Responses of Vitis vinifera 'Pinot gris' Grapevines to Exogenous Abscisic Acid (ABA): I. Yield, Fruit Quality, Dormancy, and Freezing Tolerance

Economic losses due to cold weather events are a major constraint to the expansion of premium but cold-sensitive winegrape cultivars in colder regions, such as Ohio (USDA) Plant Hardiness Zones 6b-5b (-17.8 to -26.1 degrees C) (ARS-USDA 2012). The purpose of this study was to determine whether a foliar application of abscisic acid (ABA) could increase the freezing tolerance (FT) of field-grown 'Pinot gris' grapevines (Vitis vinifera), and whether the effectiveness of ABA treatments can be influenced by the phenological timing of the application. Mature 'Pinot gris' grapevines were treated with a foliar application of ABA at a concentration of 0 mg L-1 (control), or 400 mg L-1 at vine phenological stages corresponding to veraison, post-veraison, and postharvest. ABA application did not affect yield components, fruit composition, or vegetative growth, but caused early leaf senescence, leaf abscission, and advanced dormancy that led to increased FT of 'Pinot gris' during the dormant season. The phenological timing of application influenced ABA effectiveness, with spray applications made at veraison and post-veraison being the most effective. It was concluded that a foliar application of ABA increased bud FT during the dormant season, and thus, ABA is a potential cultural practice tool for mitigating economic losses from cold injury in production regions with damaging cold events.