用国外优良玉米杂交种作材料，通过多代自交分离选择，育成了自交系前２１－３，对该系主要经济性状的一般和特殊配合力进行了测定，并与国内外优良自交系进行了比较，表明南２１－３主要经济性状的配合力都接近或超过国内外优良自交系。我所应用该系作亲本组配的优良玉米杂交种有４个，累计推广面积已达８０万ｈａ，获得了显著的经济效益。 The excellent and good maize hybrids from abroad were used as materials, and the first 21-3 inbred lines were bred by multiple generations of selfing, and the general and special combining ability of the main economic characters of the line were determined. The results showed that the combining ability of main economic traits in South 21-3 are close to or surpass that of inbred lines at home and abroad. There are 4 excellent maize hybrids that I used for this parental group, with an accumulated promotion area of ​​800,000 ha and significant economic benefits.