Showing papers in "Vitis: Journal of Grapevine Research in 2017"

Photosynthesis in vine leaves as a function of light intensity, temperature, and leaf age

Abstract: Photosynthesis and respiration were measured in the laboratory with an infrared CO 2 analyser using attached leaves on Sultana vines growing either in the glasshouse or out of doors At light saturation (2,500-3,000 f c) the photosynthetic rates approximated 85 and 105 mg CO/h/dm 2 with light compensation points of 50 and 125 f c respectively The optimum temperature for photosynthesis was between 25 and 30° C Age effects were examined using shoots from well established field vines Small but rapidly expanding terminal leaves showed no net photosynthesis but had a high rate of dark respiration and a CO 2 compensation point above 300 ppm With further expansion the leaves showed a steady increase in photosynthetic activity with a corresponding decline in dark respiration and CO 2 compensation point The rate of photosynthesis again declined with the onset of senescence

Leaf age and photosynthesis in Vitis vinifera L.

Abstract: The photosynthetic activity of individual vine leaves was measured on potted plants grown out doors, using both infrared C0 2 analysis and 14 C0 2 fixation techniques. Peak photosynthetic activity occurred at the time when the leaf became fully expanded, approximately 40 days after unfolding. Thereafter, photosynthesis declined gradually. The increase in photosynthesis during leaf expansion was not attributable to increased chlorophyll concentration, altered spectral characteristics, or to any outstanding anatomical change. Nevertheless, a sensecent leaf was readily distinguished anatomically from an expanding or mature leaf.Irrespective of leaf age, sucrose was the major 14 C0 2 fixation product. Oligo- saccharides also incorporated label, and accounted for a higher proportion of the 14 C fixation products in older leaves. Regardless of leaf age, malic and citric acids became labelled, but the formation of 14 C tartaric acid was restricted to the rapidly expanding foliage. The amino compounds serine and aspartic acid showed some incorporation of label in all leaves examined.

lnfluence of grape variety, climate and soil on grape composition and on the composition and quality of table wines

Abstract: The influence of grape variety, soil type, climatic area and year of vintage on grape composition and wine quality was studied over a six-year period with three grape varieties in a eo-operative investigation. The wines were made under carefully controlled conditions to eliminate, as far as possible, any effect of winemaking technique. All viticultural and oenological treatments were replicated so that the data could be analysed statistically. When grapes from different viticultural areas were made into table wines, the quality of the wines was most closely related to grape variety, followed by climatic area and least of all by soil type. Reproducible differences in grape and wine composition were found for the grape varieties studied. For fhe same sugar content Riesling grapes and wine contained more acidity and a higher tartaric acid/malic acid ratio than Clare Riesling grapes and wine. They also contained less nitrogen, phosphorus and potassium. Shiraz grapes were relatively high in malic acid. The year of vintage strongly influenced the tartaric acid/malic acid ratio, particularly for Riesling and Clare Riesling, and also certain other constituents. Certain years could be designated as either high or low malic acid years for a particular grape variety. The soil type influenced the amounts of certain of the constituents of grapes and wine, but had no significant effects on the wine quality. Wines from the same varieties grown on two widely different soils in the same area could not be differentiated in replicated taste tests. The soil depth, drainage and waterholding capacity appeared to be more important than composition per se . Wines made from irrigated vineyards in the warm River Murray viticultural region, contained similar amounts of tartaric and malic acids, but were higher in pH, than wines made from the same grape varieties in the cooler non-irrigated Barossa Valley. Wines from irrigated grapes were generally of somewhat lower quality than those made from grapes of the same variety grown without irrigation in a cooler area. The time of harvesting irrigated grapes appeared to be critical to achieve the necessary balance between sugar, acid and flavour. Shiraz grapes grown under irrigation contained considerably less colour than grapes of the same variety grown without irrigation. Aroma was correlated with flavour in assessing wine quality, but numerical values ascribed to these parameters did not correlate generally with the wine constituents measured. A positive correlation existed between high tasting scores and high Ball/acid ratio.

Estimating biophysical and geometrical parameters of grapevine canopies ('Sangiovese') by an unmanned aerial vehicle (UAV) and VIS-NIR cameras

Abstract: Three zones of different vine vigour were identified in a mature vineyard (Vitis vinifera 'Sangiovese') to test the potential of the Visible-Near Infrared (VIS-NIR) spectral information acquired from an unmanned aerial vehicles (UAV) in estimating the leaf area index (LAI), leaf chlorophyll, pruning weight, canopy height and canopy volume of grapevines. A significant linear correlation between the normalized differential vegetation index (NDVI) and LAI or between NDVI and leaf chlorophyll was found at day of the year (DOY) 162 and 190, whereas in August the relationship between NDVI and leaf chlorophyll was less evident. The canopy volume of low-vigour (LV) vines was 35 and 45 % of the high-vigour (HV) and medium-vigour (MV) ones, respectively. The pruning weight was linearly correlated with NDVI values of each vigour cohort. A good correlation between the measured canopy volume and UAV-estimated one as well as between measured and estimated canopy height was found. Our results indicated that the combined use of VIS-NIR cameras and UAV is a rapid and reliable technique to determine canopy structure and LAI of grapevine.

Antiradical activity of phenolic metabolites extracted from grapes of white and red Vitis vinifera L. cultivars

Abstract: A diet rich in plant foods is strongly recommended for its beneficial effect on human health. In fact, plant secondary metabolites may exert various biological activities on mammalian cells. Among them, phenolics are excellent natural antioxidants able to rescue cell redox unbalance responsible for the onset of different pathologies. For these reasons, the present work was focused on the study of grape extracts obtained from eight different Italian Vitis vinifera cultivars, quite rare in Italian viticulture and not yet completely chemically characterized. For each preparation, total simple phenolic, flavonoidic and anthocyaninic content was measured through spectrophotometrical assays, while detailed biochemical profile was revealed by LC-MS analyses. In order to valorize the products of these varieties and increase our knowledge about their potential healthy role, the antioxidant power of the samples was evaluated by two different in vitro antiradical tests: DPPH and FRAP. Moreover, free radical scavenging properties of eleven grape pure compounds were investigated, with the aim to: a) compare their real antiradical property with the theoretical one; b) identify which one of them possessed the best bioactivity; c) understand how they might singularly contribute to the nutraceutical effect of the whole grapevine phytocomplex.

Anatomical aspects of grape berry development

Abstract: The anatomical development of the sultana-grape berry has been followed from anthesis to maturity on material grown under glasshouse and field conditions including field-grown clonal lines differing in final fruit size. Fresh weight, volume, berry dimensions, moisture content and dry weight were measured on whole berries. Pericarp growth was studied at the cell level. Pericarp growth is basically responsible for the overall growth of the berry and this tissue represents 64% of the mature fruit's total volume. The period required for complete berry development (approximately 100 days) falls into two major growth periods separated by a lag phase. Before the lag phase pericarp growth results partly from cell division but mainly from cell enlargement. After the lag phase pericarp growth results entirely from cell enlargement. Cell division in the pericarp ceases about one week before the lag phase. Berry size differences between clonal lines were primarily due to differences in the size of pericarp cells. Berry size differences between fruits grown in the glasshouse and in the field at Merbein were due to differences in both pericarp cell number and cell size.

Proline content of grapes and wines

Abstract: The proline, ammonia and total nitrogen content of some California grapes and the praline, total free amino acids and total nitrogen of the wines have been measured. The juice contains the predominant amount of the proline (50 to 80 %) in the grape cluster ; while the skins and seeds contain in excess of 50 % of the total nitrogen. Very little proline is found in the stems. A moderate portion is in the pulp (5 to 20 %). The praline can make up from 5 to 43 % of the total nitrogen in the juice depending o n vari ety and on grape m aturity. The Cabernet family of grapes appears to have highest percentages of prnline. A large percentage of the total amino acid left in the wine is in the form of proline. The amount of proline in the wine can vary from O to about 90 % of the total nitrogen. The wines with larger amounts of total nitrogen have higher percentages of residual proline. Rootstock affects the amount of total nitrogen but does not appear to affect the ratio of proline to total nitrogen. Th e ranges found in California grape juices range from 304 to 4600 mg/l of proline and in the wines from O to 3400 mg/l of proline. The average proline value for 78 juices was calculated as 742 mg/l and for the tabul ated data of 42 wines (from mainly cool climate grapes) - one half fermented on the skins the other half not - an average value of 869 mg/l of proline was found.

Dormancy and bud burst in sultana vines

Abstract: Dormancy and bud burst have been studied for sultana vines in the Murray Valley, Australia. The vines are in deep dormancy at the beginning of autumn and the intensity of dormancy decreases gradually during autumn and winter. Bud burst of cuttings taken during the dormant period occurs the more rapidly the higher the temperature at which they are held. There is evidence to suggest that sultanas have no chilling requirement and no clear distinction between organic and enforced dormancy. Treatment with 3 ml of ethylene chlorhydrin in a.201 container for 24 hours is effective in breaking dormancy. The most effective treatment veries slightly with the intensity of dormancy. Removing the outer bud scales or soaking buds in water decreases the intensity of dormancy. The pattern of bud burst found on canes in the field is established on pruned canes at least one month before the shoots appear. Both auxin and gibberellin will delay bud burst and reduce the proportion of buds which burst but auxin will not affect a bud above the point of application whereas gibberellin will do so.

Climate change and viticulture - a quantitative analysis of a highly dynamic research field

Abstract: In this study, we analyzed the newly emerging research field of climate change in combination with viticulture. Our analyses have two objectives: First, the overall publication output and the growth of research on climate change and viticulture is presented and analyzed. We developed a sophisticated search query to cover the relevant literature as completely as possible and to exclude irrelevant literature. The time evolution of the publications of the research topic as well as the most contributing journals and countries of authors, and the major research areas are presented. Second, most important publications in the historical context of this field are identified. Both analyses are based on a carefully selected publication set of 1039 papers (articles, reviews, and conference proceedings) dealing with the implications of climate change for viticulture. The results reveal that the number of papers published per year dealing with climate change and viticulture shows a strong increase: Since around 2000, the number increased by a factor of ten, whereas in the same time period the overall number of papers increased by a factor of around two. We identified 14 citation classics which include fundamental early works of viticulture with a weak connection to climate change and more recent works with a stronger connection to climate change.

Effect of plant regulators on set and berry development in certain seedless and seeded varieties of Vitis vinifera L.

Abstract: Flowering clusters on ungirdled, nondefoliated shoots of 'Black Corinth', and girdled shoots defoliated to 1 /ia leaf, were dipped in 4-CPA at 15 ppm, or GA3 at 5 or 15 ppm. In nondefoliated shoots the set was decreased about 13 °/o at 15 ppm, but there were no significant differences among the other treatments. All treatments produced heavier rachises, berries, and clusters than the ungirdled, untreated controls. In defoliated shoots the set was decreased approximately 85 °/o by GA3 at 15 ppm. 4-CPA significantly increased set, but a mixture of GA3 and 4-CPA did not alter set. Similar experiments were carried on with the seeded varieties 'Pinot Chardonnay', 'Muscat of Alexandria', and 'Grenache'. Clusters on ungirdled nondefoliated shoots were dipped in GA3, 4-CPA, or a mixture of the two compounds. Like treatments were made on other clusters on shoots defoliated to 1/4 leaf. There was a varietal difference in response among the seeded varieties. The compounds injured the Muscat and reduced the set and berry size. All treatments increased the set of seedless berries on nondefoliated shoots of 'Pinot'. In both 'Chardonnay' and 'Grenache' there was a shift from seeded to seedless berries. Application of 4-CPA resulted in a significantly greater set in total number of berries on defoliated shoots of 'Chardonnay' and 'Muscat'. All solutions containing GA3 increased siz'e of seedless berries on nondefoliated shoots of 'Pinot'. GA3 applied at shatter stage increased size of seedless 'Muscat' berries. With one exception, there was no increase in size of one-, two-, or three-seeded berries. Percentage set was significantly increased in defoliated shoots of 'Muscat' by 4-CPA, and in 'Pinot' by 4-CPA or a mixture of 4-CPA and GA3. A kinin, benzyladenine, failed to increase set or berry size, but intensified the development of a purple anthocyanin pigment in 'Muscat'. The possible importance of the ratio of a leaf-produced set factor to gibberellin in berry set in 'Black Corinth' is discussed.

Fruitfulness in grape-vines: Effects of water stress

Abstract: Plants of Vitis vinifera L. cv. Cabernet Sauvignon were grown in undrained containers in a glasshouse and watering was controlled by weighing. There were three treatments with water contents of the growing medium falling either to 60% (A), 40% (B) or 20% (C) of field capacity before re-watering. As water stress increased the amount of water used decreased as clid extension growth of shoots. At harvest 13 weeks after bud burst the weight of C plants was less than two thirds that of A plants. Fruitfulness (number and weight of bunch primordia per bud) was progressively depressed with increase in water stress. Number and weight of leaf primordia in buds were unaffected. Die Fruchtbarkeit der Rebe: Auswirkungen von Wassermangel Reben der Sorte Cabernet Sauvignon ( Vitis vinifera L.) wurden in nicht dranierten Gefasen im Gewachshaus herangezogen; die Wasserversorgung wurde durch Wagen kontrolliert. Bei den drei Varianten wurde die Pflanzerde bei Erreichen eines Wassergehaltes von 60 °/o (A), 40°/o (B), oder 20°/o (C) der Feldkapazitat wieder gegossen. Mit zunehmendem Wassermangel nahm die Menge des benotigten Wassers ab, entsprechend der wachstumsbedingten Ausdehnung der Triebe. Bei der Ernte 13 Wochen nach dem Austrieb betrug das Gewicht der C-Pflanzen weniger als zwei Drittel der A-Pflanzen. Die Fruchtbarkeit (Anzahl und Gewicht der Infloreszenzprimordien) war mit zunehmendem Wassermangel progressiv vermindert. Anzahl und Gewicht der Blattprimordien blieben unverandert.

The glucose - fructose ratio of California grapes

Abstract: Because of the high sweetness of fructose table grape varieties of high fructose content would be of interest for cold climates For producing stable sweet table wines with ordinary yeasts high fructose varieties would be desirable With the Sauternes strain of yeast high glucose varieties would be favored The LOTHROP-HOLMES method gave good recovery of added glucose, duplicable results, and minor interference of fructose The glucose/fructose ratio of California grapes at maturity varies over a wide range, from at least 080 to 112 There is, however, considerable variability in the ratio between different vines Further data should be obtained for a large number of varieties in order to discover as wide a range of ratios as possible Plant breeders could then use this information in their experiments

A simple method for demonstrating macroscopically the location of polyphenolic compounds in grape berries

Abstract: Slices of berries of several varieties of Vitis vinifera were stained with HCl, vanillin-HCl or FeCl 3 to demonstrate macroscopically that the bulk of the polyphenolic compounds occur in the skins, seeds and conducting tissue of grape berries at all stages of development. Eine einfache Methode zur makroskopischen Lokalisation polyphenolischer Verbindungen in Weinbeeren Schnitte von Beeren verschiedener Vitis vinifera -Sorten wurden mit HCl, Vanillin-HCl oder FeCl 3 angefarbt, um makroskopisch zu zeigen, das der Hauptanteil der polyphenolischen Verbindungen in allen Entwicklungsphasen in der Schale, den Samen und den Leitbundeln der Weinbeere lokalisiert ist.

Attempts at grapevine (Vitis vinifera L.) breeding through genetic transformation: The main limiting factors

Abstract: Breeding through genetic transformation offers the possibility to add or modify single traits in cultivars without changing desirable characteristics. In grapevine this technology has been scarcely used, taking into account the economic importance of this crop. Up to now, the breeding of grapevine through genetic transformation has been mainly focused on biotic stress resistance, mainly to fungi and viruses. Among the factors that can explain the limited reports of success are the difficulty in regenerating transgenic plants, the availability of only a few characterized genes, and/or the quantitative character of the trait. Another influencing factor is the negative perception of consumers, mainly in Europe. In this review, we discuss the methodology and factors that have limited the success of grapevine transformation, as well as outlining the attempts at breeding grapevine through genetic transformation reported so far. It is expected that the use of transformation, a powerful tool for breeding plants, will increase in grapevine in the coming years as a consequence of the growing knowledge of the function and regulation of grapevine genes and promotors, and of technologies for gene editing.

Gluconeogenese in reifenden Beeren von Vitis vinifera

Abstract: Im Verlaufe der Reifeperiode 1973 wurde Traubenbeeren in wochentlichen Intervallen Fumarsaure-2,3- 14 C injiziert und nach einer Stoffwechselzeit von 6 Stunden der Einbau des Tracers in Malat sowie die Neutralfraktion untersucht. Es konnte nachgewiesen werden, das - mit geringer Randomisierung des C-Skelettes des Prakursors - vorwiegend Apfelsaure entsteht. Daneben erscheinen aber bis zu 17% der Radioaktivitat in den Zuckern (Glucose, Fructose und Saccharose). Aufgrund der 14 C-Verteilung im Glucosemolekul, welche ein Schwergewicht der Markierung in den C-Atomen 1, 2, 5 und 6 aufweist, kann auf die Existenz des „klassischen" Gluconeogeneseweges (mit Oxalacetat, Phosphoenolpyruvat und Phosphoglycerat als Intermediarprodukten) in Traubenbeeren geschlossen werden. Die Inkorporationsrate des biogenetisch aus '"C-Fumarat entstandenen 14 C-Malats in die Neutralfraktion ist bei c a. 20 °C am hochsten. Dieses relativ tiefe Maximum durfte auf die in diesem Temperaturbereich optimale Versorgung der Fruchte mit stoffwechselaktiver Apfelsaure als Edukt fur die Zuckersynthese zu erklaren sein. Vergleiche der Zuckergehalte von Trauben mit bzw. ohne direkte Sonnenbestrahlung lassen wahrend des Reifeverlaufes bei den Fruchten an beschatteten und damit kuhleren Standorten eine deutlich intensivere Zuckerbildung erkennen, so das dadurch der zum Zeitpunkt der „Veraison" bestehende Unterschied im Zuckergehalt nahezu verschwindet. Es wird die Bedeutung der Gluconeogenese fur diesen Ausgleich diskutiert. Gluconeogenesis in the ripening fruit of Vitis vinifera Fumaric acid-2,3- 14 C was applied to grape berries at weekly intervals and the incorporation of radioactivity into other acids and the neutral, watersoluble substances determined. Malic acid, predominantly labelled in the inner C-atoms, proved to be the main metabolic product, and up to 170/o of the 14 C-activity of the extract was discovered in the neutral fraction. The t4C-glucose thus synthesized carried more label in the Cl/C2 and the C6/C5 positions than in the two central C-atoms. Based on these results it is concluded that the ripening fruit transforms acids into sugars by reactions involving a formal reversal of the glycolytic pathway. Incorporation of radioactivity of 14 C-fumaric and -malic acids into sugars shows a temperature optimum of about 20 °C. Comparisons between the sugar concentrations of grapes growing in the sun or in the shade, indicate that the r a t e of sugar synthesis during the final ripening-stages is greater in the shade. Thus, the marked difference in sugar content at veraison disappears during maturation. The contribution of sugar synthesis from acids to the observed compensation is discussed.

Effect of various combinations of trellis, pruning, and rootstock on vigorous Sultana vines

Abstract: The combined effects of three trellis, three pruning, and three rootstock treatments were tested on vigorous Sultana vines (Vitis vinifera L.) growing in a lighttextured, nematode- and phylloxera-free, virgin soil of the Australian Murray Valley. Vines on Salt Creek rootstock outyielded vines on 1613 C rootstock or on their own roots by about 40 per cent during the first four cropping seasons after planting, which preceded the experiment, and by about 30 per cent during the four seasons of the experiment, because they had more and larger bunches. A wide, high trellis with two cane-wires 1.2 m apart and 1.5 m above ground level, a narrow, high trellis (0.3 m X 1.5 m) and a narrow, low trellis (0.3 m X 1.0 m) were compared. On the wide trellis, the foliage canopy was divided naturally into two halves. In the season following the trellis conversion, vines on the wide trellis yielded slightly better than those on either of the narrow trellises, possibly because there was less mould damage. In the subsequent seasons, the wide trellis was much more productive. lt produced 40 to 50 per cent more crop because the vines had more bunches with more berries per bunch, while the concentration of sugar or acids remained unaltered. The amount of pruning wood was also somewhat greater. For the three pruning treatments, vines were given 126, 196, or 266 nodes (i. e. 9, 14, or 19 canes of 14 nodes each). In the later years of the experiment, the lightest pruning level could not be maintained on the narrow trellis, and pruning weight tended to become smaller. Yield increased disproportionately with increasing nodenumber; a two-fold increase in the number of nodes led to only a 20 per cent increase in yield. There were few interactions between the trellis, pruning, and rootstock treatments. The beneficial effects of wide trellis, Salt Creek rootstock and of light pruning, at least up to the level of 196 nodes per vine, tended to be additive. Thus lightly pruned Sultana vines on Salt Creek rootstock grown on a wide trellis with split canopy produced twice as much fruit as the conventionally treated Sultana, i. e. an own-rooted vine with 126 nodes grown on a narrow, low trellis. lt is concluded that Sultanas benefit from wide trellis through an effect on bud fruitfulness which leacls to more berries per vine, and through better photosynthetic activity which allows f4ll maturation of this increased crop potential. The economic implications of using wicle trellises and Salt Creek rootstock are discussed. Der Einflus verschiedener Kombinationen von Drahtrahmen, Rebschnitt und Unterlage auf starkwuchsige Sultana-Reben Der vereinte Einflus von drei Drahtrahmen-Typen und drei Schnittarten auf wurzelechte Sultana-Reben und auf Sultana, gepfropft auf den Unterlagen Salt Creek und 1613 C, die in einem leichten, Nematoden- und Phylloxerafreien Urboden des australischen Murray-Bewasserungsgebietes wuchsen, wurde untersucht. Alle Resultate wurden der Varianzanalyse unterworfen. In den ersten vier Ertragsjahren nach der Pflanzung, die dem Versuch vorausgingen, war der Ertrag von Sultana auf Salt Creek um 40°/o hoher als derjenige von wurzelechten oder auf 1613 C gepfropften Reben. In den folgenden vier Versuchsjahren betrug dieser Unterschied etwa 30°/o. Mehr und grosere Trauben waren der Grund hierfur. Die drei Drahtrahmen hatten die folgenden Dimensionen: Ein weiter, hoher Rahmen mit zwei Drahten, die mit 1,2 m Abstand 1,5 m uber dem Boden angebracht waren; ein enger, hoher Rahmen (0,3 m X 1,5 m) und ein enger, niedriger Rahmen (0,3 m X 1,0 m) mit einem weiteren Draht fur das Blattwerk. Am weiten Drahtrahmen teilte sich das Blattwerk spontan in zwei Halften. In der ersten Vegetationsperiode nach dem Erstellen der Drahtrahmen war der Ertrag am weiten Rahmen etwas besser, vermutlich wegen des geringeren Faulnisbefalles. In den folgenden drei Vegetationsperioden brachten die Reben am weiten Drahtrahmen um 40 bis 50°/o hohere Ertrage, da mehr und grosere Trauben vorhanden waren, wahrend Beerengrose, Zucker- und Sauregehalt unverandert blieben. Auch das Gewicht des Schnittholzes war etwas groser. Die Reben wurden zu 9, 14 oder 19 Tragruten von je 14 Knospen, demnach zu 126, 196 oder 266 Knospen, geschnitten. Am engen Drahtrahmen konnte man die hochste Knospenzahl in den letzten Jahren des Versuches nicht erhalten, und auch das Triebgewicht wurde kleiner. Im allgemeinen hatte die Verdopplung der Knospenzahl nur einen 20prozentigen Anstieg im Ertrag zur Folge. Wechselwirkungen zwischen den Behandlungsarten Drahtrahmen, Schnitt und Unterlage kamen nur vereinzelt vor. Die vorteilhaften Einflusse von weitem Drahtrahmen, Salt Creek-Unterlage und von hoheren Knospenzahlen, wenigstens bis zu 196 Knospen je Rebe, waren additiv. Infolgedessen war der Ertrag der zu 196 Knospen geschnittenen Sultana auf Salt Creek und auf weitem Rahmen zweimal so gros wie derjenige der wurzelechten Sultana auf engem Rahmen mit 126 Knospen. Es wird geschlossen, das Sultanaknospen am weiten Drahtrahmen fruchtbarer sind und das folglich im nachsten Jahr die Reben mehr Traubenbeeren tragen, die uberdies durch Verbesserung der Photosynthese vollig ausreifen konnen. Die okonomischen Verhaltnisse fur den Gebrauch von weiten Drahtrahmen werden diskutiert.

Laboratory evaluation of insecticidal activity of plant essential oils against the vine mealybug, "Planococcus ficus"

Abstract: Planococcus ficus is a principal mealybug pest of vineyards worldwide. Minthostachys verticillata and Eucalyptus globulus essential oils (EO) were evaluated as insecticidal products on P. ficus , and the main components of M. verticillata and E. globulus EO were also tested as insecticidal compounds against vine mealybug females under laboratory conditions. The results revealed that M. verticillata EO was more toxic than E. globulus EO, while pulegone (LC50 39.60 µL/L) was more toxic than the other constituents of the EO studied. Menthofuran, an oxidation product of pulegone by cytochrome P450 enzymes, showed an LC50 value of 63.97 µL/L. Thus, the mechanism of insect detoxification did not reduce the toxic potential of the pulegone. In addition, 1,8-cineole had a higher insecticidal property than its isomer 1,4-cineole. Our studies suggest that the pulegone can be a useful fumigant botanical insecticide to protect crops against vine mealybug attacks.

Interprétation chimique de la couleur des vins rouges

Abstract: Dans la prem1ere partie de ce memoire, l'intervention specifique des anthocyanes et des tanins sur la couleur des vins rouges est etudiee en solutions modeles: Les anthocyanes seules ne possedent pas une couleur identique a celle des vins rouges que l'on trouve dans les melanges d'anthocyanes et de tanins. En presence d'air, les tanins subissent une transformation de nature oxydative, acceleree par la presence d'ions Fe+++, qui conduit a une coloration brunorange-tuile qui rappelle la couleur des vins vieux. Dans les memes conditions, les anthocyanes en solution pure sont peu modifiees. Par contre ces pigments, en melange avec les tanins, disparaissent rapidement et la coloration est alors peu differente de celle des solutions de tanins. On demontre donc d'une maniere indiscutable l'existence d'une reaction entre ces deux types de pigments. On peut admettre que ces transformations reproduisent approximativement les modifications lentes de la couleur au cours de la conservation et du vieillissement. On confirme ainsi le role preponderant des tanins, par rapport aux anthocyanes, dans la couleur des vins vieux. Certains faits laissent supposer que les anthocyanes peuvent etre reduites sous forme de flavenes incolores dont la reoxydation n'est que partielle. Cette reaction interviendrait au cours de la vinification, phenomene reducteur, et influe sur la couleur du vin. Dans la deuxieme partie on a cherche a decrire les mecanismes chimiques susceptibles d'interpreter les faits precedemment signales; certains sont bien demontres, d'autres sont des hypotheses de travail sur lesquelles sont basees les recherches actuellement en cours clans ce domaine important de l'oenologie des vins rouges: Les anthocyanes sont decolorees par diminution de l'acidite, addition de bisulfite ou reduction; dans certaines conditions ces phenomenes sont reversibles. Independamment de son intervention comme catalyseur d'oxydation, l'ion Fe+++ donne des complexes colores en bleu-vert avec les anthocyanes et surtout avec les tanins dont la concentration dans les vins rouges est beaucoup plus importante; ce phenomene est responsable de la casse ferrique des vins rouges. Plusieurs transformations, chimiques ou enzymatiques, oxydatives ou non, provoquent une destruction irreversible des anthocyanes. Differentes reactions de condensation des molecules de flavanes conduisent aux proanthocyaniclines (dimeres ou trimeres) et aux flavolanes (oligomeres) constituants des tanins condenses. Ces transformations influent sur la coloration des tanins, donc du vin, et sont responsables de la couleur brun-tuile des vins vieux; elles interviennent aussi clans le developpement des caracteres organoleptiques propres au vieillissement et la precipitation de la matiere colorante des vins rouges. La disparition des anthocyanes en presence de tanins peut s'interpreter par une reaction de condensation qui fait perdre a la molecule d'anthocyane ses proprietes, sans destruction de cette molecule. On peut envisager egalement la formation d'un pigment jaune du type xanthylium. Der Chemismus der Rotweinfarbung Untersuchungen an Modellosungen liesen eine Beeinflussung der Rotweinfarbung sowohl durch Anthocyane als auch durch Tannine erkennen. Die Oxydation der Tannine, katalysiert durch Fe +++ -Ionen, ruft eine ziegelrote Farbung hervor, die in erster Linie die Farbe alter Rotweine bedingt. Unter den gleichen Bedingungen werden die Anthocyane nicht verandert; andererseits verschwinden diese Pigmente im Gemisch mit den Tanninen schnell. Somit besteht kein Zweifel am Vorhandensein einer Reaktion zwischen beiden phenolischen Verbindungen. Gleichermasen kann man annehmen, das die Anthocyane durch Reduktion zu unstabilen Flavenen entfarbt und nur teilweise reoxidiert werden. Es wird eine ausfuhrliche Beschreibung aller chemischen Vorgange gegeben, die in diesem Zusammenhang moglicherweise eine Rolle spielen. Die Anthocyane konnen durch bestimmte Reagentien reversibel entfarbt, aber auch irreversibel verandert werden. Kondensationsreaktionen der Flavanmolekule verandern die Struktur, die Farbe und die organoleptischen Eigenschaften der Tannine; die Anthocyane konnen an solchen Kondensationen teilnehmen.

Conversion and determination of sex in Vitis vinifera L. ( sylvestris )

Abstract: Sex conversion in the male V. vinifera ( sylvestris ) clone 030-44 could not be attributed to germinal mutation of the major gene for sex. The differences in sex expression among male seedling vines can best be explained on the basis of an undetermined number of minor modifying genes able to shift a very sensitive threshold. The frequency of sex conversion within a given seedling vine was greatly influenced by environmental, both local and seasonal, conditions. The following facts were established in Vitis vinifera L. ( sylvestris ): (1) the male sex is heterogametic and is inherited as a simple Mendelian factor, maleness being completely dominant; (2) homozygous males are as viable as heterozygous males, they are phenotypically alike and can only be identified by breeding tests; (3) pure and hermaphroditic males are genetically alike as far as the major gene for sex is concerned; (4) sex chromosomes are not differentiated, either morphologically or physiologically. A pair of alleles, SuF and Sum, were used to explain the results obtained on selfing the hermaphroditic male clone 030-44. The gene Su F determines maleness and its allele Su m in homozygous condition determines femaleness. The gene Su F is completely dominant over its allele Sum. The genotypes of the homozygous and heterozygous males are Su F Su F and Su F Su m respectively, and that of the female is Su m Su m . The evolution of cultivated V. vinifera hermaphrodites in the light of present results is discussed.

The importance of yeasts in determining the composition and quality of wines

Abstract: From the wine makers' view point at present the advantages of the use of selected yeasts are the rapid and predictable onset of fermentation, its evenness and completion and the absence of undesirable aromas and flavours. However it is now apparent from our work that wine yeasts differ considerably in other characteristics which can also be of oenological importance. Compounds formed by yeasts which can directly affect the flavour of wines include hydrogen sulphide and mercaptans, iso-amyl alcohol, and ethyl and amyl acetate. Othex· aroma materials which are not reminiscent of pure compounds, but which affect wine quality, can also be produced. These may confer a quality improvement or, in the case of spoilage yeasts, a reduction in quality. Compounds which indirectly affect the quality of wines are those which bind sulphur dioxide and prevent it from carrying out its antioxidant and germicidal functions. The most important compounds in this connection in normal wines are acetaldehyde, pyruvic and a-ketoglutaric acid, and the amounts produced are influenced by the yeast strain. It is also possible to exercise control over reduction in acidity during the fermentation by controlling the amount of 1-malic acid metabolised by choice of a suitable yeast strain. Likewise some control is possible over the quantities of ethanol and higher alcohols produced and the prevention of off-flavours resulting from fermentation. One of the most important results of our work has been the prevention of hydrogen sulphide formation in wines. This formation is basically a microbiological reduction of elemental sulphur or sulphur-containing compounds during fermentation, and the control has been to carry out the fermentation with a yeast which is unable to produce hydrogen sulphide. Such yeasts exist naturally and may be selected on the basis of suitable laboratory tests. These yeasts need to have other desirable attributes such as high ethanol tolerance, the ability to carry out a regular and complete fermentation and to be able to grow fast enough to dominate the indigenous microflora. As a result of ·our investigations the use of selected yeasts has become widespread in Australian wine making, and the strain of yeast is now regarded as one of the controllable factors necessary to make wines of high and consistent quality.

The Determination of induction and differentiation in grape vines

Abstract: The induction and differentiation of 8-year-old Alphonse Lavallee and Sultana grape vines were studied Defoliation methods enabled us to determine the induction time in grape vines as in other fruit species Induction and differentiation in the tested varieties were not connected with temporary growth cessation; on the contrary, process took place during the most intensive growth A correlation was found between the number of leaves and induction period 18-21 leaves above the examined buds were needed in bot-h varieties to complete the induction The leaf area needed for induction in a bud of Sultana was lYe times larger than that needed for Alphonse The efficiency of the leaves of Alphonse to induce differentiation was thus greater The primordia ,development from induction to detection under the microscope (differentiation) was connected with a constant vegetative development The time needed for this development was determined by the growth rate of the variety (18 days in Sultana, 14 days in Alphonse) The translocation of materials inducing differentiation from the base of the shoot upwar,ds has not been proved in our work In Alphonse a lag period of two days was found for the differentiation of each bud along the cane

The effect of reducing leaf area on the growth of roots, stems and berries of Gordo grape-vines

Abstract: To measure the effect of leaf number during berry growth on all organs of the grape vine (Vitis vinifera) a pot experiment was done using Muscat Gordo Blanco plants maintained in the open. Each plant was allowed to develop one fruitful shoot and 4 treatments (12 plants each) were applied following fruit set: (1) control (2) 6 leaves left (3) 3 leaves left (4) 1 leaf left. Leaves left (by tipping the shoot) were primary leaves at and above the first node above the bunch. When primary leaves senesced or were wind damaged a corresponding area of lateral-shoot leaf (125 cm 2 ) was permitted to re>:main. Leaf area measurement of sample plants gave values of 2470 cm 2 , 850 cm 2 , 470 cm 2 and 125 cm 2 respectively for the 4 treatments. On each shoot there was one bunch limited to 30 berries. Measurements of berry volume and sugar suggested that there was a diphasic growth curve and that wit h fall in leaf number there was a longer lag phase and a shorter second growth phase. Growth rate in the second phase was not greatly affected. Acids fell more slowly where leaf number was less, and the sugar: acid ratio was reduced. From final plant dry weights it was found that the trunk (parent stem) was least affected by leaf reduction, followed in order by shoot, berries and roots. Sugars and starch in trunk and shoot were affected in a way similar to berries. When needs of trunk, shoot and berries were fully met it appeared that cxcess leaf assimilate was channelled into root growth. The minimal leaf area for unimpeded growth of aerial organs was estimated to be 1500 cm 2 (12 leaves), but in the field where bunches have more berries a greater leaf area would be required. The data has been interpreted to show that leaf efficiency in terms of carbon fixation, was markedly increased with reduction in leaf number.

Physiological studies on dormancy in grape seeds ( Vitis vinifera var. Black Muscat) II. On the effect of exogenous application of growth substances, low chilling temperature and subjection of the seeds to running water

Abstract: In order to break the dormancy of grape seeds in the minimum possible time, a number of treatments, including stratification, growth substances and subjecting the seeds to running water, were used. It was observed that grape seeds kept in running water for 8 days germinated in the muslin cloth itself (34.00%). The maximum percentage of germination obtained was 73.00% when the seeds were kept in running water for 16 days. However, the seedling stand was best under the 12 day treatment (72.11 %). This was followed by GA3 treatment (2000 ppm) before stratification, whereby grape seeds germinated within 8 days of stratification and maximum germination percentage was 81.05 after one month. Third best result was obtained under stratification for one month and then a treatment with GA3. Further, grape seeds, when soaked in water for 96 hours, leached some water soluble inhibitor. This could antagonize the germination of GA3 treated grape seeds. When this leached water was bioassayed by the cress seed germination test, it showed the presence of inhibitor at R1 0.7 to 0.85. It appears that the water soluble inhibitor might be responsible for masking the effect of growth substances present in the seeds and thereby disturbing the metabolism of germination. Physiologische Untersuchungen zur Dormanz von Rebensamen (Vitis vinifera var. Black Muscat). II. Uber den Einflus auserlich angewandter Wuchsstoffe, niedriger Temperaturen und des Auswaschens der Samen in fliesendem Wasser Um die Dormanz von Rebensamen in der kurzestmoglichen Zeit zu brechen, wurden sie stratifiziert, mit Wuchsstoffen behandelt und in fliesendem Wasser ausgewaschen. Es wurde beobachtet, das Rebensamen, die in einem Musselinsackchen 8 Tage lang ausgewaschen wurden, schon in dem Sackchen keimten (34,00°/o). Der h ochste Keimungsprozentsatz (73,000/o) wurde erzielt, wenn die Samen 16 Tage lang mit fliesendem Wasser behandelt wurden. Bei einer 12tagigen Behandlung (72, 11% gekeimter Samen) war die Standfestigkeit der Samlinge jedoch am besten. Das zweitbeste Resultat wurde mit GS3-Behandlung (2000 ppm) vor der Stratifikation erzielt, wobei die Rebensamen nach 8tagiger Stratifikation keimten; der hochste Anteil gekeimter Samen betrug - nach 30tagiger Stratifikation - 81,05%. 1monatige Stratifikation mit an schliesender GS3-Behandlung lieferte das drittbeste Ergebnis. Ferner gaben Rebensamen, die 96 Std. lang in Wasser gequollen waren , einen wasserloslichen Inhibitor ab. Dieser konnte die Keimung GS3-behandelter Samen hemmen. Mit Hilfe des Kressewurzeltests lies sich im Einweichwasser ein Hemmstoff mit ein em Rr von 0,70-0,85 nachweisen. Moglicherweise stort der wasserlosliche Inhibitor den Stoffwechsel der Keimung, so das die Wirkung der Wuchsstoffe in den Samen verdeckt wird.

Considérations générales sur le rythme végétatif et la dormance des bourgeons de la Vigne

Abstract: La variation de la vitesse de debourrement des bourgeons en fonction de la temperature a ete etablie durant le cycle vegetatif annuel pour des varietes de precocite de debourrement differente. La vitesse de debourrement d'une variete precoce est toujours superieure a celle d'une variete tardive, quelles que soient l'epoque et la temperature. De 20 a 35°C le debourrement est toujours possible chez les varietes precoces dont la dormance des bourgeons ne se manifeste que par une diminution momentanee de la vitesse de debourrement. Par contre, les varietes tardives presentent une vitesse nulle ou tres faible quand les bourgeons sont en dormance. Le cycle vegetatif annuel des bourgeons a ete subdivise en cinq phases: phase de pre-dormance, phase d'entree en dormance, phase de dormance, phase de levee de dormance, phase de post-dormance, L'entree en dormance des varietes tardives se produit plus tot que celle des varietes precoces. Mais ces dernieres, qui exigent des temperatures moins basses, subissent la levee de dormance avant les varietes tardives. Le phenomene de levee de dormance est reversible quand les temperatures depassent un seuil, plus eleve pour les varietes precoces que pour les tardives (13°C pour Perle de Csaba, 8°C pour Ugni blanc). La dormance des bourgeons est levee quand leur etat physiologique a atteint un certain niveau d'evolution, appele s e u i l d'irreversibilite. Deux processus physiologiques distincts se deroulent dans les bourgeons durant les phases de dormance et de levee de dormance: P r o c e s s u s : A d a p t a t i o n a u x b a s s e s t e m p e r a t u r e s . Sous l'action des temperatures decroissantes de l'automne, les bourgeons s'adaptent progressivement a subir l 'action des temperatures basses qui levent leur dormance. Ils deviennent en meme temps aptes a debourrer plus rapidement, quelles que soient les temperatures. Des hypotheses sont formulees pour expliquer cette adaptation. P r o c e s s u s : L e v e e d e d o r m a n c e . Ce processus, qui peut etre decienche naturellement par les temperatures basses inferieures a un seuil, ou artificiellement par des agents physiques ou chimiques (anaerobiose, substances inhibitrices de la respiration), permet aux bourgeons d'atteindre un etat physiologique qui rend le debourrement homogene et en augmente la vitesse. Des reactions fermentaires induites par les inhibiteurs de la respiration constituent une condition suffisante pour la realisation de ce processus. Le mecanisme physiologique de l'entree en dormance et de la levee de dormance, n'est pas encore connu avec exactitude. General considerations regarding vegetative rythm and bud dormancy in the vine The variation of the rate of bud burst as a function of temperature has been evaluated throughout the annual vegetation cycle for varieties differing in regard to their earliness of bud burst. The rate of bud burst of an early variety was found to be always greater than that of a late variety. In the range 20°C to 35°C, bud burst is always possible in early varieties whose bud dormancy is reduced to a temporary decrease in the rate of bud burst. On the other hand, late varieties have a zero or very low rate of bud burst during bud dormancy. We have divided the annual vegetation cycle of the buds into five phases: predormancy, going-into-dormancy, dormancy, dormancy-breaking, post-dormancy. Going-into-dormancy occurs earlier in late varieties as compared with early ones. These, however, undergo the breaking of dormancy earlier than the late ones, because they do not require as high a temperature. Dormancy-breaking is a reversible process, if temperature rises above a threshold which is higher for early varieties than for late ones before it is completed (13°C for P e r l e d e C s a b a), (8°C for U g n i b l a n c ). Bud dormancy is broken once the physiological state of the bud has reached a given level of evolution, which we call irreversibility threshold. Two different physiological processes occur in the buds during the course of the dormancy and dormancy-breaking phases: A d a p t a t i o n t o l o w t e m p e r a t u r e s : As the temperature decreases in the course of autumn, the buds adapt themselves progressively to undergo the action of low temperatures which will eventually break their dormancy. At the same time, they are becoming able to burst at a faster rate whatever the temperature. Hypotheses are proposed that account for this adaptation. B re a k i n g - d o r m a n c y : This process, which can be triggered naturally by temperature lower than a threshold, or artificially, by physical or chemical agents (anaerobiosis, respiration inhibitors) brings the buds to a physiological state in which bud burst is homogeneous, and occurs at an increasing rate. Fermentative reactions induced by the respiration inhibitors are a sufficient condition for this process to occur. The exact nature of the physiological mechanism of going-into-dormancy and of dormancy-breaking, however, remains unknown.

Effects of vine rootstocks on chloride concentration in Sultana scions

Abstract: Sultana vines in the field grafted on any one of a number of rootstocks being tested for compatibility showed substantially reduced petiole chloride as compared with ungrafted sultanas. Self grafted sultanas did not differ from ungrafted in chloride status. There were significant differences between the various effective rootstocks - the degree of reduction of chloride concentration was better than 50 per cent for Dogridge and 1613 stocks, but about 75 per cent for Salt Creek and 101-14.

Microecology of yeasts and yeast-like organisms associated with an English vineyard

Abstract: An extensive environmental study, with particular reference to yeasts and yeast-like organisms, was made of the vineyard at Lang Ashton. The results of this microecological survey were obtainecl by using a variety of techniques in which a quantitative estimate was macle of the yeasts and yeast-like organisms. Sampling was carried out at all stages of grape vine cleveopment. Sources of yeasts and yeastlike organisms included all vine parts as well as the soil, air, other plants ancl animal vectors which frequented those sources. Many potential spoilage organisms, e. g. film yeasts, were present but fermenting yeasts ( Saccharomyces spp.) were rarely found. Among the microorganisms isolatecl were new unreported species of Trichosporonoides, Saccharomycopsis (synonym of Endomycopsis ), Sporobolomyces, Sporidioboltis, Rhodosporiditim, Candida, Nadsonia and Schizosaccharomyces . Other isolates were identified as species within the genera Aureobasidium, Trichosporon, Sporobolomyces, Rhodotorula, Cryptoccus, Metschnikowia, Torulopsis, Candida, Pichia, Hansenula, Kluyveromyces, Saccharomyces and Kloeckera . Mikrookologie der Hefen und hefenahnlichen Organismen aus einem englischen Weinberg Mit Hilfe verschiedener Schatzmethoden wurde die quantitative Verteilung der Hefen und hefenahnlichen Organismen im Weinberg von Long Ashton ermittelt. Die Probenahme erfolgte in allen Stadien der Rebenentwicklung. Hefen und ahnliche Organismen fanden sich an samtlichen Teilen der Rebe, im Boden, in der Luft, an anderen Pflanzen sowie an tierischen Ubertragern dieses Biotops. Es traten viele potentielle Urheber von Fehlgarungen, z. B. Kahmhefen, auf, wahrend Weinhefen ( Saccharomyces spp.) nur selten festgestellt wurden. Unter den isolierten Mikroorganismen befanden sich aus Weinbergen bisher nicht bekannte Arten der Gattungen Trichosporonoides, Saccharomycopsis (syn. Endomycopsis ), Sporobolomyces , Sporidiobolus, Rhodosporidium, Candida, Nadsonia und Schizosaccharomyces . Des weiteren wurden Species von Aureobasidium, Trichosporon, Sporobolomyces, Rhodotorula, Cryptocciis, Metschnikowia, Torulopsis, Candida, Pichia, Hansenula, Kluyveromyces, Saccharomyces und Kloeckera identifiziert.

β -Phenethanol and n-hexanol in wines: Influence of yeast starin, grape variety and other factors; and taste thresholds

Abstract: β-Phenethanol and n-hexanol were measured by gas chromatography in a wide range of commercial and experimental wines. Commercial wines ranged from 5 to 74 ppm β-phenethanol and 1.3 to 12 ppm n-hexanol. Dry red wines and fino sherries were high in p'-phenethanol, and ports, muscats (both sweet dessert wines) and dry red wines were high in n-hexanol. The strain of yeast strongly influenced formation of β-phenethanol. Mean yields by eight yeasts (Saccharomyces) during fermentation of grape juices from three varieties of Vitis vinifera under comparable conditions ranged from 5.6 to 20 ppm. The strain of yeast had little effect on amounts of n-hexanol in the wines. Varieties of V. vinifera differed in amounts of β-phenethanol and n-hexanol formed in the wines made therefrom, irrespective of the yeast strain used. Wines made from Shiraz (Syrah) grapes were characterised by high levels of fi-phenethanol in comparison with white grape varieties examined. The year of vintage influenced amounts of β-phenethanol in wines, and the soil type and viticultural area also effected the amounts of both β-phenethanol and n-hexanol formed. More β-phenethanol was formed by fermentation at 15° C and 25° C than at 35° C, and more was formed at pH 3.5 and 4.0 than at pH 3.0. n-Hexanol content was not influenced significantly by either temperature of fermentation or pH of the must. Addition of β-phenylalanine to the must resulted in formation of more β-phenethanol by fermentation, and the mechanism of formation of both β-phenethanol and n-hexanol is discussed . Taste thresholds were measured as minimum detectable differences in a Riesling dry white wine. Values for different tasters ranged from 30 to > 200 ppm for β-phenethanol (10 tasters) and 4 to > 30 ppm for n-hexanol (9 tasters). Added β-phenethanol, but not n-hexanol, was considered to improve the quality of the wine.

The interaction of gibberellic acid and 2-(chloroethyl) trimethyl ammonium chloride on fruit cluster development in Vitis vinifera L.

Abstract: The effects of applications of GA and CCC in factorial combinations and at different stages of development were measured on reproductive development of five cultivars of Vitis vinifera : Doradillo and Muscat (seeded), Sultana (stenospermocarpic), and Cape Currant and Zante Currant (parthenocarpic). The effect of GA on fruit set varied with concentration, stage of development when applied, and the cultivar, that is whether seeded, stenospermocarpic, or parthenocarpic. Set was decreased in the parthenocarpic cultivars by GA applied before anthesis; other timings were without effect. On Sultana, set was decreased by GA applied at anthesis but was increased by earlier or later applications. With the seeded cultivars, GA reduced the number of seeded berries but increased the number of seedless berries, the net effect being usually an increase. The application of CCC two weeks. before anthesis generally increased set. The amount of seed development also influenced the effect of GA on berry fresh weight; seeded berries were unaffected but seedless berries were usually enlarged. The enlargement was greatest in parthenocarpic berries especially when treated at anthesis. On stenospermocarpic berries, treatment two weeks after anthesis had the greatest effect. CCC reduced berry size whether applied before or after anthesis; the reductions ranged from 2 to 20 per cent. GA increased the length/width ratio of berries, particularly when applied at anthesis, but the amount of change depended on the cultivar. CCC reduced the length/width ratio of Sultana berries. The effects of GA and CCC on rachis elongation were also opposite: GA increased the length of the rachis and pedicel, particularly if applied before anthesis; CCC reduced their length. There were few instances where GA and CCC interacted significantly; their effects within the concentration ranges chosen were generally additive. Der Einflus von Gibberellinsaure und CCC auf die Traubenentwicklung bei Vitis vinifera L. Der Einflus von Gibberellinsaure (GS)- und CCC-Gaben in faktorieller Kombination und in verschiedenen Entwicklungsphasen auf die generative Entwicklung der funf Vitis vinifera -Sorten Doradillo und Muskat (samenhaltig), Sultana (stenospermokarp), Cape Currant und Zante Currant (parthenokarp) wurde gemessen. Der Einflus der GS auf den Fruchtansatz hing von der Konzentration, dem Entwicklungsstadium zur Zeit der Applikation und von der Sorte ab, d. h. ob samenhaltig, stenospermokarp oder parthenokarp. Vor der Anthesis angewendet, verminderte GS den Fruchtansatz; spatere Anwendungen waren ohne Wirkung. Bei Sultana verminderte GS den Fruchtansatz, wenn sie zur Blutezeit, und erhohte ihn, wenn sie vorher oder nachher appliziert wurde. Bei den samenhaltigen Sorten verminderte GS die Zahl der samenhaltigen und erhohte die der samenlosen Beeren; die Gesamtzahl der Beeren war gewohnlich vergrosert. Die Anwendung von CCC zwei Wochen vor dem Bluhen erhohte allgemein den Fruchtansatz. Uber die Samenentwicklung beeinfluste GS auch das Frischgewicht der Beeren; samenhaltige Beeren liesen keine Wirkung erkennen, wahrend samenlose meistens vergrosert waren, und zwar am starksten bei parthenokarpen Beeren, besonders nach Behandlung wahrend der Anthesis. Bei stenospermokarpen Beeren hatte die zwei Wochen nach der Blutezeit applizierte GS die groste Wirkung. CCC, vor oder nach dem Aufbluhen angewendet, verminderte die Beerengrose; der Ruckgang betrug 2-20%. Durch GS wurde - sortenabhangig - das Verhaltnis Lange/Breite der Beeren vergrosert, besonders bei Anwendung wahrend der Anthesis. CCC verminderte dieses Verhaltnis bei Sultana-Beeren. Auch das Wachstum des Traubenstieles wurde durch GS und CCC gegensatzlich beeinflust; GS forderte das Langenwachstum von Traubenund Beerenstielen, besonders bei Anwendung vor der Blute; CCC verminderte es. In einigen Fallen beeinflusten sich GS und CCC gegenseitig signifikant; im allgemeinen wurden hierdurch bei den verwendeten Konzentrationen ihre Wirkungen gesteigert.

Untersuchungen über die Beziehungen zwischen Blütenbildung und Triebwachstum bei Reben

Abstract: Der Differenzierungsablauf der Infloreszenzbildung in den Winterknospen wurde unter gleichzeitiger Berucksichtigung des Triebwachstums an alteren, im Freiland wachsenden Pflanzen beobachtet. Als Entwicklungskriterien der reproduktiven Organbildung dienten die Stadien O (praeflorales Primordium), I (Infloreszenzprimordium), II (Verzweigung der Infloreszenz) und III (Blutenprimordium). In den Winterknospen der 5. bis 7. Insertionshohe treten bei den Sorten Aris und Riesling Infloreszenzprimordien etwa 35 Tage nach dem Knospenaustrieb im Fruhjahr auf. Der Bluhimpuls breitet sich mit dem wachsenden Trieb in distaler Richtung aus, wobei ca. 6-10 Knospen unmittelbar unterhalb der Sprosspitze vegetativ bleiben. Die maximale Zahl an Infloreszenzen/Knospe ist etwa 12 Wochen nach dem Austreiben erreicht. Bei den zuerst angelegten Infloreszenzprimordien erscheinen die ersten Blutenprimordien bei Aris etwa 50 Tage nach dem Austrieb (20 Tage nach Stadium I) und bei Riesling etwa 80 Tage nach dem Austrieb (rund 45 Tage nach Stadium I). Bis zur endogenen Wachstumsruhe enthalten bei Aris 24,5% und bei Riesling 5,9% aller infloreszenzbildenden Knospen Blutenprimordien. Die Anlage von Infloreszenzen ist mit der Blattentfaltungsgeschwindigkeit des Haupttriebes korreliert. Die Hohe der fur die Determination erforderlichen Blattzahl/Trieb ist sortenspezifisch. Eine Klassifizierung der Sorten nach dieser Blattzahl/Trieb ergibt: Sorten mit sehr fruher Infloreszenzbildung: 11-12 Blatter/Trieb ( V. silvestris , Klon Ketsch 30), mittelfruher: 13-15 Blatter/Trieb ( V. silvestris , Klon Ketsch 6, V. labrusca , Aris, Riesling), mittelspater: 16-18 Blatter/Trieb ( V. cinerea , Rupestris du Lot, Portugieser, Gutedel) und spater Infloreszenzbildung: 20-22 Blatter/Trieb (Tschausch, Rkazeteli, Rasaki). Durch Applikation von Gibberellinsaure auf die Blattspreiten wird eine signifikante, vom Zeitpunkt der Behandlung und von der Sorte abhangige Hemmung und Blockierung der Infloreszenzbildung festgestellt. Das Maximum des Gibberellineffektes liegt bei der Sorte Aris ca. 24-28 Tage oder bei 6-9 Blattern/Trieb vor der Infloreszenzdetermination. Die Gibberellinhemmung der Blutenbildung wird itn Maximum der GS-sensiblen Phase von morphologischen Veranderungen innerhalb der Knospen begleitet. Dabei kann es mitunter zu einem Absterben der Hauptknospe einer Winterknospe kommen. Eine gesteigerte N-Dungung fuhrte bei der Sorte Aris zur Erhohung der Infloreszenz-und Blutenzahl/Knospe bzw. je Trieb. Eine uberoptimale N-Zufuhr reduzierte die Intensitat der Blutenbildung. Bei horizontal und senkrecht wachsenden Trieben werden weniger Infloreszenzen/Knospe als bei aufrecht wachsenden Trieben angelegt. Die entwicklungsphysiologischen Schritte der Infloreszenz- und Blutenbildung werden dargelegt und mit den an anderen Holzpflanzen gewonnenen Befunden eingehend diskutiert. Es wird angenommen, das die Anlage von Infloreszenzen eine Funktion des entwicklungsphysiologischen Alters der Knospen und Laubblatter darstellt, wahrend die Anlage von Blutenprimordien primar als Ausdruck korrelativer Wechselwirkungen innerhalb der Knospe zu werten ist. Ernahrungsphysiologische Komponenten bestimmen uberwiegend die Infloreszenz- und Blutenzahl/Knospe. Die Klimakomponenten wirken primar uber ein beschleunigtes Wachstum (Temperatur, Langtag) oder uber eine verbesserte Photosynthese (Licht) auf den Prozes der Infloreszenz- und Blutenbildung ein. Die zuchterischen und weinbaulichen Aspekte der vorliegenden Untersuchungen werden angefuhrt.

Evolution des Aminoacides au Cours de la Maturation des Raisins

Abstract: Pour completer nos connaissances sur le metabolisme azote du raisin et mieux determiner les formes les plus utiles a la mutrition des microorganismes, nous avons suivi l'evolution des aminoacides du raisin au cours de sa maturation a l'aide de la chromatographie sur papier et des techniques de dosage microbiologique. La teneur de la plupart des aminoacides augmente, mais la proline est l'objet d'une accumulation considerable surtout accusee dans les jours qui precedent la maturite. Nous avons fait cette remarque, importante par ses consequences oenologiques, qu'au cours de la maturation, l'azote du raisin passe progressivement sous des formes de moindre valeur pour l'alimentation des levures.