'Plant Breeding: Sustaining the Future' Abstracts of the XVIth EUCARPIA Congress, Edinburgh, Scotland, 10-14 September 2001 IMPROVEMENT OF PERENNIAL RYEGRASS IN NITROGEN RECOVERY AND WATER SOLUBLE CARBOHYDRATE CONTENT P.W. WILKINS, D.K. ALLEN, LR MYTTON, S. LISTER Institute of Grassland and Environmental Research, Aberystwyth, SY23 3EB, Wales

Grassland farmers need to reduce the costs of animal production while at the same time reducing nitrogen (N) surpluses on their farms. Increasing the water soluble carbohydrate (WSC) content of herbage reduces the amount of N excreted by ruminants and also tends to increase their production. Two recently recommended varieties (AberDart and AverAvon) were compared with two old varieties (S321 and S23) at five levels of applied N under monthly cutting to simulate rotational grazing. Mean annual dry matter yield, annual yield of N and monthly recovery of ¹⁵N in the herbage were all 10-14% higher in the new varieties than the old ones in the second harvest year. The mean WSC content over all harvests of the new varieties was 22-24% higher than that of S23.