TY - JOUR T1 - Cold Hardiness of <em>Vitis vinifera</em> Roots JF - American Journal of Enology and Viticulture JO - Am J Enol Vitic. DO - 10.5344/ajev.2017.16109 SP - ajev.2017.16109 AU - Eric J. Gale AU - Michelle M. Moyer Y1 - 2017/06/22 UR - http://www.ajevonline.org/content/early/2017/06/15/ajev.2017.16109.abstract N2 - Grapevine buds have identifiable cold acclimation and deacclimation patterns. Whether roots follow these patterns is unknown. If root cold hardiness thresholds and/or acclimation patterns were better understood, mitigation strategies could be developed to reduce the likelihood of root damage. This study encompassed two major objectives: 1) To improve protocols for electrolyte leakage and then quantitatively compare to differential thermal analysis; and 2) To quantify whether Vitis vinifera roots acclimate to preconditioning temperatures. Existing protocols were optimized and root cold hardiness was evaluated on own-rooted Vitis vinifera ‘Merlot’ and ‘Chardonnay’. To determine whether grapevine roots acclimate to their environment, three preconditioning regimes were applied: ambient air temperature when vines were actively growing; 12°C for one week during dormancy; and 0°C for one week during dormancy. Following preconditioning, root samples were collected and exposed to fixed temperatures: −2.0°C, −4.0°C, −6.0°C, or −8.0°C. Electrolyte leakage, the standard indicator of root cold damage, was measured. The incidence of low temperature exotherms from differential thermal analysis was used as a potential alternative to identify temperatures that cause tissue damage. Overall, Chardonnay and Merlot roots did not have dynamic cold acclimation patterns like grapevine buds. There was little variation in maximum cold hardiness (&lt;1.2°C) regardless of preconditioning. Maximum root cold hardiness was experimentally derived for both varieties (Chardonnay median −5.9°C; Merlot median −5.7°C). Differential thermal analysis was an effective alternative method to electrolyte leakage in estimating damage thresholds for these two varieties The lethal temperature at which 10%, 50%, and 90% of roots were killed were calculated for grapevine roots, with values of −4.0°C, −5.8°C, and −7.0°C, respectively. ER -