Genetic Analysis of White Maize (Zea Mays L.) Inbred Lines Under Low Soil Nitrogen

Low soil nitrogen (N) is among the major constraints causing low grain yield of maize in sub-Saharan Africa. This study was conducted to (i) determine the level of tolerance of the hybrids under low-N, (ii) examine the mode of inheritance of grain yield and other traits of the inbreds, and (iii) assess the genetic diversity of the inbreds. Ninety-one hybrids developed from fourteen inbred lines using diallel mating design together with nine hybrid checks were evaluated under low (30 kg N ha-1) and optimum (90 kg N ha-1) nitrogen conditions at the KNUST Maize Breeding Pipeline in 2024. The results revealed a preponderance of the general combining ability (GCA) effect over specific combining ability (SCA) effects for the traits under low-N, optimum, and across environments, indicating that additive gene action is more important in the inheritance of the traits. The inbreds were classified into three clusters based on the GCA effect of multiple traits of inbreds (HGCAMT). Inbred lines CML 126, TZEEI-76, and USTEWI-7 were identified as the best testers for clusters 1, 2, and 3 respectively. Out of the best 15 and the worst 10 performing hybrids selected based on the base index, USTEWI-7 × USTEWI-11 and TZEEI-50 × TZEEI-4 were identified as the highest yielding and low nitrogen tolerant hybrids. The tolerant hybrids identified should be extensively evaluated to verify their consistency in performance under low nitrogen conditions. Inbred lines with desirable traits could be utilized to develop low nitrogen tolerant hybrids in maize breeding programs.