Background and Aims: Grapevine berry ripening is driven by water and sugar loading from the phloem, beginning with berry softening and ending at physiological maturity. This study aimed to characterise the kinetics of sugar and water accumulation at the berry population level under different climatic, vigour and crop management conditions. Methods and Results: The experiments were conducted in a commercial vineyard of the ‘Tannat’ cultivar in Uruguay, for 8 years. Two zones with high (H) and low (L) vigour were delimited. In two contrasted rainy and dry years, specific treatments (nitrogen, water availability and leaf/fruit ratio) were carried out. The sugar and water accumulation kinetics were studied on populations of berries, which were both synchronised from the onset of ripening to maximum sugar loading and normalised by their maximum volume. A bilinear model between berry growth and sugar accumulation was fitted, indicating an apparent uncoupling between water and sugar loading. Wet and high‐vigour conditions accentuated this apparent uncoupling compared to dry and low‐vigour conditions, with maximum berry growth reached earlier than the maximum sugar content. In addition, management practices favouring plant water and carbon status positively influenced the duration of ripening (up or down). Conclusions and Significance: This study provides a deeper understanding of how management practices can be harnessed to improve grape production. Water management was a key lever to counteract the climatic and/or vigour impact both on the apparent uncoupling between berry growth and sugar loading at the population level and the asynchrony of berry development within the population.

The 'Tannat' grapevine variety is known for its high polyphenolic content in grapes but low anthocyanin extractability. Secondary metabolite accumulation during ripening is influenced by a complex interplay of environmental factors and plant responses. While scientific literature indicates that abscisic acid (ABA) applications at veraison can modify the polyphenolic content of grapes, the effects can vary based on the dosage and climatic conditions. However, limited literature exists on the changes of grape skin anatomy in response to exogenous ABA applications during ripening. This study aimed to investigate the effects of ABA applications on 'Tannat' grapevines on the grape skin anatomy and polyphenolic compounds during ripening at two different locations. The results demonstrate that location was a key factor that significantly affected grape polyphenol content, under temperate-warm climate conditions and temperate, sub-humid nights (TSH) resulting in higher phenolic compound levels. Additionally, warm climates favored anthocyanin extractability. Grape skin cell typologies evolve differentially; while empty cells (type I) were independent of the climatic conditions, cells with anthocyanin accumulations (type II, III, IV and V) vary based on their polymerization degree in response to the climate conditions. ABA applications increased the total anthocyanin contents in the grapes harvested in the TSH location but did not affect their content in the WH site. The evolution of the anatomy of skin cells of 'Tannat' can help to better adjust 'Tannat' vineyard management in different viticulture regions (canopy management, exogenous ABA treatments, irrigation) and to improve wine production techniques (maceration days for anthocyanins extractability, aging of wines, etc.).

Grape ripening is a complex process conditioned by climatic factors, which influence the evolution of solutes and define its composition. The objective of the study was to evaluate the behavior of the red Tannat variety in contracting climatic situations, considering the dynamics of berry growth, the rate of accumulation and reduction of solutes during ripening, and their composition at harvest. The trial was installed in two regions, warm and temperate climate, in rainfed commercial vineyards, during 2018 and 2019. Primary berry composition at ripening and secondary composition at harvest were determined. Multivariate analysis and comparison of means (Fisher's LSD test) were performed. The climatic type (region) conditions the evolution of solutes at ripening, but their interaction with annual conditions determines berry composition. The annual variability is explained by rainfall, with a direct influence on the duration of the cycle and the ripening, size, and composition of the berry. In warm climates, there is greater sensitivity to the ripening year effect, with a strong influence on the rapid phase. In temperate climates, the greater stability between years results from a thermal condition more favorable to ripening processes.

Grape ripening is a complex process conditioned by climatic factors, which influence the evolution of solutes and define its composition. The objective of the study was to evaluate the behavior of the red Tannat variety in contracting climatic situations, considering the dynamics of berry growth, the rate of accumulation and reduction of solutes during ripening, and their composition at harvest. The trial was installed in two regions, warm and temperate climate, in rainfed commercial vineyards, during 2018 and 2019. Primary berry composition at ripening and secondary composition at harvest were determined. Multivariate analysis and comparison of means (Fisher’s LSD test) were performed. The climatic type (region) conditions the evolution of solutes at ripening, but their interaction with annual conditions determines berry composition. The annual variability is explained by rainfall, with a direct influence on the duration of the cycle and the ripening, size, and composition of the berry. In warm climates, there is greater sensitivity to the ripening year effect, with a strong influence on the rapid phase. In temperate climates, the greater stability between years results from a thermal condition more favorable to ripening processes.

This study aimed to assess the variability of soil properties and its association with vine vigor in a commercial vineyard to identify homogeneous management zones based on soil properties. Soils were sampled on a regular grid. The spatial distributions of several soil properties were mapped and, later, a multivariate technique was employed to delineate site-specific management zones (MZ). Correlation between soil properties variability and normalized difference vegetation index (NDVI) variability was studied, to identify the more efficient method for the delineation of zones. Soil properties that mainly contributed to the soil variation within a vineyard were: apparent soil electrical conductivity (ECa), clay, sand, soil bases, soil moisture, soil penetration resistance, and pH. Two management zones were delineated. Positive relationship between ECa and NDVI was found on one of the vineyards, being the highest grapevine vigor associated with greater clay, calcium, magnesium, pH, and soil moisture content, and lower soil penetration resistance, sand, and sodium content. The opposite trend was observed in the vineyard with higher clay content and greater soil penetration resistance. The characterization of soil spatial variability through multiple variables, proved to be more effective in identifying relevant properties that impact plant vigor when analyzed collectively using geostatistics. The zoning was primarily influenced by properties that determine water and nutrient supply and root development. This study validates a methodology for delineating MZ on clayey soils and raises a question regarding the inverse relationship between EC and NDVI in clayey soils.

Climate is one of the main components that define the development and behaviour of the plant, conditioning the health status and the final quality of the grapes. The objective was to describe the precipitation (PP) variability during the last 32 years and how Tannat and Albariño responded in three growing seasons (GS). We analyzed PP data from two agro-meteorological stations and calculated descriptive indexes. In addition, we measured vine water potential, plant physiological parameters, grapes’ final composition and health status at harvest in 2019, 2020 and 2021. In the last 32 years, PP during GS ranged from 133-1154 mm and 10-599 mm during the grape ripening period. An average of 51 days had PP, which means one event every four days. However, when analyzing the dry periods (moving average of 15 days with PP<6 mm), 24 events per GS were recorded with a variability from 0-101, which shows the alternation between excess and deficit of water in the terroir. Regarding plant response, both cultivars showed differences in soluble solids, pH and berry weight between GS. In particular, Albariño showed differences in bunch weight. In contrast, Tannat showed differences in total acidity, anthocyanins, leaf area, yield with the incidence of Botrytis cinerea sp., pruning weight and bunch weight between GS. Therefore, the inter-annual variability had an impact on Tannat performance. Still, Albariño was more stable than Tannat between rainy and dry GS, an interesting option for winegrowers searching for durable and sustainable products.

Climate is one of the main factors conditioning the chemical composition of grapes and wine. At a vineyard scale, during the growing season, topography can explain spatial temperature variability. Furthermore, each topographical factor (altitude, slope, exposure) may have a different impact on grapevine pro-duction, even in low altitude terrains. This work aims to evaluate the mesoclimate of Uruguay's Atlantic region and determine the topography and ocean's effect on temperature and, thus on the response of the 'Tannat' grapevine. Data from 19 temperature sensors, installed in a coastal vineyard under contrasted topog-raphy conditions, were used over three growing seasons in order to study the relationships between bioclimatic indicators of dif-ferent sites and the plant response of nine 'Tannat' plots under similar agronomical management and soil type. Mesoclimate, especially due to altitude and exposition to the ocean winds, mostly explained 'Tannat' variability. Significant differences in ex-treme temperatures (minimum and maximum) were observed: The plots at higher altitudes (118-140 m a.s.l.) exposed to oce-anic winds had a lower daytime temperature than the plot shel-tered at lower altitude (70-94 m a.s.l.). The average difference was 0.9 degrees C during the hottest summer, reaching 1,7 degrees C between the most contrasted sites. In particular, the local sea breeze cir-culation during heat waves of the ripening period, prevent ex-treme high temperatures in sites facing the ocean. Temperature drop of 4.3 degrees C in upwind sites was noticed, against 0.9 degrees C in shel-tered plots. The plots at lower altitude presented a nighttime temperature lower than plots at higher altitude (up to 1.0 degrees C low-er, on average, during ripening), thus resulting in greater diurnal thermal amplitude (1.5 degrees C greater). A direct association between altitude, mesoscale temperature and 'Tannat' grape metabolites was observed for three consecutive years: plots at higher alti-tude recorded significative greater malic acid (+1.7 g L-1), while plots at lower altitude recorded greater anthocyanin potential (ApH1) (+1920 mg L-1). Other variables such as soluble solids, total titratable acidity, pH and polyphenols were differentiated at least over one growing season. No significant differences agronomic response parameters such as yield, pruning weight and Ravaz Index were observed. Topographic differences less than 70 m a.s.l. but enhanced by the Atlantic Ocean influence, made it possible to differentiate plots with equal vine respons- es. Seasonal and spatial climatic characterization of the region fine scale along with grapevine response will allow to optimize agronomic decisions especially in search of fresh terroirs where the vines can adapt to climate change.

This study aimed to determine how within-plot soil heterogeneity combined with yearly climate variability can promote the heterogeneity of vine growth at plot level, and which soil-climate parameters influence final yield and berry composition the most. An 8-year experiment was conducted on grapevine in two zones of a vineyard (1 ha) differentiated according to grapevine vigour as determined by NDVI: high vigour (HV) and low vigour (LV). The heterogeneity of the soil properties (depth, texture and composition), plant growth (shoots and roots) and plant production (yield components and berry composition) were determined at plot level. Compared to the LV zone, the HV zone was associated with deeper soils, higher soil water and nitrogen availability, CEC and montmorillonite/illite ratio. More extended root systems, higher vegetative growth and higher yield were observed in the HV zone compared to the LV zone. Drier and warmer vintages increased the difference in heterogeneity of vine growth and yield between the two zones. Berry composition (primary and secondary metabolites) also differed between HV and LV zones but seemed unconnected to vigour and mainly depended on soil-climate-plant interactions over the years. The heterogeneity of plant vigour within the vineyard mainly resulted from differences in root exploration, soil profile and composition (notably montmorillonite/illite ratio). The present study identified soil and crop factors that, depending on weather conditions, can be drivers for reducing the heterogeneity of plant development and improving productivity at vineyard level.

Climate scenarios in the medium and long term (2010-2070) foresee increased summer rainfall for Uruguay and the region, with increased water deficits and excess episodes. Although at the international level irrigation in viticulture has a long experience and tradition, at the local level (Uruguay), only 10% of the vineyard surface area implements a fixed or complementary system for water supply in their crops. This work aimed to model the crop water requirements for a vineyard in southern Uruguay based on pedo-climatic variables. In addition, the plant response to controlled deficit irrigation was evaluated in two consecutive seasons. The experiment was conducted in a 1.1 ha commercial vineyard in Canelones, Uruguay (34°36'S, 56°14W), during two successive seasons (2020-2021). The additional irrigation (I) treatment was compared against a control (C) without irrigation. A controlled water deficit was established from flowering to harvest. The adjustment in the demand was made as a function of a percentage of crop evapotranspiration. The Kc of the crop was estimated using digital tools. The simulation of the water balance made it possible to evaluate the vineyard water needs. Plants subjected to controlled deficit irrigation showed higher vegetative growth, positively impacting yield and the accumulation of sugars and anthocyanins in the berry. Based on our results, a supplementary water supply, at the right doses and time, allows us to face water deficit situations, positively impacting the productive and economic variables. Knowing the variability in a vineyard is necessary to achieve proper irrigation scheduling and optimize water use. New technologies applied to irrigation are an opportunity for winegrowers to obtain more sustainable vineyards and production.

The spatial variability of vineyards can be characterised through precision viticulture that will allow setting the boundaries of homogeneous management zones. This study aimed to evaluate the impact of soil and plant management (site-specific management) to increase yields and improve berry quality. During three consecutive seasons, contrasting treatments designed ad hoc for two zones of vigour pre-established by NDVI were tested: high vigour zone (HV) and low vigour zone (LV). The treatments were aimed at reducing water and nitrogen supply and improving microclimatic conditions in the cluster zone in the HV zone. In the LV zone, treatments were aimed at increasing water and nitrogen supply. Leaf removal in the HV zone was the most efficient treatment to improve productivity and quality. Moreover, the water restriction improved grape quality, especially in a rainy year. The regulated deficit irrigation strategy applied in the LV zone at specific phenological stages was shown to increase vegetative growth, yield and to improve grape anthocyanins and phenols contents. The benefits of additional nitrogen supply in the LV zone on plant nitrogen status, yield, and berry composition were highly dependent on water availability. Ultimately, this study provided new insights into the relationship between water and nitrogen availability and how this determines vigour and influences yield and grape quality and influences the deviation from a “Productive Target” pattern. The use of site-specific techniques could be adjusted on a small production scale, thanks to mapping carried out with precision viticulture technologies.

Soil physical and chemical characteristics play a key role on vine growth and yield. The soils of South Uruguay display high content of montmorillonite or illite. The proportion of these minerals deserves special attention as they influence the soil structure and its hydrological properties. The present study was conducted in a 1.1 ha vineyard of this region (Canelones), characterized by a high heterogeneity of plant vigour. It was aimed to determine and map the physical and chemical properties of the soil and their relations with plant vigour and yield. The cation exchange capacity (CEC) and the clay and organic matter contents were measured in 84 locations within this vineyard to calculate the montmorillonite and illite contents of the soil. In addition, the type and abundance of clays was corroborated by X-ray diffractometry analysis. The CEC and montmorillonite contents were positively correlated with vine vigour, expressed by the Normalized Vegetation Index (NDVI), trunk diameter, pruning weight, leaf area, and with yield. Thus, the within vineyard distribution of the ratio montmorillonite/illite conditioned the heterogeneity of vine growth and yield at the field level. The impact of those minerals on water and mineral supply to the plant is discussed.

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