Effects of growth retardants on Vitis vinifera L.

Four growth retardants, CCC, Phosfon-D, Alar and CO 11, have been tested on Vitis vinifera over five seasons. Applications have been made by vine spraying or cluster dipping.Spraying with CCC resulted in darker green leaves, shortened internodes, retarded tendrils, increased numbers of inflorescences differentiated on lateral shoots, greater berry set and smaller berry size. Not all of these effects occurred together, the most frequent effects being on tendrils and berry set and size. Cluster dipping affected berry set and size in the same way as vine spraying but had no effects on other organs.Set was increased more than 20 per cent in about half of the 46 experiments. At the same time, berry size was reduced by about 10 per cent so that cluster weight or yield was only increased by more than 20 per cent in two-fifths of these experiments.Comparison of concentrations of CCC between 10 and 1000 ppm showed, in general, an increasing effect on set with increasing concentration. The most effective time of treatment was one to three weeks before anthesis; timing does not appear to be critical.Phosfon-D, like CCC, increased setting but caused a severe patchy chlorosis of leaves. Alar and CO 11 were, in general, without effect in these experiments

Shoot growth and anthesis in Vitis

In the majority of shoots on a grapevine the number of internodes is fairly constant at anthesis. The number of visible internodes was higher in Vitis vinifera L. (16-19) than in V. labruscana BAILEY (12-14). This synchrony in the rates of development of nodes at the shoot tip and of the flowers on the inflorescences was found in a wide array of conditions (time, cultivars, countries, climates, cultural practices). The factor found to cause greatest variation between vines was vine vigour.La croissance des rameaux et l'anthese de la vigneLa majorité des rameaux verts de la vigne montre un nombre assez constant d'entrenoeuds au moment de l'anthèse. Vitis vinifera L. (16-19) présente un plus grand nombre d'entrenoeuds que V. labruscana BAILEY (12-14). On retrouve dans diverses conditions (années, variétés, pays, climats, pratiques culturales) cette synchronisation de la vitesse du développement des noeuds de l'apex végétatif avec celle des fleurs sur les inflorescences. La vigueur de la vigne elle-même est le facteur responsable des plus grandes variations dans le nombre d'entrenoeuds au moment de l'anthèse. 

Influence of berry growth and growth regulators on the development of grape peduncles in Vitis vinifera L.

Removal of grape berries (cv. Roter Gutedel) after setting (10 d after anthesis) had just a slight effect on the subsequent health of the peduncle. But if younger berries of flowers were removed before this stage the peduncle formed abscission layers along its length, and/or it died. Treatment of deflowered peduncles with a-naphthalene acetic acid (NAi\) prevented peduncle abscission and death; it is suggested that auxins produced by flowers have a hormonal role in maintaining normal development of the peduncle. Treatment with 2-chloroethyltrimethyl ammonium chloride (CCC), benzyladenine (BA), indole-3-acetic acid (IAA) or 3-indolebutyric acid (IBA) did not give these effects. The lack of effect of the latter two compounds (auxins) is possibly due to their catabolism.Treatment with gibberellic acid (GA) resembled NAA in that it also maintained the health of deflowered peduncles, but GA had the additional effect of causing prolonged development of metaxylem. Gibberellin produced by developing berries may also have a hormonal role in peduncle development. The occurrence of grape peduncle necrosis (stiellaehme), which appears associated with a gibberellin deficiency during setting, supports this idea

Early bunchstem necrosis in grapes - a cause of poor fruit set

A disorder affecting the inflorescence of grapevines was identified and described. It occurs at any time from the early appearance of the inflorescence until flowering, causing shrivelling and death of some or all branches on the peduncle or bunch. It seems not to be caused by fungi or other pathological agent. Its appearance and development resemble stiellaehme or bunchstem necrosis (BSN), excepting that it occurs much earlier; thus the name 'early bunchstem necrosis' (EBSN) is suggested. Like BSN its aetiology appears to be related to the effects of specific inorganic chemicals. EBSN-like symptoms were induced by the cations Ca++ and NH4+but no response was found to K + and Mg++. There was considerably more EBSN in shaded compared with unshaded vines. No control or protective measures have so far been found

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

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 Einfluß von Gibberellinsäure und CCC auf die Traubenentwicklung bei Vitis vinifera L.Der Einfluß von Gibberellinsäure (GS)- und CCC-Gaben in faktorieller Kombination und in verschiedenen Entwicklungsphasen auf die generative Entwicklung der fünf Vitis vinifera-Sorten Doradillo und Muskat (samenhaltig), Sultana (stenospermokarp), Cape Currant und Zante Currant (parthenokarp) wurde gemessen. Der Einfluß 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; spätere Anwendungen waren ohne Wirkung. Bei Sultana verminderte GS den Fruchtansatz, wenn sie zur Blütezeit, und erhöhte ihn, wenn sie vorher oder nachher appliziert wurde. Bei den samenhaltigen Sorten verminderte GS die Zahl der samenhaltigen und erhöhte die der samenlosen Beeren; die Gesamtzahl der Beeren war gewöhnlich vergrößert. Die Anwendung von CCC zwei Wochen vor dem Blühen erhöhte allgemein den Fruchtansatz.Über die Samenentwicklung beeinflußte GS auch das Frischgewicht der Beeren; samenhaltige Beeren ließen keine Wirkung erkennen, während samenlose meistens vergrößert waren, und zwar am stärksten bei parthenokarpen Beeren, besonders nach Behandlung während der Anthesis. Bei stenospermokarpen Beeren hatte die zwei Wochen nach der Blütezeit applizierte GS die größte Wirkung. CCC, vor oder nach dem Aufblühen angewendet, verminderte die Beerengröße; der Rückgang betrug 2-20%. Durch GS wurde - sortenabhängig - das Verhältnis Länge/Breite der Beeren vergrößert, besonders bei Anwendung während der Anthesis. CCC verminderte dieses Verhältnis bei Sultana-Beeren. Auch das Wachstum des Traubenstieles wurde durch GS und CCC gegensätzlich beeinflußt; GS förderte das Längenwachstum von Traubenund Beerenstielen, besonders bei Anwendung vor der Blüte; CCC verminderte es. In einigen Fällen beeinflußten sich GS und CCC gegenseitig signifikant; im allgemeinen wurden hierdurch bei den verwendeten Konzentrationen ihre Wirkungen gesteigert

Primary bud-axis necrosis of grapevines. I. Natural incidence and correlation with vigour

The incidence of primary bud-axis necrosis (PBN) was studied from 1980 to 1985 in Australian vineyards of varying vigour. Fifteen cultivars of Vitis vinifera L. were initially examined for the presence of PBN and, because Shiraz (syn. Syrah) proved to have the highest incidence, subsequent work emphasized this cultivar. Compound buds at nodes 2 to 9 from the base of the shoot (node 9 being the most distal node) were scored for the presence of PBN. PBN was found to be a significant cause of unfruitfulness in the Australian vineyards examined. Incidence was higher in seeded compared with seedless cultivars. Shiraz had the highest incidence but not as great as for other cultivars reported in Israel, Japan, Chile and USA. PBN incidence was highest in the basal nodes of thick shoots, especially if the node bore a lateral shoot. Buds with PBN produced more shoots but fewer bunches. Thinning of shoots ten days before and after flowering increased both shoot vigour and PBN incidence. This association was attributed to the greater vigour per se and not to any change in canopy light environment. PBN-caused loss of primary shoots is concluded to be a major cause of unfruitfulness in basal nodes of grapevine

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