Abstract

Wood quality of commercial tree species is important for many wood processing
industries and thus should be considered for inclusion in forest tree improvement
programs. This thesis evaluated the suitability of various proxy methods for rapid and
non-destructive assessment of wood quality traits on standing trees of Scots pine and the
potential for genetic improvement of different wood quality traits through recurrent
selective breeding.

Penetrometer Pilodyn and micro-drill Resistograph were tested for non-destructive
assessment of wood density (DEN_PIL and DEN_RES, respectively), using SilviScan density
(DEN_SILV) as a benchmark. A strong additive genetic correlation was observed between
DEN_SILV and DEN_RES (r_A = 0.96), whilst the correlation with DEN_PIL was substantially
lower (r_A = 0.74). Furthermore, SilviScan stiffness (MOE_SILV) was used as a benchmark
for evaluation of several approaches of calculating the dynamic modulus of elasticity
(MOE) from standing-tree acoustic velocity (VEL_TREE). The combination of VEL_TREE
and adjusted DEN_RES provided the most accurate estimate of MOE_TREE (r_A = 0.91).
Additionally, non-destructive acoustic sensing tools were tested at different stages of
wood processing (on standing trees, felled logs and sawn boards) using destructively
measured sawn-board stiffness (static modulus of elasticity, MOE_S) and strength
(modulus of rupture, MOR) as benchmarks. They proved to be capable of accurately
predicting MOE_S (rA ≈ 0.8) while VEL_TREE, adjusted DEN_RES and MOE_TREE well
reflected MOR (rA ≈ 0.9). Genetic variation of shape stability of sawn boards (bow, crook
and twist) was also investigated. Under-bark grain angle (GRA) was found to be a good
predictor of sawn-board twisting and crooking (r_A = 0.84 and 0.62, respectively). The
chemical composition of juvenile wood (proportion of cellulose, hemicelluloses, lignin
and extractives) was predicted from Fourier transform infrared (FTIR) spectra using
partial least squares regression (PLSR) modeling. Individual-tree narrow-sense
heritabilities (ℎ_i²) for all of the studied wood quality traits varied from low to moderate.

Genetic improvement of sawn-board DEN, MOES and MOR as the target traits could
be achieved through selective breeding for MOE_TREE, DEN_RES, stem straightness (STR)
or GRA. Selection focusing on GRA would also result in lower bow, crook and twist.
Despite the negative genetic correlations between growth and wood quality traits, a
possibility of their simultaneous improvement was identified. An index combining stem
diameter (DBH) and MOE_TREE provided the best compromise.

Keywords

Density; stiffness; strength; shape stability; chemical composition; non-destructive testing; genetic correlation; heritability; breeding; genetic improvement

Published in

Acta Universitatis Agriculturae Sueciae
2020, number: 2020:9
ISBN: 978-91-7760-536-2, eISBN: 978-91-7760-537-9
Publisher: Department of forest genetics and plant physiology, Swedish university of agricultural sciences

SLU Authors

• Fundová, Irena

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Genetics and Breeding
Forest Science
Wood Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/105018