TY - JOUR T1 - Foliar Application of Abscisic Acid Increases Freezing Tolerance of Field-Grown <em>Vitis vinifera</em> Cabernet franc Grapevines JF - American Journal of Enology and Viticulture JO - Am. J. Enol. Vitic. SP - 377 LP - 384 DO - 10.5344/ajev.2012.12006 VL - 63 IS - 3 AU - Yi Zhang AU - Imed E. Dami Y1 - 2012/09/01 UR - http://www.ajevonline.org/content/63/3/377.abstract N2 - The purpose of this study was to develop a method to increase freezing tolerance of field-grown grapevines using foliar application of abscisic acid (ABA). The specific objectives were to evaluate the morphological and physiological changes of field-grown Vitis vinifera Cabernet franc grapevines in response to exogenous ABA application and to determine an optimum timing for foliar application of ABA that results in enhanced freezing tolerance. Cabernet franc grapevines grown at two locations were treated with 400 and 600 mg/L ABA at different stages of development corresponding to veraison and 20, 30, 40, and 55 days postveraison. ABA did not affect yield components or basic fruit chemical composition. However, it enhanced anthocyanin concentration, advanced dormancy, decreased bud water content, and ultimately increased freezing tolerance under simulated freezing events. The increased freezing tolerance by ABA was confirmed by assessing bud injury following natural freezing events of −19°C and −23°C in two locations. The effectiveness of ABA may have been enhanced by application timing, which was optimum at veraison and 20 to 30 days postveraison. Results suggest that ABA application has the capacity to enhance dormancy and increase freezing tolerance and can be used as a prophylactic tool to protect against winter injury of grape cultivars grown in cold regions. ER -