|KOVALESKI, ALISSON - Cornell University|
Submitted to: American Journal of Enology and Viticulture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2016
Publication Date: 1/6/2017
Citation: Londo, J.P., Kovaleski, A.P. 2017. Characterization of wild north american grapevine cold hardiness using differential thermal analysis. American Journal of Enology and Viticulture. ajev.2016.16090. DOI: 10.5344/ajev.2016.16090.
Interpretive Summary: Winter temperature is the primary limiting factor for cultivation of European grape (V. vinifera) in the U.S. outside of California and the Pacific Northwestern States, a rapidly growing sector of the grapevine industry. Breeders, growers, and vinters in these regions rely on the development of new cold hardy grape varieties which combine the fruit quality of V. vinifera with adaptive traits from wild grapevine species. Yet very little information is available regarding the performance of wild species under winter cold stress. This manuscript examines the relative cold hardiness of thirty-three different wild and hybrid grapevine genotypes, collected from the USDA cold hardy grapevine germplasm. Dormant buds were evaluated for freeze hardiness using differential thermal analysis (DTA) of low temperature exotherms(LTE) over three years. DTA analysis is a method of slowly freezing dormant buds to evaluate the lethal temperature of different varieties. Grapevine uses a mechanism called supercooling that allows them to survive temperatures far below freezing. When the grapevine bud is overwhelmed by freezing stress, it freezes rapidly, allowing us to observe the lethal temperature. This freezing point is called the LTE point. Results of the study validate observations that northern wild species such as V. riparia, V. labrusca, and V. amurensis possess the greatest capacity for deep midwinter hardiness, having the lowest freezing point during winter. However, these species are also highly reactive to midwinter warm weather changes, losing freeze hardiness quickly. This trait is a negative trait as it subjects the dormant bud to higher risk of damage if winter temperatures return to normal cold levels. In contrast, southern species such as V. aestivals, V. vulpina, and V. rupestris were nearly as cold hardy, yet were much less responsive. The implications of these results are evident when considering climate change predictions of more variable winters. This work represents the most comprehensive examination of these traits in grapevine and contributes key information regarding germplasm resources for grapevine breeding and sustainable viticulture.
Technical 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 in 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 during the study demonstrated that wild grapevine has a great capacity for responding to both warm and cold temperature events during the dormant season. Results indicate that wild grapevine species with Northern distributions tend to exhibit greater cold hardiness overall, but also tended to have increased responsiveness to temperature fluctuations. Modeling of low temperature exotherm results across the three winters indicates that each grapevine species has a different and innate capacity for responding to temperature. These results are important for a future of grapevine breeding where increases in winter temperature variation are expected. Additionally, these results demonstrate the potential for genetic determinants of temperature responsiveness that can now be investigated and mapped for future grapevine improvement.