Comparative assessment of genetic variation of young high-elevation lodgepole pine for height and western gall rust resistance across two sites in Alberta

Abstract

A total of 456 half-sib families of superior lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) trees found mostly in high-elevation natural stands in west-central Alberta were outplanted in 1990 at two geoclimatically different sites, Norris and Redrock, Alberta. The trials were measured at age 6 for survival, height, and incidence and severity of western gall rust (WGR) (Endocronartium harknessii (J.P. Moore) Y. Hiratsuka). Survival at both sites was very similar (85-87%). Mean family height at Redrock was almost 10 cm higher (60.5 cm) than that at Norris (51.0 cm). Mean family WGR incidence was 25% with a range of 0-76% at Norris, but only 1.6% with a range of 0-27% at Redrock. A similar site difference was also observed for WGR severity. Strong site x family interactions were detected for height growth and WGR infection. The interaction for WGR infection did not seem to involve a change in family ranks because there was very little contribution to the interaction variance from lack of perfect genetic correlation between the two sites. The contrasting patterns of family variation in WGR infection across the two sites may be the outcome of epidemiological (environmental) or genetic causes or both.