MORPHOLOGICAL VARIATION IN DUTCH PERENNIAL RYEGRASS (LOLIUM-PERENNE L) POPULATIONS, IN RELATION TO ENVIRONMENTAL-FACTORS

Twenty-one Dutch Lolium perenne populations, fifteen European populations and six L. perenne cultivars were compared for morphological variation. Dutch populations clearly differed from the European populations and the cultivars. Dutch populations generally had reduced plant length and smaller leaves. For other characters, e.g. date of ear emergence, the Dutch populations showed as much variation as the European populations and cultivars they were compared with in this trial. Correlations between morphology and environmental factors at the site of origin were significant in several cases but were generally weak, and dependent on the set of populations studied. In order to maximize the phenotypic differences between the collected populations, soil type and management type appeared to be the most important factors for the choice of collection sites in the Netherlands. To determine suitable collection sites all over Europe, other factors like precipitation, latitude, altitude and temperature factors were also important. For subsampling of the locations, variation in management type within the location determined whether or not phenotypic different samples could be collected. The extensive use of cultivars in the Netherlands does not seem to have prevented the formation of distinct populations. Therefore in situ conservation of grassland seems a good alternative for genetic conservation of L. perenne in the Netherlands.