Potential for improving adaptation ofLolium perenne L. to continental climates in Norway

Summary Breeding of perennial ryegrass has been conducted in Norway for more than 30 years. The little progress achieved so far can, most probably, be explained by a restricted genetic variation within our indigeneous plant material. In order to increase the variation in the Norwegian ryegrass germplasm, we have tested populations of diverse origin and adaptations under contrasting climatic conditions in Norway. Data is presented for winter survival and dry matter yield obtained in two experiments, one in a dense stand with 20 populations of Norwegian and Russian origin, and one as a spaced plant experiment with 26 populations of Norwegian, Russian and Swiss origin. In both cases commercial foreign cultivars and breeding populations were included.The results show that the commercial varieties were superior when grown in dense stand. The Norwegian material showed, however, a significant better adaptation at the continental location, measured as plant cover after three years. There was considerable variation between populations in all characters. In the spaced plant experiment, the Norwegian diploid breeding populations were the highest yielding. The commercial cultivars also performed well. Winter survival was generally good in this experiment, and only small differences between populations could be detected. Winterhardy and productive populations of different origin and contrasting adaptations have been selected, and breeding populations constructed. Surprisingly enough, Swiss Alp populations, presumably adapted to long lasting snow-cover, do not show any better adaptation to the continental climates in Norway than indigeneous ryegrass populations.