Genetic correlations between spiral grain and growth and quality traits in Picea abies

In Norway spruce (Picea abies (L.) Karst), spiral grain is a major cause of twist development in sawn timber; this problem could be addressed by breeding for reduced grain angles. This study presents estimates of genetic correlations between grain angle under bark and height and diameter growth; branch number, angle, and thickness; stem straightness; ramicorn occurrence; and pilodyn penetration using data from three progeny trials. The genetic relationship between grain angle development and radial growth was also investigated by measuring multiple annual rings (3–15) in stem sections from two clonal trials. Grain angles under the bark exhibited substantial heritability but near-zero genetic correlations with all the other traits studied. The genetic correlations between multiple ring grain angle and radial growth were also close to zero among all rings. However, radial growth exhibited positive genetic correlations with grain angles at specific distances from the pith and with radial grain angle trends, ...