Bromegrass in Alaska. I. Winter Survival and Forage Productivity of Bromus Species, Types, and Cultivars as Related to Latitudinal Adaptation
Leslie J. Klebesadel, Emeritus Professor of Agronomy
Agricultural and Forestry Experiment Station; Palmer, Alaska
and
D.J. Helm, Research Assistant Professor of Vegetation Ecology
Agricultural and Forestry Experiment Station; Palmer, Alaska
Bulletin 87; May 1992 (14 pages)
Summary
This report summarizes seven separate field experiments, conducted over more than two decades at the University of Alaska's Matanuska Research Farm, that compared strains within three bromegrass (Bromus) species for winter hardiness and forage production. Species were (a) smooth bromegrass (B. inermis Leyss.), (b) native Alaskan pumpelly bromegrass (B. pumpellianus Scribn.), and (c) meadow bromegrass (B. biebersteinii Roem. and Schult.), a species native to southwestern Asia.
*Regar, the only cultivar of meadow bromegrass evaluated, was not winter-hardy and performed poorly in this area, far north of latitudes to which this species is adapted.
*All cultivars of southern-type smooth bromegrass evaluated in these experiments were inadequately winter-hardy for dependable use in this area; those cultivars included Achenbach, Elsberry, Fischer, Lancaster, Lincoln, Lyon, and Sac.
*Saratoga and Redpatch, relatively northern-adapted cultivars of southern-type smooth bromegrass, were intermediately winter-hardy between northern-type cultivars and southern-selected, southern-type cultivars.
*The generally excellent winter hardiness of the Alaska hybrid cultivar Polar (predominantly B. inermis x B. pumpellianus) in all experiments where it was included, confirms that it is the most winter-hardy, dependable, and productive of all cultivars evaluated.
* Following mild to moderately stressful winters, introduced cultivars of northern-type smooth bromegrass produced forage yields equivalent to those of the Alaska cultivar Polar and native Alaskan pumpelly bromegrass. More severe winters injured introduced
northern-type cultivars and reduced their forage yields. The introduced northern-type strains evaluated were Canadian "commercial" and the cultivars Carlton, Frigga, Magna, Manchar, Mandan 404, and Martin.
* Native Alaskan pumpelly bromegrass was extremely winter-hardy and persisted well for the full term of all tests where it was included, producing high yields of forage. Its first-cutting yields averaged 104% of those of Polar, but second-cutting yields were only 63% of those of Polar. Total forage dry-matter yields of pumpelly brome were about 90% of those of Polar when averaged over 20 two-cut harvest years in four experiments.
*Good forage yields of the relatively unselected native Alaskan pumpelly bromegrass used in these experiments suggest potential for direct utilization of this subarctic-adapted, very winter-hardy grass for forage. It also could be used in additional controlled hybridization with the introduced smooth bromegrass to produce superior, adapted, interspecific hybrids for forage production or soil stabilization purposes in northern environments with extreme winter stresses.
*The marginaltopoor winter survival of bromegrass cultivars grown far north of their latitude of adaptation is believed due to inadequate cold-hardiness development when their growth in Alaska subjects them to an unaccustomed environmental stimulus pattern during late-summer/autumn at this latitude. Such introduced cultivars experience an inadequate term of appropriately short photoperiods/long nyctoperiods (conducive to cold-hardiness development) prior to onset of winter stresses.
*The relative proportions of total-season forage yield harvested in first vs. second cutting can be influenced by (a) date of first cutting, (b) extent of winter injury that may curtail first-cut yields, (c) adequacy of soil mois