Multienvironment genomic variance decomposition analysis of open-pollinated Interior spruce (Picea glauca x engelmannii) Omnia Gamal El-Dien & Blaise Ratcliffe & Jaroslav Klápště & Ilga Porth & Charles Chen & Yousry A. El-Kassaby Received: 25 April 2017 /Accepted: 29 January 2018 /Published online: 15 February 2018 # The Author(s) 2018. This article is an open access publication Abstract The advantages of open-pollinated (OP) fam- ily testing over controlled crossing (i.e., structured ped- igree) are the potential to screen and rank a large number of parents and offspring with minimal cost and efforts; however, the method produces inflated genetic parame- ters as the actual sibling relatedness within OP families rarely meets the half-sib relatedness assumption. Here, we demonstrate the unsurpassed utility of OP testing after shifting the analytical mode from pedigree- (ABLUP) to genomic-based (GBLUP) relationship using phenotypic tree height (HT) and wood density (WD) and genotypic (30k SNPs) data for 1126 38- year-old Interior spruce (Picea glauca (Moench) Voss x P. engelmannii Parry ex Engelm.) trees, representing 25 OP families, growing on three sites in Interior British Columbia, Canada. The use of the genomic realized relationship permitted genetic variance decomposition to additive, dominance, and epistatic genetic variances, and their interactions with the environment, producing more accurate narrow-sense heritability and breeding Mol Breeding (2018) 38: 26 https://doi.org/10.1007/s11032-018-0784-3 O. G. El-Dien : B. Ratcliffe : J. Klápště : I. Porth : Y. A. El-Kassaby (*) Department of Forest and Conservation Sciences, Faculty of Forestry, University of British Columbia, Vancouver, BC V6T 1Z4, Canada e-mail: y.el-kassaby@ubc.ca O. G. El-Dien e-mail: omnia.gamal@alumni.ubc.ca B. Ratcliffe e-mail: b.ratcliffe@gmail.com J. Klápště e-mail: klapste.j@gmail.com I. Porth e-mail: porth@mail.ubc.ca O. G. El-Dien Pharmacognosy Department, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt J. Klápště Department of Genetics and Physiology of Forest Trees, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamycka 129, 165 21 Prague 6, Czech Republic C. Chen Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078-3035, USA e-mail: charles.chen@okstate.edu Present Address: J. Klápště Scion (New Zealand Forest Research Institute Ltd.), 49 Sala Street, Whakarewarewa, Rotorua 3046, New Zealand Present Address: I. Porth Départment des Sciences du Bois et de la Forêt, Faculté de Foresterie, de Géographie et Géomatique, Université Laval, Quebec City, QC G1V 0A6, Canada