[Combining ability analysis for SP4 lines of maize from space flight]

Three maize (Zea mays L.) inbred lines 08-641, RP125, and 18-599 were carried into cosmic space by recoverable satellite "Shijian 8". Some mutant lines were selected from SP4 and combinations were made according to the NC II genetic design. The materials were planted in Sichuan and Yunnan separately to analyze combining ability based on the incomplete diallel cross design. The results showed that space flight affected the combining ability of mutant lines, and the GCA value of mutant lines were different in two kinds of environmental condition. The GCA of ear length, row per ear, kernel per row, and yield per plant for the mutant line C03 showed substantial increase compared with the control 08-641; the GCA of row per ear, kernel per row, and other yield component traits for the mutant lines C01 and C04 were significantly higher than those of the control. The SCA of yield and yield components for the combinations derived from the mutant lines C06, R18, and S22 were higher than others. These results laid a material foundation for maize breeding and provided some important references for improving and utilizing the mutant lines.