Stalk lodging (mechanical failure of stalks or stems before harvest) is a major problem in grain production that significantly reduces yield. Efforts to improve stalk lodging are hampered by a limited understanding of the determinants of stalk failure. This study examined the structural bending properties and material bending properties of maize () stalks. First, an in-field phenotyping device known as DARLING (Device for Assessing Resistance to Lodging In Grains) was used to determine structural properties of maize stalks. Stalks were then subjected to a rind penetration protocol and morphological measurements were acquired. Finally, small strips of rind tissue were excised from the stalks and micro three-point bending tests were conducted to determine the material properties of the rind tissue. Results showed that the material bending strength of the rind tissue was approximately twice as large as the bending stresses present in the rind tissue when failure occurred during field testing. This indicates that stalks ultimately fail due to some form of buckling (i.e., structural failure) as opposed to material failure. This result is relevant to genetic and breeding studies seeking to address the problem of stalk lodging. In particular, these results suggest that improvements in stalk lodging resistance should focus on the stalk's geometric features, such as the ratio of rind thickness to diameter, rather than solely on enhancing material strength. For the samples in this study, material strength ranged between 64 and 197 MPa whereas material stiffness ranged between 4 and 12 GPa. Rind penetration resistance was found to be a good predictor of material properties but a poor predictor of structural properties.

中文翻译：

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结构弯曲特性与材料弯曲特性对玉米秆倒伏的影响


茎倒伏（收获前茎或茎的机械损坏）是粮食生产中的一个主要问题，会显着降低产量。对茎秆衰竭的决定因素了解有限，阻碍了改善茎秆倒伏的努力。本研究考察了玉米秆的结构弯曲性能和材料弯曲性能。首先，使用称为 DARLING（谷物抗倒伏评估装置）的田间表型装置来确定玉米秆的结构特性。然后对茎进行外皮穿透实验并获得形态测量结果。最后，从茎上切下小条的外皮组织，并进行微三点弯曲试验以确定外皮组织的材料特性。结果表明，外皮组织的材料弯曲强度大约是现场测试中发生失效时外皮组织中存在的弯曲应力的两倍。这表明茎最终由于某种形式的屈曲（即结构失效）而不是材料失效而失效。这一结果与寻求解决茎倒伏问题的遗传和育种研究相关。特别是，这些结果表明，茎秆抗倒伏性的改进应集中在茎秆的几何特征上，例如外皮厚度与直径的比率，而不仅仅是提高材料强度。对于本研究中的样品，材料强度范围在 64 至 197 MPa 之间，而材料刚度范围在 4 至 12 GPa 之间。人们发现，外皮穿透阻力可以很好地预测材料性能，但不能很好地预测结构性能。