PARENT SESSION

Symposium S6D Crop photosynthesis, agricultural biotechnology
Thursday September 2nd, 2004 10:20 AM-12:20 PM Room 510A
Chair: Vince DeLuca
Co-Chair: Maurice Ku

Photosynthesis in winegrape: A depressed process to produce high quality wine. Claudio Pastenes^*,1, Álvaro Peña², ¹ Universidad de Chile, Santiago, Chile² Universidad de Chile, Santiago, Chile

ABSTRACT- The crop yield and biomass production are highly dependent on the functioning of the photosynthetic process. Therefore, agronomical practices are mainly focused on decreasing the interference of biotic and a-biotic constraints on the capacity of plants to reduce CO₂ through photosynthesis. Winegrape production is one exception to the rule. Wine quality and yield are often inversely correlated. This is because the products conferring the price to bottles i.e. color, flavor and aromas must be concentrated in small berry grapes. In order to reduce berry volume, and therefore to concentrate secondary metabolites, wine grapes are subjected to severe water stress in the field. Obviously, such practice induces: stomata closure, increases in leaf temperature, reductions in the CO₂ concentration at the carboxilation sites and, therefore, affects the production of photosynthates needed for sugar accumulation in the berries and the secondary metabolites itself. In the present study, photosynthesis is characterized through the growing season in the field in Central Chile, an important wine production area. The impact of water stress on CO₂ assimilation, stomatal conductance, leaf temperature, leaf age and the consequent results on sugars, acidity and polyphenols, among others in Cabernet Sauvignon is discussed. The authors thank Conicyt (Fondecyt 1020151) for funding, and the vineyards Perez Cruz, Santa Rita and Haras de Pirque.

KEY WORDS: water stress, winegrape, berrygrape, wine