Assessment of root architecture traits in seedlings of Algerian maize populations grown under two nitrogen levels

Despite the critical role played by roots for the acquisition of water and nutrients from the soil, especially in stressful conditions; root characteristics are rarely utilized as selection criteria to improve nutrient uptake efficiency in maize breeding programs. In this study, seedlings of twelve Algerian maize populations with two commercial maize hybrids were evaluated to: (i) study the phenotypic variation of nine root traits under low nitrogen (LN) and high nitrogen (HN) levels and (ii) determine root traits accounting for most of the phenotypic variation among the evaluated populations. High phenotypic diversity was observed for all studied traits under both N levels. Under LN conditions, seedlings adapt by rapidly increasing their root systems to exploit nitrogen (N) resources, resulting in significant increases in primary root length (PRL), seminal root length (SRL), seminal root number (SRN), and total root length (TRL). Conversely, shoot dry weight (SDW) decreased. The first two principal components explained 73.46 and 74.82% of the total variation among the maize populations under LN and HN conditions, respectively. Thus, root dry weight (RDW) and TRL were major contributors of the phenotypic variation. In addition, RDW and TRL were significantly correlated with most of the other traits under both N levels. Therefore, during the seedling stage, RDW and TRL can be used as favorable selection criteria. This diversity gives opportunities for enhancing N use efficiency, potentially leading to reducing N fertilizer requirements. As a result, this can contribute to reduce input costs and maintaining environmental quality.