Australian Journal of Grape and Wine Research最新文献

Sustainability in grapevine cultivation requires the precise use of water and fertilizers, particularly nitrogen (N), to produce grapes of the highest quality for winemaking, while simultaneously avoiding harm to the surrounding waters and atmosphere by reducing NO₃⁻ losses and N₂O and NH₃ emissions from the vineyards. To address the challenge of optimizing N use in viticulture, many N fertilization trials have been carried out over the last decades, and a compilation and analysis of worldwide trials was therefore needed. The present study tackled this challenge through a meta-analysis of published research, which included 374 fertilization trials. From the compiled data, six vine production parameters and eight grape quality traits were extracted and normalized to enable comparisons between experiments. The Mitscherlich law of diminishing returns was able to satisfactorily describe the set of vine production parameters against nitrogen application rate, and the same occurred with the yeast assimilable nitrogen (YAN). In vines, both reproductive and vegetative growth similarly responded to the N application rate. In general, the nitrogen requirements for 95% of the maximum grape yield amounted to rates between 30 and 40 kg·N·ha⁻¹, which increased nitrogen use efficiency (NUE) to values between 0.27 and 0.36 t·kg·N⁻¹. Although several grape quality traits could not be described against the N rate in terms of any mathematical relationship, an N rate between 20 and 25 kg·N·ha⁻¹ could be considered as maximizing grape quality for winemaking. Such N fertilization range increases NUE up to values between 0.41 and 0.47 t·kg·N⁻¹, thus almost doubling the known NUE standards when grape quality is targeted instead of yield, although soil fertility could be exhausted in the mid-to-long term. Whatever the case, anthocyanins and polyphenols are well preserved in red grapes at such low N rates, although YAN is not. The results of this work will be useful for guiding new vine N nutrition research and N nutrition management in vineyards, thus increasing wine growing sustainability.

One of the major challenges that global warming poses to viticulture is the maintenance of adequate acidity at maturity in white grapes for sparkling winemaking. This issue arises from three main occurrences: (i) with higher temperatures, degradation of malic acid is significantly enhanced; (ii) with a general advancement in grapevine phenology, grape maturity may occur under suboptimal climatic conditions; and (iii) harvesting grapes at “traditional” dates results in overripe fruits for sparkling destinations. In this biennial work, we compared the fruit and must composition of a local, widely grown white grape variety in the Colli Piacentini area (cv. Ortrugo, ORT) with those of a minor autochthonous variety, namely, Barbesino (BRB). Furthermore, we compared the composition, aromatic, and sensory profiles of wines obtained from ORT and BRB grapes picked on the same date and, in addition, of a second Barbesino wine from late harvest (BRB-LH). ORT and BRB had a similar sugar accumulation dynamic, whereas BRB exhibited a delayed loss of titratable acidity. In more details, BRB had lower malic acid degradation rates when malate concentration was <9 g/L. As a result, with comparable yield and total soluble solid content (TSS) (∼20°Brix), BRB had a higher berry titratable acidity and malic acid concentration at harvest than ORT. BRB wines showed the highest titratable acidity (TA), while ORT had the lowest TA and a higher pH, and as expected, BRB-LH had the highest pH and a lower TA than BRB although still higher than those of ORT wine. The aroma profiles of wines were mainly characterized by fermentative aromas, including esters, fatty acids, higher alcohols, and C₆ compounds, and BRB-LH wines showed the highest concentration of higher alcohols, while the fermentative esters were higher in ORT wines. Panelists considered BRB significantly fresher and with bigger aroma intensity than ORT, confirming that the higher acidity detected in BRB musts is well preserved in final wines. Our work demonstrates that local minor varieties can be reconsidered in light of the new climate change-related issues impairing viticulture sustainability today. In particular, currently neglected cultivars could help preserve must acidity as compared to traditional varieties having early ripening, maintaining the links with terroir and local traditions at the same time.

Background and Aims. Drought harms the growth and productivity of grapevines; it thus poses a major threat to the development of viticulture in the background of ongoing climate change. Arbuscular mycorrhizal fungi (AMF) can be used to enhance the resistance/tolerance of plants to environmental stress. The effects of AMF on the osmotic regulation, antioxidant substances, and expression of drought-responsive genes in the grapevine Vitis vinifera L. cv. Ecolly were studied. Methods and Results. The experiment was conducted in a greenhouse in a completely randomized block design with four treatments: AMF colonization, well-watered; non-AMF colonization, well-watered; AMF colonization with drought stress; and non-AMF colonization with drought stress. The concentration of sucrose and proline in the leaves was higher in mycorrhizal grapevine than in nonmycorrhizal grapevine under drought stress. The concentration of malonaldehyde, hydrogen peroxide, superoxide anion, and glutathione and the activity of superoxide dismutase and peroxidase activity in leaves were higher in mycorrhizal grapevine than in nonmycorrhizal grapevine under drought conditions. AMF inoculation affected the expression of drought-responsive genes. Mycorrhization upregulated the expression of VvNCED, VvP5CS, VvSIP, VvPIP1;2, and VvTIP2;1 genes under drought stress. Conclusions. AMF could reduce the harm caused by drought stress by regulating osmosis, antioxidant activities, and the expression of key drought-responsive genes and aquaporin genes. Significance of the Study. This work provides insights into the physiological and biochemical activities influenced by AMF on grapevine under drought stress.

Background and Aims. A wide range of Chardonnay styles exist on the market, from fruit-forward examples to wines displaying “empyreumatic” aromas such as flint, smoky, mineral, and struck-match. The thiols 2-furylmethanethiol and phenylmethanethiol have been linked to these aromas, and this study aimed to determine the contribution of these compounds to specific sensory properties in Chardonnay wines, as well as the consumer acceptance of wine displaying “empyreumatic” aromas. Methods and Results. Twenty-four Australian and New Zealand Chardonnay wines were selected for volatile analysis and quantitative sensory descriptive analysis. Consumer liking of a subset of six wines was also determined, and a further sensory study involving additions of the thiols to a base wine was conducted. Partial least squares regression showed that flint/struck-match/mineral aromas were related to 2-furylmethanethiol concentration with phenylmethanethiol less well associated. The odorant addition study confirmed that 2-furylmethanethiol directed flint/struck-match/mineral aromas and exerted strong suppression of other aromas while phenylmethanethiol played a lesser role. Consumer acceptance (n = 92) was overall lower for wines displaying high flint/struck-match/mineral aromas, although cluster analysis of the liking scores identified a sizeable consumer group (33%) who preferred wines with this attribute. Conclusions. The potent thiol 2-furylmethanethiol was indicated to be the primary contributor to flint/struck-match/mineral aromas in Chardonnay wines, with phenylmethanethiol playing a subordinate role. Significance of the Study. Increased concentration of 2-furylmethanethiol and the conferred “empyreumatic” odours should be carefully considered when producing wine styles to appeal to consumers.

In a global warming context, the advancement and compression of maturity in early ripening grape varieties suited to sparkling wine making can easily expedite harvest within the first two weeks of August (in northern Italy). Such earliness, albeit safeguarding acid retention, involves potential suboptimal grape composition and triggers logistical issues related to grape harvest and delivery. Hence, this three-year study beginning in 2020 was conducted on cane-pruned Chardonnay vines, grown in the Franciacorta district of Lombardy, to assess if a single-step delayed winter pruning was able to postpone vine phenology and ripening, without harming yield potential. Control (C) vines pruned midwinter were compared with those subjected to late winter pruning (LWP), performed when the apical shoots growing on the unpruned canes had reached the 2-3 unfolded leaf stage (T1) as well as 7-8 days later (T2). In 2022, a fourth treatment was added, consisting of a two-step procedure with finishing performed at T1 (LWP-two canes). Vegetative growth, yield components, ripening dynamics, and maturity at harvest were followed in each year of this study. Budburst delay induced by LWP treatments across seasons varied between 4 and 9 days, whereas harvest was postponed by 5–14 days. The extent of delay was especially pronounced in 2020, when the removed leaf area (LA) was also found to be the highest. The higher the removed LA, the higher the yield constrain was in the concomitant year. In 2020 and 2021, despite the harvest delay, LWP vines were able to assure full matching with desirable features in must composition, set at total soluble solids (TSS) of about 18°Brix and a titratable acidity (TA) of at least 8 g/L. In the very hot and dry phase of 2022, none of the treatments facilitated the required ripening status, while data showed that an even earlier ripening would not have allowed the harvest to reach the minimum TSS level. Notably, even in 2021 and 2022, when the removed LA was quite low, a delaying effect was prompted in the seasonal trends of all main ripening parameters. This suggested that besides the amount of LA removal, other unknown factors drive the postponement of ripening. In 2022, the behavior of added-treatment LWP-two canes was found to be quite similar to that of the C vines. Depending upon the desired yield level and local climate feature, the protocol entailing a single-step late winter pruning, performed at any time between the T1-T2 time window used in this study, is deemed as effective in achieving a significant harvest delay while maintaining or even improving the compositional patterns recorded for midwinter pruned vines.

This study aimed to examine the various Swiss wine consumer segments, evaluate whether and how these segments had changed during the past decade, and formulate recommendations for targeted marketing. Data were collected through an online survey involving randomly selected Swiss households who were invited using flyers; the final sample size was N = 512. With the use of a shortened version of the questionnaire devised for a similar study published in 2011, we were able to compare the results of the said study with the present results. The results of the principal component analyses revealed eight factors. The factor scores were then used in hierarchical cluster analyses, which in turn revealed seven distinct segments of wine consumers. Four of these had already been identified 10 years ago: involved (21.9%), price-conscious (20.3%), lowbrow (16.0%), and image-oriented (5.3%) consumers. Three new segments emerged: local (15.2%), traditional (11.9%), and relaxation-seeking (9.4%) consumers. Our results show that each wine seller has its own place in the market and can benefit from the present study, which determines the appropriate marketing mix for a specific segment.

Leafroll and red blotch are two of the most consequential viral diseases threatening the sustainability of the wine grape industry. To promote uptake of management practices, there is a critical need to understand the motivating factors for decision makers and optimize the dissemination and acquisition of knowledge. From 2019 to 2020, we conducted semi-structured interviews with 42 wine grape industry professionals (“decision makers”) in the Western United States, from California (n = 32) and Washington (n = 10). The interview questions explored the perceptions and experiences of these decision makers as they learned about disease ecology, interacted with their immediate and extended community, and adopted management practices. Utilizing qualitative thematic analysis, we identified nine economic, knowledge, and social-behavioural factors along with 24 sub-factors. These factors illustrated the interplay between knowledge, communication, economics, labour, government subsidies, regulatory practices, and collaborative efforts that influence adoption. The quality of knowledge dissemination emerged as a critical aspect. Using the interview data along with a quantitative survey (n = 145), we also explored how growers use 14 educational resources to learn about grapevine viruses. Using these findings, extension educators can optimize their activities to disseminate knowledge on grapevine viral disease management. In total, this study provides context for the agricultural industry, research scientists, extension educators, and other supporting partners of the financial, interpersonal, and technical issues that must be overcome to successfully manage grapevine viral diseases.

Wine producers perform early wine quality prediction based on berry morphology, the taste of the berry and the measurement of basic chemical parameters. Incorporating analysis on grape and wine volatiles could potentially achieve a more accurate prediction of wine quality, but forming these models requires careful selection of grapes, controlled fermentations, and standardised quality assessment. Here, we present 3 models for the prediction of quality in Shiraz wine. Modelling was performed by general regression analysis with 4-fold cross-validation: Model 1 (R² = 99.97% and 4-foldR² = 97.61%) for prediction of wine quality from wine volatiles, Model 2 (R² = 99.89% and 4-foldR² = 98.42%) for early prediction of wine quality from free-bound and glycosidically bound grape volatiles, and Model 3 (R² = 91.62% and 4-foldR² = 80.21%) for the prediction of wine quality from free grape volatiles only. The accuracy of these models presents an advancement in the early prediction of wine quality and provides a valuable tool to assist grape growers and winemakers to support the understanding of quality in the vineyard to better direct scarce resources.

Background and Aims. Shiraz (Syrah) is a dark-skinned cultivar of the wine grape Vitis vinifera that forms the basis of some of the world’s most iconic wines. Worldwide, Shiraz is the fourth most planted grapevine cultivar; however, it represents the most planted cultivar in Australia. Given the importance of Shiraz to worldwide wine production, this study aimed to produce a reference genome for this cultivar while investigating the unique genetic variants and ancestral origins of this iconic variety. Methods and Results. Long-read ONT data were selected to produce a highly contiguous genome assembly for Shiraz. Phylogenetic reconstruction using high-quality genome assemblies for wine grape cultivars provided further support of a kinship between Shiraz and Pinot Noir. Harnessing long-read data, transposable element insertions potentially affecting gene function were characterized in Shiraz and assessed relative to other cultivars. This revealed a heterogenous landscape of transposon insertion points across cultivars and uncovered a specific combination of allelic variants at the VviTPS24 terpene synthase locus. Conclusions. This establishment of a Shiraz genome provides a detailed view of the genetics that underpin this cultivar, including the discovery of a specific combination of VviTPS24 variants, which when combined with appropriate environmental triggers may allow Shiraz to produce high levels of rotundone, the aroma compound responsible for the distinctive peppery characteristics of this cultivar. Significance of the Study. The availability of a reference genome for Shiraz expands the pool of genomes available for wine grapes while providing a foundation resource for whole-genome studies involving this iconic cultivar, including intracultivar variant identification and transcriptomic studies using a matching reference genome.