Abstract
This study was attempted with the view to looking into the evolutionary dynamics of ultivated rice. A review of previous theoretical studies on partly self-pollinated plant populations was set out first. Then, the writers' computations were reported which dealt with the effects of seed dormancy and vegetative propagation on population structure, and the change in frequency of a gene controlling selfing probability. It was pointed out that the breeding system of the Perennis type of wild rice, which is partly cross-pollinated and capable of propagating vegetatively, and has seeds dormant for a long period, would be quite suitable for accumulating genetic variation in its populations. It was also suggested that selfing genes can increase by themselves unless counteracted by another force favoring heterozygotes. Therefore, if the habitat assumes conditions of cultivated fields and homozygous plants become relatively advantageous, the populations will tend toward selfing.
