The success of hybrid maize (Zea mays L.) breeding depends on understanding the combining ability effects of the inbred lines. The study aimed to evaluate the general combining ability (GCA), specific combining ability (SCA), and heterotic effects in yellow maize for various traits. Ten inbred lines’ crossing with three testers used the line-by-tester mating scheme. The resulting 30 F₁ hybrids underwent evaluation against two check genotypes in a randomized complete block design (RCBD) with three replications during the kharif growing season of 2021 at the Cereal Crop Research Institute (CCRI), Nowshehra, Pakistan. Significant heterotic and combining effects were evident for the studied traits. Inbred lines YL-02 and YL-06 showed significant positive GCA for ear length, 100-grain weight, and grain yield. The F₁ hybrids YL-02 × YD-04 (8209.6 kg ha^-1) and YL-01 × YL-07 RC (6979.6 kg ha^-1) revealed maximum grain yield and significant positive SCA effects, indicating potential for yield improvement. Estimates of SCA were greater than GCA for all the studied traits, signifying the importance of the non-additive gene action in the inheritance of studied traits. Based on combing ability effects and yield performance, the F₁ crosses YL-02 × YD-04 and YL-01 × YL-07 RC are desirable for future breeding programs.

Keywords: Maize (Z. mays L.), hybrids, mean performance, combining ability, heterosis, heterobeltiosis, grain yield, gene action.

Key findings: The maize (Z. mays L.) inbred lines YL-01, YL-02, and YL-06 emerged with desirable and significant GCA effects. The F₁ hybrids YL-02 × YD-04 and YL-01 × YL-07 RC exhibited with significant SCA effects and maximum grain yield. These parents and hybrids could be beneficial in future hybridization programs of yellow maize.