• Iriantono, Djoko
  University of Maine
  

A progeny test of black spruce from throughout Maine has been established for 13 years. In this study, the height growth of these trees was analyzed to estimate heritability and expected gain, to detect genotype x environment (GE) interaction significance, to examine age-age correlation effects, and to identify parent-tree class and parental stand effects. In addition to height growth, cone yield and seed viability of these 13-year-old black spruce were examined in this study.

The heritability and expected gain may be higher than expected. Individual and family heritability are 0.20+/-0.02 and 0.55+/-0.21, respectively. These fairly high heritability estimates resulted after eliminating interactive families detected from the examination of GE interaction. As a result of this high heritability, 0.69-2.67% of additional expected gain may be obtained by applying a given selection strategy.

Examination of age-age correlation indicates that selection at a young age may not be effective in identifying genotypes for height growth. The significant parent-tree class and parental stand effects coupled with environment effects during 13 years may account for low juvenile-mature correlation.

Another finding of this study is that selection for height growth tends to also select genotypes superior in cone yield. These selected genotypes also bear seeds with a fairly high germination percentage (ranging from 77 to 80% for the top 4 selected families).

These findings are valuable for tree breeders and forest managers. The tree breeders can use the genetically improved materials for advanced generations, white the managers can use seeds from the genetically selected trees for reforestation activities.