Accumulation of potassium and calcium by ripening berries on field vines of Vitis vinifera (L) cv. Shiraz

Ripening berries of Vitis vinifera (L) cv. Shiraz can show pre-harvest weight loss at sub-optimal sugar content (shrinkage). This later-age decline in berry weight implies that water loss from mature berries has begun to exceed water inflow from the parent grapevine. Such decrease in net inflow has been attributed to a cessation of xylem flow subsequent to veraison, followed by a cessation of phloem flow into berries during later stages of ripening. We address this issue in this present paper, and show a continuing increase in berry content of both potassium and calcium throughout ripening. We measured changes in berry fresh weight and berry content of potassium (phloem mobile) and calcium (phloem immobile) in fruit on field vines sampled from set to harvest. Berry fresh weight reached a plateau between 81 and 95 days after flowering, then declined to 75% of maximum fresh weight by 115 days. Dry weight maximum occurred 14 days after the onset of the fresh weight plateau. Potassium accumulation was slow pre-veraison, increased 3.5-fold post-veraison, and continued during berry shrinkage. Calcium content per berry also showed a linear increase throughout fruit enlargement and ripening phases. Assuming both potassium and calcium were entering berries via vascular conduits, our results imply a continuing connection between parent grapevine and ripening berries. Moreover, an abrupt change (increase) in the ratio of potassium/calcium content per berry subsequent to veraison implies that phloem inflow has increased relative to xylem inflow during post-veraison enlargement.     

Direct measurement of hydraulic properties in developing berries of Vitis vinifera L. cv Shiraz and Chardonnay

Berries of Vitis vinifera L. cv Shiraz can undergo weight loss during later stages of ripening. Existing published views on how weight loss occurs are based on changes in capacity of the vascular system to import water during development (McCarthy and Coombe, Australian Journal of Grape and Wine Research, 5, 17–21, 1999). One important element of these views is the proposed cessation of water flow through the xylem after veraison. We have now measured the water flow into berries of Shiraz and Chardonnay as they develop using the pressure probe and the high pressure flow meter (HPFM). The pressure probe connected to the pedicel of individual berries provided measurements of single berry hydraulic conductance. By systematic excision of tissue segments of the berry and pedicel we determined where in the pathway hydraulic conductance changed during development. The HPFM was used on whole bunches showing that berries (including pedicels) represent parallel high hydraulic resistances and that the hydraulic resistance of the bunch axis was rather small. The hydraulic conductance per berry could be determined from excision experiments. There was close agreement between the pressure probe and HPFM measurements. Both showed a ten‐fold reduction in hydraulic conductance of whole berries from veraison to full ripeness. Shiraz had hydraulic conductances that were 2‐ to 5‐fold higher than those for Chardonnay. Shiraz maintained a higher hydraulic conductance past 90 days after flowering than Chardonnay. The decrease in hydraulic conductance occurred in both the distal and proximal parts of the berry for both varieties. The pressure probe also provided measurements of the xylem pressure that non‐transpiring berries could develop. These pressures were –0.2 to –0.1 MPa until veraison and increased to zero when the juice osmotic potential reached about –3 MPa in Chardonnay and –4 MPa in Shiraz. The results suggest values of the reflection coefficient of the osmotic barrier around the xylem vessels of about 0.1–0.2 at veraison decreasing to 0 at harvest. It is suggested that in addition to changes in xylem anatomy, aquaporins in berry membranes may play a role in regulating hydraulic conductance. Water movement from the berry back to the parent vine via the xylem (backflow) may be an important component of berry weight loss in Shiraz, particularly if the phloem ceases functioning at high osmotic potentials near maximum weight. Backflow could account for a weight loss of 43 mg per day in Shiraz berries for a relatively small gradient of 0.1 MPa.     

Weight loss from ripening berries of Shiraz grapevines (Vitis vinifera L. cv. Shiraz)

Environmental and phenological correlatives associated with the onset of weight loss during ripening in Vitis vinifera cv. Shiraz berries were examined. An irrigation experiment concerned with transient water deficit effects on berry growth over four consecutive seasons provided source data. Timing of maximum berry weight was more closely correlated with the number of days after flowering than with temperature summation. Prior to maximum berry weight, Brix was more closely correlated with days after flowering than with temperature summation, while the number of days from flowering to 10 and 15Brix was remarkably uniform despite contrasting seasons. Driving variables for weight loss during advanced ripening remain a matter of conjecture, but loss of berry water under highly evaporative conditions of late summer is a likely contributor.     

Developmental variation in sensitivity of Vitis vinifera L. (Shiraz) berries to soil water deficit

A large-scale, long-term irrigation experiment was established near Waikerie in the South Australian Riverland to investigate the feasibility of controlling berry size and ripening at the vineyard scale with modern irrigation systems. Irrigation treatments were devised to impose water stress, by withholding irrigation, during four periods of berry development after flowering of Vitis vinifera (variety Shiraz). Varying water deficits were achieved during each period and between the four seasons, which were climatically diverse. In one season water deficit during the period after flowering resulted in the greatest reduction in berry weight compared with that of well-watered vines, however, in another, water deficit during this period had no effect on berry weight. By comparison, berries appeared to be insensitive to water deficit during the month before harvest in all four seasons. A soil water deficit index was derived to compare the varying levels of water deficit between treatments and seasons on berry development. Deficit effects on berry development were assessed using either comparative growth rate or berry weight near harvest. Regression analysis of berry development against soil water deficit indicated that berries were most sensitive to water stress during the post flowering period.     

Development of seed polyphenols in berries from Vitis vinifera L. cv. Shiraz

Polyphenols extracted from the seeds of Vitis vinifera L. cv. Shiraz berries were monitored during berry development. Initially seeds were green, plump and had pliable seed coats, but beginning at veraison the seeds browned in colour, became desiccated and the seed coats hardened. Isolated polyphenols consisted of flavan-3-of monomers ((+)-catechin, (-)-epicatechin and (-)-epicatechin-3-O-gallate) and procyanidins. The procyanidins were maximal in the 3 weeks prior to veraison, increasing little during this period. The amounts of flavan-3-ol monomers increased 5-fold during this same period of time, indicating that the procyanidins and the flavan-3-ol monomers accumulate at different stages. Beginning at veraison, amounts of all polyphenols declined and changed in composition. The decrease in amount followed second-order kinetics. Polyphenol changes after veraison could be explained by oxidation and therefore, electron paramagnetic resonance (EPR) spectroscopy was used to follow the potential development of radical species in the developing seeds. Spectra consistent with a phenoxyl radical were observed in the developing seeds. The concentration of radicals remained low until veraison but then increased, reaching a maximum three weeks later, declining slowly thereafter. Changes in radical intensity together with other documented changes in the seed are consistent with an oxidative event occurring during fruit ripening.     

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.     

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.     

Synthesis of flavonols and expression of flavonol synthase genes in the developing grape berries of Shiraz and Chardonnay (Vitis vinifera L.)

Flavonols were determined in Shiraz and Chardonnay grapes throughout berry development. The predominant flavonols were quercetin-3-glycosides with trace amounts of kaempferol-3-glycosides detected in Shiraz flowers but not in developing berries. Flavonols were present in the skin of ripening grapes but were not detected in seeds or flesh. Flavonols were also present in buds, tendrils, inflorescences, anthers and leaves. The concentration of flavonols in flowers (mg/g fresh weight) was high and decreased between flowering and berry set then remained relatively constant through berry development. The total amount of flavonols in berries (mg/berry) was low until pre-veraison then increased during berry development, particularly before veraison, the onset of ripening, in Chardonnay and during ripening in Shiraz. Two cDNA fragments with homology to genes encoding the enzyme flavonol synthase (FLS) were isolated from Shiraz flowers. In the overlapping region of the two cDNAs, they had 80% sequence identity at the nucleotide level and both had high homology to FLS genes from other plants. VvFLS1 was expressed in leaves, tendrils, pedicels, buds and inflorescences as well as in developing grapes. Expression was highest between flowering and fruit set then declined, increasing again during ripening coincident with the increase in flavonols per berry. Expression of VvFLS2 was much lower than for VvFLS1 and did not change during berry development. The results indicate that two distinct periods of flavonol synthesis occur in grapes, the first around flowering and the second during ripening of the developing berries.     

Scion photosynthesis and leaf gas exchange in Vitis vinifera L. cv. Shiraz: Mediation of rootstock effects via xylem sap ABA

Limited water resources are placing pressure on the wine grape industry to improve vineyard water use efficiency by continuing improvements in vineyard management. One way to improve vineyard water use efficiency is to improve transpiration efficiency, and judicious use of scion-rootstock combination can play a role. Accordingly, this paper examines the influence of rootstocks on the water use physiology of a common scion variety (Shiraz) and assesses the importance of variation in xylem sap abscisic acid (ABA) as an indicator of relative water use efficiency of different scion-rootstock combinations. Shiraz scions (clone BVRC12) grafted to seven rootstock varieties (along with an ungrafted control), were observed over two consecutive seasons in a field trial located in Adelaide, South Australia. Those two seasons (2001/02 and 2002/03) offered sharp contrasts with respect to soil and atmospheric water stress. Rootstock genotype had a significant impact on scion gas exchange, water status, canopy growth and yield in both seasons. Those impacts were associated with an inverse relationship between xylem sap ABA and stomatal conductance. We suggest that strategic analysis of xylem sap ABA may provide a marker for comparative water-use physiology of different stock-scion combinations, while recognising that irrigation pre-history, and associated degree of vine water stress, will be a further source of variation in grapevine water use.     

红地球葡萄单穗不同留果量对果实品质的影响

以9年生红地球品种为试材,在中等偏上肥力、每667m2留果穗2000个左右的情况下,探讨了单穗3种不同留果量对葡萄果实相关指标的影响.结果表明:单穗留果50粒、70粒、90粒时,平均粒重分别为10.60g、10.14g、9.33g,单穗重分别为0.53kg、0.71kg、0.84kg,总糖含量分别为13.49%、12.65%、12.36%,糖酸比分别为31.81、28.74、27.27.粒重、总糖含量、糖酸比均随留果数量的增加而减少,单穗重随留果数量的增加而增加.3处理间果实表面亮白程度、红色程度相当,单穗留果50粒的果实表面颜色更蓝.从产量与销售价格综合考量,以单穗留果90粒为好.     

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.     

The effect of transient water deficit on berry development of cv. Shiraz (Vitis vinifera L.)

A new method for quantitative evaluation of the microbial load of cork and cork stoppers, coded CORA (Cork Activity Assay) is described. It is based on measurement by gas chromatography of dimethylsulfide (DMS) evolving from the reduction of dimethylsulfoxide (DMSO) by microbial activity. The method is accurate, gives results within 48 h and can be automated. Test results for various types of cork, sampled before, during and after the manufacturing process of bottle closures, are provided. The use of CORA as a tool for the development of better production processes to limit cork infection by micro-organisms and for advanced microbiological quality control is discussed.     

Influence of partial rootzone drying on the composition and accumulation of anthocyanins in grape berries (Vitis vinifera cv. Cabernet Sauvignon)

Background and Aims: The aim of the study was to investigate anthocyanin composition and accumulation in grape berries in response to the partial rootzone drying (PRD) irrigation technique.
Method and Results: The experiment was on Vitis vinifera cv. Cabernet Sauvignon, wherein PRD had a 40% water deficit relative to the control treatment. PRD decreased berry weight compared with the control, but did not influence total anthocyanin concentration. A significant increase in glucosides of delphinidin, cyanidin, petunidin and peonidin was found in response to PRD from the onset of anthocyanin accumulation (veraison), while malvidin-glucosides were unaffected by the irrigation treatment. The PRD treatment did not cause changes in the proportions of acetyl-, 3- p -coumaroyl- and monoglucoside anthocyanins. Wines produced from the treatments showed no difference in total monomeric anthocyanin, but relative increases (15%) in wine colour density, total tannin and polymeric pigment occurred in response to the PRD treatment. The anthocyanin composition of the wines reflected the response shown in the grapes, where the relative contribution of non-malvidin anthocyanins to total anthocyanins was significantly increased in wines from the PRD treatment.
Conclusions: The differences in anthocyanin composition observed in response to PRD could not be accounted for by changes in bunch microclimate, and most likely reflect differences in the methylation step of anthocyanin synthesis.
Significance of the Study: The observed changes in anthocyanin composition under the PRD irrigation system have not been previously reported in response to water deficit, and may reflect a unique response to within-vine signalling induced by PRD.     

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.     

利用AMDIS技术解析雷司令果实发育过呈中的降异戊二烯类香气物质

自动质谱图解卷积和鉴定系统(AMDIS)是美国标准化委员会推出的一款辅助气质数据定性分析的软件,利用该软件可有效的克服GC-MS定性分析中基质效应和共洗脱效应的干扰,增加解谱的准确性和可靠性.本研究将GC-MS检测技术和AMDIS辅助解谱相结合,从雷司令葡萄果实中鉴定出15种降异戊二烯类物质,他们多数以游离态形式存在,在果实发育早期或转色前期含量最高;此外还检测到4种结合态该类化合物.在成熟果实中,β-大马士酮和β -紫罗兰酮含量远高于其感觉阈值,呈现煤油味的TDN也略高于其阈值.该研究为AMDIS技术在果实香气成分分析中的推广应用提供了参考.     

Characterisation and evolution of grape polyphenol profiles of Vitis vinifera L. cv. Tannat during ripening and vinification

Background and Aims: Changes in different polyphenol families during grape ripening and vinification were determined in Tannat grapes. This was done to establish a polyphenol profile for Tannat grapes during ripening and for young wines. Methods and Results: We demonstrated, by high‐performance liquid chromatography with diode array detection and mass spectrometry (HPLC‐DAD‐MS) analysis, that the content of flavan‐3‐ols in Tannat seeds was higher than that reported for a large number of other grape varieties analysed. Forty per cent of the total flavan‐3‐ols in seeds were galloylated compounds, whereas the flavan‐3‐ol profile in skins was characterised by the absence of galloylated forms. Prodelphinidins in skins ranged between 30 and 35% with very low values for epigallocatechin. Epicatechin gallate was not detected in Tannat wine and galloylated forms represented a low percentage of total flavan‐3‐ols. Tannat grapes had very high concentrations of anthocyanins in skins with levels increasing during ripening. Eleven phenolic acids were identified in Tannat grape skins and wines, but only gallic and protocatechuic acids were found in the seeds. Conclusions: Tannat wines were shown to have one of the highest levels of phenolic compounds reported for vinifera grape varieties. The profiles for different polyphenol families present in Tannat grapes (skins and seeds) and wines were determined. Significance of the Study: The results presented will help to better understand the phenolic winemaking potential of this variety and its functional properties within food chemistry.