Abstract: Three full-sibling binary cytoplasmic male sterility(CMS) lines, 11 back-cross binary CMS lines, 10 half-sibling binary CMS lines, 10 CMS lines and 5 restorer lines Nanhui 04, Minghui 86, Fuhui 838, Xianhui 207 and Milyang 46 were chosen to make 50 single cross hybrids(SHs) and 120 modified single cross hybrids(MSHs) by the way of NCⅡ design. The grain yields of three types (full-sibling type, bock-cross type, half-sibling type) of MSH rice were higher than SHs on average. Among all the MSHs, 74 of them had superiority to the two corresponding SHs in grain yield, including 9 full-sibling type MSHs, 37 back-cross type MSHs and 28 half-sibling type MSHs. The coefficient of variability of the three types of MSHs were similar to single cross hybrids in plant height, flag-leaf length, flag-leaf width, number of effective tillers per plant and panicle length of main culms on average. The three types of MSHs were a little larger than the single cross hybrids in the days from 10% to 80% plants...ding in a plot, the days from the first plant heading to the latest plant heading in a plot, and the coefficient of variability of days from sowing to initial heading. A total of 10 good MSHs were selected according to the grain yield and the population uniformity, and its grain yield increased from 10.43% to 26.39% compared with the corresponding higher SHs.

Key words: modified single cross hybrid, binary cytoplasmic male sterile line, full-sibling, half-sibling, superiority rate, coefficient of variability, hybrid rice

摘要： 利用3个全同胞型二元不育系、11个回交型二元不育系、10个半同胞型二元不育系和10个亲本纯合不育系，与南恢04、明恢86、辐恢838、先恢207和密阳46等5个不同类型的恢复系，配制了50个单交种和120个不同类型的改良单交种，研究比较了各类改良单交种与普通单交种单株产量的差异以及株高、剑叶长、剑叶宽、主穗长、抽穗期等与群体整齐度关系较为密切性状的变异情况。三种类型的改良单交种平均产量均比普通单交种的平均产量增加；有74个组合比其两个对应单交种都增产，占所有改良单交种的61.67%，其中全同胞型改良单交种9个，回交型改良单交种37个，半同胞型改良单交种28个；三类改良单交种株高、剑叶长、剑叶宽、主穗长等性状的变异系数与单交种差异不大，单株播种至始穗历期、始穗至齐穗历期、抽穗历期的变异系数比普通单交种略有增加。通过综合考查各改良单交组合的产量优势及群体整齐度，筛选得到10个有可能在生产上应用的改良单交种，其产量比相应高产单交种增加10.43%~26.39%。

关键词: 改良单交种, 二元不育系, 全同胞, 半同胞, 优势率, 变异系数, 杂交水稻