Combining ability analysis in quality protein maize (Zea mays L.) for grain yield and its component traits

A study was undertaken to estimate combining ability effects in maize for different characters in a line × tester programme comprising 70 hybrids produced by crossing 14 lines and 5 testers. The interaction of line × tester was highly significant for twelve traits studied except for protein content. Significant general and specific combining ability variance were observed for all characters except protein content. The variance due to SCA was higher than GCA indicating the predominance of non-additive type of gene action. The ratio of GCA:SCA variance was lower than unity for all characters indicating predominance of non -additive gene action over additive gene action. Among the lines, genotype QPM 3 was found to be the best general combiner with better mean performance for most yield contributing traits followed by QPM 1 and QPM 187. Among the testers, T 323-8 was found to be the best general combiner with better mean performance for most of the yield contributing traits followed by T 209 and T 295 genotypes. Among the crosses, QPM 35 × T 295 was superior with positive significant SCA effects and better mean performance for grain yield and plant height. Similar superior positive significant SCA effects with better mean performance were also observed in QPM 6 × T 295 (ear length, test weight and grain yield per plant) and QPM 43 × T 193-2 (ear length and grain yield per plant).