Genetic control of reproductive plasticity through prolificacy and tillering in maize

Context Prolificacy and tillering have not been traditional targets of maize breeding programs. As agriculture expands into marginal environments, these traits may become increasingly relevant under low plant densities. Nevertheless, knowledge of their genetic basis remains limited, restricting their incorporation into breeding strategies. Aims This study aimed to (i) estimate genetic variance components, broad-sense (H2) and narrow-sense (h2) heritabilities, general and specific combining ability (GCA and SCA), and mid-parent heterosis (MPH) for nine vegetative–reproductive plasticity traits; and (ii) identify secondary traits with high heritability and strong genetic correlations with grain yield for indirect selection. Methods A half-diallel field experiment involving six maize inbreds and 15 single-cross hybrids was conducted over two growing seasons under late sowing and low plant density (3 plants m−2), with non-limiting water and nutrient supply. Key results Ear number from tillers, tillers per plant and tiller prolificacy showed high H2 (>0.84) and h2 (>0.74), predominance of GCA (>68%) and positive MPH (13–54%). These traits were positively genetically correlated with ear number per plant and kernel number from tiller ears. Main shoot prolificacy exhibited high H2 (0.87) but low h2 (0.44), reflecting greater SCA contribution (64%), and low genetic correlation with tillers per plant. Conclusions Tillering and prolificacy-related traits are promising indirect selection criteria. Improving reproductive plasticity requires combining selection for additive effects on tillering with specific parental combinations that enhance prolificacy. Implications Incorporating tillering and prolificacy traits into breeding programs may contribute to developing maize genotypes better adapted to marginal environments and low plant densities.