Chemical composition and sensory properties of Albariño wine: Fertigation effects.

Interannual climate variability and management practices, including fertigation, can alter volatile compound concentrations in wines from a given grapevine cultivar. These compounds are highly relevant for wine aroma. The current study aimed to assess the effect of two levels of fertigation on the volatile composition and sensory properties of wines from Albariño grown in two vineyards in NW Spain over three years. Treatments were fertigation to 60% (F-60) and 100% (F-100) of crop needs since budbreak, and a rain-fed control (F-0). Volatile compounds were determined through gas chromatography and mass spectrometry (GC-MS) and wine sensory evaluation was performed by nine experts using quantitative descriptive analysis. General chemical parameters of wines were similar among treatments; however, F-60 and F-0 slightly reduced volatile total concentrations in both vineyards. Wines from the fertigation treatments had greater concentrations of volatile fatty acids, ethyl esters, acetates and C6 compounds. However, terpene concentrations slightly decreased when fertigation was applied. Higher alcohols showed a different behavior between vineyards, mainly related with grapevine water status during the growing season. Seven sensory descriptors differed significantly between vineyards. This study indicates that fertigation could be a tool for modulating wine chemical and sensory characteristics.

Influence of supplementary irrigation on the amino acid and volatile composition of Godello wines from the Ribeiro Designation of Origin.

Concentrations of amino acids and volatile compounds of a given grapevine cultivar might be altered by inter-annual climate variability and management practices such as irrigation. These compounds determine, in part, aroma and sensory characteristics of wines. The current study aimed at assessing the amino acid profile of musts and wines and the volatile composition of wines from Vitis vinifera (L.) cultivar 'Godello' grown in the Ribeiro Designation of Origin (NW Spain) under rain-fed and supplementary irrigation (SI) conditions over three years (2012-2014). Supplementary irrigation increased must titratable acidity. However, must amino acid concentrations were not significantly altered by SI. In contrast, the concentrations of ethyl lactate and geraniol were greater in wines from the SI treatment. Significant correlations between amino acids in musts and volatiles in wines were observed. Our results highlight the low impact of SI on must and wine composition, likely due to the low level of water stress experienced by Godello vines. Understanding the effects of SI on wine properties could aid to adapt management practices in the future.

Disentangling the Effects of Water Stress on Carbon Acquisition, Vegetative Growth, and Fruit Quality of Peach Trees by Means of the QualiTree Model.

Climate change projections predict warmer and drier conditions. In general, moderate to severe water stress reduce plant vegetative growth and leaf photosynthesis. However, vegetative and reproductive growths show different sensitivities to water deficit. In fruit trees, water restrictions may have serious implications not only on tree growth and yield, but also on fruit quality, which might be improved. Therefore, it is of paramount importance to understand the complex interrelations among the physiological processes involved in within-tree carbon acquisition and allocation, water uptake and transpiration, organ growth, and fruit composition when affected by water stress. This can be studied using process-based models of plant functioning, which allow assessing the sensitivity of various physiological processes to water deficit and their relative impact on vegetative growth and fruit quality. In the current study, an existing fruit-tree model (QualiTree) was adapted for describing the water stress effects on peach (Prunus persica L. Batsch) vegetative growth, fruit size and composition. First, an energy balance calculation at the fruit-bearing shoot level and a water transfer formalization within the plant were integrated into the model. Next, a reduction function of vegetative growth according to tree water status was added to QualiTree. Then, the model was parameterized and calibrated for a late-maturing peach cultivar ("Elberta") under semi-arid conditions, and for three different irrigation practices. Simulated vegetative and fruit growth variability over time was consistent with observed data. Sugar concentrations in fruit flesh were well simulated. Finally, QualiTree allowed for determining the relative importance of photosynthesis and vegetative growth reduction on carbon acquisition, plant growth and fruit quality under water constrains. According to simulations, water deficit impacted vegetative growth first through a direct effect on its sink strength, and; secondly, through an indirect reducing effect on photosynthesis. Fruit composition was moderately affected by water stress. The enhancements performed in the model broadened its predictive capabilities and proved that QualiTree allows for a better understanding of the water stress effects on fruit-tree functioning and might be useful for designing innovative horticultural practices in a changing climate scenario.

Effects of irrigation over three years on the amino acid composition of Treixadura (Vitis vinifera L.) musts and wines, and on the aromatic composition and sensory profiles of its wines.

Amino acids and volatile compounds play an important role in wine aroma and sensory characteristics. The concentrations of these compounds might be altered by climate interanual variability and by management practices such as irrigation. The aim of the current study was to assess the amino acid profile of musts and wines, volatile composition and sensory profile of wines from Vitis vinifera (L.) cultivar 'Treixadura' obtained from vines under rain-fed and irrigation conditions over three consecutive vintages (2012-2014). Musts and wines from the irrigation treatment tended to be higher in acidity than those from rain-fed. However, amino acid and aromatic profiles were mostly affected by climate conditions of each year; although irrigation exerted a significant effect on several compounds (proline, cysteine, tryptophan, phenylalanine, α-terpineol and geraniol). Wines from both treatments received similar marks in the sensory tests, suggesting that irrigation did not greatly modify wine quality under the conditions of this study.

Grape Composition under Abiotic Constrains: Water Stress and Salinity.

Water stress and increasing soil salt concentration represent the most common abiotic constrains that exert a negative impact on Mediterranean vineyards performance. However, several studies have proven that deficit irrigation strategies are able to improve grape composition. In contrast, irrigation with saline waters negatively affected yield and grape composition, although the magnitude of these effects depended on the cultivar, rootstock, phenological stage when water was applied, as well as on the salt concentration in the irrigation water. In this context, agronomic practices that minimize these effects on berry composition and, consequently, on wine quality must be achieved. In this paper, we briefly reviewed the main findings obtained regarding the effects of deficit irrigation strategies, as well as irrigation with saline water, on the berry composition of both red and white cultivars, as well as on the final wine. A meta-analysis was performed using published data for red and white varieties; a general liner model accounting for the effects of cultivar, rootstock, and midday stem water potential was able to explain up to 90% of the variability in the dataset, depending on the selected variable. In both red and white cultivars, berry weight, must titratable acidity and pH were fairly well simulated, whereas the goodness-of-fit for wine attributes was better for white cultivars.