Test guidelines

DUS Test for Potato

(cuctrongtrot - 10/05/2007,11:37:52) Procedure to conduct test for distinctness, uniformity and stability of potato variety

Socialist republic of Vietnam
Ministry of Agriculture and Rural Development

Procedure to conduct test for distinctness, uniformity and stability of potato variety

10 tcn 552 - 2002
(issued in accordance with document no 143/2002/BNN-KHCN
on December 6th, 2002)

1. Subject and Application scope

1.1. The procedure provides principles, contents and methods for the conduct of Distinctness, Uniformity and Stability tests – in abbreviation as DUS tests - for all potato varieties of Solanum tuberrosum L, excluding the seedling varieties.
1.2. The procedure apply to all new potato varieties of all foreign and national organizations, individuals who registered for DUS tests in order to protect the breeder’s right or to be released in the national variety list.

2. Definition

In the procedure, the hereunder words and phrases should be construed as follows:

2.1. Applicant variety: is a new variety registered for DUS tests.
2.2. Example variety: is a variety to be used as a standard of a certain expression of a specific characteristic and mentioned in the Table of characteristics of rice varieties.
2.3. Check variety: is a variety in the same group of applicant variety, possess the most similar characteristics with that of the candidate one.
2.4. Standard seed sample: is a seed sample obtaining characteristics corresponding to the Table of characteristics that was approved by competent professional authorities.
2.5. Essential characteristic: is characteristic stable of genetic, rarely varied by the cause of environmental impacts, could be recognized and described exactly.
2.6. Off-type plant: is a plant showing one or more essential characteristics that do not correspond to that as in the Table of characteristics.

3. Material Required

3.1. Applicant variety.

3.1.1. The minimum quantity of tubers to be supplied to the Evaluation Office for conduct of DUS tests is 150 tubers in each year of testing. The minimum quality of tubers should at least meet the standards of 10 TCN 316-2002. The diameter of the tubers to be delivered should be 35-40 mm. The plant material supplied should be visibly healthy, not lacking in vigor or affected by any important pest or disease.
3.1.2. The plant material must not have undergone any treatment unless the Evaluation Office allows or requests such treatment.
3.1.3. The competent authority decides when the plant material required for DUS tests.

3.2. Check variety:

3.2.1. The Breeders should propose the reference varieties for applicant variety in the registration for tests and describe the distinct characteristics between the check and the applicant variety. The Evaluation Office will examine the breeder's proposals and decide the variety selected to be check variety.
3.2.2. The tubers of check variety should be drawn from standard sample of the Evaluation Office. In necessary cases, the competent authority may require breeder to provide and take responsibility for the quality of check variety’s tuber sample. Minimum quantity and quality of tuber sample are regulated in item 3.1.

4. Grouping of Variety:
The testing varieties are separated basing on the characteristics as follows:
- Lightsprout: anthocyanin coloration of base( Characteristic 3)
- Flower corolla: color of inner side( Characteristic 38)
- Tuber: color of skin( Characteristic 47)
- Tuber: Color of flesh( Characteristic 49)

5. Conduct of tests

5.1. Duration of tests: the minimum duration of tests should normally be two independent growing cycles with the same conditions.
5.2. Place of tests: the tests should normally be conducted at one place. If any important characteristic of the variety cannot be seen at that place, the variety may be tested at an additional place.
5.3. Test arrangement: The minimum quantity of applicant material should be 100 tubers for each variety. Each variety should be planted in 2 replication plots. Each replication of applicant variety is transplanted with 2 rows of 25 plants with the distance of 70 cm and the distance between plants is 40 cm.
5.4. Other technical methods will be applied in accordance with the procedure for conduct tests of potato TCN 310-98.

6. The Table of characteristics

6.1. In order to assess DUS, the Table of potato variety characteristics should be used.
Characteristics noted with (*) symbol are used to evaluate all the varieties and always has to be incorporated in the Table of Characteristics, except when the state of expression of a preceding characteristic or regional environmental conditions render this impossible. Characteristics noted with (+) symbol to mind there is further explanation or illustration on the Appendix 1.

6.2. The characteristics of assessment will be observed at the optimal stage of development.
The stages of development are coded as follows:
1. About 12 weeks after sprouting
2. Budding stage
3. Flowering stage
4. Ripening stage
5. After harvest

7. Methods and Observations

7.1. For the assessments of distinctness:

7.1.1. All observations for the assessment of distinctness and stability should be made on at least 20 plants randomly selected or parts taken from each of those plants.

7.1.2. The distinctness to be determined by the clarification of difference between a specific characteristic of applicant variety and that of check variety.

-As to the qualitative characteristics(observation, taste): The applicant variety and check variety are considered as distinctness when a specific characteristic of each variety states in 2 different expressions.
-As to the quantitative characteristics(counting): The substantial distinctness between applicant variety and that of check variety is determined basing on the value of LSD at the minimum of 95%.

7.2. For the assessment of uniformity:

The main method for assessment of uniformity of applicant variety is basing on the calculation of ratio between off-type plants and plant population on observation plot.
-The proportion of standard sample against off-type plants is at the minimum of 2%, the minimum reliable ratio must be 95%. In the case of a sample size of 100 plants (of 2 replications), the maximum number off-types allowed would be 3 plants.

7.3. For the assessment of stability:
The Stability of variety should be assessed indirectly through the assessment of Distinctness and Uniformity. If the assessment data of experimental seasons are the same or reaching the minimum distances of 95% the candidate will be regarded as stability

7.4. The specific method for DUS tests is regulated in the guidelines for the conduct of tests for distinctness, uniformity and stability( UPOV -TG/1/3) and other related documents of International Union for the Protection of New Varieties of Plants ( UPOV).

7.5. To limit errors, one officer (or a group of officers) should be employed to carry out the observations, assessment and record of data during experimental seasons.

8. Summary of data and issuance of assessment results:

The evaluation agency has to complete the report on results of DUS tests not later than 60 days from the finishing date of tests.

The competent authority will announce the testing results to organizations, individuals who own the tested varieties and make a report to the Science and Technology Council of MARD for approval of release or to the Plant Variety Protection Office for breeder’s property right certificates purposes.

P.P. minister of Ministry
of Agriculture and Rural Development
Vice minister
Bui Ba Bong