Ecological-Genetic Studies on Rice Germplasm in Tropical Asia (3rd Survey)

本研究对普通栽培稻及其野生祖先进行了变异调查。rufipogon）的遗传学和生态学观点。1989年，我们在不丹和孟加拉国进行了考察。在1989年和1990年，我们三次访问了位于泰国中部平原的野生稻永久研究点。不丹-在不丹西部，我们对分布在沿着三个山谷的22块稻田进行了观察，并收集了158个种子样本。我们参观过的海拔最高的田地（可能是世界上最高的稻田）位于海平面2700米处。群体内水稻田表现出不同程度的异质性，包括高落粒率和半不育性的变异体。这种“杂草”类型的起源仍然没有解决。对种子样品的性状调查表明，高海拔地区采集的样品多为粳稻型，低海拔地区采集的样品多为籼稻型.孟加拉国-稻田 ...更多信息 在孟加拉国，大部分分布在低洼地区，雨季洪水泛滥。我们走遍了三个种植深水水稻和野生水稻的地区。在14个地点采集了66份栽培稻和30份野生稻样品。传统的混种方法（两种不同生长期的品种混种）提出了一个有趣的生态遗传学问题。尽管热带地区的低地品种被认为是籼稻，但一些品种的种质被发现带有粳稻特有的同工酶等位基因。在野生稻方面，发现大多数野生稻群体靠近稻田，并渗入了栽培类型的基因。幸运的是，我们发现真正的野生种群分散在一个巨大的沼泽地，形成小种群，这些沼泽地以曼陀罗为主。泰国的种群研究-在我们自1983年以来监测的8个永久性研究地点中，有4个野生种群已经灭绝或接近灭绝。它们都是年度类型。其余4种为多年生或多年生-一年生中间型，在相对稳定的生境中持续存在。因此，自然人口的破坏或城市化。少

We have carried out the variation survey of the common cultivated rice (Oryza sativa) and its wild progenitor (O. rufipogon) from the viewpoint of genetics and ecology. In 1989, we made study-tours in Bhutan and Bangladesh. In 1989 and 1990, we visited three times our permanent study sites of wild rice which are located in the Central Plains of Thailand.1. Bhutan --- In West Bhutan we made observation of 22 rice fields distributed along three valleys and collected 158 seed samples. The field of the highest altitude we visited (probably the highest rice field in the world) was in 2700 m MSL. Rice fields were heterogeneous in varying degrees within population including variants which showed high seed shattering and semisterility. The origin of such "weedy" type remains unsolved. Character investigation of seed samples revealed that samples collected in higher altitude were mostly Japonica type, while those collected in lower altitudes were mostly Indica type.2. Bangladesh --- Rice fields … More in Bangladesh are distributed mostly in low-lying areas which are deeply flooded in the rainy season. We traveled three districts which are planted to deepwater rice and inhabited by wild rice. 66 cultivated and 30 wild rice samples were collected on 14 sites. Traditional methods of mix-cropping (mixture of two varieties having different growth duration) suggested an interesting problem of ecological genetics. Some of the accessions of cultivars were found to carry Japonica-specific isozyme alleles, although lowland cultivars in tropics have been believed as Indicas. In regards to wild rice, most of wild rice populations were found to be in close proximity to rice fields, and to be introgressed by genes of cultivated type. Fortunately, we found truly wild populations scattered forming small populations in a huge marsh places which were dominated by Datura.3. Population study in Thailand --- Among eight permanent studysites which we are monitoring since 1983, four wild populations became extinct or nearly extinct. They are all annual type. The remaining four are perennial or intermediate perennial-annual type, and persist in relatively stable habitats. Thus, natural populations destruction or urbanization. Less