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Distinctness, Uniformity and Stability, DUS Requirements

	D - Distinctness
	U - Uniformity
	S - Stability
	Additional distinctiveness

(a) Distinctness

The basis of Distinctness is an objective comparison of the variety with the most similar variety(ies) of common knowledge. Quantitative and qualitative differences between the new and existing varieties must be established and recorded.

Morphological characteristics, especially those least affected by environmental factors are preferred. However, tests such as comparative DNA or protein profiles are acceptable as supporting evidence. Clear repeatable varietal differences must be demonstrated.

Performance attributes can also be included as distinguishing characteristics provided they are clear and consistent.

(b) Uniformity

Unless the UPOV technical guideline on the species recommends otherwise, the required standard of uniformity for each type of propagation is as set out below.

For characteristics that are assessed visually (that is, not by measured characteristics), uniformity is usually assessed using the off-type method (a plant is an off-type when it does not conform to the distinctive characteristics of the variety under consideration).

1. In vegetatively propagated or fully self-pollinated varieties, the number of off-types must not exceed the numbers given in the table. Using the tomato example above, if the comparative growing trial contained between six and 35 plants of the new variety and more than one plant did not conform to the distinctive characteristics, the variety would be considered as lacking uniformity and therefore could not be registered under PBR

Number of plants or plant parts measured	Maximum Number of Off-Types
5	0
6-35	1
36-82	2
83-137	3

2. For partially self-pollinated varieties the allowable number of off-types is doubled.

Uniformity in cross pollinated varieties is usually assessed using the relative variance method (see Measured characteristics). Where a characteristic is visually assessed, the new variety is considered uniform if the number of off-types is the same as, or less than, the number found in other known varieties.

Measured characteristics

Variance is a statistical term that describes the dispersion of population. It is easily calculated from the square of the standard deviation

For measured characteristics where it is often difficult to determine what is or is not an off-type, uniformity can be assessed using a statistical technique called the relative variance method. Here, the variance of a measured distinctive characteristic of the new variety is compared with the average variance of the comparator varieties for the same characteristic. Measured characteristics are considered uniform if their variance is less than 1.6 times the average of the variances of the varieties used for comparison.

While this might sound complicated, it is reasonably straight forward as the following example demonstrates. As 0.939 is less than 1.6, the conclusion is that the new variety is uniform for the plant height characteristic.

Characteristic	Variance of new variety	Variance of comparator variety 1	Variance of comparator variety 2	Variance of comparator variety 3	Average variance of comparator varieties	Ratio of new variety /average of comparator varieties
Plant height (cm)	5.1	6.5	5.5	4.3	5.43	0.939

(c) Stability

A variety is stable if it remains true to description after repeated propagation or reproduction. Breeders of varieties propagated from seed need to demonstrate stability by including two generations in the comparative trial (If necessary stability can be demonstrated in a separate trial). If the variety is to be vegetatively propagated and is uniform, a demonstration of stability is usually not required. It is the applicant's responsibility to ensure that the variety remains true to the description.

Additional Distinctness

As an additional test of distinctness, applicants for PBR on varieties of Australian species are required to provide a herbarium specimen to the Australian Cultivar Registration Authority (ACRA). ACRA provides the Plant Breeders Rights Office with advice on whether the variety is considered new. Applicants are asked to forward a fresh, flowering specimen about 40 cm in length and wrapped in damp newspaper, to:

The Registrar, ACRA, Australian National Botanic Garden, Clunies Ross Street, ACTON ACT 2601.

To identify the specimen, applicants should include with the specimen, a completed copy of ACRA Herbarium Specimen form, available from the PBR office. Plant Breeder's Rights will only be granted after this procedure has been finalised.