抄録
The frequency of chlorophyll-deficient genes and other detrimentals per gamete was estimated by conducting more than 1, 000 full-sib matings in six Japanese populations of buckwheat. The following types of abnormalities were observed in cotyledons; albinos 0.2%, yellows 3.7%, pale yellows 4.5%, pale green 5.6%, variegateds 3.4% and morphological abnormalities 1.9%. Each type of abnormality was also found in the foliage leaves at about a half the frequency in the cotyledons. The total frequencies were not very different among the populations, they ranged from 22 to 34%, except in the Togakushi population where the frequency was very low, 12%. The frequencies of all the abnormalities except the morphological one were also examined in random mating populations in farmer's fields. The total frequency of homozygotes was very low, around 0.02-0.05% in the cotyledons and not much different in the foliage leaves, probably because the population sizes are large and breeding is by insect pollination.-Based on the frequencies of abnormalities in the inbreeding experiment and those in random mating populations, the mechanism whereby detrimental genes are maintained in buckwheat populations was discussed. It seems that such detrimental genes are maintained by mutation-selection balance.-Information on the contribution of other factors to genetic loads, such as female sterility genes and cytoplasmic factors, were also given.
