Relationship of Latitude-of-Origin to Winter Survival and to Forage and Seed Yields of Wheatgrasses (Agropyron species) in Subarctic Alaska
Leslie J. Klebesadel, Emeritus Professor of Agronomy
Agricultural and Forestry Experiment Station; Palmer, Alaska
and
D.J. Helm, Research Assistant Professor
Agricultural and Forestry Experiment Station; Palmer, Alaska
Bulletin 88; July 1992 (22 pages)
Summary
Five field experiments evaluating and comparing numerous grasses were conducted over seven years at the Matanuska Research Farm (61.6°N) near Palmer in southcentral Alaska. Grasses were 34 strains within 14 species of wheatgrass (Agropyron) derived from various geographic areas spanning 32 degrees of latitude; also included were the intergeneric hybrid Agroelymus palmerensis Lepage, Siberian wildrye (Elymus sibiricus L.), two bromegrass (Bromus) cultivars, and one timothy (Phleum pratense L.) cultivar. They were grown in broadcast-seeded plots for forage (two cuts per year), in drilled rows for seed production, and as individual plants in rows for winter-survival determinations.
*Strains within the following species were the least winter-hardy, and therefore were least productive of forage and seed: thickspike wheatgrass (A. dasystachyum [Hook.] Scribn.), tall wheatgrass (A. elongatum [Host] Beauv.), beardless wheatgrass (A. inerme [Scribn. and Smith]), and pubescent wheatgrass (A. trichophorum [Link] Richt.). All 10 strains tested among those species originated from below 47°N.
*A considerable range of winter hardiness was found among strains within the following species: crested wheatgrass (A. desertorum [Fisch.] Schult.), bluebunch wheatgrass (A. spicatum [Pursh] Scribn. and Smith), pubescent wheatgrass (A. trichophorum [Link] Richt.) and, to a lesser extent, slender wheatgrass (A. trachycaulum [Link] Malte); this was more apparent with individual plants than in broadcast-seeded plots.
*Canadian cultivars from 51° to 53°N were more winter-hardy and generally more productive of forage than strains from the western states (below 49°N) in fairway wheatgrass (A. cristatum [L.] Gaertn.), intermediate wheatgrass (A. intermedium [Host] Beauv.), crested, and slender wheatgrass.
*Sodar streambank wheatgrass (A. riparium Scribn. and Smith) was unusual in being the only wheatgrass strain tested from below 49°N that was winter-hardy and produced forage yields equivalent to native Alaskan wheatgrasses.
* Sodar streambank wheatgrass, and native Alaskan strains of A. sericeum Hitchc., A. trachycaulum, A. violaceum (Hornem.) Lange, and Siberian wildrye were extremely winter-hardy and produced forage yields approximately equivalent to the two bromegrass cultivars, Polar and Manchar, and surpassed Engmo, one of the most winter-hardy timothy cultivars for this area.
*The hybrid Agroelymus palmerensis was slightly less winter-hardy than the native Alaskan wheatgrasses but produced high forage yields.
*Highest seed producers, when moisture was adequate, were four native Alaskan species: slender, arctic, and violet wheatgrasses and Siberian wildrye.
*High seed producers less sensitive to moisture stress than native Alaska grasses were S-7171 crested wheatgrass, selected near 52°N, and the slender wheatgrass strains Alaska-44S, naturalized at 61.6°N, and Revenue, selected at 52°N in Saskatchewan.
*These results demonstrate that latitude-of-origin, and therefore adaptation to climatic influences related to global latitude, governs considerably the performance of wheatgrasses in this northern area. Species that occupy a natural range that does not reach northern latitudes generally perform poorly here. With species that occupy a natural range with an extensive north-to-south dimension, strains from the northernmost areas of the total range possess best adaptation to Alaskan conditions and therefore exhibit superior performance here.
*For several species brought to Alaska from elsewhere and included in these experiments, the strains evaluated may not represent the best-adapted germplasm available within each species for use in Alaska. Building on knowledge gained in this study, future evaluations should seek the northernmost-adapted strains or ecotypes available within each species.
*For superior performance in Alaska, grasses should be brought directly to this area from other high-latitude origins, thereby circumventing the loss of north-latitude adaptational characteristics that would be lost or discarded in selection programs at more southern latitudes.