Berry Composition of Vitis vinifera Cultivars as Influenced by Photo- and Nycto-Temperatures During Maturation

Total acidity was increased and pH reduced in ‘Cardinal’, ‘Tokay’, and ‘Pinot noir’ berries under a phototemperature of 15°C as compared to 35°C. Nyctotemp of 10, 15, and 20°C also increased acidity and reduced pH of fruits compared to those ripened at nyctotemp of 25 or 30°C, provided phototemp was not greater than 25°C. At 35°C phototemp, acidity of fruits ripened at 10°C nyctotemp was greater than that in fruits ripened at 30°C nyctotemp. Acidity and pH were usually not significantly different, however, between grapes matured at 15 and at 25°C nyctotemp. The level of malate in grape berries was inversely related to temp. Degree Brix of ‘Tokay’ fruits ripened at 35°C phototemp was less than that of fruits ripened at 15°C. However, nyctotemp had relatively little effect on concn of sugars in ‘Tokay’ and ‘Cabernet Sauvignon’ berries. Temperature during maturation had no significant effect on berry wt or on the level of arginine. The amount of proline in grapes depended on cultivar, fruit maturity, and temp during the ripening period.