Flavour compounds of clones from different grape varieties

The selection of highly productive and characteristic clones is essential for the maintenance and improvement of the viticultural and commercially valuable qualities of certain grape varieties. In the future, this very difficult and time consuming selection of adapted clones will be supplemented with more precise analytical techniques. In this regard, GC analysis will be most valuable. Analytically, German white wines can be divided into three groups by the content of only a few monoterpene compounds ('terpene profiles'): 'Riesling', 'Muscat' and 'Sylvaner' or 'Weissburgunder' types. Furthermore, the use of linear discriminant analysis on some components allows the differentiation within types (e. g. for 'Riesling'-tpye: Riesling, Müller-Thurgau, Bacchus, Kerner, Ehrenfelser, Scheurebe). Till now no significant differentiation could be made from flavour compounds of Riesling clones, although clear differences can be perceived between wines from Traminer clones. Wines with a low sensory appraisal typically have a low content of monoterpene compounds. Differences can also be recognized in the aroma profiles of Chardonnay clones, allowing an analytical differentiation between aromatic and non-aromatic types. Certain clones, however, show differing compositions of flavour compounds when grown in different areas (clones with an 'unstable' aromatic character). Also during ripening of the berries, differences occur within individual Chardonnay clones, resulting in a few clones having recognizable ripening curves for monoterpene compounds

Potassium partitioning between leaves and clusters: Role of rootstock

Different scion/rootstock combinations in grapevine (Vitis vinifera/Vitis spp.) were tested for nutritional properties and juice composition. Chardonnay and Cabernet Sauvignon each grafted on 22 rootstock varieties (10 new crosses and 12 already used in viticulture) were grown in outdoor pots containing very poor nutritional substrate. Crop load had a strong effect on juice composition and potassium nutrition. Results indicate that under our experimental conditions rootstock can have an effect on potassium partitioning between leaves and cluster 9 out of 22 rootstocks that we tried were able to improve leaf potassium content without inducing a significant increase in juice potassium conten

Variability of must acidity in self pollinated Chardonnay progeny

From a total of 2,200 seedlings, obtained by self-pollination of cv. Chardonnay clone SMA 130, 250 plants were chosen and grown in a hot microclimate area. During 1986-88, morphological traits of shoot tip, leaf and bunch, as well as juice quality (sugars, pH, titratable acidity, malic and tartaric acid) were evaluated. A wide variability of the acid characteristics was noticed in the offspring. There was a significant positive correlation between total acidity and bunch size. Tartaric acid concentration was highest in medium-size bunches. A highly significant negative correlation was found between tartaric acid concentration and berry volume. More acid juice was also obtained from grapevines with a narrower apex

Relationships between seed number, gibberellin and abscisic acid levels and ripening in Cabernet Sauvignon grape berries

In grapes of Cabernet Sauvignon, berry growth, content of anthocyanin and hormonal composition affected by seed number were investigated.Gibberellin-like substance content showed highest values 45 d after anthesis, while abscisic acid content (on a per-berry basis) had two peaks, the first one just after berry set, the second coinciding with ripening phenomenon.Seed number was positively correlated with the cöncentrations of gibberellinlike substances and abscisic acid (on a per-berry basis). One-seeded berries, however, had a higher amount of anthocyanin than two or three-seeded ones.Beziehungen zwischen Anzahl der Samen sowie Gibberellin- und Abscisinsäuregehalt und Reifeverlauf der Traubenbeeren bei Cabernet SauvignonBei den Trauben von Cabernet Sauvignon wurden das Beerenwachstum, der Anthocyangehalt und die Zusammensetzung der Phytohormone in Beziehung zur Anzahl der Samen untersucht.Die Gibberellinaktivität erreichte 45 d nach der Anthese ihren höchsten Stand, während der Abscisinsäuregehalt (je Beere) zwei Maxima zeigte; das erste trat kurz nach dem Beerenansatz auf, das zweite fiel mit dem Beginn der Beerenreife zusammen. Die Anzahl der Samen war positiv mit der Gibberellinaktivität und der Abscisinsäurekonzentration (je Beere) korreliert. Einsamige Beeren. wiesen jedoch einen höheren Anthocyangehalt als zwei- oder dreisamige Beeren auf

Wild grapevine (Vitis vinifera var. silvestris) in Italy: Distribution, characteristics and germplasm preservation-1989 report

Research on the distribution and characteristics of wild grapevines (Vitis vinifera var. silvestris) in Italy was started whose main goals are: the preservation of the germplasm by setting up plant collections;the furthering of biological knowledge about this plant;the study of relations between wild and cultivated grapevines by means of chemotaxonomic techniques;the assessment of the possibility of using wild plants for genetic improvement of grapevines.The gathering of data began in 1984. 221 sites in 15 out of the 20 Italian regions have been indicated as possible locations in which wild grapevines grow. So far, 49 of these sites have been inspected. The greatest number of individuals were found in central Italy. This population is dioecious (male/female = 1.8) with few (2.0 %) hermaphrodite examples.The leaves of the Italian wild grapevines generally have 3 lobes (57 %), but 5 to 7-lobe (36%) and non-lobed (8.9 %) plants exist. Lower variability exists with regard to leaf shape. The study of seed morphology has classified the plants into three groupe, one of which is very numerous.Two germplasm collections have been established with approximately 400 vines

Chloroplast SSR markers to assess DNA diversity in wild and cultivated grapevines

Research Not

Differential effects of canopy manipulation and shading of Vitis vinifera L. cv. Cabernet Sauvignon. Leaf gas exchange, photosynthetic electron transport rate and sugar accumulation in berries

Partial cluster and leaf removals were performed on Vitis vinifera L. cv. Cabernet Sauvignon at veraison during two years to give 4 treatments: control (C), cluster thinning (CT), leaf removal (LR) and cluster thinning + leaf removal (CT+LR). A half of each plot was shaded by a 50 % shading net at veraison (40 % berries coloured). Shading significantly reduced stomatal conductance but not CO2 assimilation rate (Pn) and carboxylation efficiency. Pn was decreased by cluster thinning and enhanced by leaf removal. Leaves of CT vines showed a photosynthetic decay 2 days after the treatment while LR leaves presented an afternoon photosynthetic enhancement 3 days after the treatment probably due to a higher photoassimilate requirement of the bunches (sink). Stomatal conductance did not totally contribute to the P-n depression or enhancement. Electron transport rate and maximum Rubisco activity were strongly affected by CT and LR suggesting that photochemical and biochemical processes were affected to a greater extent than physical processes. Juice sugar concentration was reduced by shading, an effect explained straightforwardly by the lessening of stomatal conductance. CT and LR had large effects on biochemical and photochemical processes but these were in the opposite direction to the expected effects on juice sugar concentration. It is suggested that CT increased sugar concentration because of the low fruit sink load per vine, and that LR decreased sugar concentration because of the low leaf area per vine. If cluster thinning is to be used by growers to gain increased sugar concentration it is recommended to do it at veraison; the sugar accumulation rate is then high and the adaptation of photosynthetic processes to thinning takes several days

RAPD markers in wild and cultivated Vitis vinifera

Some Vitis vinifera cultivars and V. vinifera ssp. silvestris individuals have been subjected to the RAPD analysis in order to estimate the genetic diversity existing within this germplasm. 44 decamer primers of arbitrary sequence have been used for PCR and reproducible band profiles have been obtained. The distribution of the individualized polymorphic DNA markers has not turned out to be different in a remarkable way between cultivated and wild grapevines but this RAPD approach provides for some characteristics useful to analyze genetic relationships even within the Vitis vinifera species

A chemotaxonomic investigation on Vitis vinifera L. 3. Characterization of Vitis biotypes via root apex proteins

Soluble proteins from root tips were used as biochemical markers to study, taxonomically and systematically, Vitis biotypes. Analyses of total proteins in the pH range 3.5-10 and of the enzymes AcP, ADH, EST, PGM and POD indicate that only in the case of proteins and AcP the staining intensity of all samples and the variation of band pattern is taxonomically informative. A comparison between seed storage proteins and root tip proteins and an automatic data acquisition system is included

Stickstoffernährung und Wasserhaushalt bei Reben

Unter Freilandbedingungen wurde bei den Rebsorten Cabernet franc, Riesling, Bacchus, Forta und B-7-2 der Einfluß unterschiedlich hoher Stickstoffgaben auf den Gesamt-N-Gehalt einzelner Organe, den Abscisinsäure- (ABS)-Gehalt der Blätter und den Wasserhaushalt untersucht.Mit einer steigenden N-Düngung war in allen untersuchten Organen eine Zunahme des Gehaltes an Gesamt-N verbunden. Die ABS-Gehalte waren bei N-Mangel (0 oder 0,5 g N/Gefäß) gegenüber den Varianten mit höheren N-Gaben deutlich erhöht.Bestimmungen des Blattwasserpotentials bei den Sorten Bacchus und Forta, wurzelecht und gepfropft auf Kober 5 BB, zeigten bei hoher N-Düngung im Verlaufe des Welkeprozesses eine raschere Abnahme des Wasserpotentials, was auf eine negative Korrelation zwischen der Höhe der N-Düngung und der Blattrockenresistenz hindeutet.Eine höhere N-Düngung (4 g N/Gefäß) führte gegen Ende der Vegetationsperiode (Ende August) bei der Sorte B-7-2 gegenüber 2 g N/Gefäß zu einem höheren Anteil nicht ausgewachsener und ausgewachsener, physiologisch aktiver Blätter; der Anteil der seneszenten Blätter war reduziert.Die stomatäre Resistenz von Rieslingpflanzen war bei 4 g N/Gefäß gegenüber 2 g N/Gefäß erhöht; bei Kober 5 BB als Unterlage wurde die geringste, bei der Unterlage Kober 125 AA die höchste stomatäre Resistenz ermittelt.Nitrogen supply and water relations in grapevinesThe effects of different levels nf nitrogen supply to open air-grown grapevines, var . Cabernet franc, Riesling, Bacchus, Forta and B-7-2, were studied analyzing the amounts of total N in several organs as weil as the abscisic acid (ABA) contents and the water r elations of the leaves . A rise of N supply was correlated with an increased content of total N in all organs. N deficiency (0 or 0.5 g N per plant) considerably increased the ABA content compared to 1, 2 or 4 g N per plant.The leaf water potential of detached leaves of Bacchus and Forta decreased during wilting more rapidly when plants were supplieu with 180 kg N per ha than with 120 or 60 kg N per ha. It is suggested, therefore, that a high N supply is negatively correlated to drought resistance of leaves.Towards the end of the growing season (end of August) a high N supply (4 g N per pot) led to more unexpanded and expanded, 9hysiologically active leaves, while the number of senescent leaves was reduced compared to plants with a low N supply (2 g N per pot).Stomatal resistance of Riesling was higher with 4 g N per pot than with 2 g N per pot; grafted on Kober 5 BB stomatal r esistance was o.t its lowest, grafted on Kober 125 AA stomatal resistance was at its highest