Terroir 2004 banner
IVES 9 IVES Conference Series 9 Shoot heterogeneity effects in a Shiraz/R99 vineyard

Shoot heterogeneity effects in a Shiraz/R99 vineyard

Abstract

[English version below]

Nous avons fait des recherches sur l’effet de l’hétérogénéité des bourgeons sur les paramètres de la croissance végétative et reproductive, la physiologie de la vigne et la composition du raisin dans une parcelle de Shiraz/Richter 99. Des bourgeons sous-développés (typiquement plus courts et moins mûrs à la véraison) ont été comparés avec des bourgeons normaux dans un couvert ombragé ou exposé à la lumière. Comparés aux bourgeons sous-développés, les normaux ont eu une plus grande surface feullière totale à cause du plus grand nombre de entre-cœurs aussi bien que des feuilles plus grandes portées par les bourgeons principaux et entre-cœurs. Vu que l’activité physiologique des feuilles des bourgeons normaux était supérieure à celle des bourgeons sous-développés, une quantité d’hydrates de carbone supérieure a été produite et mise en réserve par les premiers. L’amidon se distribuait plus régulièrement le long des sarments normaux, plus épais et longs en comparaison avec les sarments sous-développés. Les grappes plus grosses des sarments normaux ont montré que la surface feuillère totale par gramme de raisin était plus favorable. Cinq semaines après la véraison les baies des sarments normaux étaient plus petites que celles des sarments sous-développés, montrant un rapport entre peau et pulpe plus grand et un plus grand potentiel d’extraction des anthocyanes et de phénols pour l’élaboration du vin. L’étrange absence d’une grosse différence de composition du raisin entre les deux types de bourgeons a montré que les assimilés nécessaires pour mûrir les raisins des bourgeons sous-développés dérivent d’autres organes que leurs feuilles [p.ex. des bourgeons normaux adjacents et du reste de la structure permanente de la vigne (le cordon, le tronc, les racines)]. Cette hypothèse est supportée par la différence de dimensions de la baie entre les deux types de bourgeons qui était supérieure à l’ombre par rapport au feuillage exposé à la lumière. L’activité photosynthétique était inférieure à l’ombre que dans le feuillage exposé. La production totale d’hydrates de carbone des bourgeons normaux ombragés apparaissait insuffisante aux besoins de maturation de leurs propres grappes et du bourgeon même aussi bien que pour la maturation du sarment et des grappes des bourgeons sous-développés. Cela était démontré par le niveau d’amidon accumulé dans les sarments normaux, qui était inférieur à l’ombre par rapport aux sarments dans le feuillage exposé. Puisque l’hétérogénéité des bourgeons de la vigne a porté à un déséquilibre physiologique qui peut avoir une influence négative sur la qualité du raisin et du vin aussi bien que sur le coût de production, il faut l’éviter sur tout terroir.

The effect of shoot heterogeneity on vegetative and reproductive growth parameters, vine physiology and grape composition was investigated in a Shiraz/Richter 99 vineyard. Comparisons between underdeveloped (typically shorter and less ripened at véraison) and normally developed shoots in both shaded and well-exposed canopies were made. Compared to underdeveloped shoots, normal shoots had a larger total leaf area, due to the higher occurrence of secondary shoots as well as larger leaves on primary and secondary shoots. Since the physiological activity of the leaves from normal shoots was higher than that from underdeveloped shoots, higher levels of total carbohydrates were produced and stored in the former. Starch was more evenly distributed over the whole shoot length in the longer and thicker normally developed shoots compared to the underdeveloped shoots. The larger clusters of the normally developed shoots were evidence of their more favourable total leaf area per gram berry mass. Berries from the normally developed shoots were smaller at five weeks after véraison than those from underdeveloped shoots, displaying a higher skin to pulp ratio and therefore higher anthocyanin and total phenolic extraction potential for winemaking. The peculiar absence of large differences in grape composition between normally and underdeveloped shoots indicated that assimilates needed for berry ripening of the latter originated in organs other than the leaves [e.g. from adjacent normal shoots and the rest of the permanent structure of the vine (cordon, trunk, roots)]. The larger differences in berry size that occurred between shoot types in the shaded compared to the well-exposed canopies may be evidence for this. The photosynthetic activity of shoots was lower in shaded than in exposed canopies. The total carbohydrate production of the normal shoots in shaded canopies seemed insufficient to supply in the ripening needs of their own clusters and of the shoot itself as well as the ripening of stem tissue and clusters of the underdeveloped shoots in the canopy. This was illustrated by the lower levels of starch that accumulated in the normal shoots from shaded compared to that of exposed canopies. Vine shoot heterogeneity clearly led to visible and physiological imbalances that would impact negatively on grape and wine quality as well as production costs and should therefore be avoided on any terroir.

Download the PDF

DOI:

Publication date: January 12, 2022

Issue: Terroir 2004

Type: Article

Authors

H Cloete (1), E Archer (2), V Novello (3) & JJ Hunter (4)

(1) Department of Viticulture and Oenology, Private Bag X1, Matieland, University of Stellenbosch, 7602 Stellenbosch, South Africa
(2) Lusan Premium Wines, PO Box 104, 7599 Stellenbosch
(3) Dipartimento di Colture Arboree, I 10095 Grugliasco
(4) ARC Infruitec-Nietvoorbij, Private Bag X5026, 7599 Stellenbosch, South Africa

Contact the author

; ; ;   

Keywords

Shoot heterogeneity, physiology, vegetative growth, reproductive growth, grape composition

Tags

IVES Conference Series | Terroir 2004

Citation

Related articles…

Local adaptation tools to ensure the viticultural sustainability in a changing climate

[lwp_divi_breadcrumbs home_text="IVES" use_before_icon="on" before_icon="||divi||400" module_id="publication-ariane" _builder_version="4.19.4" _module_preset="default" module_text_align="center" module_font_size="16px" text_orientation="center"...
Read More

Extreme canopy management for vineyard adaptation to climate change: is it a good idea?

Climate change constitutes an enormous challenge for humankind and for all human activities, viticulture not being an exception. Long-term strategic changes are probably needed the most, but growers also need to deal with short-term changes: summers that are getting progressively warmer, earlier harvest dates and higher pH in musts and wines. In the last 10-15 years, a relevant corpus of research is being developed worldwide in order to evaluate to which extent extreme canopy management operations, aimed at reducing leaf area and, thus, limiting the source to sink ratio, could be useful to delay ripening. Although extreme canopy management can result in relevant delays in harvest dates, longer term studies, as well as detailed analysis of their implications on carbohydrate reserves, bud fertility and future yield are desirable before these practices can be recommended.

Read More

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

Read More

Assessing the climate change vulnerability of European winegrowing regions by combining exposure, sensitivity and adaptive capacity indicators

Winegrowing regions recognized as protected designations of origin (PDOs) are closely tied to well defined geographic locations with a specific set of pedoclimatic attributes and strictly regulated by legal specifications. However, climate change is increasingly threatening these regions by changing local conditions and altering winegrowing processes. The vulnerability to these changes is largely heterogenous across different winegrowing regions because it is determined by individual characteristics of each region, including the capacity to adapt to new climatic conditions and the sensitivity to climate change, which depend not only on natural, but also socioeconomic and legal factors. Accurate vulnerability assessments therefore need to combine information about adaptive capacity and climate change sensitivity with projected exposure to new climatic conditions. However, most existing studies focus on specific impacts neglecting important interactions between the different factors that determine climate change vulnerability. Here, we present the first comprehensive vulnerability assessment of European wine PDOs that spatially combines multiple indicators of adaptive capacity and climate change sensitivity with high-resolution climate projections. We found that the climate change vulnerability of PDO areas largely depends on the complex interactions between physical and socioeconomic factors. Homogenous topographic conditions and a narrow varietal spectrum increase climate change vulnerability, while the skills and education of farmers, together with a good economic situation, decrease their vulnerability. Assessments of climate change consequences therefore need to consider multiple variables as well as their interrelations to provide a comprehensive understanding of the expected impacts of climate change on European PDOs. Our results provide the first vulnerability assessment for European winegrowing regions at high spatiotemporal resolution that includes multiple factors related to climate exposure, sensitivity, and adaptive capacity on the level of single winegrowing regions. They will therefore help to identify hot spots of climate change vulnerability among European PDOs and efficiently direct adaptation strategies.

Read More

Influence of grapevine rootstock/scion combination on rhizosphere and root endophytic microbiomes

Soil is a reservoir of microorganisms playing important roles in biogeochemical cycles and interacting with plants whether in the rhizosphere or in the root endosphere. The composition of the microbial communities thus impacts the plant health. Rhizodeposits (such as sugar, organic and amino acids, secondary metabolites, dead root cells …) are released by the roots and influence the communities of rhizospheric microorganisms, acting as signaling compounds or carbon sources for microbes. The composition of root exudates varies depending on several factors including genotypes. As most of the cultivated grapevines worldwide are grafted plants, the aim of this study was to explore the influence of rootstock and scion genotypes on the microbial communities of the rhizosphere and the root endosphere. The work was conducted in the GreffAdapt plot (55 rootstocks x 5 scions), in which the 275 combinations have been planted into 3 blocks designed according to the soil resistivity. Samples of roots and rhizosphere of 10 scion x rootstock combinations were first collected in May among the blocks 2 and 3. The quantities of bacteria, fungi and archaea have been assessed in the rhizosphere by quantitative PCR, and by cultivable methods for bacteria and fungi. The communities of bacteria, fungi and arbuscular mycorrhizal fungi (AMF) was analyzed by Illumina sequencing of 16S rRNA gene, ITS and 28S rRNA gene, respectively. The level of mycorrhization was also evaluated using black ink coloration of newly formed roots harvested in October. The level of bacteria, fungi and archaea was dependent on rootstock and scion genotypes. A block effect was observed, suggesting that the soil characteristics strongly influenced the microorganisms from the rhizosphere and root endosphere. High-throughput sequencing of the different target genes showed different communities of bacteria, fungi and AMF associated with the scion x rootstock combinations. Finally, all the combinations were naturally mycorrhized. The root mycorrhization intensity was influenced by the rootstock genotype, but not by the scion one. Altogether, these results suggest that both rootstock and scion genotypes influence the rhizosphere and root endophytic microbiomes. It would be interesting to analyze the biochemical composition of the rhizodeposition of these genotypes for a better understanding of the processes involved in the modulation of these microbiomes. Moreover, crossing our data with the plant agronomic characteristics could provide insights into their roles on plant fitness.

Read More