Embryonic Development And Seed Germination In Dioscorea Fordii Prain Et Burk

This study used 57 germplasm resources of Dioscorea fordii Prain et Burk.as materials which was collected from Hainan province,using observation method to study the blossom and the development of male and female flowers and their inflorescences in D.Prain et Burk..Using the method of germination in vitro to determine pollen vigor,and using conventional paraffin sections technique to study megasporogenesis,female gametophyte development,fertilization and embryo,endosperm development of D.Prain et Burk.,preliminary explored the characteristics in reproductive development of D.Prain et Burk..This paper also studied the different temperature,different hormones(GA3,NAA,6-BA)concentration effects on seed germination of D.Prain et Burk.,explored the seed germination conditions of D.Prain et Burk..This paper laid the foundation for the study of embryology and hybridization breeding of D.Prain et Burk..The results were as follows:(1)46 materials in 57 materials of D.Prain et Burk.bloomed,there were four types of blossom:female plants,male plants,monoecism with different inflorescence plants and androgynous with different flowers plants.Number Df 58?Df 59?Df 63 materials were monoecism with different inflorescence plants,and number Df 2?Df 49 materials were androgynous with different flowers plants.(2)Female inflorescences was spike,and single inflorescence grew between the main stem and branch axil,its female flower florescence was from September to November,female flowers had six pieces of perianth,and had 6 staminodes,axile placenta,ovaries inferior,there were 3 rooms in its ovary,and each room had two ovules.Seeds were grew in th e centre of ovary axis,and were brown when is ripe,and were surrounded by a thin fin.Male inflorescences usually clustered at 2-4 in the leaf axils,spike or spicate,only 1-2 male flowers could completely develop on one inflorescence,its male flower florescence was from August to October,male flowers had six pieces of stamens,filament and anther were equal-length.Pollen germination rate was very low,was only 16.01%.(3)Mature ovule of D.Prain et Burk.was anatropous,crassinucellate,bitegmic.The archesporial cell gradually developed into megasporocyte mother cell.Then the megaspore mother cell underwent meiosis and formed 4 megaspore in line,and only one near chalazal end developed into functional megaspore.The uninucleate embryo sac formed mature embryo sac with 7 cells and 8 nuclei after three consecutive mitosis,the embryo sac was Polygonum type.Antipodal cells degenerated before fertilization.(4)The fertilization of egg cell was premitotic type.The fusion between sperm and polar nuclei was earlier than the fusion between sperm and egg muclei.The development of embryo was onagrad type,and went through 5 development stages,including two cell proembryo,inverted T type proembryo,globular embryo clavate embryo and pear shaped embryo.The development of endosperm was karyotype.Ovule development of D.Prain et Burk.was related with the external female development.(5)The optimum temperature for seed germination of D.Prain et Burk.was 25 ?-30?,the germination rate at 25? had no significant difference when at 30?.The optimum concentration of GA3 for seed germination was 100 mg/L,and the best treatment time was 24 h,the germination rate was 61.67%.When the concentration of NAA was 1 mg/L,and the treatment time was 24 h,it was suitable for seed germination of D.Prain et Burk.,and the germination rate was 53.33%.When the concentration of 6-BA was 50 mg/L,and the treatment time was 24 h,the seed germination rate could be higher,and was 51.67%.