Clone Testing and Genotype x Environment Interaction in Picea abiesKarlsson, Bo
Clones are used for accurate genetic tests of Picea abies (Norway spruce) in the Swedish breeding programme. This thesis deals with the efficiency of clone tests in genetic testing. Special focus is placed on the problems associated with the genotypexenvironment (GxE) interaction.
Results from three different series of clone tests show low broad sense heritabilities for survival, moderate for growth traits and high for bud-break, branch angle and wood density measured as pilodyn penetration.
For growth, clones should be selected after field-testing rather than on the basis of ortet behaviour in the nursery. However, for highly heritable traits, such as bud-break, early selection can be used.
The genotypexenvironment interactions for growth were statistically significant. The genetic correlations did not indicate any geographic trend. Such traits as bud-break, branch angle, and wood density were little affected by the GxE interaction.
Ecovalence estimates exhibited small differences between clones with respect to the interaction. The main cause of the GxE interaction in southern Sweden is late spring frost. In sites where late spring frosts are likely during the initial period after planting, clones with late bud-break contributed less to the interaction. Material with late bud-break is recommended for use where spring frosts are likely. In areas with low frequency of frost-prone sites, selection should be carried out only for general performance.
The GxE interaction for height increment was larger than for early height measurements, suggesting that the interaction is an increasing problem with age. Residual C-effects from the nursery could explain the relatively smaller interaction effects associated with early measurements.
No important change in the Norway spruce breeding strategy was proposed.
KeywordsPicea abies; provenance; clone; genotypexenvironment interaction; genetic correlation; variance component; ecovalence; c-effect
Published inActa Universitatis Agriculturae Sueciae. Silvestria
2000, number: 162
Publisher: Department of Forest Genetics, Swedish University of Agricultural Sciences
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