Biomass distribution and nitrate assimilation in response to N supply for Vitis vinifera L. cv. Cabernet Sauvignon on five Vitis rootstock genotypes

Effects of nitrogen (N) supply on biomass distribution as well as N effects on NO₃"assimilation, were examined in two-year-old graftlings of Vitis vinifera L. cv. Cabernet Sauvignon on five rootstocks. Whole-plant biomass in all graftlings more than doubled with increased N supply in solution from 0.25 to 8 mM. Whole plant biomass was also affected by rootstock genotype, but to a lesser extent than by N supply. Biomass allocation to roots declined with increased N supply for all stock-scion combinations, but the magnitude of that response varied with rootstock genotype. Nitrate reductase activity (NRA) in leaves increased with increased N supply for all stock-scion combinations, whereas root NRA increased only up to 1 mM N supply, dropping markedly with additional N. NRA in leaves was one to two orders of magnitude higher than NRA in roots - a difference that increased steadily with increased N supply. By implication, grapevine leaves have a much higher capacity for NO₃^-_- reduction than do grapevine roots, and any contribution by roots to whole-vine NO₃^-_- assimilation declines even further as NO₃^-_- availability increases.     

Mass-spectrometry evidence confirming the presence of pelargonidin-3-O-glucoside in the berry skins of Cabernet Sauvignon and Pinot Noir (Vitis vinifera L.)

Background and Aims: Anthocyanins are a group of important phenolic compounds which are responsible for the colour of red grape and wine. This study aimed to confirm the existence of pelargonidin-3-O-glucoside in Vitis vinifera grape berry skins. Methods and Results: The anthocyanin profiles in the berry skins of Cabernet Sauvignon and Pinot Noir were analysed by high performance liquid chromatography – electronic spray ionization – tandem mass spectrometry. Besides 17 anthocyanins that are commonly determined in the berries of these two varieties, pelargonidin-3-O-glucoside was also detected at trace levels. Conclusions: The mass-spectrometry evidence confirmed the existence of pelargonidin-3-O-glucoside in non-teinturier V. vinifera grapes. Significance of the Study: This finding will be beneficial for the further understanding of anthocyanin profile and its biosynthesis in grape berries.     

Crop thinning (hand versus mechanical), grape maturity and anthocyanin concentration: outcomes from irrigated Cabernet Sauvignon (Vitis vinifera L.) in a warm climate

Crop thinning subsequent to fruit set can help regulate yield and improve fruit composition at harvest. Accordingly, an experiment was established in two vineyards (Site 1 Riverland District of South Australia; Site 2 Sunraysia District of Victoria) to investigate effects of crop removal after fruit set (when berries were pea size) using a machine harvester. Specific zones of the canopy were targeted for thinning to remove a predetermined percentage of the fruit and avoid over‐thinning. Cropping responses to mechanical thinning were compared with control (un‐thinned) vines, and with hand thinned vines (where fruit was removed from a similar portion of the canopy as for mechanical thinning). In a fourth treatment, bunches damaged by mechanical thinning were removed by hand. Inclusion of hand thinning treatments enabled us to distinguish between the potential benefits of reduced yield and the potential damage caused by the mechanical harvester to foliage and/or remaining fruit. Both the mechanical and the hand thinning treatments reduced bunch number as well as yield by a similar amount (approximately 24% on Site 1 and approximately 45% on Site 2) and advanced fruit maturity (soluble solids accumulation at harvest), relative to un‐thinned controls, by approximately 1.6 % and 1.7% respectively. Soluble solids accumulated at a similar rate for all treatments at sites, despite differences in yield, implying that the impact of thinning treatments originated prior to veraison. Berry weight was increased by hand thinning at Site1, and by all thinning treatments at Site 2. Anthocyanin concentration (berry fresh weight basis) was higher in fruit from the mechanically thinned vines compared to controls (un‐thinned). Mechanical thinning successfully reduced crop level to the target yield, and improved fruit quality. Mechanical thinning, via modified use of a machine harvester, thus offers some potential to regulate yield over large and minimally pruned vineyards, in a timely and cost‐effective fashion.     

The effect of post-veraison water deficit on yield components and maturation of irrigated Shiraz (Vitis vinifera L.) in the current and following season

Given their perennial nature, grapevines can respond to deficit irrigation during both the current season as well as during the following season, even though full irrigation may have been restored during that second season. To define the cropping responses involved, three post-veraison irrigation treatments were imposed on spur, mechanically and minimally pruned Shiraz vines that were already receiving restricted water application using Partial Rootzone Drying (PRD). The treatments resulted in the vines receiving 1.25 ML per hectare pre veraison and the three irrigation treatments receiving 1.25, 0.65 and 0 ML of water per hectare in the post-veraison period. Water deficit during the current season reduced berry and bunch weight, and yield. Sugar concentration was reduced, and phenolic concentration increased when less water was applied, but anthocyanin concentration was unaffected. Although irrigation was returned to standard practice (PRD) in the following season, yield was reduced in accordance with deficit irrigation treatments the previous season. This reduction in yield was primarily caused by fewer bunches per vine, which in turn was a direct consequence of fewer shoots per vine (lower budburst). The lower crop load on the vines that had received restricted irrigation post-veraison in the previous season resulted in higher sugar and antho-cyanin concentrations in fruit the following season. Lighter pruning resulted in a greater number of smaller bunches comprising smaller berries. In both seasons the minimal pruning treatment delayed fruit maturity as measured by sugar accumulation. Post-veraison water deficit thus has the potential to impact on both yield and fruit composition during the current season as well as during the subsequent season.     

浸渍酶对蛇龙珠葡萄酒酿造过程中类黄酮化合物变化的影响

研究了浸渍酶Lallzyme Ex-V对蛇龙珠葡萄酒酿造过程中(从酒精发酵到橡木桶贮藏12个月)类黄酮动态变化的影响。结果显示,经浸渍酶处理加快了儿茶素、表儿茶素、杨梅素、山奈酚和槲皮素等5种类黄酮化合物在葡萄酒酒精发酵期间的浸提速度,但不影响杨梅素和槲皮素在后续酿造过程中的含量,杨梅素在葡萄酒酒精发酵结束后含量逐步下降,槲皮素在橡木桶陈酿期间含量逐渐增加;酶处理对儿茶素和表儿茶素的影响一直持续到苹-乳发酵的第2周,酶处理酒中儿茶素和表儿茶素的含量高于对照;浸渍酶对山奈酚含量的影响一直持续到橡木桶陈酿3个月,处理酒中的含量高于对照。     

Stomatal density of grapevine leaves (Vitis vinifera L.) responds to soil temperature and atmospheric carbon dioxide

Background and Aims: Leaf stomatal density, i.e. number of stomata per unit area of leaf, is a primary determinant of the carbon and water relations of plants. However, little is known about the plasticity of grapevine stomatal density during leaf formation in response to environmental factors. In this study, we determined responses in stomatal density to soil temperature and atmospheric carbon dioxide during leaf development following dormancy to gain further understanding of grapevine carbon and water relations, and adaptation to climate change. Methods and Results: Using potted plants of Vitis vinifera (L.) cv. Chardonnay, we found that a period of soil warming from budbreak reduced stomatal density of concurrently formed leaves, whereas CO₂ depletion increased it. Furthermore, stomatal density of concurrently formed leaves was closely and inversely correlated with starch concentration in roots and trunks. Conclusion: We conclude that the stomatal density of grapevine leaves varies greatly in response to soil temperature and atmospheric CO₂ concentration. Significance of the Study: This is the first study to show that soil temperature influences stomatal density of plants. It also confirms that stomatal density of grapevines, like many other plants, responds inversely to atmospheric CO₂ concentration. Our findings demonstrate that stomatal density must be accounted for in any attempt to predict grapevine adaptation to climate change, and attendant impacts on CO₂ assimilation and water use efficiency in viticulture. More fundamentally, they indicate that the carbohydrate reserve status of perennial, deciduous plant species may be an important endogenous determinant of stomatal density.     

Environmental effects on cv Cabernet Sauvignon (Vitis vinifera L.) grown in Hawke's Bay, New Zealand.: 1. Phenology and characterisation of viticultural environments

Six Cabernet Sauvignon vineyard sites in Hawke's Bay (New Zealand), selected out of 28 sites observed in 1996/97, were studied over three consecutive seasons in order to characterise viticultural environments of this region for this cultivar. Indices of precocity of vine phenology were used to analyse the relationship between phenology at the selected sites and vegetative growth, productivity, fruit ripening and wine sensory characteristics. Marked differences in indices of precocity existed between sites. These differences were mostly correlated with vine vegetative growth and canopy indices. There was no relationship between yield and vine phenology. Indices of precocity were correlated with certain juice constituents measured on a common date, as well as the sensory scores of wines produced by microvinification from grapes harvested on different dates and maturity levels. Vineyard sites that differed in indices of precocity also differed in their environmental characteristics, particularly in soil physical properties and water balance.     

Environmental effects on cv Cabernet Sauvignon (Vitis vinifera L.) grown in Hawke's Bay, New Zealand.: 2. Development of a site index

Based on observations of Cabernet Sauvignon phenology, cropping and fruit characteristics at six vineyard sites in Hawke's Bay (New Zealand) studied over three seasons, a numerical model is proposed to characterise environmental conditions of a vineyard site. The proposed model is based on air temperature in October and January, seasonal rainfall, rooting depth, gravel percentage and clay-to-silt ratio in topsoil. The 'Site Index' (SI) calculated from these variables was significantly correlated with soil temperature and volumetric soil moisture content, themselves closely linked with clay-to-silt ratio, air temperature and rainfall. Vegetative growth, canopy characteristics, precocity of veraison, total anthocyanins, TSS and malic acid concentration in grapes, as well as wine sensory score, were all significantly correlated with the SI values at six sites and over two seasons. Over the same period, correlation of SI with several viticultural variables was generally stronger than five existing climatic indices for viticulture calculated for these sites. The proposed SI index appears to have potential use for vineyard zoning and site selection and evaluation.     

An assessment of rootstocks for Sunmuscat (Vitis vinifera L.): a new drying variety

Sunmuscat scions, either grafted onto one of seven rootstock, or as own-rooted vines, were grown under irrigation according to the practices of warm-climate viticulture in north-western Victoria. The trial was located within a commercial vineyard on a sandy loam soil, and represented a typical replant situation. Grapevine performance was assessed over five seasons, viz. 1999–2004 inclusive, in terms of yield per vine, berry weight, juice composition and vigour (based on trunk girth). The highest yielding rootstock over the trial period was 1103 Paulsen (28.9 kg /vine) followed by 140 Ruggeri and Ramsey (26.1 and 25.8 kg /vine respectively), S04 (22.5 kg /vine), Schwarzmann, 101-14 and Teleki 5A (19.9, 18.7 and 18.4 kg /vine respectively). Scions on their own roots returned lowest yield (15.5 kg /vine). Berry weights were largest for the three high yielding rootstocks (2.3 g) and smallest with own roots (2.0 g). Total soluble sugars in harvested fruit were largely unaffected by rootstock in most seasons, although taken over all seasons, fruit from scions grafted onto Ramsey rootstock had the lowest levels, while Teleki 5A had the highest levels (viz. 23.4^oBrix and 24.7^oBrix respectively). Comparative vigour for all seven graft combinations was inferred from trunk circumference. There was a 2-fold difference in rootstock girth below the graft union (viz. 265 mm for 1103 Paulsen, compared to 135 mm for S04), whereas differences in the scion girth above the graft union were minor (only 16%). Relative compatibility of scion and stock was inferred from 'girth ratio' of trunk circumference above compared with below the graft union. Girth ratio was highest for Sunmuscat scions grafted onto SO4 rootstock, and lowest for scions on 1103 Paulsen. Scion girth and vine yield were broadly correlated.     

Effects of temperature and light (before and after budburst) on inflorescence morphology and flower number of Chardonnay grapevines (Vitis vinifera L.)

Plastic mini‐chambers were used as tiny ‘glass houses’ to increase bud temperature in the vineyard. Open containers, with holes cut in them for ventilation, were used as controls, and inflorescences produced in those chambers were compared with inflorescences from modified chambers where either shade cloth or reflective foil were used to alter internal levels of photosynthetically‐active radiation (PAR) as well as temperature. Buds were treated for either14 days prior to budburst or for 13 days subsequent to budburst. Temperature and PAR were monitored immediately adjacent to the buds. Applied prior to budburst, the closed mini‐chambers increased bud temperatures and reduced flower numbers per inflorescence. Both ‘clear’ and ‘reflective foil’ treatments resulted in similar flower numbers. However, the shading treatment increased flower numbers by approximately 13%. Prior to budburst, there was a significant but weak correlation between average temperature and flower number per inflorescence for both the basal and apical inflorescence. Average PAR was not significantly correlated with flower number on either inflorescence, and did not improve the correlation when included with temperature in a multiple linear regression. Subsequent to budburst, flower numbers per inflorescence were decreased by the closed container but were unaffected by either the shading or foil treatment. The correlation between temperature and flower number on the apical inflorescence was maintained but the correlation between temperature and flower number on the basal inflorescence was no longer apparent. These results suggest that temperatures encountered in a vineyard during budburst can influence the number of flowers per inflorescence to the extent of a 15 to 25% variation in flower number. PAR, apart from influencing bud temperature, does not appear to influence flower number. The effect of temperature on flower differentiation diminishes as budburst advances.     

Management practices for Sunmuscat (Vitis vinifera L.): a new drying variety

Sunmuscat grapevines, managed on one of three trellis × two row spacing configurations, and grown on either their own roots or grafted onto Ramsey rootstock, were assessed over nine seasons (1990–1998 inclusive). The three trellis systems comprised (1) a 0.3 m narrow T‐trellis (NT), (2) a 1.2 m wide T‐trellis (WT), both with a 3.3m row spacing and a height of 1.2 m, and (3) a high (1.8 m) hanging cane (HC) system based on bi‐lateral cordons with a 2.2 m row spacing. Vine spacing within rows was 2.4 m irrespective of row width. A trellis drying treatment was compared with hand harvest during 1991–1995. Over the nine seasons, individual WT vines sustained highest yields of fresh grapes (23.7 kg/vine.season) compared to either NT (20.9 kg/vine) or HC vines (20.8 kg/vine) respectively (P < 0.001). However, HC vines expressed a considerable production advantage on a per hectare basis, viz. 41.3 t/ha, due to closer row spacing. Corresponding vineyard productivity for NT and WT vines was 26.4 and 29.9 t/ha respectively. Both WT and HC vines showed significantly higher bunch and shoot numbers than the NT treatment (P < 0.05 and P < 0.001, respectively). Nevertheless, trellis treatment had no effect on fruitfulness, berry weight, bunch weight, total soluble solids or titratable acidity. Taken overall, vines grafted to Ramsey rootstock had higher mean yields than vines on their own roots (i.e. 23.6 and 20.1 kg /vine, respectively P < 0.001) due to more berries per bunch and larger berries, despite having significantly fewer shoots and bunches. There was no long term evidence for incompatibility of Sunmuscat grafted to Ramsey rootstock. Compared to hand harvest of fresh grapes, trellis drying had no effect on yield, shoot and bunch numbers. Development of significantly smaller berries with trellis drying was offset by higher levels of total soluble solids. Sunmuscat is clearly a highly productive variety and is suited to canopy management on tall, cordon‐based hanging cane systems which are also amenable to trellis drying.     

A functional association in Vitis vinifera L. cv. Cabernet Sauvignon between the extent of primary branching and the number of flowers formed per inflorescence

The number of primary branches (those branches that arise directly from the rachis) and the total number of flowers were counted for inflorescences of Vitis vinifera L. cultivar Cabernet Sauvignon over a range of climates and a number of seasons as part of a yield prediction study. Regression analysis indicated that the number of primary branches per inflorescence exerted a strong control over the total number of flowers per inflorescence, with highly significant ( P < 0.01) relationships explaining between 51 and 80% of the variation in flowers per inflorescence. Because the extent of primary branching is largely determined prior to grapevine buds entering dormancy, this strong functional association between branching and flower numbers, suggests that season-to-season differences in potential inflorescence size will be greatly affected by conditions during that phase of primordial differentiation in the previous growing season. A general tendency for the number of flowers per inflorescence to be positively related to other measures of vine fertility, supports this view. Lower orders of branching (secondary and tertiary) down to formation of individual flowers at budburst, also have the potential to influence eventual inflorescence size. As to the timing of such influences, we noted that increased severity of winter pruning significantly increased both flowers per inflorescence (by 9%) and the number of primary branches per inflorescence (by 21%). Such responses provide strong support for our contention that although the extent of primary branching is largely determined prior to grapevine buds entering dormancy, differentiation of new primary branches in Cabernet Sauvignon inflorescences continues to occur after the onset of dormancy.     

Light (minimal) pruning enhances expression of higher yield from clones of Vitis vinifera L. cv. Sultana following thermotherapy for virus attenuation

High-yielding clones of Sultana (syn. Thompson Seedless) were grown in a warm climate under irrigation as either cane-pruned or minimally-pruned field vines. Test material included Sultana clone H5, six heat-treated clones originating from H5, and a heat-treated clone of Thompson Seedless (TS-HT91) sourced from California. Vine performance was measured over 10 seasons (1984–1993). Previous thermotherapy had eliminated leafroll viruses from three of the six selections originating from H5 and from TS-HT91. When cane-pruned, the TS-HT91 clone was 9% more productive than H5 as well as all selections originating from thermotherapy of H5. With minimal pruning all selections free of leafroll viruses had superior performance (approximately 14% increase) compared to those still infected with leafroll viruses. In those clones where thermotherapy had not removed leafroll viruses, yields from two out of three clones (minimally-pruned) were increased relative to H5; one remained lower. Clonal differences in productivity were related to vine growth, particularly above-ground components, but there were no significant clonal effects on berry weight, pH or titratable acidity. While long-term field trials are necessary to clearly demonstrate positive effects from thermotherapy, light pruning can enhance prospects for confirming an improvement in yield. Indeed, severe pruning can even limit expression of yield from putatively superior clones, and thus mask expression of positive outcomes from thermotherapy.     

Effects of mechanical thinning on fruit and wine composition and sensory attributes of Grenache and Tempranillo varieties (Vitis vinifera L.)

Background and Aims: Cost-effective yield control is required by the wine industry in order to reduce the existing worldwide wine surplus and to improve grape quality. The object of this study was to evaluate the chemical and sensory effects on the resulting wines of mechanical cluster thinning performed at different intensities on Grenache, and at different timings (pea size and veraison) on Tempranillo. Methods and Results: The experiments were conducted with a machine harvester in 2007 on two commercial vertical shoot-positioned vineyards in Spain's Rioja region. In both varieties, mechanical thinning was effective in yield reduction and resulted in more ripened fruit, and wines with higher alcohol and pH values, more intense colour and increased phenolic content. Regardless of the thinning intensity, sensory changes were less noticeable in Grenache than in Tempranillo wines. Of the latter, those from vines thinned during veraison were less aromatic and sour, but had increased astringency. Conclusions: Yield management through mechanical thinning induced changes to the chemical composition of fruit and wines as well as to the wines' aroma, taste and mouthfeel. The extent of the sensory implications seems to depend on several factors such as the variety and timing of thinning application. Significance of the Study: This is one of the first studies addressing the effects of mechanical thinning on the sensory properties of the resulting wine and has implications for viticultural management practices.     

Physicochemical characteristics and functional properties of grape (Vitis vinifera L.) seeds protein

The amino acid composition, physicochemical and functional properties of grape (Vitis vinifera L.) seeds protein (GSP) were evaluated and compared with those of soybean protein isolate (SPI). Amino acid analyses of GSP revealed high levels of glutamic/glutamine, glycine and aspartic/asparagines. SDS‐PAGE analysis demonstrated that globulin was the major protein component in GSP, whose subunit molecular weights were mainly varied from 25.5 to 40.0 kDa. The isoelectric pH of GSP was found to be at the acidic pH of around 3.8. At all the pHs tested except pH 2.0, no significant changes of GSP secondary structure were observed. GSP exhibited beneficial functional properties such as preferable solubility and emulsifying activity, while the foaming properties and water holding capacity were relatively poor compared to SPI. It could then be employed to soup, sauce, beverage or meat product for improving nutritional and sensory quality of these foods at appropriate pHs.     

Growth, photosynthesis and cropping of potted grapevines (Vitis vinifera L. cv. Cabernet Sauvignon) in relation to shoot trimming

The present study was conducted to evaluate how changes in leaf area affected vine growth, yield and grape quality of five‐year‐old potted Cabernet Sauvignon grapevines. At the beginning of flowering vines were randomly assigned to the following five treatments: untrimmed (control); shoot trimmed at either node 12 (T12) or node 6 (T6) with laterals either retained (R) or excised (X). Those four manipulations are abbreviated to: T12LR, T12LX, T6LR and T6LX, respectively. Total leaf area per vine was significantly lowered in T12LX and T6LX as compared to the other treatments, whereas lateral formation was able to offset foliage loss due to trimming in T12LR and T6LR with respect to control vines. T6LR also showed a more prolonged lateral node production. Yield per vine and its components did not differ significantly among treatments except for berry size, which was reduced in T6LR and T6LX. Grape ripening was severely retarded in T6LX, as shown by lower Brix, pH, colour and phenolics, and higher TA, tartrate and malate. A maturity delay was also shown in T6LR as lower soluble solids and total anthocyanins per berry in comparison with untrimmed vines. No difference in grape quality versus control was shown by the T12 treatments. Post‐trimming assimilation rates (A) clearly indicated a large compensation capacity of retained main leaves despite their mean age being higher than that calculated for main leaves sampled the same day on control vines. The assimilation rates recorded on lateral leaves increased proportionally with lateral shoot size and inversely to the number of main leaves retained with trimming. Based on present results, both the area and photosynthetic effectiveness of source leaves will drive overall vine responses to shoot trimming. For example, T6LX showed the worst performance with respect to the other treatments, in agreement with lowest leaf area, leaf‐to‐fruit ratio and oldest canopy. However, T6LR had a somewhat retarded ripening despite its non‐limiting leaf‐to‐fruit ratio, relatively young canopy and maximum whole‐canopy photosynthesis and efficiency at veraison. Under such circumstances, duration of growth and possible competition with the berry sugaring process may have played a role.