POTENTIAL FOR IMPROVING ADAPTATION OF LOLIUM-PERENNE L TO CONTINENTALCLIMATES IN NORWAY

Breeding of perennial ryegrass has been conducted in Norway for more t han 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 ry egrass germplasm, we have tested populations of diverse origin and ada ptations under contrasting climatic conditions in Norway. Data is pres ented for winter survival and dry matter yield obtained in two experim ents, one in a dense stand with 20 populations of Norwegian and Russia n 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 tha t the commercial varieties were superior when grown in dense stand. Th e 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 characte rs. In the spaced plant experiment, the Norwegian diploid breeding pop ulations were the highest yielding. The commercial cultivars also perf ormed well. Winter survival was generally good in this experiment, and only small differences between populations could be detected. Winterh ardy and productive populations of different origin and contrasting ad aptations have been selected, and breeding populations constructed. Su rprisingly enough, Swiss Alp populations, presumably adapted to long l asting snow-cover, do not show any better adaptation to the continenta l climates in Norway than indigeneous ryegrass populations.