Characteristics of normal-crowned and pendula spruce (Picea abies (L.) Karst.) examined with reference to the definition of a crop tree ideotype.

Sixty-four 19-year-old Norway spruce trees were felled and the roots excavated during 1987 and 1988. The trees were open-pollinated progenies from a small stand located in southern Finland. Several characteristics of stem, crown, and roots were measured and analyzed on 36 pendula and 28 normal-crowned trees in the sample. Total fresh weight, stem fresh weight, and crown fresh weight were 47.6, 27.5, and 61.4% greater in normal-crowned trees than in pendula trees. The mean harvest index (including roots) of pendula spruce was 0.32 compared with a value of 0.27 for normal-crowned trees. This difference reflects the difference in crown biomass between the two groups of trees. The crown structure of pendula spruce appears to permit higher stand densities than is possible with normal-crowned spruce. Thus the results indicate that genetically narrow-crowned trees with a small total crown mass could provide useful basic material for selection of crop trees with a high stemwood production per hectare.