DUS testing of apple varieties practice notes

Technical notes for the DUS testing of apple varieties at the Cultivar Centre (CC)

The following guidelines for the supply of candidate apple varieties for DUS testing apply.

1. Material Required
2. Method of Evaluation and Length of Testing
3. Distinctness, Uniformity and Stability
4. Examination and Decision
5. The technical questionnaire
6. Costs and Fees
7. Checklist

1. Material Required

1.1. Varieties originating as seedlings. Varieties generally selected in a managed breeding programme or as chance seedlings.

Ten (10) trees are required to be supplied on standard M9 rootstock. Other M9 type rootstock varieties may be acceptable providing prior agreement has been received from the CC and Plant Variety Rights Office (PVRO). Please supply trees between 1 June and 30 September. All trees must be individually labelled, identifying the rootstock variety and the scion. When trees are supplied, the confirmation of supply form must be returned to PVRO. At the time of application a reasonable deadline for the supply of trees is set. Should this deadline not be met the application could lapse under section 7(3) of the Plant Variety Rights Act 1987.

1.2. Varieties originating as mutations (sports).

Five (5) trees are required to be supplied on MM106 rootstock. The trees should be second generation trees with no more than 20% of the trees coming from any single stick of budwood. Currently all other varieties originating from mutations are on MM106 rootstock and variety to variety comparison would not be possible using other rootstock varieties. All trees must be individually labelled clearly identifying each tree. Please supply trees between 1 June and 30 September. When trees are supplied, the confirmation of supply form must be returned to PVRO. Should this deadline not be met the application could lapse under section 7(3) of the Plant Variety Rights Act 1987.

In addition to the five trees supplied to the CC, separate test trees will be required for the assessment of uniformity and stability. These trees can be located on a site selected by the breeder or agent. This trial should be established at the same time as trees are supplied to the Cultivar Centre, and the PVRO notified, otherwise the examination towards grant of PVR may be delayed or declined. The location of these trees is to be supplied to the CC, with contact information, when trees are supplied to the CC. The minimum number of trees required is 25 trees on MM106 or 30 trees on M9. The trees for the assessment of uniformity and stability should be second generation trees with no more than 20% of the trees (e.g. 6 out of 25 or 30) coming from any single stick of budwood.

1.3. Quality of trees: The DUS evaluation of the variety will be based upon the trees supplied.

The trees supplied should be visibly healthy, not lacking in vigor, nor affected by any important pest or disease. The plant material should not have undergone any treatment which would affect the expression of the characteristics of the variety, unless this has received prior approval from the CC and PVRO.

A reliable and representative variety description cannot be drafted or a robust assessment of the variety cannot be made if trees are substandard or of the wrong variety. If trees are supplied of poor quality that they fail to grow sufficiently to allow full evaluation, or if they are another variety, the application could lapse under Section 7 (3) of the Plant Variety Rights Act 1987.

2. Method of Evaluation and Length of Testing

Two independent growing seasons are generally required to complete the evaluation. The work to draft the Objective Description (OD) for the variety will normally commence in the second year of fruiting. The first year fruiting season is used to check whether the variety is true to type or to indicate any other matters. All steps are taken to ensure that the OD is completed in the second year of fruiting. For varieties originating as seedlings, one growing season for evaluation may be sufficient, depending on the number of fruit available in that season and the advice of the apple experts. For varieties originating as mutations, a minimum of two growing seasons are required. It is essential that a satisfactory crop of fruit is produced in each of the two seasons, with a satisfactory crop defined as in the vicinity of forty (40) fruit per tree.

In general, a minimum period of four years is required from when trees are planted to a possible decision.

The OD is prepared using the internationally agreed list of characteristics in the International Union for the Protection of New Varieties of Plants (UPOV) test Guidelines for Apple. This is the same descriptor as used in other UPOV member states such as Australia, European Union, South Africa and Chile.

The list of possible characteristics which may provide distinctness is not fixed, however any new characteristic must be consistent, repeatable and provide adequate variation between varieties. Additional characteristics may be considered for evaluation; however these characteristics will not be added to a variety evaluation which has already started. The use of additional characteristics must be requested or raised before an evaluation for that variety begins. Such characteristics cannot be adopted before a level of understanding and experience is gained at the CC and comment from overseas apple testing authorities has been received.

3. Distinctness, Uniformity and Stability

Distinctness 

Consistent Differences

The differences observed between varieties may be so clear that more than one growing season is not necessary. In addition, in some circumstances, the influence of the environment is not such that more than a single growing season is required to provide assurance that the differences observed between varieties are sufficiently consistent.

Clear Differences

Determining whether a difference between two varieties is clear depends on many factors, and should consider, in particular, the type of expression of the characteristic being examined.

Uniformity

The assessment of uniformity is based on the basis that 99% of all trees of the variety are uniform and true to type. Trees and fruit are monitored for evidence of mutation or other genetic instability, such as chimeral fruit striping or fruit with skin colouration or patterning outside the expected range. The assessment does not consider variation normally found within a tree caused by abiotic factors such as light effects or nutrition.

Stability

In practice, it is not usual to perform tests of stability that produce results as certain as those of the testing of distinctness and uniformity. However, experience has demonstrated that, for apple varieties, when a variety has been shown to be uniform, it can also be considered to be stable.

4. Examination and Decision

The examination of the variety and the decision whether or not to grant a Right is the sole responsibility of the PVR Office. The Office is provided with technical assistance by designated pipfruit experts. The Pipfruit Advisory Group meets annually in April or May where the varieties under evaluation in that season are discussed and fruit samples viewed. The Group also provide general technical advice as needed and may carry out field observations during the season. The decisions for that season are normally advised to the applicant in June or July. On conclusion of the first evaluation season, applicants will be provided by PVRO with an interim report for varieties where a second season is required. The interim report will advise if there are any concerns regarding distinctness or uniformity or any other matters that may affect future testing and any decision.

5. The technical questionnaire

The technical questionnaire supplied at application is the primary source of information about the variety for the PVRO and CC. The information supplied provides the basis for the identification of similar varieties and assists the planning of testing. If incorrect or inaccurate information is supplied then this may prolong the testing period as an additional season may be necessary. When completing the section on similar varieties, varieties of common knowledge available in New Zealand should have priority. For varieties originating as mutations, the parent may not be the closest variety, but other varieties from that same parent. The PVRO holds a variety description for each protected variety and has technical information regarding other varieties.

It is essential that two prints of high image quality of the fruit be supplied at the time of application. In addition, jpg or tiff files may also be supplied to the PVRO.

6. Costs and Fees

The costs associated with use of the CC and any contractual arrangements are directly agreed upon between the applicant and the CC and PVRO has no involvement. On completion of the evaluation and all testing, PVRO will invoice the applicant for the examination fee. A schedule of fees to complete the variety description and uniformity assessment at the CC and the assessment of uniformity for sports on another site can be obtained from the CC on request.

7. Checklist

7.1. Complete application form and technical questionnaire and supply images of candidate variety to PVRO. Ensure that all application requirements have been met.

7.2. Take note of deadlines for tree supply set by PVRO and supply trees to CC between 1 June and 30 September. 

7.2.1. Varieties originating as seedling. Supply 10 trees on M9. Individually label trees with scion variety name and rootstock variety name.
7.2.2. Varieties originating as mutations (sports). Supply 5 trees on MM106 and notify PVRO and CC of location of U & S trial which must be planted concurrently.

7.3. Return confirmation of supply form to PVRO.