Latitude

Latitude Native grass species in northern regions cease growth early in autumn and start preparation for the winter climate. Non-native grasses, however, do not cease growth early enough for successful acclimation to the cold, which increases the risk of winter killing. Perennial ryegrass and festulolium hybrids are examples of species that have been moving from south to north during recent decades. Their adaptation to the Nordic climate has been increased by breeding work even though they are still behind the native species in winter survival. Østrem et al. (2014) found, in a study of perennial ryegrass, Festulolium hybrids and meadow fescue, that increased photosynthetic activity in autumn had a positive effect on winter survival at Fureneset (61°N) whereas at Vågønes (67°N) increase in photosynthetic activity in autumn had no or a negative effect on winter survival. This difference in response was mainly due to low light conditions in the north, which require an alternative mechanism for triggering growth cessation. Low photosynthetic activity in autumn was associated with better spring cover in meadow fescue var. Norild and two northern adapted varieties of perennial ryegrass. Increased temperature in late summer/early autumn has shown a decrease in frost tolerance in timothy and perennial ryegrass (Dalmannsdottir et al., 2013). These findings show that a temperature x photoperiod interaction has to be taken into account in future plant breeding. However, the results from Iceland show that we can to some extent use species that are aimed for more southern areas like our experience with meadow fescue, cocksfoot and perennial ryegrass show. In warm periods they have given good results.

Fig. 16. Grass species at Korpa 2009 (GÞ).