Genetic parameters for grain angle in 28-year-old Norway spruce progeny trials and their parent seed orchard

Abstract

• Sawn wood which acquires twist during drying is a substantial problem for the sawmill industry and is to a large extent caused by spiralled grain in the tree. • In this study, the feasibility of using spiral grain angles as a selection trait in Norway spruce (Picea abies (L.) Karst) tree breeding and the extent of grain angle and its breeding values were investigated. Grain angles under bark and diameter were measured at breast height in three 28-year-old Norway spruce progeny trials and in their parent seed orchard. • The mean grain angle value was 1.76 ◦ in the progeny trials and 1.84 ◦ in the seed orchard. Estimated genetic standard deviations for grain angle were almost 1 ◦ . Progeny trial heritabilities (H 2 > 0.3) were larger than the seed orchard heritability (H 2 = 0.24). Genotype by environment interaction among the progeny trials was negligible for grain angle. Progeny trial grain angles exhibited genetic correlation with seed orchard grain angles in the range 0.66 to 0.84. • Thus, mature wood grain angles are also under considerable genetic control, raising the opportunity to reduce the occurence of left-grained trees, which are prone to producing twisted wood.