Utvärdering av klontester och avkommeförsök med vårtbjörk

Field tests, each including 39-83 Swedish plus-tree clones of silver birch (Roth) planted on 10 different sites in the southern part of Sweden, were evaluated at up to 10 years of age. The main conclusions can be summarized as follows. Growth traits were mostly under strong genetic influence, and showed sustantial genetic variation and high potential genetic gain. Survival did not seem to be a trait of genetic importance. The genetic correlation between growth and growth cessation was weak, suggesting that it should be possible to find clones combining high growth and early autumn growth. Non-significant transfer effects for clones of different origin and weak G x E interaction were found, indicating that southern Sweden can be treated as a single utilization zone and that few sites are needed for genetic tests. Strong genetic age x age correlations were detected, suggesting that short test periods could be used. (Scandinavian Journal of Forest Research, 2005; 20: 292-303)