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.     

Effect of irrigation on changes in the anthocyanin composition of the skin of cv Tempranillo (Vitis vinifera L) grape berries during ripening

The impact of water availability on the yield and on the chemical composition in the skins of cv Tempranillo grapes at different phases of berry growth was studied over a 2 year period by determining changes in berry weight, °Brix, titratable acidity, pH and different phenolic compounds. The evolution of phenolic compounds during berry growth followed similar patterns to those reported by previous investigators. Over the 2 year study, concentrations of total phenols and total tannins in the skins were always higher for the non-irrigated than for the irrigated vines, though the differences were not significant on some sampling dates. Total anthocyanin concentrations in 1992 were significantly higher in the non-irrigated than in the irrigated grapes, except at véraison and harvest. In contrast, in 1993, concentrations were higher in the non-irrigated grapes on the first three sampling dates and in the irrigated grapes on the last three sampling dates, but with significant differences only on day 136 after budbreak. In the first year, anthocyanin concentrations for the non-irrigated grapes were higher than for the irrigated grapes, except at harvest, though the differences at harvest were not significant. However, in the second year, concentrations in the berries from the irrigated vines were significantly higher on most sampling dates. In both years, concentrations of the five anthocyanins at harvest were higher for the irrigated treatment, the treatment that produced higher berry weights and crop yields. © 2001 Society of Chemical Industry     

ABA during reproductive development in non-irrigated grapevines (Vitis vinifera L. cv. Tempranillo)

In grapevines, stomatal aperture decreases after a mid-morning peak during summer days. Afternoon stomatal closure increases in non-irrigated plants as water limitation progresses, which suggests the involvement of abscisic acid (ABA) in the control of stomatal aperture. The objective of this work was to study the seasonal and diurnal time-courses of CO₂ assimilation rate, leaf conductance, leaf water potential +, and ABA concentration in xylem sap, leaves, flowers and berries in non-irrigated field-grown Tempranillo grapevines throughout reproductive development. Leaf decreased throughout fruit development because water availability decreased towards the end of the reproductive cycle. CO₂ assimilation rate, leaf conductance and xylem ABA concentration also decreased during the course of the growing season. Combining all measurements xylem ABA was either not correlated, or only slightly correlated, with leaf water status + and daily leaf conductance, respectively. This lack of relationship indicates that xylem ABA during fruit ripening had functions other than provision of a non-hydraulic signal. On a seasonal basis, xylem ABA concentration measured in non-irrigated grapevines was well related to berry ABA concentration, especially at the end of fruit development (veraison and harvest).     

琐琐葡萄总黄酮提取工艺

研究琐琐葡萄果实总黄酮的醇法提取工艺。在考察各影响因素的基础上设计正交试验,得出各种因素对提取效果影响的主次顺序为料液比＞提取时间＞提取温度＞乙醇体积分数,总黄酮提取最佳工艺条件为：提取温度80℃、乙醇体积分数60%、提取时间120min、料液比1:30(g/mL)。     

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.     

Impact of node position and bearer length on the yield components in mechanically pruned Cabernet Sauvignon (Vitis vinifera L.)

Background and Aims: Bunch number per node or shoot varies significantly between seasons and is a major cause of yield variation. Varying total node numbers by pruning is the least expensive way to regulate yield. However, there is little information available on how varying bearer length (and thus node number) in a machine‐pruned canopy alters yield components. Methods and Results: The impact of bearer length on yield components was investigated in a mechanically pruned vineyard in Coonawarra, South Australia. Yield components were analysed according to the node position on the bearer at which the shoot arose. Both budburst and inflorescence number per node were highest at the distal node positions regardless of bearer length. When node positions two and three were located in the two most distal nodes made terminal by the pruning, they were significantly more fruitful than equivalent nodes on longer bearers. Shoots that arose from the two most distal node positions had the highest flower number per inflorescence and berry number per bunch. Conclusions: Budburst, and the number and size of the inflorescence and bunch were affected more by the node position at which the shoot occurred relative to the cut end of the bearer, than the position of the node from the base of the bearer. Significance of the Study: Our understanding of how pruning regimes impact on yield and how these pruning regimes may be modified to achieve a target yield has been improved.     

Relationships between different berry components in Tempranillo (Vitis vinifera L) grapes from irrigated and non‐irrigated vines during ripening

The impact of water availability on Vitis vinifera L cv Tempranillo grape yields and juice composition over a 3 year period was studied. Grape juice composition during the different stages of berry growth was compared. The analytical data collected were used to investigate the relationships between some of the different components studied in these berries during the ripening period. The object was to determine whether the relationships could be used to derive mathematical equations for use as indicators of the changes taking place in the different parameters considered and thus of the optimum time for harvesting the grapes for a given wine‐making process. Very similar equations were derived for this grape variety irrespective of the culture conditions (use or non‐use of irrigation) or the different ripening conditions employed. A high degree of correlation between some of the components considered was observed. In any case, cause‐and‐effect relationships could only be established for certain of the parameter pairs considered (total acidity/pH, pH/potassium, °Brix/glucose + fructose, total acidity/tartaric acid and malic acid). For other parameter pairs (berry weight/°Brix, °Brix/pH, °Brix/total acidity) the relationship found was attributable to accumulation and breakdown processes which took place concurrently or overlapped in time. In two cases only there was uncertainty as to whether the relationship observed between the parameters was a cause‐and‐effect relationship or whether the parameters were so closely related that they acted as mutually limiting factors (°Brix/proline, °Brix/total anthocyanins). © 2002 Society of Chemical Industry     

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。     

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.     

Susceptibility of 44 grapevine (Vitis vinifera L.) varieties to downy mildew in the field

Background and Aims: Downy mildew, which occurs worldwide, is one of the most destructive of all grapevine diseases. Several authors have examined the host–pathogen interaction in different Vitis species, crosses and hybrids, but only a few studies comparing this in true V. vinifera varieties have been undertaken. The aim of the present study was to examine the in‐field susceptibility to infection by Plasmopara viticola, the causal agent of downy mildew, of 44 grapevine varieties, all belonging to the collection of the Misión Biológica de Galicia. Methods and Results: Over a period of 2 years, the incidence and severity of downy mildew on the leaves and clusters of all 44 varieties was determined using a visual scale. Some of those examined showed high susceptibility (Chenin Blanc, Albariño and Prieto Picudo), others showed low susceptibility (Silveiriña, Caiño Bravo, Follajeiro and Brancellao Blanco), and still others showed intermediate susceptibility. Some varieties showed high disease incidence but low disease severity and vice versa. No significant correlation was detected between disease incidence and severity in either leaves or clusters, nor indeed between leaves and clusters. Neither berry colour, cluster compactness nor any other studied variable bore any clear relationship with susceptibility. Conclusion: The different grapevine varieties examined showed great variation in terms of their susceptibility to downy mildew. The susceptibility of most varieties was the same in both study years. Significance of the Study: The results of this work could help provide new material that might be of use in grapevine genetic improvement programs, and in the study of resistance to downy mildew. The selection of old varieties from the Iberian northwest may contribute towards the growth of organic viticulture in this area and even other winemaking regions around the world.     

Dependence of wine sensory attributes on vine water status

The dependence of wine sensory attributes on the water status of the source vines was determined following vineyard irrigation treatments which included early and late season water deficits and continually irrigated vines. In both seasons, the experimental wines made from the different irrigation treatments did not differ in the concentration of residual sugar or ethanol, titratable acidity, or pH. The concentrations of anthocyanins and total soluble phenolics in the wines were greater from water deficit treatments than from continually irrigated vines. For sensory evaluation, a novel protocol for paired comparisons was developed to test separately for differences in wine appearance, flavour, taste and aroma; differences were detected for each wine comparison. In both seasons, continually irrigated wine differed from early and late season water deficit wine, and early season water deficit wine differed from late season water deficit wine in appearance, flavour, taste and aroma. The sensory differences were not attributable to differences in vine yield or fruit maturity. When professional wine tasters were sampled using similar tests, a majority was able to detect visual but not flavour differences between a selected pair of wines. It is concluded that, where vine water status can be altered, irrigation offers a means to manipulate wine sensory characteristics in the vineyard.     

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.     

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.