Dissemination and population dynamics of rice in the tropics

为了了解水稻在热带地区的起源，我们研究了水稻野生祖先（Oryza rufipogon）的种群动态和自然种群的传播。此外，我们还调查了亚洲热带不同地区栽培水稻的遗传特征。获得的数据如下：1。根据形态和生理特征将野生稻分为一年生型和多年生型。本研究发现，大部分一年生型种群与籼稻品种具有较高的相似性，而多年生型种群与粳稻品种具有较高的相似性。在湄公河三角洲地区经常看到类似日本的种群。当地人称野生富庶稻为“鬼米”，因为这种水稻在自然状态下种子肥力较低在本次调查中，我们在老挝西北部地区发现了新的野生稻居群。它们似乎属于多年生类型。在1983年进行的上一次调查中，我们观察了毗邻老挝西北部的泰国北部每年的种群数量。有趣的是，为什么在老挝看到的是多年生类型，而在泰国看到的是一年生类型。3我们试图建立四个永久性观察点来就地保护野生水稻。其中一个设在普拉钦布里水稻研究中心，另外三个设在老挝。我们对种群的大小（密度和面积）、种群的流动和动态进行了观察在中国，最近的考古工作揭示了水稻和水稻种植诞生的可能性。我们试图收集中国考古学和生物学领域的这类著作。我们强烈地感到有必要在未来对目前的亚洲野生水稻项目进行持续的调查，以便全面了解水稻的起源。

To know the origin of rice in the tropics, we investigated population dynamics and dissemination of natural populations of wild ancestor of rice (Oryza rufipogon). Also, we investigated genetic feature of cultivated rice in various areas in the tropical Asia. Data obtained were as follows.1. Wild rice is separated in annual and perennial types based on the morphological and physiological features. In the present study, we revealed that most population of annual type had high similarity of indica cultivars, while those of perennial type had that of japonica cultivars. Japonica-like populations were frequently seen in Mekong delta area. People in the area calls wild rich "ghost rice', because such type shows low seed fertility in the natural stand.2 I the present survey, we discovered new populations of wild rice in the north western part of Laos. They were seemingly belonging to perennial type. In the previous survey that was performed in 1983, we observed annual populations in north Thailand that is neighbored to north western Laos. It is interesting why perennial type was seen in Laos while annual was seen in Thailand.3 We attempted to set up four permanent observation sites for in situ conservation of wild rice. One of them was set at Prachinburi Rice Research Center, while other three were set up in Laos. We made observations for population size (density and area), flux and dynamics of the populations.4 In China, recent archaeological works reveals a possibility of the birth of rice and rice cultivation. We attempted to gather such works in the field of archaeology and biology in China.We strongly feels a necessity of the continuous survey of the present project for wild rice in Asia in the future, in order to reach comprehensive understanding of the origin of rice.