我国两系法杂交水稻研究的形势,任务和发展前景

从育种上讲，杂交水稻育种可以分为三系法、两系法和一系法三个发展阶段；从利用杂种优势水平来看，杂交水稻育种可以分为品种间、亚种间和远缘杂种优势利用三个发展阶段。与三系法比较，两系法具有配组自由、种子生产成本低、无不育细胞质负效应、易转育新不育系等优点。迄今为止，我国已育成２０多个通过省级鉴定的实用光温敏核不育系，７个通过省级审定的两系法杂交稻组合，解决了低温敏不育系繁殖产量低而不稳的难题，实施了光温

Current Status and Developing Prospects in Two-line Hybrid Rice Research in China

Hybrid rice breeding can be devided into three developmental phases,i.e,three line system,two line system and one line system in terms of breeding methodology,and inter-varietal heterosis,inter-subspecific heterosis and distant heterosis in terms of enhancing heterosis level.The superority of two line system over three line system is:(1)The choice for restoring lines greatly broadened;(2)no negative sterile cytoplasmic effect;(3)easy development of new sterile lines.So far,more than 20 practically usable PGMS and TGMS lines and 7 two-line hybrid varieties have been cerificated.The problem of low and unstable multiplication yield of TGMS line with low sterility inducing temperature has been solved through running cold water irrigation.The special procedure for purifying and producing foundation seeds of PGMS and TGMS lines have been established and proved to be effective.The two line hybrid rice technology has been ripened.Pioneer combinations proformed very well in farmers'field and outyielded the three line check by about 10%. It is predicted that two line hybrid rice will cover 4.5 million ha and the grain yield increased will amount to 2.5 billion kg by the end of this century.