| Ginkgo biloba originates from China. It is a economic important species which has many uses in China. Unique Chemical compounds have been found in Ginkgo leaf-extracts, such as flavonoids and ginkgolides which possess medicinal propeties for the treatment of cardiovascular disorders, thrombosis cases and inflammatory reactions. Therefore, the extract of Ginkgo biloba (EGB) and its products sell well on world markets. In recent years, Industries of Ginkgo biloba have been developed rapidly in China. However, some problems such as low producing ratio of EGB, low content of medicinal composition in EGB and so on exist in many leaf-processing factories of Ginkgo biloba in China. Selecting leaf-used strains that contain high medicinal composition is a crucial means to circumvent the problems mentioned above and realize high yield, High quality and high benefit in factories in the long run. Meanwhile, it is very important that industrialized production of Ginkgo flavonoids be carried out with modern biotechnology.This dissertation was conducted on the establialiment of the evaluation system of germplasm resources and in vitro culture in Ginkgo biloba. The main results were obtained as follows:1. The leaf characters of 50 female varieties of Ginkgo bilobawere systematically studied for the first time. The results showed that there were remarkable or very remarkable differences in leaf area, thickness, single leaf weight and contents of flovonoids and ginkgolides among varieties, which proved that inheritable variation exist in varieties. The selected items and standards of leaf-used strains were put forward and the three strains of Taishan 1, Taishan 2 and Taishan 4 had been selected.2. The contents of flavonoids and ginkgolides of grafted, cutted and seedling plants and strains in different regions and seasons were compared. These results provided a scientific basis for the establishment and management of leaf-picked orchard of Ginkgo biloba.3. The results of isozyme analysis revealed that there were certain differences in POX isozyme pattern among male or female strains, but EST, GOT and SOD isozyme patterns were identical or almost identical. This showed that the range of inheritable variation of Ginkgo biloba. was limited.4. Chromosome numbers of 50 female varieties and 40 male types were investigated for the first time, all of them were diploid ( 2n= 2z =24). Artificial inducing tests to callus were conducted and polyploidy variation was not discovered. The karyotype of the five representative varieties of Changzi, Fuzhi, Ma ling, Meihai and Yuanzi types were identical. It was testified that the chromosome numbers and morphology of Ginkgo biloba had strong inheritable steadiness in its long evolution.5. Karyotypes of female and male plants of Ginkgo biloba were systematically studied. The results showed that the karyotypes of female and male plants of Ginkgo biloba were identical. The only difference is that the female tree has four chromosomes bearing satellites, while the male one has only three chromosomes hearing satellites.6. The sex of 75 young seedlings from embryo culture were verified according to the result of karyotype analysis, 31 female seedlings (41.3%) and 44 male seedlings (58.7%).7. The inducing of leaf-derived callus and browning control were systematically studied. Phytic acid (PA) was used for the browning control of Ginkgo callus for the first time and good results were gotten. It is testified the PA can promote the grouth and control the browning of Callus effectively.8. In this study, Callus culture of Ginkgo biloba was connected with flavonoid production for the first time and the technical system of two step culture had been set up. In callus production, more fresh callus can be gotten when MT medium was supplemented with PA. In flavonoid production, the content and biological yield of flavonoids of callus were raised when MT medium was supplemented with PVP mixture (PM).9. The Optimum methods of the isolation and purification...
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