aussi une tol6rance envers les autres sels qu'on retrouve couramment dans les sols de l'Alberta. Chez l'agropyre 6lanc6 I'aptitude ir la levde dans une solution nutritive saline r6v6lait une h6ritabilit6 moyenne (61-68%) ce que ouvre la porte aux possibilit6s d'am6lioration g6n6tique par la s6lection.

Pearen, J. R., Pahl, M. D., Wolynetz, M. S. and Hermesh, R. 1997. Association of salt tolerance at seedling emergence with adult plant performance in slender wheatgrass. Can. J. Plant Sci. 77: 81-89. Regrowth of 15 slender wheatgrass (SWG, Elymus trachycalus sp. trachycalus (= Agropyron trachycaulum Link Malte) lines was evaluated after 3 (harvest-one) and 11 wk (harvesttwo) after clipping at four salinity levels. Lines were previously categorized into salt-tolerant (TOL) and non salt-tolerant (NT) accessions based on percent emergence at 15 mS cm -1 relative to a salt-tolerant control, tall wheatgrass (TWG, Agropyron elongatum (Host) Beauv. [= Thinopyron ponticum (Podpera) Lu & Wong]. Regrowth of five TOL, five NT, five untested (UT) SWG lines and TWG were compared in a greenhouse with nutrient solutions salinized to EC e values of 2, 7, 15, and 23 mS cm -1 . Regrowth of all SWG lines decreased from 68 to 98% as salinity increased. Orbit tall wheatgrass shoots were about threefold larger than SWG shoots at 15 and 23 mS cm -1 . Phenological development of NT lines was slower (P ≤ 0.05) than that of TOL and UT lines at all EC e levels. However, shoot growth of NT lines exceeded (P ≤ 0.05) that of TOL lines at 23 mS cm -1 . Regrowth after 3 and 11 wk were correlated within EC e levels, (r = 0.22 to r = 0.34, P ≤ 0.01). Lack of a positive relationship between lines selected for emergence in saline media and their subsequent growth under saline conditions indicates that improvements in adult plant growth under saline conditions will require additional selection for appropriate traits in SWG. A tous les niveaux de EC e , le développement phénologique des lignées non tolérantes était plus lent (≤ 0,05) que celui des lignées non tolérantes ou non testées. Toutefois, la croissance des pousses des lignées non tolérantes dépas-sait (≤ 0,05) celle des lignées tol à 23 mS cm -1 . Pour chaque niveau de salinité (EC e ), on relevait une corrélation entre la repousse à trois et celle à 11 semaines après la précoupe (r = 0,22 à r = 0,34, P ≤ 0,01). L'absence de rapport net entre les lignées sélec-tionnées sur le pourcentage de levée en milieu salin et leur croissance subséquente en conditions salines laisse à penser que l'amélioration de la croissance au stade adulte dans ces conditions demandera une sélection plus ciblée sur les composantes significatives de la croissance chez l'élyme élancé.

AcHARy,\, S.N., Csu, C.B. ANDHERMESH, R. 1989

No abstract

Seeds from 55 populations of native Alberta red-osier dogwood (Cornus stolonifera Michx.) were collected over 2 years (1984 and 1985) to determine the range of variability for seed germination and the effect of ecoregion and moisture conditions in the collection sites on this trait. Each year the unscarified seeds were stored at 3 °C for 30 days, stratified at 3 °C for an additional 30 days and then incubated on an 8 h light: 16 h dark cycle at a temperature of 25:10 °C (light:dark) for germination. A wide range of germination percentages was observed among populations collected in any 1 year. However, the variability was not due to the ecoregion or moisture condition of the collection site. Germination percentage of populations collected in 1984 and 1985 formed five and seven groups, respectively. A study involving eight sites that were common to 1984, 1985, and 1986 revealed a significant effect of population on seed germination. This population effect was not obscured by the combined effects of year, precipitation, temperature, and seed size. The year effect was significant only when population was used as a covariate. Precipitation during seed formation significantly influenced germination performance even after adjustments were made for population and year. Seed germination in red-osier dogwood appears to be influenced by the population from which the seeds are collected and by yearly environmental fluctuations. Therefore, germination studies in this species must include seeds from diverse populations collected over several years. Key words: red-osier dogwood, Cornus stolonifera Michx., germination, population, environment.