ラン科植物の生殖器官の形成に関する研究 : エビネ属を中心に

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Orchidaceae plants are distributed widely in the world and a great numbers of the species, about 17 , 000 species, were recognized. Among them, 176 species are known in Japan. The plants of Orchidaceae is wellknown as plant groups with difficulty to propagate by seeds. In this study, a total 47 species (5 subfamilies, 11 tribes, 13 subtribes, 22 genera), such as mainly genus Calanthe (20 species), 5 species closely related to Calanthe, 13 species of wild orchids, 9 species of foreign ones were examined. A series of progress concerning formation of the reprodutive organs from germination of pollen to completion of hypertrophy in seed and embryo was studies. 1. Elongation of pollen tubes When pH value is high and concentration of sucrose is low in culture medium, vigorous germination and elongation of pollen tubes were observed. Even culture medium with only water, almost no differences were seen among species. Earlier elongation of the pollen tube at stigma was observed in species having earlier developmental degree of ovary at the time of flowering. The degrees of development were grouped into 4 types, such as only placenta, differentiated ovule primodium, differentiated embryosac and finished formation of ovule. The time concerning to formation of ovule by pollen is earlier than the species having lower developmental stages. As soon as finishing formation of ovule, the pollen tube penetrated through micropyle and elongated towards embryosac. 2. Development of ovule and progress of development in embryo Formation of ovule was closely related with pollination, and species in condition of proceeded development of ovary formation showed much shorter days of finishing ovule formation. There was a parallel phenomenon with shorter necessary days from pollination to fertilization and from pollination to embryogenesis in case of species proceeded development of ovary in flowering time. Numbers of nuclei in embryosac were counted as 3 types, such as 5 , 5〜6 and 8 nuclei. Numbers of nuclei in endosperm were counted as 3 types, such as 3〜5 , 4〜8 and 6〜8 nuclei. Five〜six nuclei were recognized in embryosac of 20 species in the genus Calanthe. Nuclei in endosperm were counted as 3〜5 . On the process of embryogenesis in Orchidanceae, a certain method of classification was established into two ways, such as 4 types in tetrad of proembryo and the later embryogenesis into 2 groups 11 types. Process of embryogenesis of examined 47 species were obserbed carefully and the author clearly reported on the belonged genera of each species of types of groups. When the classification method is used, inherent characteristics in Calenthe discolor, the genus Cymbidium and Orchis were found. Suspensor was recognized in all species in the genus Calanthe, while in the other examined species, species having no suspensor or species having both suspensor and embryonal tube were found. However, those types or characters did not become characteristics of 5 subfamilies in Orchidaceae. In connection with the addition to every processes in reproduction, germination and every items of those, no clear characteristics in the subfamily were found. 3. Progress of hypertrophy of ovary After pollination, ovary grows quickly and reaches to the maximum in hypertrophy. A tendency was recognized in shorter necessary days to complete embryogenesis with shorter necessary days to complete hypertrophy of ovary after pollination. In cases of size of completed ovary, larger ovary was recognized in later progressed species in flowering time, and smaller ovary was recognized in earlier progressed species. Furthermore, beginning day of hypertrophy showed later in later degree of development and early in earlier development depending upon the species. The ratio of hypertrophy in ovary was larger in width than in length. In cases of species having smaller plant body, smaller ovary and smaller ratio in hypertrophy of ovary after completion of hypertrophy and shorter necessary days to
恵泉女学園園芸短期大学の論文

ラン科植物の生殖器官の形成に関する研究 : エビネ属を中心に

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恵泉女学園園芸短期大学 | 論文

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