杂交稻杂株的表现型及保纯对策

根据５６２份样品的海南纯度鉴定，从遗传学角度把杂株的表现型分为当代表现型、隔代表现型、多代表现型、变异表现型等四类，并提出了防杂保纯的对策．

The Phenotypes of Off-Type Plants in Hybrid Rice and The Measures to Ensure Purity

Based on the identification of the purity of 562 hybrid rice seeds in Hainan, the phenotypes of off-type plants may be classified into 4 categories from a genetic angle. (1) The phenotype of the present generation: caused by the internal and external factors.in the seed production field, off-type plants emerge in the generation when seed production is done. (2) The phenotype of another generation: off-type plants emerge in the ms line multiplication which is dome 1 or 2 generations prior to seed production. (3) The phenotype of the polygeneration: off-type Plants emerge due to the multi-generation use of three parental lines, which leads to admixture and degeneration when purification and rejuvenation are not done. (4) Tile phenotype of variation: variation often occures in crop varieties, and three parental lines in rice are no exception; so about 5% -20% of off-type plants emerge due to variation in three parental lines. In order to make thorough roguing and ensure purity, the following measures may be adopted: (1) In foundation seed production it is necessary to pay equal attention to each of three parental lines, that is, the ms line, restorer line and mantainer line. (2) To do seed production, it is important to use the ms line to multiply elite seeds of the first class, and the seeds of the male parent in the seed production field should not be used as the male parent. (3) In foundation seed and ms line multiplication both space islolation and time isolation are required. (4) When foundation seed production and ms line multiplication are being done, it is necessary not to apply gibberellin or only to apply a litte gibberellin, so that the self-fertility induced by gibberellin can be avoided. (5) Sparse seeding for raising vigorous seedlings as well as ratooning rice cultivation may be practised so as to shorten the multiplication generations.