Influence of Planting Date and Latitudinal Provenance on Winter Survival, Heading, and Seed Production of Bromegrass and Timothy in the Subarctic1
- L. J. Klebesadel2
Latitudinal ecotypes of bromegrass (Bromus sp.) and timothy (Phleum pratense L.), planted in rows at approximately 10-day intervals from 20 May to mid-September during two years in south-central Alaska (61.5°N), were compared over the 12 planting dates for winter survival, heading, seed yield, and aftermath forage the following year.
‘Climax’ from Canada, and commercial and ‘Clair’ timothy from the conterminous USA, displayed poor winter survival, produced very few heads and negligible seed yields. ‘Achenbach,’ a variety of “southern-type” smooth bromegrass (B. inermis Leyss.), sustained considerable winter injury in both tests, produced very low seed yields one year and none in the other. ‘Engmo’ timothy from northern Norway, two Alaskan bromegrasses—native B. pumpellianus Scribn. and ‘Polar’ (predominantly B. inermis ✕ B. pumpellianus)—and ‘Manchar’, a “northern-type” smooth bromegrass from the Pacific Northwest, displayed excellent winter survival when seeded earlier than mid-July to mid-August.
B. pumpellianus and Polar bromegrass produced highest seed yields of all grasses compared. The native bromegrass produced higher seed yields than Polar with planting dates prior to mid-June; with later planting they were about equal. Both produced most heads and highest seed yields with May planting the previous year, declined precipitously in both yield characters with planting dates between May and early August, and produced no heads with later planting. Manchar bromegrass headed much less than B. pumpellianus or Polar, producing mostly sterile culms. Different planting dates prior to early July had little effect on Engmo timothy heading and seed yields the following year, but later planting until September resulted in progressively less heading and lower seed yields.
Percent crude protein in aftermath forage was inversely related to forage yield and seed production.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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