Genetic variation in wood stiffness and strength properties of hybrid larch (Larix gmelinii var. japonica × L. kaempferi)

Abstract

Genetic parameters for wood stiffness and strength properties were estimated in a 29-year-old hybrid larch stand (Larix gmelinii var. japonica × Larix kaempferi). The study included 19 full-sib larch families from Hokkaido, northern Japan. Implications of these genetic parameters in wood quality improvement are subsequently discussed. Traits included in the analyses were the dynamic modulus of elasticity of green logs (E log ), the modulus of elasticity (MOE), the modulus of rupture (MOR), compression strength parallel to the grain (CS) in small clear specimens, wood density (DEN), and diameter at breast height (DBH). DEN had the lowest coefficients of variation and MOE the highest. The narrow-sense heritability estimates of E log , MOE, MOR, and CS were 0.61, 0.44, 0.60, and 0.43, respectively, and those of DEN and all mechanical properties increased from an inner to outer position within the stem. E log and DEN had high positive phenotypic (0.52-0.83) and genetic (0.70-0.92) correlations with MOE, MOR, and CS. The mechanical properties of the inner position of the stem had rather high phenotypic and genetic correlations with those of the outer position and overall mean. The predicted gains in wood stiffness (E log and MOE) were higher than those of the strength properties (MOR and CS). The predicted correlated responses in MOE, MOR, and CS when selecting for E log and DEN were 72.6%-97.8% of a gain achievable from direct selection of these traits. DBH showed an insignificant correlation with all mechanical properties, although selection of this trait had a slightly negative effect on the mechanical properties.

Early genetic evaluation of morphology and some wood properties of Tectona grandis L. clones

“…These results confirmed the low heritability of wood properties in juvenile KUMAR (2004) and KUMAR et al (2002) mention that the study of this variable should be continued and it should be very careful because most genetic programs are based on the selection of individuals for fast production and this has a negative impact on the mechanical properties of the tree (FUJIMOTO et al, 2006). Among wood properties, only ED lumber and ED dried exhibited a significantly positive genetic correlation.…”

“…While in the present study with teak, comparison of the relationships of young and adult wood have not been done, other studies have made this comparison (FUJIMOTO et al, 2006) and they have concluded that it is possible to make an effective selection of clones at early ages without altering the quality of adult trees.…”

“…Nonetheless, this low heritability found in our study or those obtained by CALLISTER and COLLINS (2008) in 4-year-old T. grandis should be taken with great caution. According to FUJIMOTO et al (2006), genetic control increases with age. Other studies with teak trees more than 10 years of age confirm this statement (HARSHAP and SOERIANEGARA, 1977;MOYA and MARÍN, 2011;RAO and SHASHIKALA, 2003).…”

Genetic relationship between wood properties and growth traits in Larix kaempferi obtained from a diallel mating test

“…In hybrid larch (L. gmelinii var. japonica 9 L. kaempferi), Fujimoto et al [16] reported a strong genetic correlation between average The abbreviations for traits are the same as in Table 1 wood density at breast height and green log MOE measured by a vibration method (r g = 0.79), and between average wood density and lumber MOE obtained by a bending test (r g = 0.87). The genetic relationship between wood density and SWV in our research was similar to what was found in these previous reports related to L. kaempferi.…”

“…Fukatsu et al [15] reported a positive genetic correlation between wood density and basal area. In hybrid larch, a strong negative genetic correlation between wood density and radial growth rate, and a weak negative genetic correlation between MOE and DBH were reported in Larix gmelinii 9 L. kaempferi hybrids [16,17], and a strong negative genetic correlation between DBH and MOE was reported in Larix decidua 9 L. kaempferi hybrids [18]. To predict how the selection of a trait will affect correlated traits in the following generations of L. kaempferi, more research is necessary.…”