Plasticity in maize: variability of reproductive traits in inbreds and derived hybrids with different tillering and prolificacy expression

Abstract

Context or problem: Prolificacy and tillering in maize are mechanisms of vegetative–reproductive plasticity that are particularly relevant at low plant densities. However, information on the genotypic variability of these traits in inbred lines and their derived hybrids remains limited.Objective or research question: This study aimed to characterize the variability on 25 vegetative-reproductive plasticity traits in six maize inbred lines and their fifteen derived hybrids, comparing their phenotypic expression, evaluating associations with plant grain yield, and quantifying the contribution of different plasticity mechanisms to plant grain yield within each genotypic group (inbreds and hybrids).Methods: A diallel experiment was conducted at late sowing date and low density, without limitations of water or nutrient.Results: Inbreds were characterized by a higher prolificacy of the main shoot, whereas hybrids exhibited greater tillers per plants and ears of tillers. The higher grain yield and kernel number per plant in hybrids compared to their parental inbreds was explained by an increased ear growth rate and reproductive efficiency of apical ears of the main shoot and ears of tillers. The analysis revealed that genotypes relied on different reproductive plasticity strategies to achieve plant grain yield. Among inbreds, four phenotypic expression patterns were identified (i.e., prolific, tillering, prolific–tillering, and low prolific-low tillering phenotypes), reflecting a wide range of plasticresponses. Notably, the prolific pattern was absent in hybrids.Conclusions: These results reveal broad genotypic variability within inbreds and derived hybrids analyzed and demonstrate diverse reproductive plasticity strategies that can contribute to grain yield per plant at low densities.Implications or significance: This study highlights the potential of vegetative-reproductive plasticity mechanisms as selection criteria in breeding programs for environments with variable resources, where farmers adopt defensive strategies such as low plant densities to mitigate reductions in maize grain yield due to water stress.