Effects of Day Temperature and Light Intensity on Growth and Composition of Vitis vinifera L. Fruits1

Three-year-old ‘Cardinal’ and ‘Pinot noir’ vines were grown from véraison to fruit maturity in a stationary and rotating phytotron at high (30°C) and low (20°C) day temperatures in combination with both high (>2,500 ft-c) and low (< 1,200 ft-c) average light intensities. Night temperature (6 PM to 6 AM) was 15°C in all treatments. Berries were collected at weekly intervals and analyzed for various constituents. Low temperature usually resulted in increased berry weight, total acidity, and malate, and in decreased pH, arginine, proline, and total N in the berry juices, as compared to fruits grown at high temperature. The concentrations of total soluble solids and tartrate in the fruits generally did not significantly differ with temperature. Low light intensity at both high and low temperatures generally resulted in reduced berry weight, total soluble solids, pH, and proline, and in increased levels of total acidity, malate, arginine, and total N in the berry juices compared to grapes grown at high light intensity at the same room temperature. The concentration of arginine was highly correlated with the level of total N in the fruits of both cultivars.