Influence of Root Temperature and Rootstock on Budbreak, Shoot Growth, and Fruit Composition of Cabernet Sauvignon Grapevines Grown under Controlled Conditions

Abstract

Two-year-old Cabernet Sauvignon vines grafted to rootstocks A x R #1, Rupestris St. George, SO4, and own-rooted growing in 20-liter containers were pruned to two 10-node canes and placed in water baths maintained at 12 or 25°C in a greenhouse. Air temperature was the same for all treatments. Total vine growth (shoot length, dry weight, and leaf area) was about threefold greater at 25°C than at 12°C root temperature. Budbreak was also greater at 25°C than at 12°C; however, the number of berries set per vine did not differ significantly between root temperatures. Fruitset per dm² leaf area with St. George stocks was about half that of the other rootstocks at both root temperatures. Degree Brix, pH, proline and K were significantly less in fruits grown at 12°C root temperature than at 25°C. However, the level of total acidity and malate in fruits were higher for all stocks at 12°C root temperature than at 25°C. The level of arginine in berries was little affected by soil temperature. Fruits from vines on St. George stock had the highest level of arginine, proline, K, and pH and the lowest total acidity.