Comparative analysis of test guidelines for distinctness, uniformity and stability of pear (Pyrus L.) formulated by China and UPOV

Abstract: Test guideline is the important basis for the test of distinctness, uniformity and stability. In this paper, the main contents of four different test guidelines for Pyrus L. were compared and analyzed, including material requirements, conducts of the tests, assessments of the test, test characteristics, example varieties and technical questionnaires. TG/169 is applied to the clonally propagated rootstock varieties of pear and was released in 2000. TG/15 is applied to scion varieties of P. communis L. and also was released in 2000. TG/149 is applied to the scion varieties of Pyrus pyrifolia (Burm. f.) Nakai var. culta (Mak.) Nakai (Syn. Pyrus serotina Rehd.) and is the earliest pear test guideline released on November 4 th, 1994. NY/T 2231 is applied to the scion varieties of four species of pear as P. ussuriensis Maxim., P. bretschneideri Rehd., P. pyrifolia Nakai. and P. communis L. and was released in 2012. The quality of the materials required is the same but the forms and the numbers are different. TG/169 requires 25 oneyear-old rooted plants (virus free) . TG/149 requires 10 one-year-old grafted plants. TG/15 and NY/T2231 require grafted plants or shoots. TG/15 requires 5 grafted plants for varieties resulting from crossing and 10 grafted plants for varieties obtained from mutation, or 3 (from crossing) or 10 (from mutation) dormant shoots for grafting. NY/T 2231 requires at least 15 grafted plants or enough dormant shoots to propagate 15 trees. In the test conduct, test duration and test place of the four test guidelines are the same, but others are different. TG/15 and NY/T 2231 require all observations to be made on 5 plants or parts taken from each of 5 plants in the case of varieties resulting from crossing, and on 10 plants or parts taken from each of 10 plants in the case of mutants. TG/149 requires all observations to be made on 20 parts of plants, four from each of five plants. TG/169 requires all observations to be made on 10 plants or parts taken from each of 10 plants. In the four guidelines, TG/149 doesn't explain the methods for assessment of DUS, TG/15 and TG/169 only explain the methods for assessment of uniformity, and NY/T 2231 explains the methods for assessment of distinctness, uniformity and stability.Characteristics are the basis for the DUS test. TG/149 has 76 standard characteristics, the largest number of standard characteristics, including 42 asterisked characteristics, 3 grouping characteristics and 3 technical questionnaire characteristics. NY/T 2231 has 68 standard characteristics, including 34 asterisked characteristics, 5 grouping characteristics, 9 technical questionnaire characteristics and 6 additional characteristics. TG/15 has 65 standard characteristics, including 34 asterisked characteristics, 5 grouping characteristics and 5 technical questionnaire characteristics. TG/169 has 39 standard characteristics, the smallest number of standard characteristics, including 15 asterisked characteristics, 3 grouping characteristics and 3 technical questionnaire characteristics. We had analyzed and divided the characteristics into 12 groups. They are plant (tree) characteristics, shoot characteristics, bud characteristics, leaf characteristics, flower characteristics, fruit characteristics, seed characteristics, phenophase characteristics, storage property, resistance, self-compatibility, and self-pollination rate. Different guidelines have different number of these characteristics. Characteristics of leaf and shoot are the main characteristics of TG/169. Fruit characteristics are the main characteristics of the other 3 guidelines. Example varieties are the standard varieties for example or correction of the state of expression of the descriptive characteristics in the test guidelines. The number of example varieties are different. TG/15 has 80 example varieties, NY/T 2231 has 45 example varieties, TG/149 has 33 example varieties and TG/169 only has 5 example varieties. Technical questionnaire is also one part of DUS test guidelines, which mainly deals with the basic information of the variety filled by breeders. The form and content of the technical questionnaire of TG/15 and TG/169 are almost the same, including eight parts as Genus/species, applicant (name and address) , proposed denomination or breeder's reference, information on origin, maintenance and reproduction of the variety, characteristics of the variety to be indicated, similar varieties and differences from these varieties, additional information which may help to distinguish the variety, and authorization for release. The technical questionnaire of TG/149 is slightly different and it doesn't have the content of authorization for release. There are many differences in the technical questionnaire in NY/T 2231 and UPOV test guidelines. The technical questionnaire of NY/T 2231 mainly includes proposed denomination, botany classification, variety type, a representative color photograph of the variety, other information, special conditions for growing the variety or conducting the examination, special conditions for maintenance of the variety and characteristics of the variety to be indicated. The potential of development of DUS test guidelines for Pyrus in China was discussed and prospected, which can provide references for formulating new DUS test guidelines in China.