Performance of genetically improved Norway spruce in one-third rotation-aged progeny trials in southern Finland

Abstract

ABSTRACT Growth data from 15 progeny trials were analyzed to assess realized and expected genetic gains associated with improved Norway spruce (Picea abies Karst.) stock in southern Finland. The study materials included 257 seedlots originating from 9 wild stands and 17 seed orchards. The measurement data were collected between 22 and 30 years of age. First-generation seed orchard progenies showed a clear superiority over unimproved trees with a realized genetic gain of 8.4% in height growth, 9.0% in diameter growth, and 20.6% in stem volume growth. The respective genetic gains expected from 1.5-generation seed orchards were 12.8%, 13.5% and 36.9%. Stem slenderness and survival did not differ between groups of improved and unimproved trees. The interaction between genetic groups and sites was insignificant for all the traits, suggesting overall robustness of the gains across environments. The results do not include the additional genetic gain due to genetic thinnings and thus, they are likely to underestimate the currently realizing gains from genetically thinned first-generation seed orchards. The results are suggested to be primary information for further studies needed to model growth and yield of genetically improved Norway spruce stands over a full rotation.