© 2005 Heron Publishing—Victoria, Canada
Photosynthesis of the grapevine (Vitis vinifera) inflorescence
Gaël Lebon (1), Olivier Brun (2), Christian Magné (3) and Christophe Clément (1, 4)
1. Laboratoire de Stress Défenses et Reproduction des Plantes, URVVC UPRES EA 2069, Université de Reims Champagne Ardenne, UFR
Sciences, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2, France / 2. Mumm-Perrier-Jouet Vignobles et Recherches, 51206 Epernay, France / 3. Laboratoire d’Ecophysiologie et de Biotechnologies des Halophytes et des Algues Marines, Université de Bretagne Occidentale,
IUEM, Technopôle Brest Iroise, 29280 Plouzané, France / 4. Corresponding author (christophe.clement@univ-reims.fr) / Received March 24, 2004; accepted October 30, 2004; published online March 1, 2005
Summary
To further characterize carbohydrate physiology in grapevine flowers, we examined inflorescence autotrophy in the ‘Gewürztraminer’
and ‘Pinot noir’ cultivars, which differ in sensitivity to flower abscission. In both cultivars, positive net photosynthesis
occurred in inflorescences. The rate of photosynthesis gradually decreased throughout flower development and there was no
net carbon assimilation at fruit set. The rate of photosynthesis was positively correlated with chlorophyll concentration
but not to stomatal conductance. Throughout flower development, the internal CO2 concentration increased in inflorescence tissues, suggesting that assimilates are also formed through refixation of respiratory
CO2 by the phosphoenolpyruvate carboxylase (PEPC) pathway. Significant differences between the two cultivars were recorded during
meiosis, when photosynthesis was higher in ‘Gewürztraminer’. We conclude that the inflorescence of grapevine contributes to
its own carbon nutrition by photosynthesizing throughout flower development. Moreover, the differential patterns of photosynthesis
in the inflorescences of ‘Gewürztraminer’ and ‘Pinot noir’ might account for their differing fertilization rates and sensitivity
to flower abscission.
Keywords:
chlorophyll, flower, gas exchanges, Gewürztraminer, Pinot noir.
