Browsing by Author "Erndwein, Lindsay"
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Item Applying mechanical testing strategies to maize brace roots(University of Delaware, 2021) Erndwein, LindsayCorn (Zea mays L.; Maize) is the top food crop cultivated worldwide and the United States alone is responsible for about 40% of the global supply. In the wake of rising global population demands, farmers need to maximize crop yields with limited land resources. Two environmental stresses that jeopardize maize cultivation and limit yields are weather and insect herbivory. Wind applies a horizontal force to stalks that can result in plant uprooting, a phenomenon known as root lodging. To reduce the negative effects of root lodging, research is needed to investigate the plant features that may contribute to lodging-resistance. One plant feature that may promote root lodging-resistance in maize is the presence of brace roots that form at stem nodes above the soil. Brace roots are proposed to enable maize plants to resist root lodging and facilitate nutrient absorption, but these functions have not been directly tested. I hypothesize that brace roots contribute to plant anchorage, the biomechanics of brace roots enhances this contribution, and that breeding maize for insect herbivory may influence brace root mechanical performance. My research uses a combination of mechanical testing methods (field-based bending tests, 3-point bend tests) and imaging techniques (MicroCT, fluorescence microscopy) to investigate the link between brace root biomechanics and their contribution to plant anchorage. My results show that: (1) maize brace roots are important to root anchorage, the extent of which varies with genotype (2) brace root whorls closest to the soil measure a higher contribution to root anchorage and higher structural mechanical properties, (3) brace root biomechanics may be a factor in increasing their contribution to plant anchorage, and (4) breeding maize for insect resistance traits may compromise plant anchorage. The results of my research provide a foundation for targeting brace roots to promote lodging resistance in maize and other cereal cropsItem Maize brace root mechanics vary by whorl, genotype, and reproductive stage(Annals of Botany, 2022-03-03) Hostetler, Ashley N.; Erndwein, Lindsay; Ganji, Elahe; Reneau, Jonathan W.; Killian, Megan L.; Sparks, Erin E.Background and Aims: Root lodging is responsible for significant crop losses world-wide. During root lodging, roots fail by breaking, buckling, or pulling out of the ground. In maize, above-ground roots, called brace roots, have been shown to reduce root lodging susceptibility. However, the underlying structural-functional properties of brace roots that prevent root lodging are poorly defined. In this study, we quantified structural mechanical properties, geometry, and bending moduli for brace roots from different whorls, genotypes, and reproductive stages. Methods: Using 3-point bend tests, we show that brace root mechanics are variable by whorl, genotype, and reproductive stage. Key Results: Generally, we find that within each genotype and reproductive stage, the brace roots from the first whorl (closest to the ground) had higher structural mechanical properties and a lower bending modulus than brace roots from the second whorl. There was additional variation between genotypes and reproductive stages. Specifically, genotypes with higher structural mechanical properties also had a higher bending modulus, and senesced brace roots had lower structural mechanical properties than hydrated brace roots. Conclusions: Collectively these results highlight the importance of considering whorl-of-origin, genotype, and reproductive stage for quantification of brace root mechanics, which is important for mitigating crop loss due to root mechanical failure.