Seasonal distribution of dry-matter production in grass varieties from different latitudes in northern Europe

Abstract

Work in controlled conditions (Cooper, 1964; østgård & Eagles, 1971) has indicated that, under short photoperiods and low temperatures, Scandinavian grass varieties tend to grow more slowly than those from lower latitudes, and are, therefore, more resistant to cold and freezing stresses. This has been confirmed in field experiments (Håbjørg, 1979). These grasses would therefore be expected to cease growth earlier in the autumn when grown in the British Isles. However, this mechanism does not appear to operate under lengthening days; indeed, there is evidence to suggest that their growth is particularly stimulated by the combination of cool temperatures and long days (Cooper, 1964; Hay & Heide, 1983, 1984). This raises the possibility that varieties from Norway and Sweden could produce more dry matter than grasses of more southern provenance in the spring in upland areas, when low temperatures are associated with rapidly lengthening photoperiod (12·5–15 h) and moderate to high levels of irradiance (> 200 W/m2) (Hay, 1985).