An Analysis of Poplar Growth and Quality Traits to Facilitate Identification of Climate-Adapted Plant Material for Sweden

Abstract

AbstractPoplar plantations harbor large potential as a renewable source of biomass for bioenergy and other industrial applications. The overall aim of this study is to analyze growth, phenology, stem form, and branching characteristics of 32 poplar clones grown in a trial in southern Sweden for their suitability to be grown as industrial feedstock. In a linear mixed model, performed for diameter at breast height and stem volume, the precision was improved by the use of two competition indices. The significance of phenology and quality characteristics for growth performance and ranking of poplar clones was evaluated through genotypic correlations, and multivariate hierarchical cluster analysis used to group the material. All traits showed moderate to high broad sense heritability. In general, higher stem volume was positively correlated with later leaf senescence, and uncorrelated with spring phenology. Selection efficiency for stem diameter and height was greatly improved between age 3 and 6 years allowing a better precision in selecting a subset of clones to be further tested in production plots and pilot plantations. Two commercial Populus maximowiczii Henry × trichocarpa Torr. & Gray cultivars performed best, while some intraspecific hybrids of P. trichocarpa are considered useful to genetically diversify commercial plantations in Southern Sweden (Belgian clones) or establish plantations in north-central parts of Sweden (Swedish clones). The cluster analysis emphasized growth traits and the grouping of the clones corresponded to their origin (or parentage). The results will facilitate decisions on the use of studied material in breeding, further testing and commercial deployment of poplar plantations in Sweden.