Background and Objectives Organic viticulture has gained prominence as a sustainable production alternative. However, integrated analyses capable of distinguishing studies directly oriented toward organic production from the broader scientific foundation that supports technical transitions remain scarce. Publications in this field exhibit convergent structures, in which supporting research provides explanatory and ecological foundations, whereas studies directly focused on production have evolved from input substitution toward a more systemic perspective. Therefore, this study aimed to examine the structure, evolution, and thematic integration of research on organic viticulture. Methods and Results A bibliometric analysis was performed using VOSviewer and Bibliometrix, based on data retrieved from the Web of Science Core Collection. The final dataset comprised 324 original research articles published between 1996 and 2025. The results revealed a marked increase in publications after 2015, with Europe accounting for the largest share of global scientific output. Brazil ranked second among the most productive countries and showed a high prevalence of single‐country publications. The main thematic axes were biodiversity, soil management, and plant health, while copper emerged as a cross‐cutting element connecting multiple research fronts. Conclusions Research on organic viticulture has evolved from an initial phase focused on input substitution toward a more integrated agroecological approach, indicating increasing interdisciplinary maturity. However, the complete replacement of copper‐based products still depends on further advances in understanding the mechanisms of action of available alternatives, as well as on their validation under field conditions.
Background and Aims Lees ageing is widely applied in Chardonnay winemaking to enhance aroma complexity and mouthfeel through yeast autolysis. Sulphur dioxide (SO 2 ) is commonly used during this stage for antioxidant and antimicrobial protection; however, consumer demand for reduced‐sulphite wines has encouraged the evaluation of alternative protectants. This study investigated the effects of chitosan and glutathione‐enriched inactivated dry yeast (GSH‐IDY), applied alone or with reduced SO 2 , on Chardonnay wine composition and sensory attributes during lees ageing and subsequent bottle ageing. Methods and Results Wines treated with SO 2 , chitosan and GSH‐IDY, or combinations with reduced SO 2 were evaluated at bottling and after 6 and 12 months of bottle ageing. At bottling, chitosan reduced browning and total phenolics and increased diacetyl concentrations. GSH‐IDY produced phenolic and colour profiles similar to SO 2 and increased free amino acid (FAA) concentrations. During ageing, treatment effects on colour became less pronounced, whereas differences in volatiles and mouthfeel‐related compounds persisted. Chitosan‐treated wines showed lower mannoproteins and ethyl lactate. GSH‐IDY treatments showed higher FAAs and mannoproteins but reduced diacetyl, and SO 2 preferentially preserved more acetate esters. Sensory evaluation showed that the control wines added with SO 2 had stronger buttery and toasted characters, whereas GSH‐IDY treatments, particularly the GSH‐IDY applied with reduced SO 2 , showed greater bitterness and longer finish. These sensory differences are associated with treatment‐dependent changes in FAAs, mannoproteins and volatile compounds. Conclusions GSH‐IDY and chitosan influenced Chardonnay wine composition and sensory attributes in treatment‐specific ways during lees ageing and bottle ageing, which may not fully replace SO 2 but may provide useful tools for modulating wine style under reduced‐SO 2 conditions. Significance of the Study These findings provide practical insights into the use of SO 2 alternatives during Chardonnay lees ageing and highlight the importance of additive selection according to the intended wine style.
Background and Aims Brettanomyces bruxellensis is an industrially relevant yeast and a major spoilage organism in wine, where tolerance to sulphur dioxide ( S O 2 ), the primary preservative used for its control, varies among strains. Although laboratory evolution experiments have shown that polyploid B. bruxellensis can rapidly acquire increased S O 2 tolerance through genomic variation and SSU1 duplication, it remains unclear whether similar genetic adaptations drive S O 2 tolerance in winery populations. To address this question, B. bruxellensis strains were isolated from wineries across Australia and subjected to phenotypic characterisation of S O 2 tolerance and detailed genomic analyses to investigate the genetic basis of S O 2 tolerance in industry isolates. Methods and Results Twenty‐six isolates from Australian wineries were phenotypically characterised and sequenced using long‐read technology. Isolates showed a wide range of S O 2 tolerance that correlated with phylogenetic clade and ploidy. Haplotype phasing of SSU1 , a sulphite efflux pump linked to S O 2 tolerance, identified nine distinct haplotypes, including the previously described high‐tolerance H1 allele. Highly tolerant strains carried duplications of H1, frequently associated with retrotransposon insertions and chromosomal rearrangements at the SSU1 locus. Comparative analyses with laboratory‐evolved strains confirmed that retrotransposons facilitated the acquisition of additional SSU1 copies. Conclusions Structural variation at the SSU1 locus, particularly duplication of the high‐tolerance H1 haplotype, is associated with increased S O 2 tolerance in winery isolates of B . bruxellensis . The similarities between industry strains and laboratory‐evolved strains suggest that comparable adaptive mechanisms operate in winery environments. These results improve our understanding of how this spoilage yeast evolves sulphite tolerance and persists in wineries.
Wine protein stabilisation, i.e., the removal of pathogenesis‐related proteins (PRPs), is a step in the white wine fining process. Winemakers use bentonite for this purpose. However, its use has drawbacks due to the production of voluminous waste, wine loss during racking, and decrease in wine quality due to the adsorption of colour components and aroma. New materials for stabilising wine proteins are the object of this study. In this context, an engineered production process for TiO 2 ‐coated glass spheres and a use protocol were developed as an alternative to bentonite treatment, providing relevant information for process scalability. This paper describes the wine protein adsorption capability of a patent‐based, innovative material consisting of thin layers of TiO 2 nanoparticles supported on food‐grade glass spheres, to be used for the protein stabilisation of wine in a flow process. Protein removal was assessed by the heat test and Pierce’s test on unstable wines. As a safety‐related criterion, the amount of TiO 2 released during use was quantified by ICP–OES. The possibility of regenerating the material during use and recycling it at the end of life was also investigated, together with a preliminary cost assessment. Overall, the proposed solution follows a “safe and sustainable by design” (SSbD) approach, matching functionality (selectivity for proteins and heavy metals), safety, cost and recyclability criteria.
Active dry yeast rehydration is a critical step in winemaking, as suboptimal temperatures can impair membrane recovery and compromise fermentation performance. This study evaluated the effects of rehydration at 20 degrees C on commercial Saccharomyces cerevisiae and Torulaspora delbrueckii strains and assessed the efficacy of two commercial rehydration nutrients on fermentation kinetics and membrane fluidity. Results showed that both nutrients enhanced early fermentation in S. cerevisiae strains, with increased CO2 production after 24 h, whereas T. delbrueckii showed no significant response. Membrane fluidity analysis revealed that yeast cells rehydrated at 20 degrees C exhibited high Laurdan generalized polarization (GP) values, indicating increased lipid order, which significantly decreased after 24 h of fermentation. FERMOPLUS Energy Glu 4.0 was associated with lower initial GP values and reduced variation between postrehydration and postfermentation measurements, suggesting a membrane-stabilizing effect that may help optimize rehydration protocols in commercial winemaking.
Background and AimsClimate is important to consider for viticulture, including its influence on grape development, yield and wine quality. The climate has already changed and is projected to change further into the future, so there is a need to understand these changes for viticulture regions. New methodologies and datasets are used here for insight into the climatology of five Australian viticulture regions, including observed changes over recent decades and projected future changes. Regions examined here are Barossa Valley (South Australia), Hunter Valley (New South Wales), Margaret River (Western Australia), Yarra Valley (Victoria) and Tamar Valley (Tasmania).Methods and ResultsA multivariate climate analogue method is used based on growing season temperature (GST) and growing season rainfall (GSR). This method identifies locations that have similar recent conditions (for 1980-2019) to those of an earlier period (1940-1979), analysed individually for each viticulture region. Results based on observations show these analogue areas are to the south, or at nearby higher elevations, from each of the five regions. This method is also applied to identify future locations projected to have similar climate conditions to those of the earlier time period. Future projections are obtained from a dataset comprising of multiple regional climate models (RCMs), based on a global warming level (GWL) of 1 degrees C above the recent period 1980-2019. The future projections indicate analogue areas shifting further away from current viticulture regions, generally shifting in a similar direction to the observed changes, but with a larger magnitude spatial displacement.ConclusionsThese findings provide insight into how climate change has already influenced viticulture regions and how this could be projected to change further in the future. Differences between regions, such as analogue regions shifting southward or to higher elevations, highlight a need to consider climate adaptation strategies tailored to local conditions.Significance of the StudyThis study uses a novel multivariate analogue method based on observations, as well as an ensemble of bias-corrected RCMs, complementary to previous studies that typically use global models or a single regional modelling approach. The results provide new insight into how climate conditions are shifting for viticulture regions, including revealing spatial details on how these shifts vary between regions. These findings are intended to help contribute to the broader set of knowledge available for guiding climate change adaptation in Australian viticulture. Potential is also noted to apply a similar methodology for other agricultural and ecological sectors.
Viticulture, spanning over 7.3 million hectares worldwide, is a key economic sector that is increasingly challenged by labor shortages, rising production costs, market competition, and climate change. Addressing these issues requires monitoring the spatial and temporal variability in vineyard productivity. Traditional ground-based observations, though accurate, are time-consuming and limited in scope. Precision viticulture offers efficient, nondestructive monitoring tools by leveraging technologies such as GPS, remote sensing, and artificial intelligence. This study aims to develop and test a technological workflow using the mobile app DIGIVIT, integrated with the AgroSat platform, to estimate yield variability in vineyards. The workflow was performed during the 2023 and 2024 growing seasons in a series of vineyards near Siena (Italy) and involved two main steps: (1) spatial variability characterization using AgroSat and (2) yield estimation using the mobile DIGIVIT app. AgroSat processed Sentinel-2 NDVI data to identify homogeneous zones, while DIGIVIT used smartphone images of grape clusters to estimate the yield. Field campaigns were conducted 3 weeks before harvest to monitor representative vines within the identified zones and upload georeferenced images for cluster segmentation analysis. Validation of yield estimates against measured weights revealed a strong linear correlation (R2 = 0.91, RMSE = 41.18 g), which improved following the exclusion of a single outlier (R2 = 0.95, RMSE = 29.97 g). Vineyard-level yield predictions were compared with harvest data, resulting in overall error of 13.77% (2023) and 14.69% (2024), aligning with previously reported methods. The study demonstrates that the DIGIVIT app provides accurate, timely yield prediction, supporting farmers in harvest planning and winemaking management. The user-friendly mobile app approach facilitates a broader adoption of precision viticulture technologies among farmers, overcoming barriers related to technical expertise.
Effective management of Cynodon dactylon (bermudagrass) is critical for grapevine production in arid environments. A three-year field study (2018-2020) was conducted in a commercial Yaghuti table grape (Vitis vinifera L.) vineyard in southeastern Iran to compare polyethylene mulch (PEM) and four selective herbicides for bermudagrass control and their effects on grape yield and fruit quality. The experiment followed a randomized complete block design in which herbicide treatments and 1 year PEM were rerandomized annually, whereas 2- and 3-year PEM treatments were maintained on fixed plots to evaluate cumulative effects. Among herbicides, clethodim provided the greatest suppression of both above- and below-ground bermudagrass biomass during the first year, followed by haloxyfop R-methyl ester. Multiyear PEM applications resulted in near-complete suppression of bermudagrass biomass by the second consecutive year, with similar levels of control observed in the third year. Grape yield varied among treatments across years. In general, treatments that effectively reduced bermudagrass competition, including clethodim and multiyear PEM, were associated with higher yields relative to the untreated control. In 2020, grapevines under clethodim and multiyear PEM treatments exhibited higher total soluble solids (TSS) at harvest, while titratable acidity (TA) also differed among treatments. These differences likely reflect indirect effects of weed suppression on vine water status and fruit microclimate rather than direct physiological effects of the herbicides. Overall, repeated PEM application provided sustained bermudagrass suppression under arid conditions, whereas clethodim offered effective short-term control. Long-term environmental and economic implications of multiyear PEM use warrant further investigation.
The transition of the agri-food system toward sustainability necessitates robust assessment frameworks to both guide and evaluate stakeholder performance. This study applies the Sustainability Strategy for Geographical Indications (SSGI) to assess the governance role of Sicilian quality wine consortia in promoting sustainability among their affiliated members. Using a customised questionnaire encompassing 84 SSGI indicators, the research evaluates the performance of these Sicilian organisations across the four pillars of sustainability. The findings reveal a fragmented and uneven level of engagement: While several consortia exhibit moderate performance in economic and governance dimensions, significant weaknesses emerge in the social and environmental pillars. Limited strategic planning, insufficient internal accountability and the absence of shared sustainability objectives impede the systemic integration of sustainable practices. This study highlights the potential of the SSGI framework to serve as a practical guideline for geographical indication organisations and producers, facilitating the identification of sustainability priorities, the monitoring of progress and fostering continuous improvement. The Sicilian case study provides a valuable example of the broader challenges encountered within the Geographical Indication systems, underscoring the imperative for integrated and collaborative strategies that align the pursuit of quality production with core sustainability principles.
Background and AimsClimate change poses increasing issues to the rapid and successful establishment of new vineyards. In this study, conducted over two consecutive seasons on potted vines, we evaluated the effects of a synthetic potassium polyacrylate hydrogel (WS-SH) and an organic-based hydrogel (WS-OH), both applied at transplanting, on vine water status, productivity, and fruit and wine composition, under progressive water deficit. These treatments were compared with a water-stressed control (WS-C) and a fully irrigated reference (WW-C).Methods and ResultsIn both years, WS-SH and WS-OH treatments delayed the decline in predawn water potential by several days and improved leaf gas exchange under limited irrigation. This led to increased leaf area and overall vine vigor. By the end of the second year, WS-OH had greater root system development compared to all other water-stressed treatments (+17% than WS-C), while WS-SH favored dry matter allocation toward aboveground organs (+17.6%). As a result, both WS-SH and WS-OH vines maintained yields comparable to WW-C, whereas WS-C showed a 33% yield reduction. Due to higher crop loads, WS-SH and WS-OH vines had lower leaf-to-fruit ratios than WS-C (-0.116 m2/kg and -0.147 m2/kg, respectively), resulting in reduced grape sugar content (-1.8 and -1.6 degrees Brix, respectively), anthocyanins (-48% and -51%, respectively), and phenolics (-21% and -23%, respectively). Wines produced at the end of the second season reflected this composition, showing significantly lower alcohol content (-1.11% v/v and -1.05% v/v, respectively), phenolic levels, and chromatic traits.ConclusionsOur results demonstrate that hydrogels applied at transplanting can enhance vine tolerance to water stress and increase yield in the first productive season, in exchange for a reduction in sugar and anthocyanin contents in grapes.Significance of the StudyHydrogels could represent valuable tools to increase vineyard tolerance to summer stresses after transplanting. No substantial differences were observed between the effects of the synthetic and organic hydrogels, highlighting the potential of organic formulations as a sustainable and effective strategy to improve vineyard resilience to summer drought conditions. These results should be confirmed under operational conditions through field experiments.
Background and AimsRootstock type is known to affect the response of grapevines to irrigation with saline water. Less is known, however, about the long-term response. The aim was to compare yield, laminae and grape juice ion composition at flowering and harvest, respectively, wine ion and spectral composition and wine sensory attributes of Shiraz on own roots and five rootstocks at a site that had been assessed over a decade earlier.Methods and ResultsRootstocks were Ramsey, 1103 Paulsen, 140 Ruggeri, Schwarzmann and 101-14. The study occurred over four seasons, including three with small-scale winemaking and two with sensory evaluation. Mean electrical conductivity of the irrigation water across all seasons was 1.84 dS/m. Frost reduced yield in 2007, with no significant difference between each root system genotype (RSG, a term encompassing own roots and rootstock). In the recovery season 2008, yield increased, without significant difference among RSGs, whereas in Seasons 2009 and 2010, yield on 140 Ruggeri and 1103 Paulsen was significantly higher than that on the other RSGs. Laminae chloride (Cl-) concentration was unaffected by season, whereas season means for juice Cl-, potassium (K+), calcium (Ca2+) and phosphorus (P) concentrations ranged from 1.2-4.3-fold higher in season 2007 (frost-affected) than in the other seasons. Mean wine Cl- concentration exceeded wine sodium (Na+) concentration and was highest on own roots and lowest on Schwarzmann and 140 Ruggeri. With one exception (101-14), there was little change in the Cl- concentration between juice at harvest and finished wine in 2007, whereas in 2008 and 2009, the mean increase over RSGs was 2.0-2.4-fold. There was a significant negative correlation between the wine Cl- concentration and palate attribute acidity. The trend in frost-affected 2007 season was lower wine color density, total and ionized anthocyanins, and total phenolics, but higher color hue, compared with Seasons 2008 and 2009, based on means across all RSGs.ConclusionsSustainable yield performance of Shiraz under irrigation with water of around 1.8 dS/m is dependent on RSG. Strong links were established between RSG and wine sensory attributes and between wine spectral and sensory attributes and plant mineral element status. The significantly higher concentration of Cl- in grape juice in the frost-affected season appeared to be a crop load effect rather than an effect on the amount of Cl- transported to the developing crop.Significance of the StudyThe study enhanced the understanding of the impact of RSG on the longer term sustainability of a Shiraz vineyard and demonstrated a role for rootstocks as a component of terroir. To our knowledge, this is the first study to demonstrate an effect of frost on Cl- concentration in fruit and wine.
Background and AimsGrapevine pruning wounds are major infection courts for trunk disease pathogens such as Eutypa lata, the causal agent of the globally devastating disease Eutypa dieback. Recently popularised pruning techniques claim to influence grapevine pathology and physiology. This study investigated whether pruning cut position influences susceptibility of wounds to E. lata and the extent of wood staining associated with natural dieback.Methods and ResultsThree trials were conducted on Shiraz vineyards in South Australia to compare (i) spur-pruning with and without retention of long stubs and (ii) cane-pruning using crown or flush cuts. Wounds were either inoculated with E. lata ascospores or left as noninoculated controls to evaluate natural infection. Retaining stubs or base buds significantly reduced staining and recovery of E. lata compared with no-stub or flush cuts. Crown cuts, where buds were retained, produced smaller wounds and more noncount shoots than flush cuts, where buds were removed.Conclusions and Significance of the StudyThese findings suggest that pruning practices that preserve internodes or base buds can limit infection by E. lata and natural dieback, complementing existing trunk disease management strategies. This is the first study to scientifically confirm the effect of pruning cut position on infection by a grapevine trunk disease pathogen. Further research using a range of cultivars, climates and pathogens is warranted to confirm these results.
An experiment was conducted during 2020 and 2021 in the Region of Murcia (southeastern Spain) to evaluate the impact of increased temperature on 'Monastrell' vine performance. Two rootstocks, 140Ru and 110R-known to confer distinct physiological and agronomic responses-were used. Vines were subjected to control (ambient) and high-temperature (HT) conditions, the latter being induced with open polycarbonate structures from fruit set to harvest. This system increased the cluster-zone temperature by an average of 1.15 degrees C across 2 years. Rootstocks did not affect air temperature or humidity; however, 140Ru exhibited elevated shallow soil temperatures and decreased volumetric water content at a depth of 15 cm, indicating rootstock-dependent dynamics within the shallow layer. In contrast, 110R under HT had higher soil respiration and evaporation rates. The heating treatment elevated VPD and evapotranspiration without inducing water stress, as Monastrell maintained high levels of stomatal conductance and photosynthesis even when cluster temperatures exceeded 35 degrees C. Stomatal regulation differed between rootstocks: 140Ru restricted stomatal aperture under HT, whereas 110R maintained a wider opening. Despite the rise in temperature, vine growth was unaffected and similar across rootstocks. However, HT increased leaf nitrogen and yield parameters (number and weight of clusters and berries) and altered the sugar-acid balance in berries. Furthermore, HT delayed the onset of veraison and early ripening in 110R but not in 140Ru. These results underline Monastrell's resilience to elevated temperatures and demonstrate the influence of rootstock selection on physiological responses in hot, semiarid regions such as SE Spain.
Oxidation-reduction potential (ORP) is frequently used as an indicator of oxygen exposure during red wine fermentation, but its role as a control variable across grape varieties and blending is not understood. In this study, alcoholic fermentations of Grenache (GR), Syrah (SY), and Mourv & egrave;dre (MO) were conducted in quadruplicate under three ORP protocols: control (no ORP setpoint), oxidative (+50 mV ORP setpoint), and reductive (-80 mV ORP setpoint), maintained via pump overs in CON and regulated by air sparging in OXI and RED. ORP protocols differed by variety, with GR exhibiting higher and more variable ORP values than SY and MO under equivalent treatments. Concurrently, SY had higher levels of glutathione, whereas GR had higher levels of the grape reaction product. There were specific treatment- and variety-dependent effects on fermentation kinetics, phenolic composition, color, and volatile profiles. The oxidative ORP protocol resulted in faster fermentation rates, reduced flavan-3-ol concentrations, anthocyanin losses, yellower color, and lower ester concentrations across varieties. To assess ORP-driven effects after blending, wines were combined in equal proportions and compared with values predicted by linear averaging. Several phenolic and volatile parameters fell below predicted values, indicating that blending does not always increase chemical parameters. These results demonstrate that the outcomes of contrasting ORP protocols during alcoholic fermentation are relatively variety dependent and can influence wine composition and the chemical outcomes of blending, highlighting the need for variety-tailored ORP protocols in red winemaking.
Vineyards are facing increased limitations in terms of productivity and quality of grapes due to climate change and rising levels of soil salinization, especially in semiarid environments. Regenerative agricultural approaches, which combine the concepts of soil biological restoration with nutrient and salinity management, offer a promising pathway to enhance sustainability in a climate change scenario. An experiment was conducted to assess a specific set of regenerative agricultural approaches in a salt-affected table grape vineyard, which involved the localized application of well-matured compost (3.0 kg/vine) and the implementation of an opposite-side emitter drip irrigation system. An experimental design was implemented to understand the dynamics of soil microbiology, salinity management, and plant nutrition in a vineyard setting. Soils were analyzed to understand the relationship between rhizosphere microbiology and vine nutrition, with petiole Na levels above 0.5% of dry weight of plant material indicating salinity stress in grapevines. Statistically significant results were obtained in terms of soil organic carbon levels, microbial biomass carbon and nitrogen, and enzyme activity levels in the vineyard soil following the implementation of the regenerative agricultural approaches. These results were supported by a reduction in exchangeable Na+ levels in the 0-15-cm depth layer of the vineyard soil, a reduction in the soil salinity ratio, a reduction in bulk ECe levels, a reduction in bulk pH levels, increased levels of petiole nitrogen and phosphorus, increased levels of leaf area index, increased levels of pruning weight, and increased levels of vineyard yield per vine. These results were obtained using a leaching fraction of 10%-15%.
Background and Aims: Potassium (K) fertilization is vital for grapevine growth and development, as well as for the quality and yield of grape berries. However, conducting experimental field studies to learn about the nutritional demand for K in table grapes can be challenging due to significant K storage in the soil. We examined the effects of various K application levels on two table grape cultivars: the early-bearing green "Early Sweet," and the late-bearing red "Crimson," for three consecutive seasons. Methods and Results: Grapevines were grown in 500-L lysimeters filled with perlite and subjected to three K-fertigation treatments (15, 40, and 72 mg L-1 K). The lowest K level resulted in improved K-use efficiency (> 80%) in both cultivars across the three seasons. However, this efficiency came at the cost of reduced vegetative growth, reflected by reduced leaf area index, and decreased pruning weight in "Early Sweet." Stomatal conductance also declined under low K supply toward the end of the summer, underscoring this mineral's (elemental nutrient's) role in stomatal regulation. Together, these resulted in reduced daily water consumption. Low K supply resulted in lower fruit juice pH in the 2022 and 2023 seasons in "Crimson." Conversely, elevated K levels in 2023 and 2024 suppressed sugar accumulation in developing berries of both cultivars. Conclusions: Varying K fertilizer levels significantly affected vegetative growth, physiological processes, and berry sugar content of early- and late-bearing table grape cultivars. Significance of the Study: Optimization of K levels is essential for promoting growth, nutrient uptake, yield, and fruit quality in table grapes.
Background and AimsLeaf area index (LAI) is an important parameter to support vineyard management decisions. However, the common indirect methods for LAI measurement using imagery pose significant challenges, including over-estimation, impracticality in block-level LAI mapping, and interaction with non target foliage.Methods and ResultsThis study proposes a method to map the LAI based on side-view imagery collected continuously by mounting a smartphone on a farm vehicle. The proposed method first estimated the absolute leaf area (LA) for the trunk-to-trunk area of each vine based on the Beer-Lambert law and then calculated the LAI by dividing this by the ground surface area. The LAI estimation from the side view was evaluated against the LAI from the traditional bottom-up view imagery and the direct destructive LAI measurements. Data were collected at four different dates during the season from a vineyard in Australia. Results showed a near 1-to-1 relationship between the proposed LAI method and the direct LAI measurements with a mean absolute error (MAE) of 0.2, whereas the traditional bottom-up view imagery showed an overestimation error with a MAE of 0.4, suggesting a need to introduce a calibration procedure specific for the vineyard. The R2 value of the proposed LAI method and LAI from a destructive assessment ranged from 0.75 to 0.94.ConclusionsThe proposed LAI method demonstrates the capability to robustly and continuously map the vine-level LAI for the whole block easily and efficiently.Significance of the StudyThis method offers an easy and inexpensive option for vineyard managers to use maps of LAI to support informed decision making.
Background and AimsClimate change and reduced precipitation pose significant challenges for the wine industry, particularly in vulnerable regions, where it is essential to incorporate irrigation management tools. Regulated deficit irrigation (RDI) is a step forward in that direction. Still, its adoption in Chile has been slow, partly due to inconsistent results regarding its impact on grape composition, a product of low experimental scalability, and, in general, highly variable applied water and vine stress due to the lack of actual evapotranspiration (ETa) assessment on study sites. This study aimed to understand the impact of RDI on yield, vine balance, and grape volatile and nonvolatile composition in an industrial-scale 5-year trial using precise ETa-based irrigation.Methods and ResultsA five-year experiment with three RDI regimes and a control was conducted in Maule Valley, Chile. Different portions of ETa from pea size to harvest were replenished as follows: 100% ETa (control), 70% ETa, 50%-100% ETa, and 35%-100% ETa (50 or 35% ETa before veraison and 100% ETa after). The experiment covered 4.54 ha, including a 1.2 ha control treatment in which a flux tower was installed to assess ETa. Midday stem water potential, yield components, and grape volatile and phenolic composition were measured. RDI reduced yield, mainly due to lower cluster weight as a result of smaller and fewer berries. Concentration on a fresh-weight basis of total anthocyanin, tri-hydroxylated anthocyanins, tannins, and specific flavonols, including quercetin, myricetin, and syringetin glycosides, was higher in the two most water-restrictive RDI treatments, while total soluble solids and acidity were lower. Also, the same treatments showed increases in positive aromas, including alpha-terpineol, beta-damascenone, linalool, and nerol, as well as possibly undesired aromas such as IBMP and hexenal. While some metabolites indeed increased their per-berry content, suggesting an upregulation of metabolism, most of the observed increments were simply driven by berry size reduction.ConclusionsOverall, most of the changes caused by RDI are positive in terms of grape quality, with higher color and aroma concentrations. To achieve most of the positive effects, RDI needs to reach at least 50% of the ETa, particularly from pea size to veraison.
While phenolics determine wine's sensory and functional properties, white grape varieties remain less studied than red grape varieties in terms of phenolic profiling. Five white grape varieties and Chardonnay (control) were analyzed from veraison to bottling for phenolics and physicochemical properties to identify suitable cultivars for temperate monsoon climate conditions. The berries of M1 had a relatively low sugar content (181.6-192.3 g/L in 2022; 160.1-165.4 g/L in 2023), making them suitable for the production of low-alcohol wine. The berries of L1 and R3 showed the most desirable sugar-to-acid balance (29.85-33.86 in L1; 30.38-34.96 in R3) for winemaking in 2022, while Chardonnay (CK) exhibited the optimal ratio (31.13-33.27) in 2023. The wine made from R3 was characterized by high acidity. During the 2 years, phenolic content in the skins of all six varieties generally decreased during their growth and development, reaching the lowest value at harvest time. The content of phenolic substances in the berries and wines of L1 was significantly higher than that of other varieties. R2 berries contained the highest resveratrol content (> 95 mu g/g, DW) among all cultivars. R1 berries contained a relatively high content of kaempferol (> 34 mu g/g, DW). The specific enrichment of these monomeric phenols marks varietal differences in antioxidant capacity and reveals inherent photoprotection mechanisms, which provides a foundation for targeted breeding and healthy wine development. Taken together, the new white grape varieties exhibited distinct phenolic profiles and physicochemical characteristics, expanding viticultural options for Yantai and similar regions.
The study aimed to develop predictive models for key grapevine phenological stages in northern climates using 15 years of field observations. The research focused on major cultivars grown in eastern Canada (Frontenac, Marquette, Seyval, and Vidal), where viticulture is expanding. Key phenological stages were grouped into six categories, and their distribution as a function of weather-based explanatory variables was modeled using multinomial logistic regression. Temperature- and humidity-related variables were evaluated based on the percent correct classification of the six categories. There were the categories: 1 (BBCH 5-9); 2 (BBCH 51-53); 3 (BBCH 57-61); 4 (BBCH 71-76); 5 (BBCH 81-83); and 6 (BBCH 88-91). Overall, the best explanatory variables were the degree days in either Tb = 0 degrees C or Tb = 10 degrees C. Adding humidity-related variables did not significantly improve model accuracy. The final models resulted in a percent correct classification of all six phenological stage categories of 90.1%, 91.4%, 89.2%, 88.2%, 87.4%, and 88.4% for the Frontenac, Marquette, Seyval, and Vidal cultivars; other cultivars; and all cultivars, respectively. The resulting models provide probability curves for each phenological stage category, allowing for prediction of stage onset and duration. We explored a different approach to modeling phenological stages in our study. Our goal was to develop single models that can predict when multiple stages are reached. These models are intended for integration into decision support tools for managing grapevine diseases, optimizing canopy management, and harvest timing.
