Grapevine cold hardiness is a critical trait that determines the geographical distribution and winter survival of cultivars, thus a key consideration for viticulture in regions with severe winter conditions. This study investigated the cold hardiness of 312 Vitis riparia F1 hybrids, using differential thermal analysis (DTA) and survival assessments at 4°C over seven and 28 days. The DTA analyses to identify significant changes in progeny lethal temperature exotherm (LTE) values with a wide range of LTE values from -24.3°C to -12.3°C observed after 28 days of cold acclimation. The mean LTE value improved from -16.8°C after seven days to -18.6°C after 28 days with 80.2% of progenies showing significant decreases in LTE values. Progenies were divided into five groups based on cold hardiness: very cold hardy, cold hardy, moderately hardy, susceptible, and very susceptible. Principal component analysis (PCA) demonstrated clear separation among the five cold hardiness groups, with PC1 accounting for 71% of the variance. This study provides valuable insights into the genetic basis of cold hardiness in V. riparia progenies, offering critical information for grape breeding programs aimed at developing cold-resistant cultivars. The identification of highly cold-hardy progenies and the understanding of their genetic diversity will aid in selecting parent plants for breeding, ultimately improving grape production in cold regions.
