Performance of clonal mixtures and single-clone plots in young Picea abies trials.
1992
Lundkvist K. | Eriksson G. | Norell L.
The growth of a series of clonal mixtures of Picea abies (L.) Karst., each containing 16 clones, has been compared to the growth of mono-clone plots in a field experiment, planted on four sites in Central Sweden. The mixtures were created from truncated and representative selection of clones with respect to time of bud-flush in spring. Assessment of height was made five years after planting. The representatively selected clone mixture performed consistently close to the site-average on all sites which is interpreted as a good stability but inadequate performance for such a mixture. Stability was also noted for two out of three mixtures created by truncated selection. Performance for those mixtures were close to average, as well. The stability of the mixtures is an illustration of the sacrifice of performance for stability when you average over several clones, i.e. the law of large numbers. High stability and high performance are two separate qualities in spruce clones that should be considered jointly in selection of clones and in the composition of clone mixtures. Frost damage occurring at one of the sites caused ranking shifts in mean heights between the clones. For most of the entries, single clones as well as mixtures, there was an association between incidence of frost damage and earliness of bud development of the clones. Competition for light has so far not begun in the plantations and future assessment is necessary to tell whether the present results are valid in a longer perspective.
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