ABSTRACT
Perennial ryegrass (Lolium perenne L.) is the most widely sown perennial forage grass in temperate regions of the world. It is of interest as it is fastgrowing, has high nutritional value and has good persistency under grazing. Swards containing improved perennial ryegrass varieties can produce dry matter (DM) yield approaching 15 t/ha over a grazing season with an average grass production of 60 kg/ha/day (Humphreys 2005). Perennial ryegrass also has important amenity value and provides many landscape benefi ts with functional (erosion control, reduction of glare, noise, heat build-up and air pollutions; stabilizing dust and soil), recreational (sport and leisure) and aesthetic impacts. To overcome the negative effect from climate changes, plants must become more resistant to many kinds of biotic and abiotic stresses such as a variety of diseases and insects, drought, and high, low or fl uctuating temperatures. Other possible environmental targets include soil C-sequestration and biodiversity, bioremediation and fl ood mitigation.
