| The paper summarized the studies on genetic diversity of Castanea genus. The studies involved the following fields: (1)Geographical distributing and original theory of castanea genus; (2)Population genetic diversity of Chinese chestnut; (3)genetic diversity of Chinese special species and groups; (4) Utilization of molecular marker technology in studying on genetic diversity of chestnut. However, till to now fewer and less systemic research on genetic diversity of Chinese chestnut have been conducted.Since 1972, Hunan Academy of forestry has being introduced 114 varieties of chestnut from the Yangtze River areas and northern-China and 21 local cultivars or varieties were collected. Based on those resources, by means of field plots, morphological marker and description, systematically study on the genetic diversity of Chinese chestnut (Castanea mollissima) was conducted in this paper. The study mainly focused on analyzing the diversity of economic characteristics, and to explore the genetic relationship among different characters of Chinese chestnut, so as to provide scientific base for preserving and utilizing chestnut germ plasm. Through experiments and analysis, breakthrough and achievements were obtained in such aspects as the synthetically evaluating the different characteristics of different varieties, the relation between dichogamy and main economic characteristics and pollen morphologic observation. The main results are as the fellows:1 Genetic diversity of biological and economic characters: varieties involved in the experiment have obvious genetic differences in early fruiting. Different varieties cultivated in different areas were different in yield. Characteristics of different species have been researched quantificationally in terms of quantity indexes and been evaluated systematically, which would provide scientific bases for choosing chestnut in different areas. The study on the diversity of size of nut showed that genetic difference among different varieties is obviously existed, moreover for most varieties the genetic difference of nut size were stability in different areas. Comprehensive analysis on involved varieties' quality by gray theory system showed that variety J (Shanbujia) is the best variety in synthetical nutrition and quality.The characteristics of storage from different varieties were genetically quite different. The investigating on diseases and pests resistant of 6 varieties from different experimental plots indicated that varieties with long stab fruits and thick shell are strong resistant to curculio. By using of systematic cluster theory, combined with yield characteristics analyses, the optimum varieties in Hunan were chosen, including Tie litou, Jiu jiazhong, Qingzha, Nian diban. The representative associated analysis for 14 characteristics showed that fruit number and yield per plant as yield index can be used to reflect the actual yield, but the yield from per square meter of crown cover area doesn't work. The path analysis for 11 characteristics of 34 plants showedthat main factors determine fruit per plan includes vigor maternal branch, leaves number per plant, height of plant(m), crown canopy (m2)s height of stem below branches(m) etc; Factors determine yield per plant includes vigor of maternal branch, the leaves number per plant, high (m), height of stem below branch(m), crown canopy(m2), and factors determine projection yield includes leaves number per plant, relatively plant height (m), vigor of maternal branch.2 Flower phonology and pollen gain observation. During crossbreeding, through observing flowering phenology and investigating main economic characteristics of 16 varieties in 3 experimental plots, the orderliness of flowering phonology was found out, and proved the dichogamy of chestnut, which provide scientific base for crossbreeding and deploying pollination varieties. The results of associated analysis between dichogamy and main eco-characteristics showed that the relationship between the order of dichogamy and individual plant yield, percentage of fru...
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