Geographical Distribution and Ecotypic Differentiation of Wild Rice in Thailand

Abstract

1) Geographical distributions of the wild rices, Oryza sativa f. spontanea and O. perennis were mapped after an extensive collection covering almost all areas in Thailand. 2) The wild rices are found to distribute in swamp areas in dry season. The cultivated rice grows well also in these areas. So the suitable area for rice cultivation might be judged from the distribution of the wild rices. 3) Collected samples were raised in a green house in order to investigate the nineteen characters in detail by the use of the principal component analysis. The ecotypes of the samples collected from north and northeast Thailand had a wide range of variation. 4) The characters that seem responsible for ecotypic differentiations are self-fertility, length-breadth ratio of grains, bending of nodes, length of uppermost internode, etc.