Abstract: Seed samples of Yuetai A,a Honglian-type cytoplasmic male sterile(CMS) line were investigated to assess the seed purity and to analyze the cause of off-types by imitating the biological contaminant to Yuetai A in Nanjing,Jiangsu Province and Lingshui,Hainan Province in 2004-2006.The results showed that male sterility of Yuetai A was stable and seed impurity of Yuetai A resulted mainly from genetic drift of restoring-gene(Rf-gene) after biological contaminant.All of maintainer lines,restorer lines and thermo-sensitive genic male sterile(TGMS) lines used in the study could pollinate Yuetai A by directly penetrating Rf-gene into Yuetai A or pollinate Yuetai B led to Rf-gene into Yuetai A indirectly,and then produce F1 plants and ’iso-cytoplasm restoring-generations’.Furthermore,Yuetai A was easily outcrossing and simultaneous heading with many materials used in hybrid rice seed production,which resulted in high biological contaminant rate.After picking out all plants with Rf-gene mixed in Yuetai A and preventing Rf-gene from drifting into Yuetai A,the seed purity of Yuetai A and Yuetai B had been raised to 100%.

Key words: seed purity, restoring gene, sterile stability, iso-cytoplasm restoring-generations, Honglian-type cytoplasmic male sterile line

摘要： 通过模拟生物学混杂试验，于2004-2006年在江苏南京和海南陵水调查粤泰A的纯度并分析其杂株类型及成因。结果表明,粤泰A不育性稳定，生物学混杂导致恢复基因的渗入是粤泰A纯度迅速下降的主要原因。常用的保持系、恢复系和温敏核不育系等的恢复基因可直接渗入粤泰A，或者间接通过对粤泰B的渗入而渗入到粤泰A，产生F1杂株及其“同质恢”后代。粤泰A、B异交结实率高，抽穗扬花期与生产上常用品种同步，是它容易发生生物学混杂的重要因素。排除恢复基因后严格隔离是确保粤泰A、B纯度的主要技术措施。

关键词: 种子纯度, 恢复基因, 不育性稳定性, 同质恢后代, 红莲型细胞质雄性不育系