Studies On Long-Term Preservation of Dormant Buds of Juglans Cinerea.

Juglans cinerea (butternut) is a deciduous tree native to the United States and Canada with oblong shaped nuts with an oily texture and a pleasant flavour. The species is threatened by a canker disease caused by the introduced fungus (Sirococcus clavigignenti-juglandacearum) which already eradicated about 90% of the native butternut at some North America sites. Over 60 different germplasm accessions of the species are maintained at the USDA-ARS, NPGS clonal repository in Corvallis, OR as field plantings, and the USDA-Forest Service (FS) maintains several field sites of selected accessions varying in canker resistance. Backing-up butternut germplasm in liquid nitrogen would contribute to securing the species genetic pool for future needs. Our three year study with five accessions of butternut dormant buds indicated survival after liquid nitrogen exposure ranging from 13 to 53% (tested by chip grafting). The developed protocol will be used to back-up the butternut germplasm maintained by the ARS-NPGS repository and the USDA-FS sites.