Guidelines for Demonstrating DUS

To receive a certificate of protection for a new plant variety, the owner of a variety must demonstrate that the variety is Distinct (D), Uniform (U), and Stable (S). DUS is defined as follows:

  1. Distinct - A variety should be measurably different from all varieties of common knowledge known to exist when the application was filed. A variety of common knowledge includes a variety already being cultivated or exploited for commercial purposes or a variety described in a publication that is available to the public.
  2. Uniform - A variety should be sufficiently uniform in its relevant characteristics, subject to the variation that may be expected from the features of its propagation. Any variation should be predictable to the extent that it can be described by the breeder and should be commercially acceptable.
  3. Stable - A variety should remain true to its description over successive generations. The variety must be stable in its essential characteristics to the degree where further generations of seed or other propagating material exhibit the same characteristics of the variety as described in the variety description which is used to establish a variety's eligibility for PVP.

DUS is demonstrated and accomplished through field trials, where the Subject Variety (SV) is grown side by side with a Most Similar Variety (MSV) under the same set of environmental conditions where morphological characteristics are observed, measured, and recorded. The outcome of the field trials should show how the SV is different from the MSV.

Under the International Union for the Protection of New Varieties of Plants (UPOV) Convention, field trials can be conducted by one of three parties: (1) a government authority conducts the field trials itself; (2) a government authority arranges for another party to conduct the field trials; or (3) a government authority considers the results of field trials carried out by the applicant/breeder.

The following are guidelines for demonstrating DUS by conducting field trials or submitting DUS reports from another authority.

Guidelines for Conducting Field Trials

The US PVPO adopts the applicant-conducted field trials system. Under this system, field trials are conducted by the owner/applicant, breeder, agent, or someone contracted by the applicant. The DUS results are submitted to the PVPO as part of an application. This makes it necessary to complete the field trials before an application is filed, in contrast to situations where government authorities conduct the trials after an application has been filed. 

The following is an explanation of the general requirements and some best practices for conducting field trials. Please contact the PVPO for further information.

1. Two Locations in One Year or One Location in Two Years

Field trials to assess the variety’s characteristics, uniformity, and stability are to be completed by the applicant before the application is submitted. These trials need to be conducted in a minimum of two years at one location or in one year at two locations. 

2. Selection of the Most Similar Variety

Another decision point is the selection of the MSV. The selected MSV is normally a variety of common knowledge. According to PVP Regulations, the criteria for determining that a plant variety is a matter of common knowledge are that:

  • the variety is already being cultivated or exploited for commercial purposes, or
  • the variety is described in a publication that is accessible to the public.

The MSV is usually the same species as the SV and is the most similar morphologically to the SV.  If there are other MSVs, these can also be used for comparison. The following factors should be considered when selecting an MSV:

  • They should be in the same species with similar characteristics as the SV. If the SV is the first variety of a species and there are no other known varieties of the same species to compare to the SV, then the wild type or original species of the same genus, regardless of its morphological similarity to the SV, should be used as the MSV.
  • Where varieties are being selected for a characteristic such as flower color, foliage color, growth habit, plant size, etc., reference varieties should resemble the SV for most, if not all, of the characteristics for which they have been selected by the breeder. For example, if a variety is selected by the breeder as an SV because it produces pink flowers, then, if possible, the MSV should also have pink flowers, not white, yellow, red, etc. Please note that this applies to all other variety characteristics as well.
  • Where varieties are being selected for a combination of characteristics such as growth habit and maturity, for example, the MSV should resemble the SV in most, if not all, of the characteristics selected by the breeder. In some circumstances, it may be necessary to have more than one MSV; one which is most similar to the SV about maturity and one which is most similar to the SV about growth habits.
  • Where the SV is a Genetically Modified Organism (GMO), the applicant should ensure that the MSV and reference varieties chosen are the most similar and contain the same modification, where applicable.
  • Where the SV is the progeny from crosses made by a breeder to develop a product line (e.g., plants developed to have the same plant form and growth habit but variations in the color of the flowers), those varieties from the product line which are most similar to the candidate variety must be used as the MSV. If other similar varieties outside the product line are identified, then they can also be considered an MSV and used in the field trial for comparison.

3. Setup of Field Trials

Field trials should be conducted under normal growing conditions for the plants being observed. For example, field crops should be planted in fields beside the MSV so observations can be made under the growing conditions recommended for that crop. Field crops should not be grown in potted plants or a greenhouse.

Both the SV and MSV in the field trials should be subjected to the same conditions. Only when the SV and MSV are subjected to identical conditions is it possible to reliably compare the two without regard for the difference in cultivation. As a result, the differences or distinguishing characteristics observed between the SV and MSV during the examination will be due to the differences between the varieties and not due to environmental factors.

In conducting the field trials:

  • The SV and MSV should be grown at the same location for two years or at two separate locations in one year. The SV and MSV should be grown in the same area of the greenhouse or the same field.
  • A backup location in case of extreme weather or other problems resulting in crop failure might be considered for row-crop species such as the small grains. For this to be effective, data should be collected at both the primary and backup locations for all years of the tests.
  • Both the SV and MSV are to be grown in the same size plots with the same spacing between plots containing the same number of plants or in the same size pots using the same number of pots for greenhouse varieties.
  • Removal (roguing) of plants and/or plant parts that do not conform to the intended description of the variety is not permitted.
  • The minimum numbers of plants for the SV and MSV are normally the same.
  • The size of plots or number of plants should be determined so that plants or plant parts may be removed for measurement and counting, without prejudice to the observations that will be made at the end of the growing cycle.

4. UPOV Test Guideline (TG) Documents

PVPO follows UPOV guidelines and requires applicants to follow the UPOV Test Guideline documents to conduct field trials for their relevant varieties. UPOV TGs detail trial methods and list relevant Table of Characteristics for crop types. PVPO’s Exhibit C form generally incorporates the Table of Characteristics; and, may include additional characteristics for some crop kinds.

The required characteristics are notated by asterisks in the UPOV TG and on Exhibit C.  Completing as many of these characteristics as possible is beneficial to the applicant because they describe the varieties more completely.

If additional information on the distinctness of the SV is available for other variety characteristics which are not found in Exhibit C, it can be included in Exhibit D Additional Description of Variety.

When measurements or counts of plants or plant parts are required, the mean, the range, the standard deviation, and the number of plants or plant parts being measured or counted should be calculated and provided on Exhibit D.

5. Description of Field Trials

Information describing the site location(s), the test parameters for the trial (e.g., plot size, planting density of plots, number of replications, number of plants, plant spacing, number of pots per variety, size of pots, number of plants per pot, application of plant growth regulator, etc.) should be included with the application in Exhibit A.

6. Submission of Photographs

Submission of one or more photographs in jpeg format is recommended to help with the examination of the variety. The applicant can submit photographs to the PVPO with the completed application as part of Exhibit D or as an attachment to an e-mail. Photographs can be taken in the field or indoors against a neutral background if possible. A common reference of measure can be included such as a ruler. It is also ideal to include both the SV and MSVs in the same photograph, with each labeled accordingly.

Guidelines for Submitting DUS Reports Produced by Other Authorities

PVPO accepts DUS reports produced by other UPOV authorities for all asexually and some sexually reproduced crops as long as they follow the UPOV TGs for that species. The DUS report replaces the Exhibit C form. The applicant must also submit Exhibits A, B, and E unless that information is included in the DUS report.

To apply for protection of a variety that has been issued a DUS report from another UPOV authority, the applicant can purchase the DUS report from the UPOV authority and provide the DUS report to PVPO as an attachment when applying using the ePVP System or include it with the application forms. PVPO can also help with the request and purchasing of the DUS report for the applicant. PVPO will request the DUS report and have the UPOV authority bill the applicant.

Once an application that includes the DUS report is received, it is checked for completeness by the examiner and the variety name is verified to ensure it does not conflict with an existing name. As with all examinations, characteristic data is entered into the ePVP System database.  Distinctness searches are performed to compare the SV with all known varieties in the database. Uniformity and stability information is also reviewed and confirmed. If the SV meets the examination criteria, then the variety is recommended for protection.

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