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IVES 9 IVES Conference Series 9 Phototropic and geotropic shoot orientation: effect on physiological, vegetative and reproductive parameters

Phototropic and geotropic shoot orientation: effect on physiological, vegetative and reproductive parameters

Abstract

[English version below]

On a étudié l’effet de l’orientation des rameaux sur les paramètres physiologiques, végétatifs et reproductif durant deux saisons de croissance (2002/2003 et 2003/2004) dans la région de Stellenbosch dans une vignoble du cépage Merlot sur 99R conduite en espalier et taillé à 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 à la véraison. La végétation a été manipulé pour avoir les rameaux sur le même cordon orientés une partie vers le haut (phototropiques) et l’autre vers le bas (géotropiques). 
L’orientation vers le bas a réduit la longueur et la surface foliaire du rameau principal et des entre coeurs. Quand le rameau est orienté vers le bas les entre coeurs sur le même rameau sont plus homogènes. Le potentiel hydrique foliaire et de tige à midi évalué sur la feuille basale et apicale était inférieur dans l’orientation vers le bas au confronte de l’orientation vers le haut. Cela était particulièrement prononcé pendant la période de maturation du raisin. L’activité photosynthétique des feuilles basale et apicale des rameaux orientés vers le haut était plus haute que celle des rameaux orientés vers le bas, probablement, à cause des conditions microclimatiques plus favorables. Le poids, le volume et la longueur des grappes n’ont pas été sensiblement influencés par orientation du rameau. L’orientation vers le haut a sensiblement augmenté le glucose et l’acide tartrique des baies, le saccharose, l’acide malique et l’acide citrique étaient pratiquement inchangés. Moins d’eau a été perdue par les peaux des baies et cela a favorisé l’intensité de la couleur. Les résultats ont des implications importantes pour l’uniformité de composition de la baie et pour le choix du système de conduite dans les différents terroirs. 

The effect of shoot orientation during two growth seasons (2002/2003 and 2003/2004) on physiological, vegetative and reproductive parameters was investigated in the Stellenbosch area in a Merlot/R99 vineyard with a vertical trellising system. 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 vèraison stages. Observations were done on vines with a natural distribution and orientation of phototropically (upward) and geotropically (downward) shoots on the same cordon.
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. Geotropic orientation reduced the primary and lateral shoot length as well as the primary and secondary shoot leaf area. With phototropic shoot position, secondary shoots were more evenly distributed along the primary shoots. Basal and apical stem and leaf water potential was lower with geotropic orientation than with phototropic orientation. This was particularly pronounced during the ripening period. In spite of this, basal and apical leaf photosynthetic activity of the phototropically orientated shoots was higher than that of the geotropically orientated shoots, most probably because of more favourable microclimatic conditions experienced by the former. Bunch mass and volume and length of bunches were not significantly affected by shoot orientation. Phototropic orientation of shoots noticeably increased glucose and tartaric acid contents of the berries, whereas sucrose, malic acid and citric acid contents were virtually unaffected. In phototropically orientated shoots, less water was lost by the skins, favouring skin colour intensity. The results have important implications for bunch and berry composition uniformity and for trellising system selection on different terroirs. 

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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

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Keywords

Merlot, shoot orientation, vegetative growth, photosynthetic activity, water potential, light interception, grape composition

Tags

IVES Conference Series | Terroir 2004

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