Southern South American maize landraces: a source of phenotypic diversity

Maize ( Zea mays L.) is a vital food and industrial crop, but breeding progress is constrained by the narrow genetic diversity of commercial varieties, derived from few inbred lines. Conversely, maize landraces offer rich genetic and phenotypic diversity. Northern Argentina, one of the southernmost regions for maize landrace cultivation, hosts ≈57 distinct landraces. These landraces are grouped into two main genetic clusters linked to contrasting agroecosystems: Northwestern (NWA, > 2000 m.a.s.l.) and Northeastern (NEA, < 2000 m.a.s.l.) Argentine maize groups. Examining overlooked phenotypic traits of agricultural value, such as biochemical characteristics and stress tolerance, in these landraces can inform conservation and breeding strategies. We evaluated 17 phenotypic traits, including morphological traits, leaf biochemical compounds, and seedling salt stress tolerance, in 19 maize landrace accessions from Northern Argentina. Substantial variation was detected across all traits, both within and among accessions, indicating that each accession harbors a distinct phenotypic profile. Although univariate analyses did not reveal significant differences between regions, redundancy analysis revealed associations between phenotypic variation and collection-site altitude. These findings highlight the value of Argentine maize landraces as sources of biochemical and stress-related traits and support their conservation and use in breeding programs aimed at broadening the genetic base of cultivated maize.