【摘要】 用30个遗传差异不大的Mo17改良系作母本与Mo17组成姊妹种（A₁×A₂）,再以30个姊妹种以及30个Mo17改良系作母本,与父本自交系E28,5003配成改良单交种和普通单交种。试验表明:改良单交种的产量、农艺性状和整齐度与相应的普通单交种基本一致,而姊妹种的产量明显地高于任一亲本自交系,故改良单交种具有制种产量高的优点。姊妹种产量的高低与其改良单交种的产量无明显相关,因而有可能选出制种产量高、杂交种产量也高的“双高”改良单交种。以A₁×B₂和A₂×B₂的平均产量可予测改良单交种（A₁×A₂）×B的产量。更多还原

【Abstract】 Each of the thirty improved lines of Mo17 was crossed as female parent withMo17 to produce the sister crosses. These sister crosses and improved lines all werecrossed with two male parents, 5003 and E28, to produce modified single crosses（A₁×A₂）×B and normal single crosses. The grain yields, agronomic traits and their variant coefficients of modified singlecrosses were similar with those of corresponding normal single crosses, the yields ofsister crosses was significantly higher than their parental inbreds, so that the substitu-tion of modified single crosses for normal single crosses would increase hybrid seed pro-duction to a great extent. However, no significant correlation was observed betweenthe yield of modified single crosses and that of their parental sister crosses. Thepresent study has indicated that modified single crosses with high yield both in hybridseed production and in grain production could be possibly developed. The average yield of two single crosses A₁×B and A₂×B can be used as predictivevalue of the modified single crosses.更多还原