Lengthened cold stratification improves bulk whitebark pine germination

Abstract

Crucial to the restoration of whitebark pine (Pinus albicaulis) ecosystems is the ability of forest managers to locate, propagate, and reintroduce viable, disease-resistant populations to these jeopardized systems. Currently, one of the most limiting steps in this process is the slow, labor-in - tensive, and expensive process of producing whitebark seedlings at forest nurseries. From a nursery production standpoint, whitebark seed dormancy is complex and more problematic that other western conifers. Although seedling culture has evolved and become more streamlined, overcoming seed dormancy is still a major challenge to efficient seed use and large-scale seedling production. Releasing seed dormancy through scarification and stratification needs to result in adequate and consistent germination percentages, and also needs to be practical and efficient at a restoration-production scale. This paper describes trials comparing germination percentages of whitebark seedlots grown under operational conditions at the Forest Service Coeur d’Alene Nursery to determine the relative influence of seed source elevation and location, seedlot (collection) age, and 60 or 90-days of cold stratification. The results of these studies indicate that, given proper seed collection, handling, clean - ing, and storage: 1) 90-day cold stratification results in significantly increased germination over the 60-day treatment; 2) within the first decade of storage, seedlot age may not play as crucial a role in reducing germinative capacity as was previously thought; and 3) seedlot source geography may not have a strong enough influence on germinative capacity to merit altering seed use calculations or culture regimes for greenhouse production.

Parent Publication

• National Proceedings: Forest and Conservation Nursery Associations - 2012

Citation

Robertson, Nathan; Eggleston, Kent; Overton, Emily; McLaughlin, Marie. 2013. Lengthened cold stratification improves bulk whitebark pine germination. In: Haase, D. L.; Pinto, J. R.; Wilkinson, K. M., technical coordinators. National Proceedings: Forest and Conservation Nursery Associations - 2012. Proceedings RMRS-P-69. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 72-76.