Distinctness, Uniformity and Stability (DUS) Testing

DUS testing is a way of determining whether a newly bred variety differs from existing varieties within the same species (the Distinctness part), whether the characteristics used to establish Distinctness are expressed uniformly (the Uniformity part) and that these characteristics do not change over subsequent generations (the Stability part).  DUS tests exist so that new varieties can legally gain access to their market via the UK National List and/or for the granting of Plant Breeders Rights, a form of intellectual property rights designed to safeguard the substantial economic investment involved in modern plant breeding.

A DUS test is usually conducted in the field or glasshouse over two successive growing seasons.  During this period a number of mainly morphological characteristics are recorded both on the new (or candidate) variety and on similar varieties in what is known as “Common Knowledge”.  Differences, if they exist, are established by observation and measurement using internationally agreed protocols.  SASA Variety Testing staff are closely involved in the design of these protocols by regularly meeting with colleagues from other countries within the International Union for the Protection of New Varieties of Plants (UPOV) based in Geneva and the Community Plant Variety Office, a European Union Agency based in Angers, France.

SASA is the UK DUS testing centre for vegetable species and offers DUS tests in the following:

Beetroot (including Leaf Beet & Chard)

Broccoli (including sprouting types)

Brussels Sprout



Vegetable Kales


Onion & Shallot




Radish (including Oriental types)

Runner Bean



Turnip Rape

See the related links box for more information about DUS