Characterization of Wild North American Grapevine Cold Hardiness Using Differential Thermal Analysis

Abstract

The cold hardiness of 33 different grapevine genotypes, representing six wild North American grapevine species, one wild Asian grapevine species, and six hybrid grapevines, was evaluated by measuring lethal temperatures for dormant buds using low temperature exotherms. Studies were conducted over three different winters to characterize the relative level of cold hardiness and responsiveness to changing weather patterns of each species. Major differences in the winter conditions demonstrated that wild grapevine has a great capacity for responding to both warm and cold temperature events during the dormant season. Results indicated that wild grapevine species with northern distributions tended to exhibit greater cold hardiness and responsiveness to temperature fluctuations than their southern-dwelling counterparts. Statistical modeling of low temperature exotherm results across the three winters indicated that each grapevine species had a distinct and innate capacity for responding to temperature. These results may be important for future grapevine breeding in areas with expected increases in winter temperature variation. Additionally, these results demonstrate the potential for genetic determinants of temperature responsiveness that may be investigated and mapped for future grapevine improvement.