However, toward the end of the trial and with reduced irrigation, Xynisteri and Maratheftiko had higher stem water potential than Shiraz and Sauvignon Blanc. Xynisteri had higher stomatal conductance and chlorophyll content than Maratheftiko and both were higher than Sauvignon Blanc and Shiraz. These results indicate that Xynisteri in particular may possess better cultivar specific growth traits than Shiraz and Sauvignon Blanc when grown under the same environmental conditions and in turn may be a more appropriate choice in areas where water is limited.

Impact of type of winemaking vessel on the chemical composition of Sauvignon blanc wines

Recently, the use of alternative vessels to oak barrels during winemaking has become increasingly popular (Rubio-Bretón et al., Nevares et al., Gil i Cortiella et al.), but little is known about their impact on the chemical composition of the final wines. To address this issue, a Sauvignon blanc wine was produced using cylindrical stainless-steel tanks, egg shape concrete vessels, egg shape polyethylene vessels and clay jars. The wines were fermented and aged on their lees for six months and chemically characterised as described hereafter.

Evaluating sources of variability in inflorescence number, flower number and the progression of flowering in Sauvignon blanc using a Bayesian modelling framework

The time of flowering is key to understanding the development of grapevines. Flowering coincides with inflorescence initiation and fruit set, important determinants of yield. This research aimed to determine between and within-vine variability in 4-cane-pruned Sauvignon blanc inflorescence number per shoot, number of flowers per inflorescence and flowering progression using an objective method of assessing flowering via image capture and statistical analysis using a Bayesian modelling framework. The inflorescence number and number of flowers per inflorescence were measured by taking images over the flowering period. Flowering progression was assessed by counting open and closed flowers for each image over two seasons. An ordinal multinomial generalised linear mixed-effects model (GLMM) was fitted for inflorescence number, a Poisson GLMM for flower counts and a binomial GLMM for flowering progression. All the models were fitted and interpreted within a Bayesian modelling framework. Shoots arising from cane node one had lower numbers of inflorescences compared to those at nodes 3, 5 and 7, which were similar. The number of flowers per inflorescence was greater for basal inflorescences on a shoot than apical ones. Flowering was earlier, by two weeks, and faster in 2017/18 when compared to 2018/19 reflecting seasonal temperature differences. The time and duration of flowering varied at each inflorescence position along the cane. While basal inflorescences flowered later and apical earlier at lower insertion points on the shoot, the variability in flowering at each position on the vine dominated the date and duration of flowering.This is the first study using a Bayesian modelling framework to assess variability inflorescence presence and flower number, as well as flowering progression via objective quantification of open and closed flower counts rather than the more subjective method of visual estimation in the field or via cuttings. Although flower number differed for apical and basal bunches, little difference in timing and progression of flowering by these categories was observed. The node insertion point along a shoot was more important. Overall, the results indicate individual inflorescence variation and season are the key factors driving flowering variability and are most likely to impact fruit set and yield.

Developing a Novel Method of Analysis for Thiols in Sauvignon blanc

<p>New Zealand wine had an export value of $1.21 billion in 2013. Of the total 170million litres of wine exported thatyear, Sauvignon blanc madeup 84.5%. Sauvignon blanc wines have specific flavours and aromas that consumers detect and enjoy including grapefruit, passion fruit,and citrus characters that are due to the presence of sulfur containing thiols. Unfortunately, thiols are also responsible for aromas such as cat’s urine, grass, and gasoline, which taint the flavour of a wine. Careful analysis of these compounds could lead to wines tailored to specific palates and a reduction of taint aromas and flavours, therefore further increasing the market potential for New Zealand Sauvignon blanc. The aim of this project was to further develop an SPME-based technique for thiol analysis of wine that is more reproducible, more accessible, and less toxic than the current method that concentrates the thiols using organomercury columns. To do this, gold nanoparticles were synthesised and coated onto SPME fibres in an attempt to selectively extract thiols from wine samples. Initial results showed an inconsistency between analyses and led to the need for a more comprehensive analysis ofthe gold surface,the gold-sulfur bond, and its RED-OX chemistry. Techniques employed for analysis of the gold surface included scanning electron microscopy, transmission electron microscopy,zeta-sizing and UV-VisSpectrophotometry. To examine the interactions between gold and sulfur, Surface-Enhanced Raman Spectroscopy and computational chemistry were used. The RED-OX chemistry was initially assessed in terms of the carrier gas in the gas chromatographs but was later changed to reductive and oxidative dips. It was found that an H2O2 dip in between samples oxidised the bound thiolates to a series of dimers that were easier to remove from the gold. While not yet completely resolving the hysteresis observed in previous attempts, this method of cleaning the fibres will lead to future experimentation and development in this area.</p>

Developing a Novel Method of Analysis for Thiols in Sauvignon blanc

<p>New Zealand wine had an export value of $1.21 billion in 2013. Of the total 170million litres of wine exported thatyear, Sauvignon blanc madeup 84.5%. Sauvignon blanc wines have specific flavours and aromas that consumers detect and enjoy including grapefruit, passion fruit,and citrus characters that are due to the presence of sulfur containing thiols. Unfortunately, thiols are also responsible for aromas such as cat’s urine, grass, and gasoline, which taint the flavour of a wine. Careful analysis of these compounds could lead to wines tailored to specific palates and a reduction of taint aromas and flavours, therefore further increasing the market potential for New Zealand Sauvignon blanc. The aim of this project was to further develop an SPME-based technique for thiol analysis of wine that is more reproducible, more accessible, and less toxic than the current method that concentrates the thiols using organomercury columns. To do this, gold nanoparticles were synthesised and coated onto SPME fibres in an attempt to selectively extract thiols from wine samples. Initial results showed an inconsistency between analyses and led to the need for a more comprehensive analysis ofthe gold surface,the gold-sulfur bond, and its RED-OX chemistry. Techniques employed for analysis of the gold surface included scanning electron microscopy, transmission electron microscopy,zeta-sizing and UV-VisSpectrophotometry. To examine the interactions between gold and sulfur, Surface-Enhanced Raman Spectroscopy and computational chemistry were used. The RED-OX chemistry was initially assessed in terms of the carrier gas in the gas chromatographs but was later changed to reductive and oxidative dips. It was found that an H2O2 dip in between samples oxidised the bound thiolates to a series of dimers that were easier to remove from the gold. While not yet completely resolving the hysteresis observed in previous attempts, this method of cleaning the fibres will lead to future experimentation and development in this area.</p>

Effect of Leaf Area Size on the Main Composition in Grape Must of Three Varieties of Vitis vinifera L. in an Organic Vineyard

The concentrations of sugars and acids are very important for the quality and the stability of wines. In addition, the proportion of the two main acids, i.e., tartaric acid and malic acid, is a significant factor for wine taste and stability. Over a period of three seasons in an organic vineyard, the influence of leaf area on the concentration of total soluble solids (TSS), pH, titratable acidity (TA), the concentration of tartaric acid and malic acid, and their mutual proportions were monitored. Vines of three varieties (‘Rhine Riesling’, ‘Pinot Gris’, ‘Sauvignon Blanc’) were treated using three different treatments (proportion of leaves removed 0%, 40%, and 70%). All varieties exhibited positive correlations between leaf area and TSS. In terms of relationships between TA and leaf area, ‘Sauvignon Blanc’ was the most sensitive variety. The highest differences between the individual variants were found for this variety. The tartaric to malic acid ratio displayed a significant seasonal effect, which was mostly more important than leaf area reduction. The size of the leaf area mainly affected the accumulation of sugars in the grapes, while content and ratio of acids was not affected so significantly. Therefore, leaf area regulation is one of the ways to optimize the composition of grapes in organic vineyards.

Aumento da carga de gemas da videira Sauvignon Blanc e seu efeito na interceptação da radiação solar e fertilidade de gemas

Buscando compreender os efeitos do aumento da carga de gemas planta-1 na interceptação da radiação solar e seu efeito na fertilidade de gemas, tem-se como objetivo desse trabalho avaliar o efeito do aumento da carga de gemas da videira ‘Sauvignon em relação a interceptação da redação fotossinteticamente ativa e o seu efeito na fertilidade de gemas em região de elevada altitude de Santa Catarina. O presente trabalho foi realizado durante a safra 2016/2017, em um vinhedo comercial, localizado no munícipio de São Joaquim. Os tratamentos consistiram em quatro diferentes níveis de cargas de gemas: 15, 30, 50 e 75 gemas planta-1. As gemas foram classificadas em férteis ou não férteis de acordo com a presença ou ausência da inflorescência. Para avaliação da interceptação da radiação fotossinteticamente ativa, utilizou-se um ceptômetro, e as medidas foram realizadas ao meio-dia durante os estádios fenológicos de plena florada, mudança de cor das bagas e maturidade. O aumento da carga gemas planta-1 reduz a fertilidade de gemas basais, não influenciando a fertilidade de gemas medianas e apicais da videira Sauvignon Blanc. Há uma redução da radiação fotossinteticamente ativa da videira Sauvignon Blanc em função do aumento da carga gemas planta-1, nos estádios fenológicos florada, veráison e colheita.

Effects of different vinification technologies and yeasts on qualitative parameters and terpene compounds of Sauvignon Blanc wines

Sauvignon Blanc represents an important grape variety. The wine made from this variety is known to have a wide range of aroma profiles from nettles to tropical fruits. Beside the raw material quality (grapes), the quality of wines can be fundamentally influenced by the technological conditions applied in the wine making process. Yeast and other microorganisms play a key role in the formation of metabolites during alcoholic fermentation. In this study, the effects of autochthonous or selected wine yeasts (Saccharomyces cerevisiae) and fermentation temperatures (15 °C and 19 °C) were tested on major monoterpenes contents of wines during the period 2016–2017. The obtained values show that the highest contents of linalool (24.36 μg L−1) and hotrienol (11.84 μg L−1) were determined in wine samples produced with active (selected) wine yeast at lower temperature. Sensory evaluation results indicated that monoterpenes can have a positive effect on the overall sensory quality of Sauvignon Blanc wines, despite the fact that their determined concentrations in the evaluated samples were not higher than their threshold values.