Exploiting genetic resources in breeding clover for sustainable grassland systems

Grassland agriculture across Europe is facing a number of significant challenges. The move towards more sustainable systems of agriculture requires the grassland sector to consider how to reduce the environmental consequences of livestock production, redress the loss of biodiversity in many grassland systems and at the same time maintain a sustainable level of profitability for the farmer. Traits that encourage biodiversity through improved compatibility with other legumes, grasses and herbs, more efficient use of P and beneficial mycorrhizal associations are increasingly important. Genetic resources will play an important role as a source of novel traits and genetic variation for future white and red clover breeding programmes, building on past success from introduced germplasm. There has been a resurgence in the use of red clover in the UK, particularly in the organic sector, as a source of safe, home-produced protein and plant breeders seek to improve its persistence, tolerance of grazing and pests and disease resistance. Where variation is not available within the gene pool interspecific hybridisation is being used to introgress novel traits into white clover from closely related species. Some success has already been achieved in introgressing reproductive traits from Trifolium nigrescens and the rhizomatous trait from T. ambiguum. Enhanced drought tolerance and forage quality characteristics more appropriate for the ruminant diet are now major breeding objectives.