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

1991-1993年对印度支那地区的野生稻和栽培稻进行了调查。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Pakse地区的野生和栽培水稻。(1)琅勃拉邦。观察到1个稻谷居群。几乎种植在旱地或旱地。它们是有黏性的品种。观察了褐条蝽的种群分布。栽培者大多是本地品种，但最近从越南和泰国引进了现代品种。1 .一年生的水藻经常被观察到。1992年，我们观察了越南和柬埔寨的水稻。在越南湄公河三角洲，多年生龙蚌以具有类似粳稻的细胞质基因组为主。现代耕耘者正在取代本土耕耘者。野生水稻在柬埔寨很常见。在金边市的西郊发现了大量的人口。1993年，我们再次访问老挝，评估老挝万象地区野生稻自然种群生物量的变化，了解老挝遗传侵蚀的程度。2个野生稻居群保持了原有的大小和密度，说明遗传侵蚀在老挝没有那么严重。在这个项目中，我们访问了泰国的野生水稻种群，我们在这个项目的第一次调查（1983年）访问了泰国。通过对各观测点野生稻种群生物量的比较，发现遗传侵蚀程度较高。特别是，由于场地的破坏，每年的种群数量受到严重损害。据估计，到本世纪末，每年的种群数量将会消失。对遗传资源进行有效的保护，如建立原地保护。

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.