Abstract: Seedling production of brown alga Saccharina japonica in China happens in recirculated cold seawater  to provide sufficiently large young plants for open sea cultivation when the seawater temperature drops below 20℃. In order to clarify whether there was a variety contamination problem in the sharing recirculated cold water system when more than one variety was produced in this investigation, a female gametophyte clone was used to test whether hybrid sporophytes could be obtained at the inlet of the water system and inside the seedling culture tanks, using parthenogenetic sporophytes as the control. Four microsatellite loci were used to further analyze the genotypes of the sporophytes. Results showed that the sporophytes obtained at the water inlet and inside the seedling production tanks were composed of alien genes indicating clearly the presence of variety contamination. Thus, this paper suggested that an independent water system was required to cultivate the parental plants in order to maintain purity and superior characteristics of each variety.

Key words: Saccharina japonica breeding, recirculated coled water system, varieties mixture, parthenogenesis, SSR loci

摘要： 我国的海带苗生产是在循环制冷水中完成，这样可以在自然海水温度下降到20℃以下时提供足够长度的幼苗完成海上养殖过程。为了探究在海带夏苗生产工艺中共用的低温循环水的使用是否会造成品种混杂,在实际生产育苗过程中，将接种雌配子体克隆的苗绳放置在低温循环水系统的育苗池和入水槽处，后期收集苗绳上的后代孢子体，以孤雌生殖孢子体作为对照，进行了形态特征的比较。同时，采用微卫星标记分析方法，以亲本雌配子体作为参照，进行了后代孢子体的基因型分析。结果表明，育苗池和入水槽处收集到的后代孢子体形态正常，这一孢子体群体中除了具有亲本雌配子体的基因片段外，还检测到了外源基因片段，表明为受精孢子体。此项研究证实了在海带夏苗生产工艺中，共用的低温循环水使用的确会造成品种混杂。为防止品种混杂、退化现象的加剧，建议育苗企业建立独立的亲本维护系统，以维持品种的优良性状。

关键词: 海带育苗, 低温循环水系统, 品种混杂, 孤雄生殖, 微卫星标记