• Horticultural Science & Technology
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• v.17 no.4
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• pp.470-472
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• 1999

When the type and ratio of male-sterile plants in $F_1$ hybrids collected from several seed companies were investigated, there were differences in the male-sterile type depending upon region, seed company and variety group. The differences were inferred due to the easiness in breeding of maintainer line among the variety groups. American seed companies mainly used petaloid type male sterility with Imperater group varieties. European companies used brown anther type male sterility mainly with Nantes group but some companies used petaloid type also in varieties that were different from Nantes group. Asian companies (Japan, Korea) used both types with Chantaney and Kuroda group varieties, but one type was mainly used depending on individual seed company. Only one type of male-sterility in one variety was observed and the results were agreed well with other's results that male-sterility type was determined by cytoplasm factor. Some breeding lines were backcrossed to both types of cytoplasm (Sa, Sp) for maintainer line selection. We could select 15 maintainer lines from 20 lines in petaloid cytoplasm (Sp) and 3 from 4 lines in brown cytoplasm (Sa). In petaloid cytoplasm, maintainer lines can be selected at considerably high frequency. But in brown anther cytoplasm, the used materials are too restricted to tell general frequency maintainer lines.