Phenotypic plasticity in <i>Populus trichocarpa</i> clones across environments in the Nordic–Baltic region

Transition towards a bio-based society requires large amounts of woody biomass to be converted into biofuels and biomaterials. <i>Populus</i> species are good candidates for growth in short rotations, but there is a lack of climate-adapted plant material suitable for growth at the high latitudes of the Nordic–Baltic region. Here we studied the growth and phenology traits in 63 <i>Populus trichocarpa</i> clones earlier preliminary selected for growth at northern latitudes, in three different field sites; i.e. in central Sweden, eastern and western Latvia. The material showed moderate broad sense heritabilities, with high values for phenology traits, indicating opportunities for selection. Genotype × environment (g × e) interaction was identified for all traits, but the phenotypic correlation between pairs of sites provided more detailed information indicating the strength of the g × e interaction. The between-clone variation in plasticity was high, and we identified some clones showing a high and stable performance across the three sites. These clones are of particular interest for the commercial deployment and future breeding of <i>Populus</i> material for the Nordic–Baltic region.