Effects of Planting Date and Latitude-of-
Adaptation on Seeding-Year
Development, Winter Survival, and Subsequent Seed and Forage Production
Potential of Grasses and Legumes in Subarctic Alaska
Leslie J. Klebesadel, Emeritus Professor of Agronomy
Agricultural and Forestry Experiment Station; Palmer, Alaska
Bulletin 86; February 1992 (11 pages)
Summary
Three to four cultivars from diverse latitudinal origins within each of five species were planted in rows on seven dates from late May to late July in three separate, similar experiments during three different years. Species included were timothy (Phleum pratense L.), Kentucky bluegrass (Poa pratensis L.), red fescue (Festuca rubra L.), red clover (Trifolium pratense L.), and alfalfa (Medicago sativa L.). After emergence, rows were thinned to individual plants. Observations and data are reported for (a) seeding-year development, (b) subsequent winter survival, and (c) seed and forage production potential of surviving plants during the second year of growth.
* Seeding-year plants of Kentucky bluegrass and red fescue developed into leafy tufts that produced no elongated culms or seed heads.
*With all planting dates that resulted in production of seed heads during the seeding year by timothy cultivars, fewer heads were produced by the northernmost-adapted cultivar Engmo than by the more southern-adapted Climax and Clair.
*With early planting dates, northern-adapted ecotypes of red clover and alfalfa generally produced seedlings with fewer flowers and fewer elongated stems by freeze-up than did the more southern-adapted ecotypes within each species.
* Early-planted northern-adapted seedlings of timothy, Kentucky bluegrass, and red fescue survived winters better, and produced more seed heads and herbage per plant the following year than the more southern-adapted ecotypes within each species.
* Differences in winter survival between the northernmost-adapted cultivar and those from more southern origins were greater within timothy than within Kentucky bluegrass or red fescue.
*The more southern-adapted ecotypes of Kentucky bluegrass and red fescue survived winters better than similar-origin timothy and alfalfa.
*Subarctic-adapted alfalfa planted in early July tended to survive winters better than when planted earlier or later.
*All red clover cultivars winterkilled regardless of origin or planting date. Even the northernmost-adapted red clovers succumbed to total winterkill under the conditions of these experiments.
*The extreme exposure of all seedlings to winter stresses in these experiments (seedlings clipped short in autumn retained no protective, insulating snow cover against the evacuation force of winter winds) demonstrates the generally poorer winter survival in this area of even the hardiest strains of the two legume species compared with the northern-adapted grasses.
*These results confirm the desirability of utilizing only northern-adapted cultivars of these species for best winter survival and for maximum seed or forage production in southcentral Alaska.
*These findings also confirm the general desirability of early planting for maximum seedling development, and for best winter survival and second-year productivity of both seed and forage.