Effects of plus tree selection and seed orchard environment on progenies of Piceaabies

Abstract

Open-pollinated progenies from selected plus trees of Piceaabies (L.) Karst., and from average performing trees (controls) in each of five northern (65–66°N) natural stands in Norway, were tested for growth, timing of bud set, and autumn frost hardiness during the first growing season. The plus trees had also been grafted in a southern seed orchard, Lyngdal (58°N). Crosses were performed in the orchard, using orchard pollen from the same plus trees. All progenies were grown in a common test. There were no differences between natural stand progenies from plus tree and from control stand trees, but the plus tree progenies were different from their seed orchard half-sibs. The seed orchard progenies were slightly taller, formed terminal buds later and were more damaged by frost in a freezing test than their northern half-sibs. Except for one mother, seeds were heavier when produced in the southern seed orchard, but the heavier seeds could not explain the more southern-like performance of the seed orchard progenies. The results are discussed in relation to a hypothesis that the non-native southern seed orchard environment affects the progenies, leading to a more southern phenotypic performance than expected.