Selection Efficiency for Solid Wood Traits in Pinus taeda using Time-of-Flight Acoustic and Micro-Drill Resistance Methods

Abstract

Abstract Conventional sampling and laboratory analysis of solid wood properties to facilitate clonal screening in tree improvement programs are prohibitively time-consuming and expensive. Alternative methods—time-of-flight acoustics and micro-drilling resistance—were assessed for efficiency in screening clones for wood stiffness (modulus of elasticity [MOE]), strength (modulus of rupture [MOR]), and density. Ninety clones, consisting of 30 from each of 3 full-sib families, were screened in an 8-year-old loblolly pine (Pinus taeda L.) field test using a TreeSonic time-of-flight tool and Resistograph drill resistance tool. The same clones were sampled for wood specimens for laboratory tests of MOE, MOR, and density. TreeSonic stress wave speed measurements produced highly repeatable clonal phenotypes that facilitated efficient selection for MOE and to a lesser extent for MOR. Resistograph amplitude measurements had a strong genetic correlation with wood density and facilitated highly efficient selection for density, with correlated responses for MOR and MOE. Combining the indirect traits into a selection index improved gain for mechanical wood traits. Both tools provided high measurement rates that resulted in cost efficiencies. Indirect measurements of solid wood properties should be attractive for clonal selection programs that must screen thousands of clones under a finite budget.