In order to comply for entry to a National List a variety must be distinct, uniform and stable (DUS), and be of value for cultivation and use (VCU). The DUS requirement is also necessary to establish eligibility for Plant Variety Rights. In the UK there are both statutory and advisory VCU systems. The statutory National List Trials are largely used to eliminate inferior varieties, and the advisory Recommended List Trials aim to select the superior varieties.

NATIONAL LIST

National List testing is conducted on an interdepartmental basis by the agricultural departments for England and Wales, Scotland and Northern Ireland. The Scottish Department coordinates the work, collates the results and prepares the reports. The National Institute of Agricultural Botany acts as agent for the Ministry in England and Wales. A National List DUS/VCU Group makes recommendations on the distinctness and merits of new potato varieties to the UK National List Committee.

Both DUS and VCU tests take place over 2 years. Distinctness tests are based on morphological characters, which closely follow the guidelines of the International Union for the Protection of New Varieties of Plants (UPOV). Uniformity and stability rarely present problems in potatoes.

VCU tests include yield trials and tests for disease resistance and quality. Yield trials consist of two replicates of 100 plants at three centres – Cambridge, Edinburgh and Belfast. Seed is provided by breeders.