Use of differential thermal analysis to quantify bud cold hardiness of grape selections and clones

Differential thermal analysis (DTA) was used to characterize primary bud mid-winter cold hardiness of Vitis spp. Bud hardiness reached a maximum and was rather stable during the months of January and February at Geneva, New York. Because cold tolerance increases during periods of prolonged cold, observed freezing temperature was adjusted on the basis of the freezing temperature of cv. Concord on the day of observation. DTA gives reproducible and meaningful estimates of bud freezing temperature. Such data account for at least 50 % of the among-cultivar variance in overall vine cold hardiness.