Maize brace root biomechanics are determined by geometry within a genotype and material properties between genotypes

Crop plants are susceptible to yield loss by mechanical failure, which is called lodging. In maize ( Zea mays ), aerial nodal brace roots impart mechanical stability to plants, with previous studies showing that the lowest whorl of brace roots contributes the most. The features of brace roots that determine their contribution to mechanical stability are poorly defined. Here we tested the hypothesis that brace root mechanical properties vary between whorls, which may influence their contribution to mechanical stability. 3-point bending tests were used to determine that brace roots from the lowest whorl have the highest structural mechanical properties regardless of growth stage, and that these differences are largely due to brace root geometry within a genotype. Analysis of the brace root bending modulus determined that differences between genotypes are attributable to both geometry and material properties. These results support the role of brace root biomechanics to determine the brace root contribution to mechanical stability. HIGHLIGHT Brace root biomechanics vary within and between genotypes. These results support the importance of biomechanics to define the contribution of brace roots to mechanical stability. ### Competing Interest Statement The authors have declared no competing interest. * (E) : Bending Modulus (BWR) : Bottom Whorl (BL) : Break Load (CT) : Computed Tomography (DC) : Digital Caliper (MWR) : Middle Whorl (MOI) : Moment of Inertia (K) : Structural Stiffness (TWR) : Top Whorl (UL) : Ultimate Load