Estimation of genetic parameters, provenance performances, and genotype by environment interactions for growth and stiffness in lodgepole pine (Pinus contorta)
Hayatgheibi H, Fries A, Kroon J, Wu HX

Genetic parameters, performance of provenances, and genotype by environment interaction (GxE) for diameter at breast height (DBH), survival, and modulus of elasticity of time-of-flight (MOEtof) (an indirect measure of stiffness), were investigated in six lodgepole pine progeny trials, aged 33-36 years, within three breeding zones in northern Sweden. Provenances of Yukon origin had the highest growth but lowest stiffness at higher latitude, while those of British Columbia (BC) origin grew faster at lower latitudes and had highest stiffness within zone 5.Combined-site heritability estimates ranged from 0.09 to 0.19 for DBH, from 0.19 to 0.27 for MOEtof, and from 0.13 to 0.26 for survival. Type-B genetic correlations () were generally high for all studied traits, except for DBH and survival in zone 4 (=0.74 and 0.40, respectively) and for MOEtof in zone 2 (=0.46). On the basis of the results obtained in this study, GxE for stiffness in northern Sweden and unfavourable growth-stiffness genetic correlation should be considered in selective breeding programmes of lodgepole pine. To achieve the highest stiffness for lodgepole pine, provenances of Yukon origin should be planted at lower latitudes and those of BC origin should be planted at lower elevations within the tested breeding zones.

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