Exogenous abscisic acid increases bud freezing tolerance of Vitis vinifera “Pinot gris” grown in cold regions of the United States

Abstract

Economic losses due to cold weather events are a major constraint to the expansion of premium but cold sensitive winegrape cultivars in cold regions of the United States. 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, Vitis vinifera « Pinot gris » grapevines, 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 véraison, post-véraison, and post-harvest. ABA application did not affect yield components or fruit composition, 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, and spray applications made at véraison and post-véraison decreased LT50 (increased FT) the most by 2 oC to 4 oC as compared to the untreated control vines. Furthermore seasonal changes of bud FT were linked with changes in soluble sugars particularly raffinose. It is concluded that a foliar application of ABA increased bud FT during the dormant season and thus ABA is a potential cultural practice for mitigating economic losses from cold injury in production regions with damaging cold events.