Criteria for protection

All applications for plant breeder's rights (PBR) must satisfy the DUS criteria (distinctness, uniformity and stability).


Distinctness is shown by making an objective comparison of the variety with the most similar variety or varieties 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 if they are clear and consistent.

Additional test of distinctness - ACRA

As part of the assessment of your application for PBR for a variety of an Australian native species, you have to submit a specimen to the Australian Cultivar Registration Authority (ACRA).

You should do this before you start your comparative growing trial, as ACRA will suggest comparators to use in your trial. (If you don't use these, you will either have to repeat the trial or justify your reasoning for not using them.)

Specimens should be fresh, flowering and about 40 cm in length. They should arrive at ACRA early in the week, ideally wrapped in damp newspaper and plastic and placed securely in a mailing tube sent by express post or air freight. Applicants should include with the specimen a completed copy of ACRA Herbarium Specimen form  and the ACRA processing fee. This fee is payable directly to ACRA. PBR examination will only be finalised if the ACRA registrar determines that the specimen is distinctive and once any unfavourable comments have been resolved.


The required standard of uniformity for each type of propagation is set out below. Exceptions and guidelines for uniformity testing for particular species are given in the UPOV technical guidelines.

Visual characteristics

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.

In vegetatively propagated or fully self-pollinated varieties, the number of off-types must not exceed the numbers given in the table below. For example, if a comparative tomato 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.

Maximum number of off-types allowed
Number of plants or plant parts measured

Maximum number of off-types









  • 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 below).

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 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'.

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.

This sounds complicated, but it is reasonably straightforward, 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.

Plant Height Variance
Characteristic Plant height (cm)
Variance of new variety5.1
Variance of comparator variety 1 6.5
Variance of comparator variety 2 5.5
Variance of comparator variety 3 4.3
Average variance of comparator varieties5.43
Ratio of new variety to average of comparator varieties0.939


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.

Last Updated: 13/12/2012

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