Effect of Controlled Day and Night Temperatures on Grape Coloration

Abstract

Fruit coloration was investigated in several cultivars of Vitis vinifera L. grown in pots in sunlit phototron rooms held at various day and night temperatures. Mature 'Cardinal', 'Pinot noir', and 'Tokay' fruits ripened at cool-day (15°C) and cool-night (15°C) temperatures had much greater coloration than fruits ripened at hot-day (35°C) and cool-night (15°C), hot-day (35°C) and warm-night (25°C), or cool-day (15°C) and warm-night (25°C) temperatures. Fruits grown at cool-day warm-night temperatures, however, had significantly greater levels of anthocyanins than fruits ripened at hot day temperatures, regardless of the night temperature. On the other hand, 'Cardinal' and 'Pinot noir' berries grown at hot-day (35°C) and warm-night (25 or 30°C) had a higher level of anthocyanins than fruit ripened at hot-day cool-night (15 or 10°C). A day temperature of 35°C completely inhibited anthocyanin synthesis in 'Tokay' berries, regardless of night temperature. Also, a 30°C night temperature (day temperature 25°C) prevented anthocyanin formation in 'Tokay' and greatly reduced the coloration of 'Cabernet Sauvignon' compared with fruits ripened at 15 and 20°C night temperatures. On the basis of fruit coloration, 'Tokay' was least tolerant to hot temperature, and 'Pinot noir, and 'Cabernet Sauvignon' were most tolerant.