COMPARATIVE-ASSESSMENT OF GENETIC-VARIATION OF YOUNG HIGH-ELEVATION LODGEPOLE PINE FOR HEIGHT AND WESTERN GALL RUST RESISTANCE ACROSS 2 SITES IN ALBERTA

A total of 456 half-sib families of superior lodgepole pine (Pinus con torta Dougl, ex Loud. var, latifolia Engelm.) trees found mostly in hi gh-elevation natural stands in west-central Alberta were outplanted in 1990 at two geoclimatically different sites, Norris and Redrock, Albe rta. The trials were measured at age 6 for survival, height, and incid ence and severity of western gall rust (WGR) (Endocronartium harknessi i (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% w ith 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 an d WGR infection. The interaction for WGR infection did not seem to inv olve a change in family ranks because there was very little contributi on to the interaction variance from lack of perfect genetic correlatio n between the two sites. The contrasting patterns of family variation in WGR infection across the two sites may be the outcome of epidemiolo gical (environmental) or genetic causes or both.