The elastic modulus for maize stems

Al-Zube, Loay; Sun, Wenhuan; Robertson, Daniel J.; Cook, Douglas D.

doi:10.1186/s13007-018-0279-6

Cited by 60 publications

(45 citation statements)

References 28 publications

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“…However, previous research has shown the inclusion of these effects to be small and in many cases insignificant. The authors do not believe inclusion of such effects would change the overall conclusions of this paper (Von Forell et al ., 2015; Al-Zube et al ., 2018).…”

Section: Discussionmentioning

confidence: 99%

Are Maize Stalks Efficiently Tapered to Withstand Wind Induced Bending Stresses?

Stubbs

Seegmiller

Sekhon

et al. 2020

Preprint

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structural 19 Highlight: Maize stem morphology was investigated through an optimization algorithm to 20 determine how efficiently their structural tissues are allocated to withstand wind induced bending 21 stresses that cause stalk lodging.Abstract 24 Stalk lodging (breaking of agricultural plant stalks prior to harvest) results in millions of 25 dollars in lost revenue each year. Despite a growing body of literature on the topic of stalk lodging, 26the structural efficiency of maize stalks has not been investigated previously. In this study, we 27 investigate the morphology of mature maize stalks to determine if rind tissues, which are the major 28 load bearing component of corn stalks, are efficiently organized to withstand wind induced 29 bending stresses that cause stalk lodging. 30 945 fully mature, dried commercial hybrid maize stem specimens (48 hybrids, ~2 31 replicates, ~10 samples per plot) were subjected to: (1) three-point-bending tests to measure their 32 bending strength and (2) rind penetration tests to measure the cross-sectional morphology at each 33 internode. The data were analyzed through an engineering optimization algorithm to determine the 34 structural efficiency of the specimens. 35Hybrids with higher average bending strengths were found to allocate rind tissue more 36 efficiently than weaker hybrids. However, even strong hybrids were structurally suboptimal. 37There remains significant room for improving the structural efficiency of maize stalks. Results 38 also indicated that stalks are morphologically organized to resist wind loading that occurs primarily 39 above the ear. Results are applicable to selective breeding and crop management studies seeking 40 to reduce stalk lodging rates. 41 65 to devote to grain filling as compared to inefficient stalks (i.e., efficient stalks would have a higher 66 harvest index). 67As mentioned previously, both the taper and probable wind loading scenarios must be 68 defined to determine the structural efficiency of maize stalks. The wind load exerted on a plant 69 stalk, known as the drag force (Df), can be approximated as (Niklas, 2000):where ⍴ is the density of air, u is the local wind speed, Ap is the projected area of the structure, and 72 CD is the drag coefficient. While this equation appears fairly simple at first glance, it is 73 complicated by the fact that the variables on the right hand side of the equation are functions that 74 can vary both temporally and spatially. For example, the drag coefficient changes spatially along 75 the length of the stalk and is also a function of the local wind speed. As the local wind speed 76 increases, the angle of the leaf blades and tassel change (known as flagging), which alters the drag 77 coefficient. 78The strong interrelationships between the factors of Equation 1 complicate attempts to 79 directly measure wind forces on maize stalks. Direct measurements of wind speeds have 80 successfully been used to estimate drag forces in past studies of trees (Niklas and Spatz, 1999; 81 Niklas, 2000). However, t...

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Section: Discussionmentioning

confidence: 99%

Are Maize Stalks Efficiently Tapered to Withstand Wind Induced Bending Stresses?

Stubbs

Seegmiller

Sekhon

et al. 2020

Preprint

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“…Using the force-displacement response of the specimen from the bending experiments, a flexural stiffness value was calculated for each specimen (Beer et al ). CT-based geometry of the internodal region was then extracted from the internodal region, and used to calculate the longitudinal Young’s modulus of the rind, E’ (Al-Zube et al , 2018). The remaining material properties were calculated based on ratios derived from prior research, tests performed in our lab, and judicious estimates.…”

Section: Methodsmentioning

confidence: 99%

Maize Stem Buckling Failure is Dominated by Morphological Factors

Larson²,

Dd³

2019

Preprint

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This study utilized physical and in silico experiments to confirm that geometric parameters are far 30 more influential in determining stalk strength than mechanical tissue stiffnesses. Abstract 32The maize (Zea mays) stem is a biological structure that must both balance biotic and structural 33 load bearing duties. These competing requirements are particularly relevant in the design of new 34 bioenergy crops. With the right balance between structural and biological activities, it may be 35 possible to design crops that are high-yielding and have digestible biomass. But increased stem 36 digestibility is typically associated with a lower structural strength and higher propensity for 37 lodging. This study investigates the hypothesis that geometric factors are much more influential in 38 determining structural strength than tissue properties. To study these influences, both physical and 39 in silico experiments were used. First, maize stems were tested in three-point bending. Specimen-40 specific finite element models were created based on x-ray computed tomography scans. Models 41 were validated by comparison with in vitro data. As hypothesized, geometry was found to have a 42 much stronger influence on structural stability than material properties. This information 43 reinforces the notion that deficiencies in tissue strength could be offset by manipulation of stalk 44 morphology, thus allowing the creation of stalks with are both resilient and digestible. 45 46 47 48 49 50 51 52 53

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“…We expect to see a distinct relationship between k and span length because diameter influences the ratio of span length to diameter. Due to the layering of the dermal tissues with the internal vasculature, we treated BRs as a “sandwich structured” polymer matrix composite (Al-Zube et al 2018). According to ASTM Standards D726, ideal span length to sample diameter ratio for such composites is 16:1.…”

Section: Resultsmentioning

confidence: 99%

“…The mechanical characterization of plant tissues is particularly advantageous for investigating stress response and failure modalities involved in crop damage. Engineering theory and mechanical testing methodologies have been employed to examine the effects of mechanical stress on development in a variety of plants including tomatoes (Coutand et al 2000), trees (Dean et al 2002), barley (Kokubo et al 1989) and maize (Robertson et al 2015a, 2015b, 2016, 2017; Al-Zube et al 2017, 2018; Stubbs et al 2019). In particular, Robertson et al (Robertson et al 2015a) used mechanical testing in maize to investigate the interplay between stalk strength and stalk lodging resistance.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, Robertson et al (Robertson et al 2015a) used mechanical testing in maize to investigate the interplay between stalk strength and stalk lodging resistance. Another study compared the mechanical properties of maize stems using different loading strategies: tension, compression, and 3-point bending (Al-Zube et al 2018). Resulting elastic moduli were reproducible among the three testing approaches (test-to-test variation < 5%), but sample preparation involved in 3-point bending was the simplest.…”

Section: Introductionmentioning

confidence: 99%

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Maize brace root mechanics vary by whorl, genotype, and reproductive stage

Erndwein

Ganji

Hostetler

et al. 2019

Preprint

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1As the world faces the challenge of feeding a growing population and increasingly 2 unpredictable weather patterns, it is important to understand the plant features that will sustain 3 food production under stress. One type of stress that plants experience is mechanical, and 4 crops are susceptible to yield loss is by mechanical failure, called lodging. Brace roots (BR), 5 aerial nodal roots of maize (Zea mays L.), are proposed to impart mechanical stability on plants, 6 but little is known about the properties of BR that contribute to this function. Here, we define a 3-7 point bending method to test the comparative biomechanics of maize BRs within and between 8 plants. We show that BR stiffness does not vary significantly within a plant neither along the 9 length of a BR nor between BRs of different whorls. However, there are significant differences 10 between plants of the same genotype. The differences manifested from variable BR diameter 11 and thus nonideal span lengths for 3-point bending. The results presented here provide the 12 foundation for widespread evaluation of BR mechanical properties and understanding their link 13 to plant mechanical stability.

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The elastic modulus for maize stems

Cited by 60 publications

References 28 publications

Are Maize Stalks Efficiently Tapered to Withstand Wind Induced Bending Stresses?

Are Maize Stalks Efficiently Tapered to Withstand Wind Induced Bending Stresses?

Maize Stem Buckling Failure is Dominated by Morphological Factors

Maize brace root mechanics vary by whorl, genotype, and reproductive stage

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