The Effect of Partial Defoliation on Quality Characteristics of Vitis vinifera L. cv. Cabernet Sauvignon Grapes 1. Sugars, Acids and pH

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The effect of variation in berry size on berry composition was studied in irrigated Syrah/R99 grapevines, located in a temperate area of South Africa. Berries from 45 clusters, sampled from both sides of the canopy (east and west), were weighed to create four categories: 1. less or equal to 1.5 g; 2. between 1.51 g and 2.00 g; 3. between 2.01 g and 2.50 g; 4. more than 2.50 g. Berry physical characteristics were determined and total anthocyanins and seed flavonoids were analysed by spectrophotometry and anthocyanin profiles by HPLC. The ratio of skin weight:berry weight did not change with increasing berry size, but the ratio of seed weight:berry weight increased. For total anthocyanins, varying results were obtained if values were expressed in mg/berry, mg/g skin, mg/kg grape and mg/cm 2 skin. The quantity of total anthocyanins changed positively with increasing berry weight if expressed in mg/berry and remained almost similar if expressed in mg/cm 2 of skin. In contrast, total polyphenols decreased with berry weight if the values were expressed in mg/kg grape and in mg/g skin. Total anthocyanins expressed in mg/kg grape and in mg/g skin were correlated positively to the number of berries as well as to the total skin surface in one kilogram of grape. In this study, the largest berries seemed to have lower quality characteristics. In order to obtain better wine quality, it seems important to reduce berry weight and, in general, berry size variability of Syrah. The obtainment and continuity of a particular wine style may be affected by berry variability.

Section: Introductionmentioning

confidence: 57%

Berry Size and Qualitative Characteristics of Vitis vinifera L. cv. Syrah

Barbagallo¹,

Guidoni²,

Hunter³

2016

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“…Source-sink ratios play an important role in the seasonal variation of water and solute transport and accumulation in the grape berry. In this regard, the reaction of the vine depends largely on the level and timing of manipulation (Koblet 1987;Kliewer et al, 1988;Hunter et al, 1991;Poni et al, 1994;Kliewer & Dokoozlian 2005). As in most fleshy fruits, water and carbon transport into and out of grape berries is essential for volumetric growth and the accumulation of primary and secondary compounds, which determine the final fruit composition and quality (Coombe & McCarthy, 2000).…”

Section: Introductionmentioning

confidence: 99%

Leaf:Fruit Ratio and Vine Water Status Effects on Grenache Noir (Vitis vinifera L.) Berry Composition: Water, Sugar, Organic Acids and Cations

Etchebarne¹,

Ojeda²,

Hunter

2016

Seasonal variation in the water, sugar, organic acid and cation contents of developing grape berries (Vitis vinifera L. 'Grenache noir') under different levels of water supply (with and without deficit irrigation) and leaf:fruit ratios (18, 10 and five leaves per primary shoot, with one bunch per shoot), were investigated over two successive years in Mediterranean conditions (South of France). Fourteen shoots per vine were left for each leaf:fruit ratio level, and each vine was considered as having homogeneous primary shoots. The growth rate of the berries was increased with irrigation. Total dry matter content of the berry was not affected by leaf:fruit ratios, but the sugar loading decreased during berry development with a lower leaf:fruit ratio (five leaves per bunch). Treatments had little effect on organic acid contents and pH. Berry cation accumulation depended on vine water status and not on the total leaf area of the vine. Under irrigated conditions, calcium continued to accumulate in the berries after véraison. This confirms a partial functioning of the berry xylem during the post-véraison period. The seasonal variation in berry composition was less dependent on the leaf:fruit ratio than on the water status of the vine (mainly cations and sugar). This study provides evidence for the importance of plant water status effects on berry composition, irrespective of the leaf:fruit ratio. Vine water status is a major regulating factor for source-sink relationships.

“…Macro-, meso-and micro-environmental conditions, as well as viticultural and oenological practices, would all affect these compounds either directly or indirectly via chemical and/or physical changes (Carbonneau et al, 2007;Iland et al, 2011). Together with, inter alia, soluble solids and titratable acidity (Hunter et al, 1991;Cliff et al, 2002;De Souza et al, 2005), the phenolic compounds therefore largely define the final wine quality.…”

Section: Introductionmentioning

confidence: 99%

Integrative Effects of Vine Water Relations and Grape Ripeness Level of Vitis vinifera L. cv. Shiraz/Richter 99. II. Grape Composition and Wine Quality

Hunter

Volschenk

Novello

et al. 2016

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Regulation of grapevine water status is a common practice to manipulate grape composition and wine quality. In this investigation the effect of plant water status (two field water capacity-based irrigation levels, 75% and 100%, applied at single and combined vine developmental stages) and ripeness level (harvesting at different soluble solid levels) on grape composition and wine quality of Vitis vinifera L. cv. Shiraz/ Richter 99 was determined. Integrative effects of vine water relations and grape ripeness level, specifically in a Mediterranean high winter rainfall area, have not yet been investigated systematically. Source:sink mechanisms and dynamics and compositional and physical changes during both green berry and ripening periods (and in response to environment changes), seemed critical for the final grape composition and wine quality/style. Despite relatively favourable conditions of the experiment terroir, additional water was still required to obtain best grape and wine quality. Skin colour and total phenolic contents were stimulated in particular by 75% (field water capacity) pea size (PS) irrigation, post-véraison (PV) irrigation and 75% pea size+post-véraison irrigation, until the last harvest stage. Treatments that included post-véraison irrigation were not negative in terms of ripening parameters. Increasing total soluble solids with ripening were not followed in parallel by anthocyanin potential. Anthocyanin extractability increased with ripening. A late, overripe harvest may result in wines that are slightly better coloured, but highly alcoholic and tannic. Furthermore, at high ripeness level, differences between treatments largely diminished. Over-ripeness of grapes may have tempering and even negative effects on expected outcomes of seasonal cultivation efforts to produce unique wines. This would not favour economic viability. Although non-irrigated wines failed to result in exceptional wine quality at any harvest stage, a better result in overall quality was obtained in comparison to irrigation treatments applied at all stages. Berry and wine composition results corresponded with findings on wine sensorial quality. The 75% PS, PV irrigation, and 75% PS+PV irrigation consistently resulted in good quality wines. At the first harvest stage, 75% PV, 100% PV, 75% PS+V and 75% PS+PV irrigations gave most prominent wines; at the second harvest stage, vines irrigated 75% at PS, 75% at PS+PV and 75% at PV delivered most prominent wines; and at the third harvest stage, 75% PV, 100% PV, 75% PS and 75% PS+PV resulted in most prominent wines. These treatments represented different wine styles at each harvest stage. Restricted PS irrigation and PV irrigation, as single or combined treatments, featured prominently in favouring grape and wine composition and wine sensorial quality. Physical and compositional changes in ripening berries and the impact on wine quality and style were further clarified. New perspectives on managing time of harvesting with varying vine water status are given. Recommendations on vi...