Terroir 2004 banner
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

Related articles…

Grape must quality and mesoclimatic variability in Fruška Gora wine-growing region, Serbia

The Fruška Gora mountain is a traditional wine-growing region in Serbia situated in the Pannonian Basin. Due to such a position, the vicinity of the Danube River and the presence of concave configuration, it is suitable for grape production. This paper provides analyses of spatial variations in meteorological parameters and grape juice quality within Fruška Gora wine region over three consecutive vintages (2018-2020). The examined period can be defined as warm with cool nights during September (AVG 18,9°C; GDD 1918°C; CI 12°CF) and with the presence of mesoclimatic variability. The East part of the study area was somewhat drier and hotter compared to other parts of the region. The analyses of grape must samples (190 in total) of five cultivars (Cabernet-Sauvignon, Merlot, Chardonnay, Sauvignon blanc and Grašac (Welschriesling)) commonly grown across the region (19 sites), were performed using Fourier Transform Infrared Technology (FTIR). Among all cultivars, Sauvignon blanc was harvested first in the East area (DOY=246±5, GDD at harvest=1552±74, 22.2±0.7 °Brix), while the latest harvest was recorded for Cabernet-Sauvignon in the West (DOY=283±5, GDD at harvest=1936±187, 23.4±1.0 °Brix ). Both the red and white cultivars had higher acidity and YAN in the grape must if the vines were grown in the North and East compared to South and West areas. According to PCA analysis, Grašac showed the lowest variation in grape must chemical composition. Thus, the results confirm that Grašac is the most stable cultivar in Fruška Gora. All monitored cultivars reached technological fruit ripeness by the end of the growing season. However, it was difficult to reach full ripeness of red cultivars, mostly beacuse of uncoupling of technolocical and phenolic ripeness. Thus, Cabernet-Sauvignon had higher variations in GDD sums at harvest compared to other cultivars, which probably increased variations in grape must quality.

Influence of weather and climatic conditions on the viticultural production in Croatia

The research includes an analysis of the impact of weather conditions on phenological development of the vine and grape quality, through monitoring of four experimental cultivars (Chardonnay, Graševina, Merlot and Plavac mali) over two production years. In each experimental vineyard, which were evenly distributed throughout the regions of Slavonia and The Croatian Danube, Croatian Uplands,

Analysis of Cabernet Sauvignon and Aglianico winegrape (V. vinifera L.) responses to different pedo-climatic environments in southern Italy

Water deficit is one of the most important effects of climate change able to affect agricultural sectors. In general, it determines a reduction in biomass production, and for some plants, as in the case of grapevine, it can endorse fruit quality. The monitoring and management of plant water stress in the vineyard

Measurement of redox potential as a new analytical winegrowing tool

Excell laboratory has initiated the development of an analytical method based on electrochemistry to evaluate the ability of wines to undergo or resist to oxidative phenomena. Electrochemistry is a powerful tool to probe reactions involving electron transfers and offers possibility of real-time measurements. In that context, the laboratory has implemented electrochemical analysis to assess oxidation state of different wine matrices but also in order to evaluate oxidative or reduced character of leaf and soil. Initially, our laboratory focused on dosage of compounds involved in responses of plant stresses and we were also interested in microbiological activity of soils. These analyses were compared with the measurement of redox potential (Eh) and pH which are two fundamental variables involved in the modulation of plant metabolism. Indeed, the variation of redox states of the plant reflects its biological activity but also its capacity to absorb nutriments. The Eh-pH conditions mainly determine metabolic processes involved in soil and leaf and our goal is to determine if this combined analytical approach will be sufficiently precise to detect biological evolutions (plant health, parasitic attack…).

Rapid damage assessment and grapevine recovery after fire

There is increasing scientific consensus that climate changeis the underlying cause of the prolonged dry and hot conditions that have increased the risk of extreme fire weather in many countries around the world. In December 2019, a bushfire event occurred in the Adelaide Hills, South Australia where 25,000 hectares were burnt and in vineyards and surrounding areas various degrees of scorching and infrastructure damage occurred. The ability to coordinate and plan recovery after a fire event relies on robust and timely data. The current practice for measuring the scale and distribution of fire damage is to walk or drive the vineyard and score individual vines based on visual observation. The process is time consuming, subjective, or semi-quantitative at best. After the December 2019 fires, it took many months to access properties and estimate the area of vineyard damaged. This study compares the rapid assessment and mapping of fire damage using high-resolution satellite imagery with more traditional ground based measures. Satellite imagery tracking vineyard recovery in the season following the bushfire is being correlated to field assessments of vineyard productivity such as canopy health and development, fertility and carbohydrate storage. Canopy health in the seasons following the fires correlated to the severity of the initial fire damage. Severely damaged vines had reduced canopy growth, were infertile or had very low fertility as well as lower carbohydrate levels in buds and canes during dormancy, which reduced productivity in the seasons following the bushfire event. In contrast, vines that received minor damage were able to recover within 1-2 years. Tools that rapidly and affordably capture the extent and severity of damage over large vineyard area will allow producers, government and industry bodies to manage decisions in relation to fire recovery planning, coordination and delivery, improving the efficiency and effectiveness of their response.