Amounts of glycosides in grapevine organs during berry development

Whole berries, leaf blades and petioles from Muscat Gordo Blanco (syn. Muscat of Alexandria), Sultana and Flame Seedless vines were sampled at intervals from three weeks after flowering to fruit ripeness. The glycosidically-bound constituents present in the samples were quantified through a determination of the glycosyl glucose. At the stage of berry ripeness, the concentration of glycosides per gram fresh weight in the leaf blades was 10–30 times higher than in the fruit. During berry development glycoside concentrations increased in leaf blades and petioles but decreased in fruit. However, when expressed on a per berry basis, the levels of glycosides in the fruit increased as ripening progressed; the levels in ripe fruit were high in Muscat Gordo Blanco and low in Sultana. Further experimentation will be needed to establish whether the glycosides are synthesised in the leaves and transported to the berries or synthesised independently in both organs.     

Effects of the rootstock Ramsey (Vitis champini) on ion and organic acid composition of grapes and wine, and on wine spectral characteristics

The influence of Ramsey, used as rootstock of the scion cvs Muscat Gordo Blanco (syn. Muscat of Alexandria), Shiraz (syn. Syrah), Riesling, Cabernet Sauvignon and Chardonnay, on the characteristics of the grape berries and of wine made from them was investigated, comparing ‘own-rooted’ and ‘grafted’, and comparing wine fermented as juice (without skins) and must (juice and skins). The study involved the partitioning of K+ within berries, changes in juice K+, malic and tartaric acid through fermentation, wine inorganic ion and organic acid composition, and wine spectral characteristics. K+ concentration was higher in berries from grafted than from own-rooted for all varieties except Chardonnay, and highest for grafted Shiraz. It was higher in skin than in pulp and seeds. In the pulp, it was highest for grafted Shiraz. K+ concentrations in all ferments using must (i.e. juice plus skins) increased during the initial two days after crushing, with the increase reflecting extraction from skins, being greatest for Shiraz and Muscat Gordo Blanco. Tartaric acid concentration in must also increased during the initial two days after crushing and then decreased. Malic acid concentration was higher in juice of Ramsey-grafted than own-rooted vines, especially for Shiraz; concentrations did not change markedly during the initial 12 days of fermentation, except where malo-lactic fermentation occurred. Wine made from grapes of grafted contained significantly less tartaric and more malic acid than that made from own-rooted for all varieties and for both fermentation types, with the exception of tartaric acid in wine of Muscat Gordo Blanco fermented as must. Wine made from juice had significantly higher tartaric acid and lower malic acid than that made from must for all varieties except for tartaric acid in wine from grafted Shiraz and malic acid in own-rooted Chardonnay. Wine had a smaller tartaric acid/malic acid ratio when made from must. Wine pH was positively correlated with K+ but negatively with tartaric acid and with the tartaric acid to malic acid ratio. Overall, Shiraz wine contained highest Cl?, Na+ and K+ concentrations. Red wines obtained from grafted had higher colour hue, especially those from Shiraz. Wines made from fruit borne on own-rooted Cabernet Sauvignon had the highest concentration of total anthocyanins, ionised anthocyanins and total phenolics.     

Occurrence of anthocyanin pigments in berries of the white cultivar Muscat Gordo Blanco (Vitis vinifera L.)

Rose coloration of skin was observed to sometimes develop late during ripening on the normally white grape berries of cv. Muscat Gordo Blanco. The nature of the pigment was investigated by HPLC analysis of skin extracts of single berries. The predominant anthocyanin was identified as cyanidin-3-glucoside with minor amounts of delphinidin- and peonidin-3-glucosides. This composition resembles the skin composition of coloured, small-seeded muscat cultivars which it also resembles by the monoterpene composition of the juice. The pigments occurred only in berries with levels of total soluble solids in excess of 24°Brix in the juice and such berries tended to have smaller fresh weight. Berry pigmentation occurred on vines with various root systems. The specific conditions under which pigment developed in Muscat Gordo berries may offer a useful tool in the study of anthocyanin biosynthesis.     

Dynamics of grape berry growth and physiology of ripening

Data from two experiments on development of grape berries is re-examined with emphasis on partitioning of berry weight into non-solutes per berry (largely water) and solutes per berry (largely sugar), using weight times juice °Brix. This approach is based on the thought that, since xylem flow is blocked after veraison, time curves of solutes per berry indicate the activity of phloem transport into the berry during ripening growth. Experiment 1: Measurements of Muscat Gordo Blanco berries from inflorescences with a spread of flowering times showed typical double-sigmoid volume/time curves but with divergent rates and amounts of volume increase. Despite this divergence, °Brix curves after veraison were almost coincident because, in each case, the rate of increase in solutes per berry was proportional to that of berry volume. These results indicate that sugar and water increments after veraison are linked and depend on the same source, namely, phloem sap. Experiment 2: An irrigation experiment on cv. Shiraz also showed divergent berry weight curves between treatments and years but with the difference that all berries shrank after a maximum berry weight was attained at 91 days after flowering (at about 20 °Brix). At this point, the curves of solutes per berry slowed then plateaued, indicating that inflow of phloem sap had become impeded. Prior to shrinkage these berries accumulated primary metabolites (mainly phloem sugar) but, during shrinkage, when berries were apparently isolated from vascular transport, non-anthocyanin glycosides accumulated. These results have implications for the study of berry flavour buildup and berry composition, and also for the understanding of sink competition within the vine, fresh and dried yield, and juice °Brix levels.     

The aroma of Muscat of Frontignan grapes: effect of the light environment of vine or bunch on volatiles and glycoconjugates

Effects of the modification of whole vine or individual cluster light environment by shade cloth from berry set to maturity were studied on the volatiles and glycoconjugates in Muscat (Muscat of Frontignan; Vitis vinifera L) berries over 2 years. Whole vines were shaded with 50 and 70% shade cloth, while bunches were shaded with 90% shade cloth. The sun‐exposed berries were chosen as control berries, and the berries naturally shaded under foliage were also studied. The natural shading of bunches under foliage did not decrease the levels of free and bound compounds in Muscat berries compared to sun‐exposed berries. The artificially shaded bunches showed lower levels of monoterpenols and C13 norisoprenoids than sun‐exposed berries and berries from naturally shaded bunches. Moreover, the effect of vine shading on the aroma composition of Muscat berries was lower compared to artificial bunch shading. In 1996 the leaf area/fruit yield ratio was modified by decreasing the bunch number per vine. This change did not influence the total amounts of glycosidically bound compounds, except for monoterpenic glycoconjugates. However, the higher monoterpenic glycoconjugate levels in these berries were likely related to their early maturity. Under our experimental conditions, berry aroma composition did not appear to be affected by foliage shade. © 2000 Society of Chemical Industry     

Exclusion of sunlight from Shiraz grapes alters wine colour, tannin and sensory properties

The aim of this study was to determine how changes in grape composition brought about by artificial shading (sunlight exclusion) influence wine properties including colour, flavonoid composition and sensory attributes. Prior to flowering, bunches of Shiraz grapes were enclosed in boxes designed to eliminate light without altering bunch temperature and humidity. This artificial bunch shading had little effect on berry ripening and accumulation of sugar but at harvest the shaded bunches had smaller berries and higher seed weight, juice pH and titratable acidity. The amount of anthocyanins in the fruit was not changed significantly but anthocyanin composition in the shaded berries was shifted towards dioxygenated anthocyanins (the glucosides of cyanidin and peonidin derivatives). Shaded fruit had increased seed tannins and decreased skin tannins but the largest relative change in flavonoids was a marked decrease in flavonols in the shaded fruit, similar to previous studies. Wines made from shaded fruit had lower wine colour density, total phenolics, anthocyanins and tannins when the wine was bottled and after ageing for up to three years. Analysis of potential flavour compounds following acid hydrolysis indicated that the wines made from shaded fruit had decreased levels of glycosides of β-damascenone and 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN). Sensory analysis of the wines indicated no significant difference in aroma attributes but the wines made from shaded fruit were rated lower for astringency, fruit flavour and flavour persistence in-mouth sensory attributes. The results indicate that extreme shading of Shiraz fruit can decrease wine colour, anthocyanins and tannins as well as altering sensory attributes.     

Rootstock effects on salt tolerance of irrigated field-grown grapevines (Vitis vinifera L. cv. Sultana). 3. Fresh fruit composition and dried grape quality

Field‐grown vines of cv. Sultana on either their own roots or grafted to a range of rootstocks, were drip‐irrigated at one of three salinity levels (0.40, 1.75 and 3.50 dS/m) over a five year period. Rootstocks were Ramsey, 1103 Paulsen, J17‐69 and 4 hybrids (designated R1, R2, R3 and R4) derived from parentage involving Vitis champini, V. berlandieri and V. vinifera. Grape juice total soluble solids, titratable acidity and pH were measured at harvest, while colour of dried fruit was measured before and after processing and again after six months storage. Damage index (an indicator of skin damage) was measured post‐processing; sugar crystal formation in dried grapes and dried grape compaction were measured post‐storage. There was a strong salinity x rootstock interaction for grape juice soluble solids concentration, soluble solids yield (the product of soluble solids concentration and fruit yield) and pH, but not for titratable acidity when analysed on the basis of 5 year means. Small increases (< 5%) in juice soluble solids concentration were recorded at medium salinity (1.75 dS/m) for the low vigour genotypes, Sultana on own‐roots and on J17‐69 rootstock, based on the 5 year means and Fisher's protected (interaction) LSDs. Moderate increases (< 10%) also occurred in years of low crop load e.g. 1993 at high salinity for the high vigour rootstock R2 and in 1995 at medium salinity for Sultana on own roots and at high salinity for Sultana on R1 rootstock. By contrast, decreases in soluble solids concentration occurred with increasing salinity for the high vigour rootstocks (Ramsey, 1103 Paulsen and R2) in years of high crop load e.g. 1992. Small (< 2%) increases in grape juice pH were recorded at high salinity for Sultana on R3 rootstock and moderate increases (< 7%) in grape juice titratable acidity were recorded at high salinity for Sultana on own roots and Sultana on J17‐69, R1, R2 and R4 rootstocks. Dried grapes from all treatments achieved a light amber colour (quality grade termed 5 crown light) and were generally of high quality. Sultanas from own‐rooted grapevines were redder (higher ‘a‐value’) than sultanas from 1103 Paulsen and Ramsey when assessed as unprocessed fruit, after processing (both years) and after 6 weeks storage. While soluble solids yields per vine were 23–31% lower at high salinity for Sultana on own roots and on R1, R3 and R4 rootstocks, they were unaffected by high salinity for Ramsey, 1103 Paulsen and R2 rootstocks. Moreover, soluble solids yields for Sultana on Ramsey, 1103 Paulsen and R2 rootstocks were 1.4 to 2.5‐fold higher than for Sultana on the other rootstocks at high salinity. This study has shown that over a 5 year period rootstocks such as Ramsey, 1103 Paulsen and R2 grafted with Sultana were tolerant of salinity, producing dried grapes of generally high quality.     

Vascular function in berries of Vitis vinifera (L) cv. Shiraz

Anatomical studies on the movement of a xylem tracer dye were combined with functional studies on changes in grape berry volume during final stages of berry ripening to gauge xylem effectiveness. Movement of a xylem tracer dye into pre-veraison fruit was compared with movement into post-veraison fruit by feeding a solution of acid fuchsin to excised shoots with bunches still attached, and then sectioning fruit for photo-microscopy. Those comparisons confirmed published studies showing an apparent blockage to dye movement along major vessels within the brush tissue of post-veraison fruit. However, our functional approach yielded a different impression of vascular activity. A continuation of xylem transport in ripening fruit was inferred from comparisons of berry volume where pedicels were either girdled (phloem interrupted, but xylem intact) or excised (both phloem and xylem interrupted). Volume changes in manipulated berries were compared with immediately adjacent intact control berries within the same bunch. Control fruit lost volume subsequent to 78 days after flowering (DAF) while manipulated fruit lost volume from the first day of treatment at 67 DAF. By harvest time at 95 DAF, both control fruit and girdled fruit had fallen to 91% and excised fruit to 46% of maximum volumes recorded around 78 DAF. Berry volume loss in girdled fruit was further enhanced by deficit irrigation. We conclude that xylem flow into those Shiraz berries must have continued beyond veraison despite dye evidence of a vessel blockage within the brush region of analogous post-veraison fruit.     

Proline and arginine accumulation in developing berries of Vitis vinifera L. in Australian vineyards: Influence of vine cultivar, berry maturity and tissue type

Using HPLC analysis, free amino acid profiles were obtained for ripe berries of six grapevine cultivars (Cabernet Sauvignon, Grenache, Muscat Gordo, Pinot Noir, Riesling and Sangiovese) grown under comparable conditions and harvested at similar maturities. Compositional differences were observed between cultivars, however proline and arginine were always the major amino acids. Mature berries of Cabernet Sauvignon contained a very high concentration of proline, but a much lower concentration of arginine. Those of other cultivars contained moderate levels of both arginine and proline.
Changes in free amino acid profiles during grape berry development were further investigated in four cultivars (Cabernet Sauvignon, Chardonnay, Gewurztraminer and Muscat Gordo). In all cases, most of the proline accumulation occurred late in ripening, around four weeks post-veraison. In contrast, arginine accumulation began before veraison and continued to full maturity, except for those cultivars in which a high concentration of proline accumulated, in which case the concentration of arginine reached a plateau relatively early in development. Accumulation of both proline and arginine appears to be develop-mentally regulated. These observations are discussed with reference to proline and arginine metabolism and possible links between them.
The distribution of free proline, arginine and other amino acids amongst pulp, skin and seed was examined using mature fruit of Cabernet Sauvignon and Riesling. Amino acid profiles were found to vary considerably between the berry components. The skin contained a greater ratio of arginine:proline compared with the pulp. This suggests that the yeast-assimilable nitrogen content of juices, and therefore their fermentability, could be enhanced in the presence of skins.     

Scions influence apparent transpiration efficiency of Vitis vinifera (cv. Shiraz) rather than rootstocks

Carbon isotope discrimination (Δ) is used to determine differences in apparent transpiration efficiency amongst genotypes of many C₃ plant species. In this present study the possible influence of certain commercially-available rootstocks on apparent transpiration efficiency in grapevines was investigated. Variation in Δ was studied for Shiraz and each of six rootstock varieties when grown either (1) on their own roots, (2) with Shiraz grafted as a scion onto different rootstocks (conventional graft) or (3) with rootstock varieties grafted onto Shiraz roots (reciprocal graft). When grown on own roots or as a reciprocal graft, there was significant variation in Δ. In contrast, there was no significant variation in Δ for Shiraz (as a scion variety) when grafted onto different rootstock varieties (conventional graft). These results imply a predominance by the scion genotype in determining variation in the leaf-level physiological characteristics that determine apparent transpiration efficiency under well-watered (and non-saline) conditions.     

Is weight loss in ripening grape berries cv. Shiraz caused by impeded phloem transport?

Berry shrinkage in ripening grapes cv. Shiraz is systemic within a given grapevine and coincident between grapevines in any given season. In this present study on weight loss in ripening berries, ripening curves of non-solutes per berry (largely water) were similar to curves for berry weight (as a function of time). Both sets of curves were equivalent with respect to timing of maximum weights and subsequent rates of weight loss. However, curves of solutes per berry (largely sugar) increased steeply up to the time of maximum berry weight, then slowed and plateau-ed. We suggest that phloem sap is the sole source for water and solutes that enter grape berries subsequent to veraison, and accumulate until maximum berry weight. We further suggest that phloem flow becomes impeded at maximum berry weight.
As berry ripening proceeds, continuation of berry transpiration leads to berry shrinkage and a concentration of solutes; i.e. any increase in juice Brix depends on shrinkage. One implication is that assimilates enter a berry up to the onset of shrinkage, whereafter accumulation of non-anthocyanin glycosides (including glycosides of flavour compounds) depends upon their synthesis in situ.     

Auxin treatment of pre‐veraison grape (Vitis vinifera L.) berries both delays ripening and increases the synchronicity of sugar accumulation

Background and Aims: Pre‐veraison auxin treatments can delay grape berry ripening, but there is little information about their effects on berry development and wine composition. The aim of this study was to further investigate these effects and explore the practical implications of delaying ripening. Methods and Results: Treatment of pre‐veraison Vitis vinifera L. cv. Shiraz berries with 1‐naphthaleneacetic acid (NAA) significantly delayed ripening as measured by the accumulation of total soluble solids (TSS) and anthocyanins. The onset of the post‐veraison phase of berry size increase was delayed in NAA‐treated fruit, but these fruit were significantly larger than Control fruit at harvest. NAA‐treatments significantly increased the synchronicity of berry sugar accumulation. GC‐MS analysis of wine headspace volatiles showed significant, but largely small, differences in the concentration of 19 compounds. No significant difference in sensory properties was found between replicate small‐scale wine lots made from Control and NAA‐treated fruit. Conclusions: Auxin treatment delayed berry ripening, increased the synchronicity of sugar accumulation between berries, increased berry size and changed the levels of some volatile compounds, but did not affect wine sensory properties. Significance of the Study: We propose that NAA sprays might be used to delay grape berry ripening and increase the synchronicity of sugar accumulation, and therefore ripening, without deleterious effects on wine quality. This may be useful in controlling winery intake and fruit composition.     

茉莉酸甲酯处理对采后葡萄离区膜脂过氧化及果实落粒的影响

分析了外源10μmol/L茉莉酸甲酯(M ethyl jasm on ate,MeJA)熏蒸处理对"巨峰"葡萄果穗在1℃贮藏期间离区膜脂过氧化及果实落粒的影响。结果表明,10μmol/LMeJA处理可显著降低葡萄果实冷藏期间落粒率、腐烂率和褐变指数,维持果实感官品质,同时显著诱导贮藏期间葡萄果穗离区组织中活性氧代谢酶(SOD、CAT、APX和POD)活性的上升并抑制超氧阴离子和羟基自由基生成量的增加。经MeJA处理的离区细胞膜中不饱和脂肪酸亚油酸和亚麻酸含量明显高于对照水平,而饱和脂肪酸棕榈酸和硬脂酸含量、相对电导率和MDA含量却显著低于对照水平。这些结果说明,MeJA处理可通过提高葡萄离区组织中活性氧代谢酶活性来减慢离区膜脂过氧化进程并维持离区细胞结构,从而降低了贮藏期间葡萄果实落粒率,改善了果实品质。     

Canopy microclimate and berry composition: The effect of bunch exposure on the phenolic composition of Vitis vinifera L cv. Shiraz grape berries

Studies on the effect of light exposure on specific phenolic compounds of berries from Shiraz vines grown in a hot climate are reported. Berries that had developed on bunches receiving high levels of ambient light generally had the highest relative levels of quercetin-3-glucoside and a lower proportion of their malvidin anthocyanins as the coumarate derivative, compared to berries that had developed on bunches in shaded canopy conditions. The response of total anthocyanin levels to treatment conditions was variable and depended on the degree of bunch shading and the resultant berry temperature. It appears that a high degree of bunch exposure in hot climates is not conducive to optimal anthocyanin accumulation in berries. The interactive effects of light and temperature on berry phenolic content and concentration are discussed.     

Identification and naming of the inception of aroma development in ripening grape berries

The accumulation of aroma in the grape berry appears to differ significantly from the accumulatory processes normally associated with berry ripening. A distinctive feature is the increase in concentration of free and glycosylated aroma compounds in the advanced stages of ripening, when sugar increase per berry has slowed. A similar pattern is shown for the levels of non-anthocyanin glycosides (red-free G-G) in Shiraz berries. It is suggested that the process of accumulation of aroma compounds should be given a name. Our proposal is the word 'engusting', meaning that the berry is acquiring attractive aromas and flavours; the verb is 'to engust'.     

Rootstock effects on salt tolerance of irrigated field-grown grapevines (Vitis vinifera L. cv. Sultana).: 1. Yield and vigour inter-relationships

Vegetative growth and yield of grapevines grown in the field on their own roots or grafted to a range of rootstocks were investigated under drip irrigation with water of three salinity levels (0.40, 1.75 and 3.50 dS/m) over a five‐year period. Rootstocks were Ramsey, 1103 Paulsen, J17–69 and 4 hybrids (designated R1, R2, R3 and R4) derived from parentage involving Vitis champini, V. berlandieri and V. vinifera. Of measured yield components (bunches per shoot, bunches per vine, weight per bunch, weight per berry and total yield), only weight per berry was significantly reduced by high salinity (3.50 dS/m) in each year of the trial with the exception of Sultana on 1103 Paulsen and R2 in 1991 and Sultana on Ramsey in 1993. Weights of one‐year‐old pruning wood were also reduced by high salinity in all years for own roots and all rootstocks, with the exception of R2. Mean yield values at each salinity level over the five‐year period of the trial were highest for Sultana on Ramsey, 1103 Paulsen and R2. High salinity had no effect on five‐year mean yields of Sultana on Ramsey, 1103 Paulsen and R2. Yield (five‐year means) of Sultana on Ramsey and R2 at 1.75 dS/m were significantly higher than at 0.40 dS/m by 14.6% and 13.4% respectively. In contrast, 5‐year mean yields of Sultana on J17–69, own roots, R1, R3 and R4 at 3.50 dS/m were reduced by 54, 30, 20, 30 and 30% respectively. Yield of Sultana on J17–69, R1 and R4 rootstocks was reduced by 47, 20 and 24% respectively at 1.75 dS/m. When yield was regressed against bunches per vine and weight per bunch for Sultana on own roots and on Ramsey rootstock, bunches per vine was the main determinant of yield, while weight per berry showed a poor correlation with yield at all salinity levels. Rootstock ranking for salt tolerance based on yield at high salinity was the same as rankings for pruning wood weights at high salinity. The same occurred at medium salinity, demonstrating that vigour imparted by the rootstock was a major factor in Sultana salt tolerance as measured by yield. Mean root weighted soil saturation paste electrical conductivities (RWEC_e) (determined from soil saturation paste salinities and root length densities) were in the range 2.0–2.6 dS/m for the low salinity treatment, increasing to approximately 5.4 dS/m with increasing salinity of irrigation water. Yield reduction for own‐rooted vines for each 1.0 dS/m increase in RWEC_e above 2.6 dS/m was 9.3%.     

Rootstock response of Shiraz (Vitis vinifera) grapevines to dry and drip-irrigated conditions

The yield and growth of Vitis vinifera cv. Shiraz scions grafted onto seven rootstocks were compared with that of own-rooted vines in a shallow sandy soil that was free of nematodes and phylloxera in the Barossa Valley of South Australia. In the absence of irrigation, own-rooted vines yielded as much fruit as vines grafted on Ramsey, the highest-yielding unirrigated rootstock-scion combination. Scions grafted to the rootstocks 110R, K51–40, 1103P and Freedom yielded poorly without irrigation. The yield and growth of all vines increased significantly when a small volume of irrigation water (40–160 mm/annum) was applied; however, only scions grafted to Ramsey and Freedom rootstock yielded more fruit than own-rooted vines.     

Shiraz berry size in relation to seed number and implications for juice and wine composition

This study was conducted over three seasons on irrigated Shiraz grapevines growing in a warm climate. We addressed the question of whether differences in berry size (within a population of berries from minimally pruned, own‐rooted or Ramsey‐grafted vines), would lead to differences in juice composition, wine composition or wine sensory score. Predictably, berry mass was found to increase with seed number, but berries in the smallest mass categories (0.3–0.7 g) still had similar juice soluble solids and pH; and similar concentrations of K+, tartaric acid and malic acid, compared with larger berries (1.4–2.0 g). Only for the very smallest mass category (0.3–0.55 g) was there any indication of better colour density (both for own‐rooted and Ramsey‐grafted vines) or higher anthocyanin concentration (for own‐rooted vines) compared with larger berries (1.4–2.0 g). Concentrations of tartaric acid and K+ in berry skins were highest in the smallest berry mass categories (0.3–0.7 g) and decreased with increasing berry mass (up to 1.4–2.0 g). A strong correlation (R²= 0.85) between skin tartaric acid and K+ concentrations was observed across that range. Small‐scale wine lots based on small berries (0.8–0.9 g) versus large berries (1.2–1.3 g) showed no differences in measures such as soluble solids, total acids or pH of juice; nor any differences in pH, total acids, K+, tartrate, malate, spectral characteristics or sensory score of corresponding wines. Moreover, small berries had a similar skin to fruit ratio, and a similar juice yield, compared to large berries. However, when measured post‐fermentation, the ratio of seed weight to skin weight was higher for small berries. The mass range of berries used here for small‐scale winemaking (i.e. from 0.8–0.9 g up to 1.2–1.3 g), covered the range of Shiraz berry mass typically found in irrigated vineyards (from 0.8 to 1.5 g), and thus confirms the relevance of present outcomes to practical winemaking. Finally, our data for variation in juice and wine composition as a function of berry size, showed consistent trends for all seasons, and thus implies that reported instances of improved wine quality from small berries (often associated with certain pruning treatments or deficit irrigation strategies), are more likely due to treatment effects that lead to small fruit, rather than to intrinsic developmental differences between large and small berries.     

A research note on the occurrence of 'star' flowers in grapevines: Observations during the 2003–2004 growing season

In 2003 star flowers were observed on three different grape varieties in the Coombe Vineyard at the University of Adelaide's Waite Campus. The earliest star flowers on Canada Muscat, and those on Gamay (which were also associated with stunted shoots), most closely resembled the structure of star flowers as described by previous authors. Later in the season, despite opening in star formation, the organs of the star flowers were normal. Star flowers may take different forms, which in turn hold implications for their comparative ability to set fruit. In contrast to previously published reports, the subsequent occurrence of normal flowers on a double-pruned Canada Muscat vine demonstrated that star flowers are not necessarily expressed during each and every generation of flowers. Occurrence of star flowers probably results from a genotype × environment × time interaction rather than a developmental aberration that is expressed during each and every generation of flowers.     

Sultana fruitfulness and yield as influenced by season, rootstock and trellis type

Field-grown vines ( Vitis vinifera L. cv. Sultana) were examined for their fruitfulness and yield performance over four growing seasons. Vines were either grafted to Ramsey rootstock ( Vitis champini ) or were grown on their own roots. Four commercially applied trellising systems were investigated, namely, a T-trellis, a Shaw trellis with a double cordon, a Shaw trellis with a single cordon and a Shaw swing-arm trellis. Fruiting potential was assessed shortly after budburst using the Merbein bunch count method. Bunches on vines that had been counted in springtime were again counted at harvest, and vine yield recorded. During the four years of the experiment fruitfulness was strongly influenced by growing season. Fruitfulness per node along the cane followed a well-established trend. Bud fruitfulness was close to zero in basal nodes but increased steeply thereafter reaching a maximum between nodes 8 and 10. Fruitfulness then decreased steadily. Grafted vines were always less fruitful than own-rooted vines, and this difference was amplified for all trellis designs in years when fruitfulness was low. At the time of pruning, more canes were retained on grafted than own-rooted vines in accordance with the greater vigour of grafted vines. This pruning strategy resulted in a larger number of bunches on grafted relative to ungrafted vines.