Grapevine fruit set: Physiology of the abscission zone

Effects of ethylene and of 'anti-ethylene' compounds on the floral pedicel abscission zone in grapevines were analysed via a laboratory model consisting of isolated flowers held in Petri dishes. Our model permitted precise determination of abscission and enabled us to test a range of physiologically-active compounds including ethylene precursors, and antagonists of ethylene action. For example, a precursor of ethylene, 1-aminocyclopropane-l-carboxylic acid, had the same effect as ethylene in promoting abscission. Conversely, an inhibition of ethylene action by silver thiosulfate or an inhibition of ethylene synthesis by amino-oxyacetic acid both strongly inhibited abscission zone function. …

Etude des relations criblo-vasculaires entre les différents organes de la tige de la vigne (<em>Vitis vinifera</em> L.)

<p style="text-align: justify;">Etude de la structure vasculaire reliant à la tige les feuilles, vrilles, grappes et bourgeons et analyse des relations entre ces organes.</p><p style="text-align: justify;">Sur un orthostique les organes de même nature ont au moins une relation entre eux ; vrilles et grappes sont en rapport direct avec feuilles et bourgeons ; il n'y a pas de communication entre feuilles et bourgeons.</p><p style="text-align: justify;">D'un orthostique à l'autre, feuilles, vrilles et grappes ne sont en relation que par les faisceaux latéraux foliaires. Les bourgeons des deux orthostiques sont anatomiquement indépendants.</p><p style="tex…

Analyse des nouveaux systèmes de corrélations de croissance entre bourgeons s'établissant après une grêle chez la vigne

<p style="text-align: justify;">A la suite d'un orage de grêle très violent des dégâts très importants sur les ceps ont entraîné des modifications profondes de l'équilibre entre les différents organes et en particulier entre tous les bourgeons épargnés par la grêle. Une étude fine des facteurs de l'entrée en croissance plus ou moins active de chaque type de bourgeon a été réalisée. Un fait intéressant a pu alors être constaté : l'entrée en croissance prématurée d'un assez grand nombre de bourgeons latents principaux (d'ordre N + 2) alors encore en état de prédormance. Celle ci ne s'est le plus souvent, pas poursuivie. Elle a néanmoins entraîné, l'année suivante, des modifications de l…

Internodal elongation in the grapevine (<em>Vitis vinifera</em> L.) : leaf influences and role of the shoot apex

<p style="text-align: justify;">The respective influences of the leaves and shoot apex on stimulation of internodal elongation were studied in the grapevine. Various defoliation or decapitation treatments were applied to the shoot of rooted hardwood cuttings grown in a controlled environment chamber.</p><p style="text-align: justify;">Concerning the foliar influences, the role of three sorts of leaves, in relation to their nodal position relative to the internode was analysed ; its own leaves, the leaves located below it and the young leaves neoformed above. The effects produced by excision of these different leaves show that the two adjacent leaves (below and above) of th…

Evaluation of the impacts of the climatic change in the various vineyards of France using the crop model STICS-grapevine

Demonstration of a correlation between young leaves, apex and young bunches specific to a young grapevine cutting in the first period of its development

<p style="text-align: justify;">The development of hardwood cutting of grapevine comprise 4 succesive phases. Phase I: first period of shoot extension. Phase II: characterized by a slow growth due to a very low activity of the terminal bud. Phase III: reactivation of the growth consecutive to a resumption of the apical activity. Phase IV: when the growth becomes maximal.</p><p style="text-align: justify;">The objective of this work has been to identify the cause of the slowdown of the activity of apical bud during the phase II.</p><p style="text-align: justify;">In a first experiment, we have compared the effects of three modes of defoliation applied from the b…

Divers aspects de la fertilité de la vigne après une grêle

<p style="text-align: justify;">Following a hail storm, the question normally posed is first to what extent a repruning is beneficial, and then to evaluate the hail's effect on the following year's fertility. A careful study of the influence of hail, using numerous measurements of fertility taken during winter has allowed to determine the parameters that should be taken into account in choosing the course of action to follow.</p>

Foliar influences on the vegetative development of grapevine

<p style="text-align: justify;">Various defoliation treatments were applied to grapevine shoots during the whole duration of the growth period: full defoliation of every shoot of vine, defoliations retaining a various number of adult leaves to the base of every shoot and defoliations retaining a various number of young leaves to the top. The effects of these treatments allow to identify the major foliar influences on the vegetative development. Total defoliation induced a lesser intemodal elongation. This result is probably due, in part, to a carbohydrates deficiency consecutive to this drastic treatment. The defoliations with variation of the number of young leaves showed that the le…

Demonstration and study of characters of foliar « compensatory growth» phenomenon in grapevine (<em>Vitis vinifera</em> L.)

<p style="text-align: justify;">Defoliation and decapitation experiments showed that the growth of a grapevine leaf was inhibited by both the terminal bud and the younger higher leaves. There is a phenomenon of synergy between these two influences. A young leaf freed of these two influences showed a higher growth rate than the norm ; this is « compensatory growth ». It is when a leaf is in its phase of maximal growth that it is most able to realize this &laquo compensatory growth ». This is not due to a longer growth time, but more to a faster growth rate. This « compensatory growth » is not the consequence of competition between leaf growth and internodal elongation. Exogenou…

Use of carbon dioxide enrichment to obtain adult morphology of grapevinein vitro

A procedure has been developed forin vitro propagation ofVitis vinifera ‘Pinot noir’ from lateral-bud cuttings under high CO2 concentration (1200 µmol mol−1). Because of inhibition of rooting by CO2, this procedure requires a rooting pre-culture of explants on medium with sucrose before the CO2-enriched culture on sucrose-free medium. Shoot growth was enhanced by CO2 enrichment as a result of both a higher rate of leaf production and greater internode elongation. Leaf expansion and tendril growth were promoted and better rooting was obtained. The more significant effect of CO2 enrichment was to promote adult morphology with, in particular, the tendril pattern. Thus, for the first time, grap…