Generation mean analysis of yield, nutritional quality, and fall armyworm resistance in provitamin A quality protein maize under natural infestation

It is crucial to develop nutritionally enhanced maize with stable agronomic performance across environments to combat malnutrition in sub-Saharan Africa. Generation Mean Analysis (GMA) was employed to elucidate the inheritance patterns, genetic parameters, and genotype × environment interactions (GEI) governing grain yield, tryptophan, and provitamin A carotenoid concentrations in quality protein maize (QPM). Two genetically divergent inbred lines, TZEEIORQ 10 (nutrient-dense and agronomically improved) and TZEEI-4 (not nutrient-dense), were crossed to produce six generations (P1, P2, F1, F2, BC1P1, and BC1P2 and evaluated under natural Fall Armyworm (FAW) infestation at two locations over two years. GMA suggested that the major component of inheritance of these traits was through additive gene action, while dominance and epistatic effects played a significant role in some environments. The F1 hybrids exhibited positive heterosis for agronomic and nutritional traits, and trait expression declined slightly in F2 due to genetic recombination. However, the backcrosses, especially BC1 (F1 × TZEEIORQ 10), carried higher values for the traits, thus indicating the additive contribution of the elite parent. GEI analysis showed that genotype and environment individually accounted for substantial variation, with genotype × environment interactions contributing 14–16%. The additive main effects and multiplicative interaction analyses identified genotypes with broad adaptability and high performance. The results confirmed that significant genotypic effects accounted for 45.2% of the variation in grain yield, with additive gene effects predominating. The results would offer information for breeding provitamin A-enriched QPM cultivars that are better resistant to FAW and adaptable to variable agroecologies.