As part of the application process to add an agricultural crop to the National List, the plant must be tested to confirm whether the variety has satisfactory value for cultivation or use (VCU).
The growing trials for all crops, except potatoes, are organised by the British Society of Plant Breeders (BSPB). The trials for potatoes are organised by Science and Advice for Scottish Agriculture (SASA).
These trials are normally carried out for a minimum of 2 years, comparing the performance of candidate varieties with varieties already on the National Lists.
The trials use the VCU protocols and procedures approved by the Plant Variety and Seeds Committee, which represents the national authorities on seed issues to establish VCU.