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Background Modern computational modeling could provide the key to obtaining new insights into the mechanisms of maize stalk failure as well as suggesting new ways to improve stalk strength. However, a complete set of mechanical properties of maize tissues is required to enable computational modeling of maize stems. This study developed two compression test methods for obtaining the longitudinal modulus of elasticity of both rind and pith tissues, assessed the influence of water content on tissue properties, and investigated the relationship between rind modulus and pith modulus. These methods involved uniform 5–7 cm segments of maize stems which were scanned using a flatbed scanner then tested in compression using a universal testing machine in both intact and dissected (rind-only and pith-only) states. Results The modulus of elasticity of pith tissues was highest for fully turgid specimens and decreased as water was removed from the specimens. Water content was negatively correlated with the modulus of elasticity of the rind. Rind and pith tissues were found to be weakly correlated. The median ratio of rind modulus to pith modulus was found to be 17. Of the two methods investigated, the pith-only specimen preparation was found to be simple reliable while the rind-only method was found to be adversely affected by lateral bowing of the specimen. Conclusions Researchers can use the information in this paper to improve computational models of maize stems in three ways: (1) by incorporating realistic values of the longitudinal modulus of elasticity of pith and rind tissues; (2) by selecting pith and rind properties that match empirically observed ratios; and (3) by incorporating appropriate dependencies between these material properties and water content. From an experimental perspective, the intact/pith-only experimental method outlined in this paper is simpler than previously reported methods and provides reliable estimates of both pith and rind modulus of elasticity values. Further research using this measurement method is recommended to more clearly understand the influence of water content and turgor pressure on tissue properties. 

Stalk lodging is the event of failure just below the ear or node. The most common failure mode is Brazier (localized) buckling, which occurs consistently near the node. Although maize stalk lodging has been a subject of study for many years, relatively little is known about the process and progression of stalk failure. Of particular interest is the issue of failure initiation. An understanding of failure initiation could be beneficial talks that are less susceptible to failure. The purpose of this study was to characterize the tissue-level failure patterns of maize stalks. Various techniques were used to examine the failure region, including imaging (scanning electron microscope, X-ray computed tomography, photographs of the failure progression), experimentation (surface strain measurements, quantification of cross-sectional ovalization). We found that ovalization occurs prior to stalk failure and that ovalization is generally correlated with the onset of buckling. However, ovalization was predictive of failure. Tissue-level analysis revealed that buckling occurs at many different scales, including organ (specifically the stalk) level, tissue level, cellular level, and at the level of the cell wall. Based on our observations, we propose a new conceptual model for stalk failure that makes sense of the mixed data on this topic. This model states that the probability of tissue and buckling failure rise together in a highly correlated fashion and that when one failure mode occurs, it immediately initiates the corresponding mode. This information provides new insights into maize stalk failure and suggests that efforts to improve stalk strength will need to address both tissue strength and buckling resistance simultaneously.