Influence of Environment on Metabolism of Organic Acids and Carbohydrates in Vitis Vinifera. I. Temperature

Abstract

Radioactive CO2 was administered to shoots of White Riesling growing in the field af two stages of maturity and under three different light conditions: ful sunlight and shaded vines receiving approximately 20 and 30% of full sunlight. The amount of C14O2 incorporated into organic acids and sugars from both immature and nearly ripe berries grown under different light conditions was determined over a period of 32 to 80 hours.Berries from 21% sun had more label in the organic acid fraction and less in the sugar fractions than berries from 30% or 100% sun. The amount of C14O2 incorporated into malic acid was usually relatively greater from shaded berries; tartaric acid, on the other hand, contained a greater proportion of the label with 100% sun.Immature shaded berries contained a relatively greater amount of label in sucrose and a decreased amount in glucose and fructose, but this relationship was reversed in mature shaded berries. Mature shaded berries contained a relatively smaller amount of label in sucrose than unshaded berries. The proportion of activity in glucose and fructose was not greatly influenced by the amount of sun.