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

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Abstract
Shoots of mature grape vines (Vitis vinifera variety "Sultanina"), each with an attached fruit cluster, were presented C14O2 at an early stage of berry development and again when the berries were nearly ripe. After a period of 8-11 hours from the time the label initially was administrated, the shoots were removed from the vines and cultured in the dark at 6 temperatures ranging from 10 to 37[degree]. The relative amounts of C14 incorporated into the organic acid and sugar fractions of berries cultured at the various temperatures were determined over a 96-hour period. Likewise, the relative amount of C14 in malic, tartaric and citric acid, and in glucose, fructose, and sucrose were measured. Maturity of the berries greatly influenced the relative amount of label in the sugar and organic acid fractions. Green berries (6.5[degree] Balling) incorporated C14 predominantly into organic acid; the optimum temperature for organic acid synthesis was between 20 and 25[degree]. The nearly ripe fruit (16[degree] Balling), in contrast, had approximately 80% or more of the total label in the sugar fraction at all temperatures. The amount of C14 incorporated into the organic acids of the nearly ripe berries was 2-3 times greater at 10 to 15[degree] than at the higher temperatures. Malic acid was the principal labeled organic acid, containing 40-90% of the activity in the organic acid fraction; tartaric acid had 4-21%, and citric acid had 2-10%. The proportion of activity in tartaric acid from green berries was several times greater than that from ripe berries. Increasing the culture temperature from 10 to 25[degree] generally increased the amount of label in tartaric and citric acid; however, temperatures higher than this resulted in a reduction of activity in these acids. The relative amounts of C14 in glucose from green berries was greatly increased at the higher culture temperatures, while fructose had corresponding decreases in activity. The relative activity of sucrose from nearly ripe berries kept at 10[degree] was 2-3 times greater than that from berries held at 20[degree] or higher.