Genetic variation in plagiotropic growth in a provenance hybrid cross with Piceaabies

Abstract

Plagiotropism (angle departure from orthotropic growth) was measured on 360 Norway spruce (Piceaabies (L.) Karst.) clones propagated in 2 subsequent years. The clones were members of 20 full-sib families (18 clones per family) from a provenance hybrid factorial cross involving 10 parents of Norwegian (N) and 10 parents of east-European (EE) origin. The clones from the EE × EE crosses showed an average of 17° and 20° in plagiotropism, those from the N × N group showed 3° and 7° in plagiotropism, while the hybrids (EE × N and N × EE) showed 8° and 13° in plagiotropism in 1988 and 1989, respectively. A large family variation was found in the EE × EE and the hybrid groups (11 and 8.5% of total variation, respectively), but variation was small (3.5%) in the N × N group. The clonal component accounted for 10, 12, and 8.5% of total variation in EE × EE, hybrids, and N × N, respectively. Among the plagiotropic clones, some were heterogeneous with a large within-clone variation and others were homogeneous. The year × family and year × clone components were rather large in EE × EE (5 and 9% of total variation, respectively) but smaller in the hybrids and smallest in N × N. The clones with best growth were not among those with the worst plagiotropic growth. The clonal material is ideal for use in future studies on the genetic and physiological regulation of maturation.