Clonal variation in wood quality and growth in young sitka spruce (Picea sitchensis (Bong.) Carr.): Estimation of quantitative genetic parameters and index selection for improved pulpwood
1998
Silva, J.C.E. | Wellendorf, H. | Pereira, H.
Repeatabilities and clonal correlations were estimated for wood properties (pilodyn and Lignin content), stem straightness and growth characters (height, diameter and volume index) measured in young Sitka spruce clones, under fastgrowing conditions. The estimates of the quantitative genetic parameters were based on a random sample of 30 clones taken from a population of 253 clones at age 9 years from field planting. The magnitude of the clone-mean repeatability estimate indicated that the examined characters are able to respond well to selection based on clone means and subsequent vegetative propagation. However, for lignin content, the phenotypic variation was rather low (i.e. coefficients of variation of 3.7% and 2.9%on the individual ramet and clone mean bases, respectively), which may Limit the magnitude of the genetic gain. The estimated clonal correlations between the wood properties and growth pointed out that clonal selection for reducing the population level in lignin content and/or increasing the whole-ring density is expected to result in an indirect genetic decline in growth. Multiple trait selection indices were constructed to explore the possibilities of improving the yield and/or the quality of young Sitka spruce wood for pulp production. In the absence of quantitative economic data - and to ascertain the possible consequences of clone selection and clonal propagation for the proposed end use - contrasting multiple trait index selection options were compared on the basis of predicted genetic responses in wood properties, growth and stem straightness.
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