Collection Age and Seed Mass Influence Germination and Seedling Growth in Midwestern White Spruce Accessions

Stored tree seed collections are essential resources for seedling production and conserving unique germplasm. As stored seeds age, however, seed viability and seedling vigor can decline. This study tests how age and seed mass correspond to germination dynamics and seedling vigor in four white spruce collections from the upper midwestern United States. Using two seedling growth experiments, this study demonstrates that white spruce seeds stored for >30 years have low seed viability and slower seedling growth rates compared with seeds from more recent (<= 10 years) white spruce collections. Seed mass also predicted seedling growth rate regardless of collection age, suggesting larger seeds from older collections generate faster growing seedlings. Study Implications: Efficient use of stored tree seeds saves nursery managers time and resources. White spruce is a collection priority, but management needs to know how seed viability and seedling vigor decline during storage. Diminished germination and seedling growth after >30 years in storage suggests older collections are most appropriate for germplasm conservation and underscore the importance of testing stored seed prior to nursery production. For collections stored <10 years, larger seeds germinate more readily than smaller seeds and produce faster growing seedlings. For older collections, seed mass does not correspond with germination, but seedling growth rate positively correlated with seed mass.