Abstract: China is cold and little snow in winter as a continental monsoon climate，cold damage to
grapes often occurs in northern regions. Freezing injury reduces grape output significantly，and causes an
enormous waste of manpower and material resources due to the requirement for re-plantation in severe
cases. The annual minimum temperature occurs in January and may reach below–15 ℃ in Shandong
Province where belongs to the buried critical areas. Although commercial grape production in Shandong
predominantly relies on own-rooted plants，there is an interest in grafting to rootstocks for its higher cold
hardiness. Therefore，comparing grape hardiness in same period to filter out the strong cold resistance
varieties for production is very important and imminent. We evaluated buds cold hardiness of 8 rootstocks
and 6 cultivars in this study，which aims to screen out strong cold hardiness rootstocks and cultivars. A
system for Differential Thermal Analysis（DTA）was applied for Low Temperature Exotherms（LTE）
analysis of buds of several grape varieties，and the regression line of temperature-injury（LT–I）of buds
was established. LTE analysis，which can be used to compare the cold hardiness of different plant varieties，has been undergoing improvement since the 1970s. Initially，the half-lethal temperature（LT50），
LT10 or LT90 was applied to analyze initial low-temperature exothermic data，but these values failed to fully
reflect the cold hardiness of different varieties. LT–I analysis obtained by LTE method could make an
overall evaluation of grapevine cold hardiness，and lethal temperature coefficient（Qlt）is calculated as the
slope of the linear portion of the LT–I regression line within 20% to 80% injury，the range of importance
to plant survival and production. Qlt represents the rate of injury increase for one-degree decrease of lethal
temperature（LT），could reflect the sensitivity of varieties to low temperature. The order of Qlt of buds was
Chancellor < 5BB < Frontenac < Beichun < SO4 < Vidal < 101-14Mgt < Beta < 3309C < 140Ru <
Moldova < Cabernet Sauvignon < 110R < 1103P；The buds 50% lethal temperature of different cultivars
was in the order of Cabernet Sauvignon > Moldova > Vidal > Chancellor > 110R > 1103P > 3309C >
140Ru > Beichun > 101-14 Mgt > Frontenac > Beta > 5BB > SO4. A comprehensive evaluation on LT20 to
LT80 of different varieties were analyzed by subordinate function value analysis. The result indicated that
the buds of Cabernet Sauvignon had the worst cold hardiness，followed by Moldova，Vidal，Chancellor，
110R，3309C，140Ru，Beichun，1103P and 101-14M，while Frontenac，Beta，5BB and SO4 had the best
cold hardiness. Buds in deep dormancy had a better cold hardiness，characterized by the buds cold
hardiness in January were better than in November.

Key words: grapevine, bud, cold hardiness, differential thermal analysis, low temperature exotherms analysis, lethal temperature-injury