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IVES 9 IVES Conference Series 9 Climatic requirements for optimal physiological processes: a factor in viticultural zoning

Climatic requirements for optimal physiological processes: a factor in viticultural zoning

Abstract

[English version below]

Les profils climatiques appropriés pour une activité photosynthétique optimale de la vigne sont déterminés dans différentes régions d’Afrique du Sud et localités à l’intérieur d’une région particulière. La moyenne horaire de température ambiante, vitesse du vent et humidité relative sont calculées pendant les périodes de pré-et post-véraison à partir de données de trois années et de quatre stations météorologiques dans chacune de trois régions viticoles [classées “chaudes” (Stellenbosch et Roberston) et “très chaudes” (Upington) selon les indices d’Huglin et de Winkler]. La période comprise entre 9 et 16 heures pour l’activité photosynthétique maximale est utilisée. La température (25-30°C), vitesse de vent (<4 m/s) et humidité relative (60-70°C) nécessaires à une activité photosynthétique optimale sont surimposés sur les profils climatiques respectifs des différentes régions. L’intensité lumineuse ambiante est acceptée comme étant suffisante. Une variation remarquable du nombre d’heures disponibles pour une photosynthèse optimale apparaît. Basées sur les seuls besoins climatiques, les conditions pour la photosynthèse seraient les meilleures dans la région de Robertson. Dans les deux autres régions, la photosynthèse serait limitée à un plus haut niveau, en raison de basses températures. en période de pré-véraison et de vents forts en période de pré-et post-véraison dans la région de Stellenbosch et en raison de températures élevées et faibles humidités pendant les périodes de pré-et post-véraison dans la région d’Upington. Les conditions climatiques pour la croissance seraient meilleures dans la région de Robertson, suivies d’Upington et Stellenbosch. Les conditions climatiques à l’intérieur d’une région particulière peuvent également varier remarquablement sur des distances très courtes, spécialement dans la Province occidentale du Cap, tandis que des régions peuvent être de climats semblables malgré des altitudes, expositions et distances à l’océan différentes. Les localités diffèrent beaucoup selon leurs possibilités à subvenir aux besoins de la photosynthèse. Les profils climatiques des différentes régions et localités peuvent évidemment avoir de sérieuses implications sur le bon fonctionnement physiologique de la vigne et l’impact de ce stress climatique potentiel (direct ou indirect) sur les processus physiologiques semblerait être un facteur à considérer dans le zonage viticole.

 

The suitability of climatic profiles for optimal grapevine photosynthetic activity in different South Afiican regions and in localities within a particular region was determined. Three-year hourly mean ambient temperature, wind speed and relative humidity data from four weather stations in each of three viticultural regions [“hot” (Stellenbosch and Robertson Regions) and “very hot” (Upington Region) classification according to Huglin and Winkler indices] were averaged during the pre- and post-véraison growth periods. A period between 09:00 and 16:00 for maximum photosynthetic activity was used. Temperature (25-30 °C), wind speed (< 4 m/s) and relative humidity (60 – 70 %) requirements for optimal photosynthetic activity were superimposed onto the respective regional climatic profiles. Ambient light intensity was accepted as being sufficient. Marked variation in number of heurs available for optimal photosynthesis occurred. Based on climatic requirements only, conditions seemed best suited for photosynthesis in the Robertson region. In the other two regions, photosynthesis would be reduced to a higher extent, due to low pre-véraison temperature and strong pre- and post­véraison wind (Stellenbosch) and high pre- and post-véraison temperature and low humidity (Upington). Climatic conditions for growth seemed best in Robertson, followed by Upington and Stellenbosch. Conditions within a particular region may also vary markedly over very short distances, especially in the Western Cape, whereas other locations may be climatically similar in spite of differences in altitude, aspect and distance fom the sea. The locations differed markedly regarding their feasibility to support photosynthesis. Evidently, climatic profiles in different regions and locations may have serious implications for proper physiological functioning of grapevines and the impact of potential climatic stress (direct and indirect) on physiological processes would seem to be a factor for consideration in viticultural zoning.

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DOI:

Publication date: February 15, 2022

Issue: Terroir 2002

Type: Article

Authors

J.J. HUNTER and V. BONNARDOT

ARC Institute for Fruit, Vine and Wine & ARC Institute for Soil, Climate and Water, Private Bag X5026, 7599 Stellenbosch, South Africa

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Keywords

Vigne, climat, zonage, physiologie, photosynthèse
Grapevine, climate, zoning, physiology, photosynthesis

Tags

IVES Conference Series | Terroir 2002

Citation

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