New generation white clovers for United Kingdom farming systems

White clover is used worldwide to improve the nutritive value of pastures and is an increasingly important component of environmentally-sustainable grassland ecosystems. In 1991, a white clover breeding program involving two New Zealand companies (AgResearch and Midlands Seed) and a European company (Barenbrug), was initiated to develop new varieties for agricultural systems in the United Kingdom. This collaborative international program has been very successful with three improved varieties, Crusader, Barblanca and Makuri, being released and listed in the United Kingdom. The improved persistence and productivity of these varieties has enabled them to secure a significant share of the UK proprietary seed market. In particular, the medium-leaved Crusader produces at least 30% more DM than any other small or medium-leaved white clovers in UK Recommended List trials. Changes in agricultural subsidies within the EU Common Agricultural Policy and the growing pressure to use environmentally sustainable agricultural practices should increase demand for new generation white clover varieties that can maximise both pasture production and animal productivity. Introduction White clover is used worldwide to improve the grazing value of pastures in temperate animal production regions and to provide low-cost nitrogen from nitrogen fixation. It is also increasingly seen as an important component of environmentally-sustainable grassland ecosystems because of its persistence under grazing, its ability to improve soil structure and its potential to reduce methane emissions. Traditionally the UK is the second largest market for white clover seed in Europe. New Zealand-bred white clovers have been extensively used in the UK with the public variety Grasslands Huia having dominated the world white clover seed market for 40 years due to low seed price. In 1991, a white clover breeding program involving two New Zealand companies (AgResearch and Midlands Seed) and a European company (Barenbrug), was initiated to develop new varieties that were better adapted to UK agricultural systems. This brought together the extensive agronomic testing network of Barenbrug, the breeding expertise and genetic resources of AgResearch and the seed production capability of Midlands Seed. This paper summarises the agronomic performance of white clover varieties and breeding lines that have been bred for the UK, and includes results from independent National List trials throughout the UK. National list testing An initial gene pool of 100 breeding lines that had been developed through intensive selection under grazing in New Zealand was evaluated at Wolfheze in the Netherlands and at Mas Grenier in Southern France beginning in 1991. Several experimental lines were identified and increased for wider agronomic testing including trials at Loughgall, Northern Ireland. The best lines were subsequently entered into United Kingdom National List trials, where they are evaluated under cutting as pure swards at 3 locations