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

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. 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 the internode play an essential role in the stimulation of its elongation. Among the subjacent leaves, these only at a position at least 6 nodes below promote internode growth. On the other hand, the young leaves neoformed in the upper part of the shoot have not influence. The results of decapitation experiments indicate that terminal bud contributes also to the stimulation of internodal elongation. However this influence appears only if an increment to the size (« compensatory growth ») of the leaves below the level of decapitation is not induced by the removal of the shoot tip. The leaves which realize this « compensatory growth » have indeed the ability to compensate for the laking apical bud stimulus. The influences vary with the stage of internode length. The longitudinal growth of very young internode (5 - 10 mm long) is stimulated by its own leaves, the terminal bud and leaves situated at least 6 nodes below. When the internode has reached at least 50 p. cent of its adult size, its elongation depends only on its own leaves and the apex. At the end of grown, only its own leaves stimulate lengthening. Exogenous applications of IAA, NAA and gibberellic acid (GA3) at different concentrations were also tested. GA3 at 100 mg.l-1 and 1 g.l-1 (incorporated to lanolin paste) applied to the cut surface of the petiole of the two adjacent leaves of young internode permits a normal elongation providing that apical bud is maintained. If the shoot is decapited the same treatment has almost the same effect only by supplying NAA at 1 g.l-1 to the shoot section. The functions of the three elements contributing to internodal elongation are discussed, taking in consideration both the experimental results of exogenous applications of IAA, NAA and GA3, and the possible trophic role of the leaves. It is proposed that the two adjacent leaves of the internode stimulate its longitudinal growth through a production of diffusible gibberellic substances and also, probably of nutrient elements. The role of subjacent leaves is certainly of trophic nature. Terminal bud being an auxin source, we can expect that its stimulating influence is due to the supply of this growth regulator

Foliar influences on the vegetative development of grapevine

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 length of internodes increased when this number was greater. This result indicates that young leaves seems exercise a morphogenetical influence on the longitudinal growth of intemodes. For the three defoliation modalities, the rythm of leaves initiation was unchanged. So, it appears that, contrary to many other species, the leaves exercise no control on the plastochronic activity of terminal bud. The results of experiments with variation of the number of leaves maintained on the shoots permit to clarify the relation between foliage and "cane ripening". The already known positive correlation between the length of the suberized part of the shoot and the number of adult leaves has been confirmed. However, the effects of these treatments indicated that this correlation was not linear. Moreover, it seems that every shoot has specific " cane ripening " potentialities determined by other factors that their foliage. The leaves seem act only as revelators of these potentialities. These same experiments retaining adult leaves showed also that such treatments induced a more growth of the not removed leaves. Their laminar extension was increased. The thickness of their lamina and so the one of their palisade parenchyma were more important that in leaves of the control. These observations confirm and explain the compensatory phenomena consecutive to a reduction of the foliar apparatus already described in previous works by other autors. The two mean results of this study consists in the demonstration of the role played by adult leaves both in growth arrest and in apical senescence towards the end of the growing season. A single leaf retained in the upper or lower part of the shoot was sufficient to cause the growth arrest. On the other hand, only old leaves inserted at the base of the shoot can produce the death of the apex. These two last results are analysed and discussed taking in consideration both our experimental results and bibliographical elements. The growth arrest is probably not only determined by the foliar influence. We can expect that a decreasing production of cytokinins by the roots contributes also to this stopping of the apical bud activity. With regard the question of the apical senescence, some results showed that this phenomenom is not caused by a nutrient deficiency. Therefore, it is a question of a correlative process in which the adult leaves inserted to the base ofthe shoot are implicated. This last foliar influence was, so far, completely unknown

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

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. The objective of this work has been to identify the cause of the slowdown of the activity of apical bud during the phase II. In a first experiment, we have compared the effects of three modes of defoliation applied from the beginning of the phase II on the apical activity: total defoliation, defoliation to have two adult leaves at the base of the shoot and defoliation to have two young leaves near the apex. The results of this experiment showed that only treatments depriving the shoot of young leaves induced an activation of the plastochronic activity. So, it appeared that young leaves exercises an inhibitory effect on the apex. The same experiment has been carried out during the phase IV of cuttings development, when the apical activity was maximal. In this condition, no treatments modified the apical activity. This suggests that the inhibition of the apex by young leaves is specifie to the phase II of the develop¬ ment of a grapevine cutting. In a third experiment, we have demonstrated that the foliar inhibition persisted during the all period of the laminart growth. Cytokinins are probably implied in this competition because exogenous applications of these growth regulators during the phase II produced a stimulation of the activity of apical bud. Results of a last experiment showed that, in cuttings prerooted before budburst, the apical activity was not decreased after the phase I. In other words, in this condition, the growth of the shoot was regular without phase II. We explain this resuit as follows. The roots preformed on the cuttings produced cytokinins in sufficient quantity for provide for needs of both foliar growth and apical activity. In previous studies, MULLINS showed that abortion of the young bunches on cuttings of grapevine was due to an inhibition by deficiency in cytokinins exercised by young leaves.The present work reveales the existence of an exactly similar correlation between the young leaves and the apex. So, in the beginning of the development of a grapevine cutting, young leaves, apical bud and young bunches are implied in a common correlative process which results on the one hand from a small availability of cytokinins due to the lack of roots and, on the other hand from a more efficient sink effect towards the cytokinins for the young leaves than for the apex and young bunches

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

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. Exogenous applications of auxins prevented or restricted this growth; gibberellic acid had no effect. These results partly explain those of other authors who demonstrate that reduction in the leaf area of a vine is accompanied by an increase in photosynthetic efficiency of the remaining leaves

Polyamines et rajeunissement de la vigne cultivée in vitro et après réimplantation au vignoble

DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF

CONTRAINTES ECOPHYSIOLOGIQUES LIEES A LA TRANSPLANTATION DES PLANTS FORESTIERS (EFFETS DE L'EXPOSITION A L'AIR ENTRE L'ARRACHAGE ET LA PLANTATION)

L'OBJECTIF DE CE TRAVAIL EST D'ETUDIER LES EFFETS DE L'EXPOSITION A L'AIR DES PLANTS A RACINES NUES AVANT PLANTATION SUR L'ETAT PHYSIOLOGIQUE DES PLANTS AINSI QUE LEUR SURVIE ET LEUR CROISSANCE APRES PLANTATION. TROIS ESPECES SONT ETUDIEES : LE PIN LARICIO DE CORSE (PINUS NIGRA SSP LARICIO VAR CORSICANA), LE CHENE PEDONCULE (QUERCUS ROBUR L.) ET LE CHENE ROUGE D'AMERIQUE (QUERCUS RUBRA L.). L'EXPOSITION A 2\C DES PLANTS DIMINUE LA CAPACITE DE REGENERATION RACINAIRE, CONDUISANT A UNE AUGMENTATION DE LA MORTALITE APRES PLANTATION. CET EFFET RESULTE DE LA REDUCTION DE LA TENEUR EN EAU DES RACINES, ENTRAINANT LA DEFORMATION DES CELLULES RACINAIRES ET DES DYSFONCTIONNEMENTS MEMBRANAIRES (EVALUES PAR LA PERTE D'ELECTROLYTES). AU-DELA D'UNE PERTE D'ELECTROLYTES DES RACINES DE 50% POUR LE CHENE ROUGE, ET 40% POUR LE CHENE PEDONCULE, LE TAUX DE MORTALITE EN PREMIERE ANNEE EST SUPERIEUR A 20%. LA REHUMECTATION DU SYSTEME RACINAIRE PAR TREMPAGE DANS L'EAU AVANT PLANTATION NE PERMET PAS DE COMPENSER CES EFFETS. POUR LE PIN, L'EXPOSITION REDUIT PLUS FAIBLEMENT LA SURVIE QUE CHEZ LES CHENES. APRES PLANTATION, LA CROISSANCE AERIENNE DES PINS N'EST PAS AFFECTEE PAR L'EXPOSITION ALORS QUE LE DESSECHEMENT DES BOURGEONS DES CHENES INDUIT DES DESCENTES DE CIMES. LA CROISSANCE DIMINUE REGULIEREMENT POUR LE CHENE PEDONCULE AVEC LA REDUCTION DE LA TENEUR EN EAU DE LA TIGE ALORS QU'ELLE N'EST AFFECTEE QU'EN DESSOUS UNE TENEUR DE 65% POUR LE CHENE ROUGE. LA CROISSANCE ET LA SURVIE SUPERIEURES CHEZ LES PINS PEUVENT ETRE EXPLIQUEES PAR UN MEILLEUR ETAT HYDRIQUE DES RACINES ET DES BOURGEONS. L'EXPOSITION A L'AIR INDUIT UNE AUGMENTATION DE LA CONCENTRATION RACINAIRE EN SUCRES SOLUBLES, PLUS FORTE CHEZ LE CHENE ROUGE. CECI PEUT EXPLIQUER SA MEILLEURE SURVIE PAR RAPPORT AU CHENE PEDONCULE. POUR UN NIVEAU DE DESSECHEMENT DONNE, LA VITESSE DE DESSECHEMENT, INDUITE PAR DEUX TEMPERATURES D'EXPOSITION (2 ET 14\C), NE MODIFIE NI L'ETAT PHYSIOLOGIQUE, NI LES PERFORMANCES DES PLANTS. DES VARIATIONS SAISONNIERES DE LA SENSIBILITE A L'EXPOSITION SONT NOTEES : AU MILIEU DE L'HIVER, LA SURVIE ET LA CROISSANCE DES PLANTS ETAIENT PLUS FAIBLEMENT AFFECTEES PAR L'EXPOSITION QU'EN AUTOMNE OU AU PRINTEMPS. DANS LA PRATIQUE, NOS RESULTATS PERMETTENT DE PROPOSER DES CRITERES PERMETTANT DE REJETER, AVANT PLANTATION, LES LOTS DE PLANTS DE MAUVAISE QUALITE LORSQUE LES VARIABLES PHYSIOLOGIQUES (TENEUR EN EAU DES RACINES, PERTE D'ELECTROLYTES DES RACINES OU POTENTIEL HYDRIQUE) SONT SUPERIEURES A CERTAINES VALEURS SEUILS.DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF

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

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 la fertilité. +++ Following a violent hailstorm, severe damage on the vinestocks have induce important modifications of the equilibrium between the different parts of the vine and particularly between the non-damaged buds. A precise study of the factors which induce, at different speeds, the beginning of the growth of each type of bud was realized. An interesting fact has been established : the beginning of premature growth of quite a number of main latent buds (N + 2 order) until then in dormancy, which frequently, stops soon thereafter. Nevertheless, it induce some fertility modifications the following year

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

Etude de la structure vasculaire reliant à la tige les feuilles, vrilles, grappes et bourgeons et analyse des relations entre ces organes. 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. 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. +++ In this work, the vascular structure which bounds leaves, tendrils, clusters, and shoots and the relation between these organs are studied. Upon an orthostic, similar organs are interelated one at least. Tendrils and clusters are directly in relation with leaves and buds, there is no relation between leaves and buds. From an orthostic to one another, leaves, tendrils and clusters are only connected by the side leafly fascicles. Shoots of the two orthostics are anatomically independant

Etudes physiologiques et génétiques de souches de Botrytis cinerea collectées dans plusieurs vignobles français

Botrytis cinerea est un champignon pathogène de la vigne et de plusieurs autres végétaux. Le comportement de cette espèce n'est pas uniforme selon la localisation du vignoble ou le type de végétal parasité. À l'heure actuelle, peu d'études de phytopathogénicité ont fait l'objet d'analyses comparées mettant en Œuvre des micro-organismes de diverses origines, peu de travaux ont traité de l'influence des facteurs environnementaux sur l'expression de la virulence de B. cinerea. Une collection de 85 souches de cette espèce a été constituée (dont 35 isolats de Bourgogne, 31 isolats 1998 du Languedoc et 19 souches de diverses origines). À partir des régions ITS des ADN ribosomaux, une étude du polymorphisme génétique de ces souches a été entreprise pour évaluer le degré d'hétérogénéité entre populations fongiques issues du même cultivar, mais aussi entre populations originaires de vignobles septentrionaux et méridionaux. Plusieurs caractéristiques phénotypiques liées à la virulence de B. cinerea (potentialité germinative des conidies, vitesse d'élongation du mycélium, mode de colonisation de la feuille de vigne et sporulation) ont été recherchées sur les 85 isolats.During unfavourable conditions, Botrytis cinerea lives as a saprophyte forming the sclerotes and attacks various tissues of the vine plant, particularly the grape bunches. The lesions produced by these attacks lead to necrosis and finally the total destruction of the infected tissues. The economic losses caused due to this disease incite the vine growers to exercise systematic control against this pathogen, which has high resistance to the fungicides. A better understanding of the biology and physiology of Botrytis cinerea and especially of genetics, of which not much is known, is essential to control this pathogen. In this context, we have endeavoured the study of 85 isolates of Botrytis cinerea of different origin: Burgundy, 35 isolates; Languedoc, 31 isolates and 19 isolates of various origins. Considering the aspects of host-pathogen interaction; the infection process on the vine and on other hosts; the genetic diversity in varied environmental conditions and the sexual reproduction and recombination aptitudes, we have attempted a comparative analysis of certain pathogenic, phenotypic and genetic characters manifested by Botrytis cinerea.DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF