Abstract
Considering to estimate the frequency of so-called type O plants as a maintainer of cytoplasmic male sterility in sugar beet populations, 23 diploid varieties collected from the various countries in the world were crossed with tester plants, namely, complete male sterile plants and each F1 progeny were classified into five classes of male sterility. From this result it was found that type O frequency in general was more or less 15 percent or less in each population, and there was no evidence of the population such as possessing only type O plants or restorers.
