Progeny testing of tropical and sub-tropical maize lines for grain yield and Striga resistance

Maize production (Zea mays L.) suffers severe losses due to infestations of Striga hermonthica (Sh) and S. asiatica (Sa). These challenges highlight the need for high-yielding Striga-resistant hybrids. Developing such hybrids requires inbred lines with strong genetic compatibility and combining ability for yield and resistance traits. This study aimed to dissect general and specific combining ability and the underlying gene action for grain yield and resistance to Sa and Sh in tropical and sub-tropical maize, and to identify elite parental lines and F₁ hybrids that combine dual Striga resistance with superior yield performance. The hybrids and parent lines were evaluated during the 2023/2024 growing season in controlled and field environments using an alpha lattice design. The analysis revealed a significant (P < 0.05) effect of the crosses on yield, agronomic traits, and Striga infestation. Non-additive genetic effects were the key drivers of trait inheritance under the study, confirming hybrid breeding's importance. The top general combiners were lines CML540, CLHP0343, and tester TZISTR1248 under S. asiatica conditions, while lines CZL99017 and CML566, and tester TZISTR1174 were top selections under S. hermonthica, and CML540, which had dual resistance across the test environments. Under Sa treatment, hybrids CML540 x TZISTR1174, CML540 × TZDEEI50, and CML539 × TZISTR1174 were the top three performers, exhibiting high yields of 7.16 t/ha, 7.00 t/ha, and 6.33 t/ha, significant specific combining ability (SCA) effects of 13.55, 31.52, and 17.69, and heterosis at 55.31%, 51.84%, and 104.85%, respectively. Under Sh treatment, CML440 × TZDEEI50, CZL99017 × TZDEEI50, and CML540 × TZISTR1015 were the top selected three hybrids with grain yields of 9.30 t/ha, 7.46 t/ha, and 7.25 t/ha, significant SCA effects of 54.13, 8.47, and 28.63, and higher heterosis of 238.18%, 78.04%, and 41.88%, respectively. Overall, the study selected the following best candidate hybrids: CML540 × TZISTR1174, CML540 × TZDEEI50, and CML539 × TZISTR1174 under Sa and CML440 × TZDEEI50 under Sh conditions. The best selected general combiner parents were TZISTR1248 for Sa, TZISTR1174 for Sh, and CML540 for dual resistance to anchor future Striga-resistant hybrid maize development to enhance grain yield and agronomic performance.