Genetic gain and gene diversity following thinning in a half-sib plantation

Status number, gene diversity, inbreeding coefficient and genetic gain were calculated following phenotypic rogueing of different intensities in a half-sib progeny plantation of Scots pine (Pinus sylvestris L.). Across most selection intensities the status number, gene diversity and genetic gain remained favorably high while the inbreeding coefficient was remarkably stable. It is suggested that phenotypic selection in half-sib progeny tests or plantations with unknown pedigrees, can be used to manage seed collection areas or as a component in low-input breeding without a fast build up of coancestry or inbreeding, provided the initial number of progenies of unrelated parents is sufficiently high and that a high number of these families are retained with a few individuals per family.