| Homonym and heteronym are very common problems in the collection and preservation of plant germplam.Therefore, the premise for reasonable collection, efficient appraisal and utilizing germplam is how to identify and accept or reject them. The regeneration of germplasm is a major program for institutes all over the world which engage in collection and preservation of germplasm.However, the study on theory of regeneration falls far behind its practice. Therefore, it is imperative under the situation to establish all kinds of technique system of regeneration of germplasm and make them standardize. This study is trying to explore the methods of identification and regeneration of germplasm. The results would be very helpful in directing the collection, appraisal, identification and regeneration of homonym germplasm in germplasm pool; The germplasm materials preserved in germplasm resource pool, where some genetic diversity exist between individuals, different from the materials for breeding. Only by screening the size of population for regeneration and the optimum methods of isolation and pollination, so can the genetic integrity of germplasm be maintained well after regeneration. The results of this study were as follows. 1. The identification of germplasm of homonym Chinese cabbage. Parts of homonym Chinese cabbage germplasm preserved in National Vegetable Germplasm Pool were selected to investigate their field morphology and identify by AFLP and to compare their extent of variance.Basic statistical analysis of 16 key morphological traits showed that the variance coefficient of these traits of 13 copies of germplasm of Siyueman from different provinces in China and 10 copies of germplasm of Huangxinwu from the same province lied between 0~46.97 % and 0~37.15%, respectively, manifesting different extent of morphological diversity. 13 copies of germplasm of Siyueman were divided into 3 groups and 10 copies of Huangxinwu were divided into 5 groups by evaluating and clustering their morphological traits, which showed the extent of similarity and dissimilarity among homonym germplasms. The results of identification by AFLP using 12 pairs of primers were that12% and 13% of polymorphism bands existed among 13 copies of germplasm of Siyueman and 10 copies of Huangxiwu on the average respectively and the average number of polymorphism bands of each primer was 4.7 and 4.9, respectively. The following was clustering results in DNA level:13 copies of germplasm of Siyueman were divided into 3 groups, which was nearly same as the results from morphological clustering results only different in sub-classification of the third group;10 copies of Huangxiwu were divided into 4 groups, which were as the same as that of morphological clustering results except the second group including Group II and Group IV. All above explained the extent of similarity and dissimilarity. The results above could direct us to treat differently with different germplasm according genetic gap. 2. Identification and comparison of genetic diversity of community with different population within the same germplasm indicated that population more than 30 plants could reflect its germplasm genetic characteristics. In order to ensure all plants inside the population can mate at random in the course of regeneration and the genetic integrity of germplasm be maintained well after regeneration, the size of population of regeneration should be 60 plants.3. In this study appropriate propagation population for field design is 60 plants. The treatments included two cultivars (Hongyou and Sijiu flowering Chinese cabbage), three kind of insect-proof nets with different desity (the specification were 20, 40, 60 respectively) , three methods of pollination(no pollination, artificial pollination and pollination by bombus) and the control( pollination in the open) .Every treatment had 60 copies. Isolation with different specification of 20-, 40- and 60-eye of insect-proof nets formed different microenvironment, which of 40-eye-net was most favorable for c...
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