Selection of a suitable rootstock lays the foundation for meeting vineyard, grape and wine objectives. Tolerance to biotic and abiotic conditions is a determining factor. Despite the significance of the grapevine root system in vegetative and reproductive growth as well as grape and wine composition and quality, root behaviour under an array of very complex and integrated environmental impacting factors is largely unknown and research in this regard is surprisingly limited. In this paper, a compilation of some of the research done over many years on root system behaviour is presented. Various aspects of the interaction between the root system and the complex natural environment in which it grows as well as commonly known viticulture practices are discussed. Results obtained under controlled and field conditions are shown. Physical and chemical properties and pre-establishment preparation of the soil have defining effects on metabolic behaviour and spatial distribution (horizontally and vertically) of roots. Alleviation of soil impediments to root penetration provides the best possible basis for above-ground growth. The health status of plant material, genetic characteristics and grafting and nursery processes have a steering impact on the ability of the root system to perform within biotic and abiotic constraints of the soil environment to such an extent that expectations in terms of growth, yield and grape quality of the scion are met. Agronomic practices exert a further tailoring impact on root system performance and support to above-ground growth. The study of only above-ground factors is clearly not sufficient to explain vineyard behaviour. Intensified inter-disciplinary research efforts are required in our quest to understand scion-root system inter-relationships and to control scion behaviour in order to facilitate greater sustainability in grape and wine production.
The implications of pre-veraison canopy management and ripeness level (19°B and 21°B) on microclimate and grape and must composition were determined on intensively micro-sprinkler irrigated Vitis vinifera L. cv. Sauvignon blanc/110 Richter vines, grown on a vertical trellis in the Breede River Valley of South Africa. Rows were east-west orientated and vines spaced 2.75 m x 1.5 m. Spurs were spaced approximately 15 cm apart. Canopy management consisted of different combinations of seasonal practices (suckering, shoot positioning, topping, leaf thinning) during the pre-veraison growth period (just after budding to pea size berry) in order to accommodate foliage and to improve the canopy microclimate. Treatments that included leaf thinning improved the light conditions in the canopy without a noticeable effect on other microclimate parameters as well as bunch and berry sap temperature. The must pH remained relatively stable, with an increase in ripeness level from 19°B to 21°B, whereas the rest of the measured grape composition components followed a decreasing pattern during this period. Treatments that included leaf thinning tended to increase titratable acidity and decrease pH at both ripeness levels. Additional leaf thinning (up to the lower half of the canopy at pea size) increased the glucose and fructose concentrations without changing their ratio. It also decreased the malic acid concentrations of the berries, whereas the free-amino-nitrogen content of the must was stimulated. Furthermore, leaf thinning in general increased the monoterpene content (fruity aroma) and apparently enhanced the 2-methoxy-3-isobutylpyrazine content (grassy/green pepper aroma), thereby increasing the total measured aroma profile. Both palate and flavour profiles were therefore changed by applying pre-veraison seasonal canopy management. The data emphasised the importance of the correct timing and application of canopy management. This seemed to be of great significance in the realisation of an improved grape composition, even for S. blanc subjected to a relatively hot terroir.
Vitis vinifera L. cv. Cabernet Sauvignon/99 Richter was grown under field conditions. The effect of partial defoliation (33%) in the lower half of the canopy at berry set stage, and thereafter at pea-size and veraison, respectively, on root development, distribution, and composition as well as on canopy efficiency, yield, grape composition, and wine quality was investigated. Defoliation evidently stimulated occurrence of fine and extension roots, which may have increased the absorptive capacity of the root system. Root number decreased with increasing depth and roots occurred predominantly in the top 800 mm of the soil profile. Starch was the principal carbohydrate storage form in the roots, irrespective of root size. Starch synthesis appeared not affected by root age. Sucrose and organic acid patterns were similar. Citric and tartaric acids were the main organic acids in roots, followed by malic acid. Elevated sugar and organic acid levels were found in roots of treated vines. The results demonstrate that the remaining leaves of partially defoliated vines were able to sustain normal metabolic functions in the roots. Canopy density was efficiently reduced by partial defoliation, leading to increased light penetration, fruit exposure, and photosynthetic activity of mature and old leaves. Although partially defoliated vines had much less leaf area per gram fresh berry mass at ripeness, yield increased considerably with defoliation at pea-size and veraison. Root density, yield, and cane mass were related. Grape total soluble sugar content was unaffected, but titratable acidity increased and the pH of the must decreased with partial defoliation. Ostensible increases in wine constituents (anthocyanins, phenolics), color density, cultivar character intensity, and overall wine quality were found in wines from treated vines.
Abstract Radioactive zinc (Zn) was applied to apical leaves, basal leaves, and roots of water cultured Muscat d'Alexandrie grapevines grafted onto rootstocks 140 Ruggeri and 110 Richter, respectively. For both rootstocks, poor assimilation, but relatively good distribution, of Zn by apical and basal leaves was found; translocation to the rootstock was lower for 110 Richter than to 140 Ruggeri. In contrast, assimilation by roots was relatively good, but translocation was poor, particularly when using 110 Richter. The apical translocation of leaf assimilated Zn was less prominent when using rootstock 140 Ruggeri compared to 110 Richter. The general pattern of Zn distribution was, however, similar between rootstocks. Maximum assimilation can be ensured by foliar Zn sprays early during the growth season. The presence of metabolically active, mature leaves will guarantee effective distribution of Zn within the grapevine.
Knowledge of vine reaction to plant spacing under relatively high potential soil conditions is limited. This study comprised effects of vine spacing (with fixed row spacing) of Shiraz (clone SH 9C)/101-14 Mgt on a high potential soil in the Breede River Valley, Robertson, South Africa, on soil conditions, root system distribution, and vine physiological reaction. The vineyard was planted in 2008 to a VSP trellis, with a fixed row spacing of 2.2 m and a row orientation of approximately NNE–SSW (30°). In-row vine spacing changed from 0.3–4.5 m with increments of 30 cm (from 15151–1010 vines/ha), totalling 15 treatments. After the completion of cordon development, results were generated over six seasons. Soil conditions seemed generally uniform and showed no obvious characteristics that could have affected treatments differentially. An increase in density occurred in fine, extension and permanent root categories with closer spacing, increasing the total number of roots/ha. Roots penetrated deeper with closer vine spacing. Vine spacing impacted physiological parameters and revealed a complex interplay between root distribution, vine structure expansion, canopy microclimate, water relations, photosynthetic output, berry temperature, carbon distribution, and day/night recovery that would affect grape composition and wine quality. Optimum vine spacing appeared to be 1.8 m, both closer and wider spacing leading to limitations in physiological activity. Interactions amongst below- and aboveground growth and physiological parameters are comprehensively discussed with a focus on sustainability.
Abstract The effect of different zinc levels on the vegetative growth, photosynthetic activity, and Zn content of water‐cultured Muscat d'Alexandrie, grafted onto 110 Richter and 140 Ruggeri, was investigated under greenhouse conditions. Typical Zn deficiency symptoms, such as small leaves and disturbed apical dominance occurred at low Zn concentrations. An increase in Zn concentration resulted in slight increases in fresh and dry mass. With rootstock 140 Ruggeri average leaf area and internode length seemed to increase with an increase in Zn concentration. The photosynthetic activity generally increased with an increase in Zn concentration.
Berry size has always been a quality factor in wine production. In this study, Syrah grapes from a singlevineyard were classified into different size groups according to diameter: small (< 13 mm), medium(13 < diameter < 14 mm) and large (> 14 mm). Smaller berries were present in the highest and largerberries in the lowest numbers. Size distributions were similar in both seasons (2010/2011 and 2011/2012).Berry physical characteristics (mass, volume and skin area) increased with size, showing the same tendencyin both years. Positive correlations between berry mass, volume and skin area were found, whereas thesevariables were negatively related with berry number/kg grapes. Berry volume was negatively correlatedwith dry skin weight. Skin surface area/berry volume seems to be an indicator of the "dilution" effectassociated with increasing size, as larger berries presented the lowest values. In 2012 the grapes wereharvested at a higher soluble solid level than in the previous year; large-sized berries presented the lowestlevels in both years. The whole-berry analysis of total anthocyanins showed a decrease in concentrationand increase in content per berry, from smaller to larger berries. Small berries and the control (naturallyoccurring berry size mixture) showed a higher extractability of anthocyanins and phenolic compoundsthan the medium and large berries. Sensorially, wines from medium berries were more consistent over thetwo years, scoring higher than the rest. Berry sizes were related to wine style differences, and knowing thepopulation of berry sizes in the vineyard close to harvest would offer a possibility to predict wine styles.
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