Ecological-Genetic Studies on Genetic Resources of Wild and Cultivated Rice(4th Survey)

1991年至1993年，我们在印度支那地区进行了野生稻和栽培稻的调查。1991年，我们访问了老挝和泰国东北部。在老挝，我们调查了琅勃拉邦、万象和帕克塞地区的野生和栽培水稻。(1)琅勃拉邦。观察到甘露野生稻1个种群。几乎所有的耕种者都种植在旱地或旱地。它们都是糯性品种。(2)万象。观察到了普通稻纵卷叶蝉的种群。栽培者多为地方品种，但最近从越南和泰国引进了现代品种。(3)解析。2.1992年，我们在越南和柬埔寨观察了水稻。在越南湄公河三角洲，具有类似于日本的细胞质基因组的多年生Rufipogon是优势种。现代耕种者正在取代地方性耕种。野生稻在柬埔寨很常见。3.1993年，我们再次访问老挝，评估了万象地区野生稻自然种群生物量的变化，以了解该国的遗传侵蚀水平。两个野生稻种群被发现保持其大小和密度，这表明遗传侵蚀在老挝并不那么严重。4.在这个项目期间，我们访问了泰国的野生稻种群，我们在该项目的第一次调查中(1983年)访问了泰国的野生稻种群。我们比较了每个观测点的野生稻种群的生物量，发现遗传侵蚀程度很高。特别是，由于遗址的破坏，一年生种群受到了严重破坏。据估计，到本世纪末，一年生种群将会消失。应采取一种有效的遗传资源保护方法，如建立原位保护机制。

We investigated wild and cultivated rice in Indochina area during 1991-1993.1.In 1991, we visited Laos and northeastern Thailand. In Laos, we investigated wild and cultivated rice in Luang Prabang, Vientiane and Pakse areas.(1)Luang Prabang. One population of Oryza glanurata was observed. Almost cultivators were grown in upland or rainfed fields. They were glutinous cultivars.(2)Vientiane. Populations of O.rufipogon were observed. Cultivators were mostly landraces, but recently modern ones were introduced from Vietnam and Thailand.(3)Parse. Annual-like O.rufipogon was frequently observed.2.In 1992, we observed rice in Vietnam and Cambodia. In the Mekong delta of Vietnam, perennial rufipogon having japonica-like cytoplasmic genome was predominant. Modern cultivators are taking place of landraces. Wild rice was frequently seen in Cambodia. A huge population was found in the west suburb of Punom Penh city.3.In 1993, we visited Laos again to evaluate the change of biomass of natural population of wild rice in Vientiane area, so as to learn the level of genetic erosion in this country. Two wild rice populations were found to be maintain their size and density, suggesting that genetic erosion is not so serious in Laos.4.During this project, we visited wild rice populations in Thailand, which we have visited at the first survey of this project (in 1983). We compared biomass of wild rice population in every observation-site, and found high level of genetic erosion. In particular, annual populations were seriously damaged due to destroy of the sites. It was evaluated that annual populations will be vanishing by the end of this century. An effective way for the conservation of genetic resources, such as the establishment of in situ conservation should be conducted.