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Dryad

Phenotypic characterization of southeastern United States open-pollinated maize landraces

Abstract

Maize is the most important crop in the United States, but food production and niche uses such as distilling often rely on varieties that are not bred explicitly for these purposes. Farmers targeting niche food grain markets have expressed interest in historical open-pollinated varieties of maize, but few such populations are widely available, and even fewer are well-characterized. We planted field trials of a subset of 76 open-pollinated heirloom varieties available from catalogs and the USDA germplasm collection along with four F1 hybrid cultivars. We measured 24 traits across three years and three locations to characterize the selected varieties and measure their phenotypic relationships. We identified a subset of 19 traits useful for phenotypic analysis. Our results demonstrate that many historical accessions contain substantial genetic variation that should permit improvement from within-population selection. Variety name and origin are often not useful indicators of phenotypic relationships or potential crop value. Cluster analysis identifies nine morphologically distinct groups within the varieties tested, which are not fully in agreement with currently accepted landrace groupings, suggesting a need for genetic analysis of larger samples of USA open-pollinated populations to better define the natural classification of maize indigenous to the United States.