Heterotic Grouping and Combining Ability of Tropical Maize Inbred Lines under Northern Blight Infested Environments

Abstract

Abstract Knowledge of combining ability and heterotic grouping among maize (Zea mays L.) inbred lines is critical for any successful hybrid program and in northern leaf blight disease prone environments. Fourty-five (45) single cross hybrids and ten corresponding parental lines evaluation was carried out at five locations in Nigeria using a 5 × 11 alpha lattice design to estimate; i. their agronomic performance and stability of inbred lines and hybrids for grain yield in NLB infested locations, ii. their combining ability across locations, iii. effectiveness of the heterotic group’s specific and general combining ability method (HSGCA), which considers a single trait versus the Heterotic group general combining ability of multiple traits (‘HGCAMT’) for classifying the selected maize into heterotic classes. Significant GCA and SCA effects across environments revealed additive and dominant gene action in the inheritance of the traits. The greater proportion of GCA over SCA across environments indicates significance of additive gene action over dominance action among inbred lines with both methods. Both HSGCA and HGCAMT provided similar classification of the inbreds into two heterotic classes. ‘TZEEI 14 × TZEI 14’ and ‘TZEEI 14 × TZEI 134’ were identified as the best hybrids in this study, therefore, both hybrids should be broadly evaluated in multi-location trials and encouraged for adoption in environments with high NLB disease pressure.