Using Electrolyte Leakage for Evaluating Hardwood Seedling Cold Hardiness

This paper describes the use of electrolyte leakage (EL) from stem tissue as a potential method for assessing cold hardiness of hardwood seedlings. The EL method has seen little use with North American hardwoods, but has successfully predicted conifer hardiness in both controlled and operational settings and has been used experimentally on hardwoods in Europe. Three species of hardwoods—northern red oak (Quercus rubra L.), black walnut (Juglans nigra L.), and black cherry (Prunus serotina Ehrh.)—were evaluated for hardiness at 4 temperatures (3, –10, –20, –40 ∞C [37, 14, –4, –40 ∞F]) after being subjected to 3 storage regimes (freezer, cooler, ambient) of varying duration. Higher EL values at lower temperatures and longer durations represent an increase in cell damage and loss of hardiness. For all species, an increase in EL over time (storage duration) corresponded to a decrease in the number of days required for budbreak under greenhouse conditions. EL levels did not appear to be related to height growth after 3 months. The EL trends were similar for all species and storage temperatures, while the 3 species exhibited differing responses to storage temperatures when placed in a greenhouse. The data presented here is preliminary. Further research is needed to gauge the effectiveness of EL as a predictor of seedling hardiness and quality for commonly produced hardwoods.