Production and growth of minimal pruned Sultana vines

Experiments with Sultana vines left unpruned for 15 years or unpruned but skirted to facilitate management (minimal pruned) for 6 years have shown that traditional pruning limits production, particularly in seasons when the district average is high. Minimal pruing increased the production of 50-year-old, non-clonal vines over 6 seasons by about 60 %. They had more bunches (106: 43) and more shoots (275 : 77) but fewer bunches per shoot (0.40 : 0.55) and smaller bunches (231 : 373 g) than pruned vines.At harvest, minimal pruned vines had a canopy similar in size to the pruned vines, and thus a smaller leaf to fruit ratio, (11.6: 17.0 cm2 ·g-1) but still matured the crop. Minimal pruned vines developed into larger vines because only 15 % of the wood was removed at pruning compared to 85 % from the controls but the weight of 1 year-old wood was lower {1.0: 2.3 kg). The shoots of minimal pruned vines were smaller (3.0 : 30.7 g), had fewer leaves (11.0 : 41.1), closer nodes with their mature length regulated by "seif pruning" (i.e. abscission of non-mature wood). Minimal pruned vines could be hand-harvested but were most suited to mechanical harvesting.Traubenertrag und vegetatives Wachstum von Sultana-Reben bei minimalem RebschnittSultana-Reben blieben entweder 15 Jahre lang ohne jeden Rebschnitt, oder es wurden über einen Zeitraum von 6 Jahren nur die frei herunterhängenden Triebe auf eine bestimmte Länge zurückgestutzt, so daß die anfallenden Weinbergsarbeiten durchgeführt werden konnten (Minimalschnitt). Die Versuche zeigten, daß der Traubenertrag durch den herkömmlichen Rebschnitt beeinträchtigt wird - besonders deutlich in Jahren mit einem hohen Gebietsdurchschnitt. Der Minimalschnitt steigerte den Ertrag 50jähriger nicht verklonter Reben in den 6 Versuchsjahren um durchschnittlich 60 %. Diese Reben besaßen insgesamt mehr Trauben (106 : 43) und mehr Triebe (275 : 77), jedoch weniger Trauben je Trieb (0,40 : 0,55) und kleinere Trauben (231 : 373 g) als die herkömmlich geschnittenen Reben. Bei der Traubenernte wies die Laubwand der minimal geschnittenen Reben ähnliche Werte (Blattgewicht, Blattfläche, Anzahl der Blätter je Rebe) auf wie jene der normal geschnittenen Reben. Die Relation Blatt : Frucht war infolgedessen verringert (11,6 : 17,0 cm2 ·g-1); trotzdem wurden die Trauben reif. Die minimal geschnittenen Reben entwickelten sich zu größeren Stöcken, da beim Rebschnitt nur 15 % des Holzes gegenüber 85 % bei den Kontrollstöcken entfernt wurden; das Gewicht des ljährigen Holzes war jedoch verringert (1,0 : 2,3 kg). Die Triebe der minimal geschnittenen Reben waren kleiner (3,0: 30,7 g), hatten weniger Blätter (11,4: 41,1) und kürzere Internodien, wobei ihre endgültige Länge durch „Selbstschnitt", d. h. Abfallen der nicht ausgereiften Enden, reguliert wurde. Minima! geschnittene Reben konnten von Hand gelesen werden, waren jedoch auch für die mechanische Ernte bestens geeignet.

Response of Riesling clones to mechanical hedging and minimal pruning of cordon trained vines (MPCT) implications for clonal selection

Three pruning treatments were superimposed on an established Riesling clonal selection trial situated in a hot irrigated Australian vineyard. Significant yield differences over 4 seasons between conventional spur pruning (mean 12.8 kg/vine) and the light pruning treatments, hedging and MPCT (means 14.2 and 13 .8 kg respectively), were found. Light pruning treatments produced smaller berries, but effects on soluble solids, pH and titratable acidity were small.Yield differences between the four clones, two Australian selections SA173 and SA140 and imported clones from Europe and California, were significant in the combined analyses of the three pruning treatments. SA173 (mean 14.7 kg/vine) h ad superior production while production by SA140 (12.7 kg) was inferior. The two imported clones gave similar yields. Clonal differences were not significant with spur pruning in any season but significant differences with the light pruning treatments were evident in 3 out of 4 seasons and over the 4 years. This-suggests that traditional severe pruning used in clonal selection trials may limit the production of improved clones

The Swing-Arm Trellis for Sultana Grapevine Management

The swing-arm trellis, designed to improve mechanical harvesting of Sultana grapevines used for raisin or wine production and to allow partial mechanization of pruning, is described. The trellis consists of seven wires, i.e. a cordon-wire and three wires each Sf>aced evenly in the horizontal and vertical plane and supported by triangular frames attached to the trellis posts. The vines are pruned to cordons that produce shoots that grow upward and attach to the vertical wires. For use as replacement canes, these shoots are placed horizontally by rotation of the frames. The yield of Sultana vines trained in this way was equal to or better than that of control vines trained in the standard manner with canes twisted around a single wire. Over fo'!r seasons, total yield was 1,31 times more for fresh fruit and 1,25 more for sugar. The yield differences occurred mainly in two seasons and were due to the combined effects of more nodes, better bud burst, more fruitful nodes and, consequently, more bunches. The advantages of managing vines trained on the swing-arm trellis are discussed

Sultana (Vitis vinifera L.) canes and their exposure to light

During three seasons, each of a number of Sultana vines were provided with three types of cane. These cane types differed, during the two seasons covering shoot development and fruit ripening, in their position within the vine canopy, and hence in exposure to solar radiation. On each vine, two canes (S) were placed outside and two canes (B) below the main body of the canopy formed in the main by the four T-canes.In all the yield components determined mainly by bud development, i.e. % bud burst, % fruitful/burst nodes and bunches/node the B-canes were inferior to the Sand T-canes, which did not differ significantly from each other. In one season, time of bud burst did not differ, but in the other season the buds of the S-canes burst first and the buds of the B-canes last. In the season when yield itself was measured, S-canes yielded about 20% more than T-canes and about 50% more than B-canes, despite the absence of any differences in yield components related to berry development, i.e. mean berry weight and concentration of sugar. There were no high-yielding B-canes, but some low-yielding S- and T-canes.It is concluded that individual shoots on the same vine respond directly to their aerial environment, and that proper cane selection or the choice of a training system allowing full exposure of the developing prospective canes can increase the productivity of Sultana vines.Die Tragruten der Sorte Sultana (Vitis vinifera L.) und ihre BesonnungIn einem dreijährigen Freilandversuch wurden an einer Anzahl von Rebstöcken der Sorte Sultana drei Typen von Tragruten herangezogen. Diese Rutentypen nahmen vom Beginn ihrer Entwicklung als Triebe bis zur Traubenreife unterschiedliche Stellungen innerhalb des Blattwerkes ein und wurden demnach unterschiedlich besonnt. An jedem Rebstock befanden sich zwei Ruten (S) außerhalb und zwei Ruten (B) unterhalb des hauptsächlich durch die vier T-Ruten gebildeten Blattwerkes. In jenen Ertragsfaktoren, die hauptsächlich durch die Knospenentwicklung bestimmt werden, nämlich in % Knospenaustrieb, % fruchtbare je ausgetriebene Knospen und in der Anzahl der Gescheine je Knospe waren die B-Ruten den S- und T-Ruten unterlegen. Unterschiede zwischen den beiden letzteren waren statistisch nicht gesichert. In einem der beiden Jahre wurden keine Unterschiede im Zeitpunkt des Knospenaustriebes gefunden, aber im anderen Jahre trieben im Durchschnitt die S-Knospen zuerst und die B-Knospen zuletzt.In dem Jahr, in dem der Traubenertrag gemessen wurde, lag dieser bei den SRuten um 20% höher als bei den T-Ruten und um etwa 50% höher als bei den B-Ruten. Dabei waren keine Unterschiede in der Beerenentwicklung, nämlich im Einzelbeerengewicht und in der Zuckerkonzentration des Saftes, festzustellen. Es gab keine B-Ruten mit großen, aber einige S- und T-Ruten mit kleinen Erträgen.Diese Ergebnisse zeigen, daß die einzelnen Triebe einer Rebe direkt auf ihre oberirdische Umwelt reagieren und daß man die Produktivität der Sorte Sultana durch Erziehungsarten, die eine volle Besonnung der nächstjährigen Tragruten ermöglichen, und durch entsprechende Wahl der Tragruten verbessern kann

Vitis seed longevity after prolonged cold storage

Research Not

A method using leafed single-node cuttings to evaluate downy mildew resistance in grapevine

A method using leafed single-node cuttings, incubated at 25 ± 2 °C and 100 % humidity, was examined to screen grapevine genotypes for resistance to downy mildew (Plasmopara viticola (Bert. & Curt.) Berl. & de Toni). Cuttings were taken at the 4th, 5th and 6th nodes back from apices of actively growing shoots. Disease symptoms, namely chlorosis, sporulation and necrosis, were observed on the leaves of cuttings within 6 days of incubation after inoculation. Based on chlorosis and sporulation, genotypes were ranked from highly susceptible to resistant in the order of Sultana, M46-32 (Bicane x Villard blanc), Joannes Seyve 23.416, Marroo Seedless and Chambourcin. The expressions of both symptoms increased with the concentration of inocula applied to leaves (1 x 105 and 5 x 104 sporangia per ml), but the overall genotypic ranking was unaltered. The third symptom of leaf necrosis occurred on infected leaves either as progressively enlarging dead areas or as smaller localised necrotic spots. The latter has been call ed the ‘necrotic response’ symptom and its expression depended on genotype, although its value for separating or ranking genotypes was unreliable. Leaf chlorosis was associated with leaf sporulation (r2=0.41-0.47). Genotypes with necrotic response exhibited reduced leaf chlorosis and sporulation. A comparison between this new leafed singlenode cutting method and a previously published leaf disc method indicated it was more reliable for separating genotypes for downy mildew resistance.

Breeding grapevines for tropical environments

Grapevines are increasingly grown in the latitudes between the Tropics of Cancer and Capricorn. In many cases environments modified by elevation are utilized to create temperate growing conditions. The majority of tropical grapes are consumed fresh but some are dried (India) and others are made into wine (Brazil, Venezuela). Currently most plantings are of pure Vitis vinifera varieties. Early ripening, low acid cultivars such as Cardinal, Perlette, Ribier and Thompson Seedless which have a relatively short cycle between budburst and harvest are commonly used, and pruning is timed to ensure maturation before the onset of heavy tropical rains. Other V. vinifera varieties used in the tropics such as Muscat Hamburg, Teneron, Anab-e-Shahi, and Italia have bunch and skin characteristics that give them some resistance to rain damage. There are a number of grapevine varieties that are hybrids between V. vinifera and other Vitis species which are currently grown in the tropics. These have some degree of resistance to fungal diseases and include Isabella, Kyoho, Delaware, Himrod, Campbell Early (V. labrusca hybrids), the Criolla hybrids (V. caribaea hybrids and Villard blanc (a complex French hybrid based on American species). There is considerable scope to increase the resistance of grapes to the main fungal diseases encountered in the tropics such as downy and powdery mildew, anthracnose and bunch rots by using a range of Vitis species as parents. These hybrids should be based on species that do not give strong 'foxy' flavours and could involve complex French hybrids, V. rotundifolia and also Asian species such as V. amurensis and V. armata. CSIRO Merbein has a small hybridisation program aimed at developing new varieties for tropical environments

Variation between and within grapevine families in reaction to leaf inoculation with downy mildew sporangia under controlled conditions

Vine reaction to downy mildew [Plasmopara viticola (Berk. & Curt.) Berl. & de Toni] inoculation was investigated between and within seven full-sib grapevine families under controlled culture conditions. Families were generated by crossing resistant x susceptible and susceptible x susceptible genotypes. Leaf infection following downy mildew inoculation was assessed using cultured leafed single node cuttings under controlled conditions. The severity of disease infection 7 days after inoculation was based on the expression of leaf chlorosis and sporulation symptoms using a 1 to 9 scale where a score of 1 meant there was no visible sign of infection and 9 meant > 80 % of the leaf area was infected. A measure of the hypersensitive response (discrete necrotic spots) was also used to rank vine reaction to inoculation. Hybrids within families varied widely in their reaction to inoculation. Any hybrid that received a mean symptom expression score ≤ 3, which was equivalent to or less than that assigned to 'Chambourcin', was classified as downy mildew resistant. The proportion of vines within families scored as resistant ranged from 4.6 to 22.5 % and from 4.6 to 47.4 % for leaf chlorosis and sporulation, respectively, between crosses. There was a strong correlation between leaf chlorosis and sporulation expression within each family (r2 ranged from 0.6 to 0.8). The number of resistant hybrids selected within families by the combined symptoms of leaf chlorosis and sporulation ranged from 3 to 7. Depending on family, segregation of resistant to susceptible phenotypes based on symptoms of leaf chlorosis and sporulation fitted 1:15, 1:7, 1:3 or 1:1 ratios. Segregation for hypersensitive reaction (HR) to non-HR fitted 1:1, 1:2 or 1:3 ratios within families. Hybrids that displayed the HR had mean scores for leaf chlorosis and sporulation less than those not displaying the necrotic spots characteristic of the reaction in four of the families investigated. The results are discussed in terms of the inheritance of resistance and the development of a strategy for future breeding.

Regulation of berry quality parameters in 'Shiraz' grapevines through rootstocks (Vitis)

The concentration of potassium (K) and pH in juice of grapevines is influenced by rootstocks (Vitis). However, the performance of rootstocks with respect to berry quality parameters and inter-relationships among berry quality parameters are not well understood. The current study addresses these issues. Berry and leaf samples at harvest maturity were collected from mature field-grown 'Shiraz' grapevines grafted with each of the rootstocks Dogridge, Freedom, Ramsey, 1103 Paulsen and 140 Ruggeri. Concentrations of K in juice and petiole and pH in juice were each highest for Dogridge and Freedom, but lowest for 140 Ruggeri and 1103 Paulsen. High concentration of K in juice was related to high concentrations of malic acid and TSS but low tartaric acid/malic acid ratio. In this study, lower concentrations of K in juice and in turn pH in juice of 'Shiraz' grapevines were maintained through rootstocks such as 140 Ruggeri and 1103 Paulsen that also show lower concentrations of K in petiole and TSS in juice, and higher tartaric/malic acid concentration ratio in juice at maturity. Selective use of these rootstocks in turn helps to produce quality grape juice and wine.