Genetic correlations for growth rhythm and growth capacity at ages 3–8 years in provenance hybrids ofPicea abies

Abstract

Genetic correlations were calculated between five phenologicai traits and two growths capacity traits at the ages 3–8 years in a nursery trial with full‐sib families of Picea abies (L.) Karst. from a 9 × 9 factorial mating. The parents originated from three regions, northern Sweden, central Sweden and central Europe, each region being represented by six parents. Out of the possible 81 crosses 57 were analysed. Genetic correlations were calculated between traits within a year at population and within‐population levels and between the same trait over years, both among and within populations. At the population level, most correlations were close to one. Within populations between individual parent trees, the correlations between the timing of the growth initiation and the growth midpoint stages were positive and strong with one exception. In most years these stages were also strongly positively correlated with growth cessation. Correlations between growth rhythm and duration of the shoot elongation period were as a rule weaker. In most years, there were weak genetic correlations between growth rhythm and height or leader length. The genetic age‐age correlations were consistently high for all growth rhythm traits except for the shoot elongation period, which was inconsistent, as was the leader length. The results indicate that selections for certain trait combinations in the nursery among populations from widely different geographic regions can be made as early as at ages 3–4, and the trait that is simplest to assess can be used.