Winter tolerance

Winter tolerance Ice cover was not observed in these experiments except during the last winter at Möðruvellir. All the varieties in the experiments presented here were also tested in 17 experiments which were located in farmers‘ grass fields in Iceland (Þorvaldsson et al., 2014). Those experiments were harvested by the farmers at the same time as the grass fields and if the grass fields were grazed, the experiments were grazed as well. The yield was not observed but survival of the varieties observed every spring. Some of these experiments in Iceland were covered with ice for more than two months, whereas others had no ice or ice for a short period only. It is interesting to compare the survival of the varieties in these two groups. In the group with a long period of ice cover the varieties can be divided into three groups according to their survival. The first group consisted of timothy, common bent grass and smooth meadow grass with about 30% cover. The second group consisted of meadow fescue and cocksfoot with 10-13% cover. The third group consisted of perennial ryegrass and tall fescue with less than 2% cover. The clover was not comparable to the grasses because it was seeded in a mixture with grass but the clover seemed to give similar results as meadow fescue and cocksfoot. White clover seemed to tolerate ice cover better than red clover. At sites with no or limited ice cover the species lined up differently. Cocksfoot had better cover than timothy, and meadow fescue only slightly lower cover than timothy. The cover of perennial ryegrass and tall fescue was not good but better than in the group with a long period of ice cover. These results agree with results from Gudleifsson et al. (1986) and Gudleifsson (2010) where ice tolerance of meadow plants was tested both on fields in situ and in artificially controlled ice experiments. In those tests Bering hairgrass (Deschampsia beringensis), tufted hairgrass (D. caespitosa), timothy and smooth meadow grass were most tolerant of ice. In the second group were creeping foxtail, reed canarygrass, red fescue and meadow foxtail. Meadow fescue, cocksfoot and perennial ryegrass constituted the third group. The rank changed when cold hardiness was tested. Timothy, smooth meadow grass and red fescue were among the best, followed by meadow foxtail, meadow fescue, creeping foxtail, tufted hairgrass and Berings hairgrass. Cocksfoot was a little behind and reed canary grass last.

Fig. 15. The experiment at Möðruvellir (ÞS).