Assessing wood properties on hybrid poplars using rapid phenotyping tools

There is a growing interest in improving wood properties through clonal selection. However, traditional methods for determining wood properties are difficult to implement at the scale required for large-scale selection programs. In this study, we used rapid phenotyping methods (i.e., drill resistance (DR) and stress wave velocity (SWV)) for assessing wood quality in a 3-year-old clonal trial containing 125 clonal poplar hybrids. These hybrids belong to interspecific crosses of Populus deltoides [D] , P. trichocarpa [T] , P. nigra [N], and P. maximowiczii [M]. We estimated clonal variation and correlations among DR, SWV, basic density (BD), and dynamic modulus of elasticity (MOE d ). Clonal repeatabilities were moderate for all traits, but were higher for BD and DR (i.e., R 2 = 0.45 and 0.46, respectively) than for SWV and MOE d (i.e., R 2 = 0.30 and 0.35, respectively). Clonal mean phenotypic correlations were high between BD and DR (r c = 0.84) and between SWV and MOE d (0.87), and the clonal correlations (r g ) were 0.90 and 0.96, respectively. Overall, there was a weak relation between BD and MOE d (r c = 0.23 and r g = 0.29, respectively). Results support the use of DR and SWV as tools for the selection of poplar clones oriented to improve solid wood properties.