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1 2

Véraison Nouaison

Maturité

Chute des feuilles Repos hivernal Fermeture de

la grappe

CYCLE DE DÉVELOPPEMENT

DE LA VIGNE

Développement des

rameaux et des inflorescences

Floraison

Formation

des baies

Remplissage

des baies

Dormance

Mise en réserve

??????? ??????? hiver ??? apex (Axe I) limbe ???????oe?? (Axe II)

PHYTOMERE

rameau

Bourgeons contaminés

pendant l"été Survie hivernale du champignon dans les bourgeons

Jeune rameau recouvert

d"un feutrage blanchâtre " drapeau »

Chainettes de conidies à la

surface des rameaux herbacés et des feuilles

Contamination (*) des organes

végétatifs : feuilles ou grappes Feuilles infectées : production importante de conidies

Ascospores libérées

au printemps

Cléistothèces

Grappe infectée

Conidies

Conidies Asques contenant

des ascospores

Formation de

cléistothèces à la fin de l"été 1 2 3

Point de départ de la

lecture du graphique Cycle de reproduction asexuée répété n fois du printemps

à l"automne, (*) à l"origine des contaminations secondaires Cycle de reproduction sexuée inter-annuel, (*)

à l"origine des contaminations primaires sexuées

Cycle de reproduction asexuée inter-annuel,

(*) à l"origine des contaminations primaires asexuées

1 2 3 LÉGENDE

A B par hectare

Nombre de

grappes par hectare ?????? ??

Nombre de

ceps par hectare ?????? ??

ANNEE n-1 ANNEE n

0°Cj ??? 400°Cj ??? 450°Cj ??? 1150°Cj ??? 1500°Cj ???? - ???

Processus physiologiques déterminant

les composantes PL.

Nombre de grappes

par rameau Nombre de rameaux / cep Poids moyen d'une baie

Nombre de baies

par grappe

Composantes du

rendement

Nombre

de ceps par hectare 0 T, H 2

O, N, C,

Pratiques ayant un impact direct sur

Am. J. Enol. Vitic. 60:4 (2009)

During the following spring, when the environmental conditions permit, bud growth resumes. The relative im- portance of branching prior to dormancy, compared with differentiation during budburst, in controlling potential in- florescence size and flower numbers is poorly understood. According to Tourmeau (1976), in the winter bud, second- ary branching is well differentiated but tertiary branching, when present, is only rudimentary. Approximately one week before budbreak, the meristems at the tip of each branch (winter meristems) resume activity. Some meristems will immediately develop flowers while others undergo a short vegetative period during which one or more bracts form. The meristems that will develop into flowers are formed in the axil of each of these bracts (Tourmeau 1976). Fre- quently, during budbreak, an additional branch is added to each winter meristem and three to eight lateral meristems arranged as a dichasium will form. Initiation of all flower primordia occurs in a very short period of less than two weeks (Tourmeau 1976). Not all meristems that will form flowers are present in the dormant bud, and therefore at- tempts to predict yield based on dissecting buds during winter or forcing dormant buds under a controlled envi- ronment are not meaningful, unless the branching pattern of the meristems is preprogrammed in the bud (Tourmeau

1976). Flower meristems sequentially form sepal, common

petal-stamen, and carpel primordia, which will differenti- ate in the corresponding flower organs (Gerrath 1993, Pratt

1971, Srinivasan and Mullins 1981).

Variability in level of differentiation. Anlagen that un- dergo extensive branching before dormancy form inflores- cences, while those that possess only two or three branches are thought to form tendrils. Within the compound latent bud, the buds axillary to the two basal prophylls on the pri- mary bud also develop a few nodes and undergo dormancy. (Srinivasan and Mullins 1981). After the formation of one the latent bud enters into dormancy (Pratt 1971). For Mer- lot in Bordeaux, buds of nodes 3, 7, and 14 ceased apical growth when they had 8, 9 and 10 leaf primordia, respec- tively (Carolus 1970). Apical growth in latent buds of Cari- gnan at Montpellier ceased after the eighth leaf primordium (Nigond 1967) and in those of Sultana in the Murray Val- ley, Australia, after the tenth leaf primordium was initiated (May 1964). By examining single-node cuttings of Merlot in Bordeaux, Pouget (1963) found that dormancy development begins at the basal nodes of the shoots. Dormancy develops over a period of 2 to 3 weeks in all the latent buds within the shoot system of a vine. This period coincides with the time when the color of the shoots changes from green to yel- lowish-brown, and when the initiation of new nodes at the shoot apex ceases. Shoot maturation (aoûtement in French, periderm formation) up to node 14 was completed by late August (northern hemisphere), thus the primordial shoot of the latent bud ceased development approximately one month before periderm appeared (Pouget 1963). Early reports indicated that calyx primordia appeared in the inflorescence primordia of the latent buds at the end of summer (Agaoglu 1971, Alleweldt 1966, Alleweldt and Balkema 1965, Alleweldt and Ilter 1969). However, later studies with scanning electron microscopy all agree that flower parts only differentiate after resumption of growth in the spring (Bernard and Chaliès 1987, Carolus 1970, Cheema et al. 1996a, Morrison 1991, Scholefield and Ward

1975, Srinivasan and Mullins 1976, Swanepoel and Archer

1988, Watt et al. 2008). The presence of bracts subtending

each branch primordium could have led to this interpre- tation in light microscope studies (Swanepoel and Archer

1988, Watt et al. 2008).

cence formation in Vitis vinifera L.

SB: start of bloom; EB: end of bloom.

Budburst was indicated as occurring in

September and veraison in January. It is

likely that the two-day interval between the initiation of anlage in two successive buds shortens as temperatures increase B

1. Removal of fruitÕs sink for photosynthate and reserves

would permit flow to other sinks in the vine to an extent depending on the timing of blockage and its anatomical location.

2. During shrinkage of Shiraz berries, yields are decreas-

ing and the juice ¡Brix increasing, with the latter dependent on the loss of water during shrinkage since there is little further increase in fruit solutes.

3. Such berries would appear to undergo engustment

processes in isolation from the rest of the vine (Coombe and McCarthy 1997). Indeed, as Figure 4 shows, Shiraz berries had completed most of the accumulation of solutes per berry by 20¡Brix but all of the increase in non-anthocyanin glycosides (red-free

G-G) occurred after that stage.

The metabolic picture indicated in (3) may not be

restricted to varieties such as Shiraz that show berry shrinkage. For instance, normally-expanding Muscat berries (like those in Figure 1a) also showed increases in red-free G-G late in ripening (Gholami et al. 1996). This is also evident in the results for several winegrape varieties currently being analysed as part of the National Vineyard Fruit Composition Survey (I.L. Francis, person- al communication). Further support for the notion that grape berries can undergo engustment (i.e. develop ßavour) while isolated from phloem translocation is provided by the research of Gholami (1996). By grafting inßorescences of varieties that develop aromatic berry ßavour onto vines that have neutral berry ßavour, and vice versa, it was shown that the ripening berries in both cases developed a mono- terpene glucoside analysis typical of their genotype with- out inßuence from the genotype of the scion (Gholami et al. 1995).

Integration

A notional picture of the relative contributions of xylem and phloem translocation to water and solute accumula- tion by grape berries is given in Figure 5, integrating Muscat and Shiraz results. Three phases are apparent.

1. From setting to veraison

Berry volume (largely determined by the amount of cell division in the pericarp during the first three weeks) increases sigmoidally to the lag phase at which time the berries remain hard and green. The water for expansion during this phase derives from both xylem and phloem transport, but especially xylem. The principal solute that accumulates is malate.

2. From veraison to 18-20°Brix

With the onset of ripening in the second cycle, berries soften and expand. Xylem ßow is impeded, hence the water that moves in during this phase is largely from phloem sap along with sugar which is the chief solute accumulating in ßesh. Sugar and potassium accumulate in skin cells, along with anthocyanins in coloured vari- eties.

3. From 18-20°Brix to harvest

Development of berries during this phase differs between the two varieties. Shirazberries at Waikerie decreased in weight. We have suggested this decrease was due to a blockage of phloem transport into the berries so that the water and sugar supplied by phloem sap was cut offÑsee the dashed lines in Figure 5 and the plateau in solutes per berry in Figure 2d. Volume decline was due to transpira- tion losses with a consequential increase in juice ¡Brix. Note that, on this interpretation, these berries during this phase had little vascular connection to the rest of the vine. With Muscat(solid lines in Figure 5), berry weights continued their sigmoid increase and solutes per berry did not depart from linear increases throughout (Figure

1a and 1c). These results imply that phloem sap supply

continued throughout ripening. The amounts of phloem ?????k???

V???????

Berry formation

Berry ripening

020406080100120

26

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? ??? ß? ????? ??? ???? ¡ ??? ??? ??? ? ??? ????? ?????k??? ??? FERM

Stades phénologiques

1 2

•T, °Cj

•FTSW, ψpredawn •LNC

SERVICE

D'APPROVISIONNEMENT

Rendement

de la vigne

SERVICE

DE REGULATION

Vulnérabilité (sensibilité) à

l'oïdium

Perturbation : épidémie

d'oïdium

•Précocité de l'épidémie

•Qté d'inoculum primaire

Conditions de l'année n

•T, °Cj

•FTSW, ψpredawn

•LNC

Développement végétatif

•LERI, NBFI, LERII, NBFII

•MSF, NBR

Dégâts

•OFF, OIF •OFG, OIG

NBG x NBB x PB

Interception de l'inoculum

Réceptivité des

tissus à l'infection

Microclimat

Climat

•Température

•Rayonnement

•Précipitations

Pratiques ayant un effet

sur l'état du milieu

•Irrigation

•Fertilisation

•Enherbement

Pratiques ayant un effet direct sur

l'état du peuplement

•Taille, ébourgeonnage

•Rognage, écimage •Égrappage

Exposition

•Durée

•Intensité

Organogénèse et

morphogénèse inflorescences

Morphogénèse

Croiss. en biomasse

baies

Organogénèse

Axes I et II

Organogén.,

morphogén., fécondation et avortement fleurs 3 AL BS FERT

IRR-FERT

???nb?? ?? ??????? ??? ??? ? ???nb?? ?? ????? ??? ?????? ? ??g????? ??????? ????? ???? ? ???nb:ha1?? ?? ??????? ??? ??????? ? ? ???t:ha1????? ??? ???? ?? ?????? ?

Conditions de l'année n-1

•T, °Cj •FTSW, ψpredawn •LNC

SERVICE

D'APPROVISIONNEMENT

Rendement

de la vigne

SERVICE

DE REGULATION

Vulnérabilité (sensibilité) à

l'oïdium

Perturbation : épidémie

d'oïdium •Précocité de l'épidémie •Qté d'inoculum primaire

Conditions de l'année n

•T, °Cj •FTSW, ψpredawn •LNC

Développement végétatif

•LERI, NBFI, LERII, NBFII •MSF, NBR

Dégâts

•OFF, OIF •OFG, OIG

NBG x NBB x PB

Interception

de l'inoculum

Réceptivité des

tissus à l'infection

Microclimat

Climat

•Température •Rayonnement •Précipitations

Pratiques ayant un effet

sur l'état du milieu •Irrigation •Fertilisation •Enherbement

Pratiques ayant un effet direct sur

l'état du peuplement •Taille, ébourgeonnage •Rognage, écimage •Égrappage

Exposition

•Durée •Intensité

Organogénèse et

morphogénèse inflorescences

Morphogénèse

Croiss. en biomasse

baies

Organogénèse

Axes I et II

Organogén.,

morphogén., fécondation et avortement fleurs RESEAU DE TEMOINS NON

TRAITES DE L'IFV

Chapitre 5

4 ??? ??? ??????? ????? ??r2??? ??????? ?????? ??? ???? predawn??? ??? ????? ??? ?mg:l1????? l l l l l l l ll l l lll l l l l l l ll l l llquotesdbs_dbs35.pdfusesText_40

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