This study was carried out in order to investigate cyto-histologically the mechanism of male-sterility on the 5 different genotypes in Raphanus sativus L. (cv. Euisung banchung). The results obtained were as follows.
1. The crisis of abortion in Smsms was observed between pre-meiotic and tetrad stage, and that in SMSms was at meiotic or tetrad stage.
2. The cause of abortion in Smsms and in a certain SMSms seemed to be hypertrophy and vacuolation of tapetum. However, most SMSms were normal in fertility.
3. Great mumber of shriveled anthers were observed in Nmsms individual at meiotic stage.
4. In some anthers of Nmsms, normal glandular tapetum was formed, but the microspores degenerated at the tetrad-seperation stage, and then became empty.
5. In the case of entirely shriveled anthers, at the stage of microspore development, no darkstained remnant was observed in IVmsms individual, inside of them, while dark-stained remnant was observed in Smsms or SMSms.
6. In most anthers of Nmsms, intermingled microspores of normal and empty were observed.
7. In some anthers of Nmsms, compared with other normal Nmsms, NMSms, and NMSMS, the cytomixis of tapetal cells showed retarded development at the stage of microspore forming.
8. Both NMSms and NMSMS, produced normal microspores and formed normal glandular tapeta.
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