Root-Zone Refrigeration Delays Budbreak and Reduces Growth of Two Containerized, Greenhouse Grown Grape Cultivars

Abstract

Following budbreak, grapevines grown in west Texas are particularly susceptible to freeze damage. If deacclimation or budbreak was delayed, damage from spring frosts could possibly be reduced. During spring 1999, two duplicate experiments were undertaken to determine if root-zone refrigeration delayed budbreak of two cultivars of Vitis vinifera L. (‘Chardonnay’ and ‘Cabernet Sauvignon’). Under greenhouse conditions, one-year-old grafted vines were planted into containers and placed in water baths. Throughout experiments, thermostats in two water baths were set to maintain temperatures at 35°F and 45°F. In addition, a non-chilled control water bath was maintained. Water and soil temperatures along with greenhouse climatic data were measured. Evaluation of budbreak was performed on a daily basis. At the conclusion of each experiment shoot and root dry mass were measured. Results indicate that when compared to controls, root-zone refrigeration delayed budbreak for both cultivars. Refrigerated grapevines also had a lower percentage of budbreak. Root and shoot mass of control plants were generally greater when compared to refrigerated water treatments. Because prolonged budbreak may allow buds to escape spring frost injury, reductions of root-zone temperature during spring deacclimation could have significant impact on the west Texas viticulture industry.