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IVES 9 IVES Conference Series 9 Shoot positioning: effect on physiological, vegetative and reproductive parameters

Shoot positioning: effect on physiological, vegetative and reproductive parameters

Abstract

[English version below]

On a étudié durant deux saisons de croissance (2002/2003 et 2003/2004) l’effet de l’orientation vertical des rameaux sur les paramètres physiologiques, végétatifs et reproductifs dans la région de Stellenbosch dans un vignoble du cépage Merlot sur 99 R conduite à espalier et taillé a cordon coursonné. Les vignes étaient espacées 2.7 x 1.5 m. L’irrigation a été appliquée quand la baie avait la dimension d’un pois et a la véraison.
Les rameaux ont été placés verticalement à la nouaison ,à la dimension d’un pois de la baie, à la véraison et trois semaines après la véraison. Après leur placement vertical les rameaux ont été tout de suite écimés à 100-155cm. Le positionnement vertical et l’écimage des rameaux n’ont pas eu aucun effet sur la croissance des entre cœurs, mais ils ont eu un effet fort sur la position de les entre coeurs sur la longueur du rameau principal. Depuis la nouaison et jusqu’à la véraison on a eu une bonne distribution de la lumière qui a favorit l’uniformité de la maturation et la qualité du raisin. Le potentiel hydrique foliaire et le potentiel de tige des feuilles basales et apicales et l’activité photosynthétique sont diminués durant le cycle végétatif. Une régression significative a été trouvée pour les feuilles apicales entre la tige et le potentiel de tige et le potentiel hydrique foliaire.
Le placement vertical des rameaux jusqu’à la véraison a induit un’augmentation significative du degré °Brix, du contenu d’acide malique et du saccharose, et une faible diminution de l’acide tartrique. Le niveau du glucose a été le plus haute dans les traitements dimension d’un pois et véraison. Aucune différence significative entre les traitements a été trouve pour le pH. L’époque de traitement pre-véraison a amélioré la couleur de la peau de la baie.
Aucune difficulté pratique a été vérifiée quand les rameaux ont été manipulés dans les première époque tandis que à les époques véraison et post-véraison on a eu difficulté à manipuler les rameaux a cause de la lignification et de la présence des vrilles. Les grappes sont très sensibles aux dommages et à la pourriture. Il s’agit de considérations importantes dans les terroirs où la gestion soigneuse du vignoble est très difficile.

The effect of vertical shoot positioning and topping at different times during two growth seasons (2002/03 and 2003/04) on physiological, vegetative and reproductive parameters was investigated in a vertically trellised Merlot/R99 vineyard located in the Stellenbosch area. Vines were spaced 2.7 x 1.5 m in north-south orientated rows. Micro-sprinkler irrigation was applied at pea size berry and at véraison stages. Shoots were positioned at berry set, pea size, véraison and post-véraison stages (3 weeks after véraison). After being positioned, they were immediately topped. Before positioning the canopy was in a “natural” condition with shoots hanging freely. Soil water typically varied according to the progress in the season and with soil depth, decreasing towards the end of the season and increasing with depth. The primary shoot length of the positioned shoots was on average approximately 100 – 115 cm, being restricted by the relatively low trellising system. Shoot positioning and topping had no marked effect on the growth of secondary shoots, but they had a noticeable effect on the position of secondary shoots along the length of the primary shoots. Pea-size shoot positioning induced slightly lower light conditions in the bunch zone, because of the low position of secondary shoot development on primary shoots. In spite of this, pre-vèraison shoot positioning treatments allowed good all-round light distribution, which would promote uniform bunch ripening and grape quality. The basal and apical stem and leaf water potential and photosynthetic activity decreased during the season as the leaves aged and the plants lost water. A significant correlation was found for apical leaves between stem and leaf water potential. 
Earlier shoot positioning (up to véraison) significantly increased the °Balling level of the must. Early shoot positioning (up to véraison) increased malic acid and sucrose contents, whereas tartaric acid contents were slightly reduced and glucose contents were higher in pea size and véraison treatments. No significant differences between treatments were found for must pH. The earlier shoots were positioned, the more water was lost by the skins, resulting in a concentration of skin contents. Pre-véraison shoot positioning and topping improved the colour of the skins. 
No practical difficulty was experienced when shoots were positioned early in the season, i.e. at berry set and pea size stages, whereas at and after véraison proper vertical positioning was primarily restricted by shoot lignification and the tightness of tendrils on the wires. Bunches were also very sensitive to damage, which led to bunch rot and a reduction in yield. These are important considerations in terroirs where timely management is difficult. 

DOI:

Publication date: January 12, 2022

Issue: Terroir 2004

Type: Article

Authors

A. Pisciotta (1), R. Di Lorenzo (1) M.G.Barbagallo (1), C.G. Volschenk (2) & J.J. Hunter (2)

(1) Dipartimento di Colture Arboree, Università degli Studi di Palermo, Viale delle Scienze 11, 90128 – Palermo, Sicily, Italy
(2) ARC Infruitec-Nietvoorbij, Private Bag X5026, 7599 Stellenbosch, South Africa

Contact the author

Keywords

Merlot, shoot positioning, vegetative growth, reproductive growth, photosynthesis, water potential, light interception, grape composition

Tags

IVES Conference Series | Terroir 2004

Citation

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