GENETIC-VARIATION, HERITABILITY AND EXPECTED GAIN OF HEIGHT IN PICEA-ABIES IN 7-YEAR-OLD TO 9-YEAR-OLD CLONAL TESTS

Clonal material propagated as cuttings and control seedling lots of No rway spruce (P. abies [L.) Karst.) were compared in two series of clon al tests. Variance components, heritability and expected genetic gain were calculated for height based on measurements carried out in the te sts at the age of seven and nine years. The mean heights of the clones were significantly higher than those of the controls in one of the te st series, but there was no significant difference between these two g roups in the other series. The variance due to clone sources was signi ficant in both test series and accounted for 10 to 19% of the total va riation. Broad sense heritabilities were 0.21 +/- 0.05 and 0.23 +/- 0. 02 on the individual level and 0.75 +/- 0.06 and 0.78 +/- 0.02 on the basis of the clone mean for the respective series. Theoretical genetic gains were calculated based on the assumption that the tallest 10% of the clones would be selected and propagated for reforestation purpose s. The expected gain in height was 13.1 and 19.1% in these test series . Utilization of this gain is, however. difficult due to the ageing of the clones.