Maize Stem Buckling Failure is Dominated by Morphological Factors

Oduntan

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18Background: Stalk lodging (breaking of agricultural plant stalks prior to harvest) is a multi-19 billion dollar a year problem. Stalk lodging occurs when bending moments induced by a 20 combination of external loading (e.g. wind) and self-loading (e.g. the plant's own weight) exceed 21 the bending strength of plant stems. Previous biomechanical plant stem models have 22 investigated both external loading and self-loading of plants, but have evaluated them as separate 23 and independent phenomena. However, these two types of loading are highly interconnected and 24 mutually dependent. The purpose of this paper is twofold: (1) to investigate the combined effect 25 of external loads and plant weight on the displacement and stress state of plant stems / stalks, and 26(2) to provide a generalized framework for accounting for self-weight during mechanical 27 phenotyping experiments used to predict stalk lodging resistance. 28 Results: A method of properly accounting for the interconnected relationship between self-loading 29 and external loading of plants stems is presented. The interconnected set of equations are used to 30 produce user-friendly applications by presenting (1) simplified self-loading correction factors for 31 a number of common external loading configurations of plants, and (2) a generalized Microsoft 32 Excel framework that calculates the influence of self-loading on crop stems. The effect of self-33 loading on the structural integrity of wheat is examined in detail. A survey of several other plants 34 is conducted and the influence of self-loading on their structural integrity is also presented. 35 Conclusions: The self-loading of plants plays a potentially critical role on the structural integrity 36 of plant stems. Equations and tools provided herein enable researchers to account for the plant's 37 weight when investigating the flexural rigidity and bending strength of plant stems. 38 39 40 42 estimated to range from 5-20% annually [1,2]. Despite a growing body of literature surrounding 43 the topic of stalk lodging in wheat, barley, oats, and maize [3-7], a detailed study on the 44 interconnected relationship between external loading (e.g. wind) and self-loading (e.g. plant 45 weight) on stalk bending strength has not been reported. Previous biomechanical plant stem 46 models have examined the influence of morphology, material, and weight on stem failure, while 47 others have separately analyzed the effects of externally induced bending forces (e.g., wind) on 48 stem failure [3,4,8-15]. However, the effects of self-weight and external loads on stem failure are 49 inextricably connected. The bending moment induced from self-weight is a function of the 50 distance between the plant's base and its center of gravity. As external loads displace the center of 51 gravity away from the base of the stem, the bending moment induced from self-weight 52 increases. Although previous studies have independently looked at external loads [4,5,16] and 53 self-weight loading [3], the authors are not aware of previ...

Section: Methodsmentioning

confidence: 99%

The Effect of Self-Loading on the Mechano-Stability and Stalk Lodging Resistance of Plant Stems

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“…The plant stem was modeled with the radius values such that that the resulting moments of inertia were as presented in Table 2 Table 2 presents each of these factors and the levels of each factor used in the experiment. The level of each factor (i.e., the value of input parameters to the model) were based on previous studies of plant stem material properties [21,22].…”

Section: Finite Element Modeling To Confirm Accuracy Of New Closed Fomentioning

confidence: 99%

The Effect of Plant Weight on Estimations of Stalk Lodging Resistance

Oduntan

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et al. 2020

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Background: Stalk lodging (breaking of agricultural plant stalks prior to harvest) is a multi-billion dollar a year problem. Stalk lodging occurs when bending moments induced by a combination of external loading (e.g. wind) and self-loading (e.g. the plant’s own weight) exceed the stalk bending strength of plant stems. Previous studies have investigated external loading and self-loading of plants as separate and independent phenomena. However, these two types of loading are highly interconnected and mutually dependent. The purpose of this paper is twofold: (1) to investigate the combined effect of external loads and plant weight on the flexural response of plant stems, and (2) to provide a generalized framework for accounting for self-weight during mechanical phenotyping experiments used to predict stalk lodging resistance. Results: A mathematical methodology for properly accounting for the interconnected relationship between self-loading and external loading of plants stems is presented. The method was compared to numerous finite element models of plants stems and found to be highly accurate. The resulting interconnected set of equations from the derivation were used to produce user-friendly applications by presenting (1) simplified self-loading correction factors for common loading configurations of plants, and (2) a generalized Microsoft Excel framework that calculates the influence of self-loading on crop stems. Results indicate that ignoring the effects of self-loading when calculating stalk flexural stiffness is appropriate for large and stiff plants such as maize, bamboo, and sorghum. However, significant errors result when ignoring the effects of self-loading in smaller plants with larger relative grain sizes, such as rice (8% error) and wheat (16% error).Conclusions: Properly accounting for self-weight can be critical to determining the structural response of plant stems. Equations and tools provided herein enable researchers to properly account for the plant’s weight during mechanical phenotyping experiments used to determine stalk lodging resistance.

“…As a point of validation [27] (1) the material properties of the stalk tissues and (2) the geometry of the stalk (e.g., the stalks section modulus, diameter, rind thickness etc. [28,29]). While both geometry and material properties are important prior research has shown that the geometry of the stalk is more influential on bending strength as compared to material properties [23,28,29].…”

Section: Comparison Of Integrated Puncture Score To Empirical Modelmentioning

confidence: 99%

“…[28,29]). While both geometry and material properties are important prior research has shown that the geometry of the stalk is more influential on bending strength as compared to material properties [23,28,29]. Interestingly, the traditional rind penetration method measures puncture force (i.e., a material property of the rind tissue) but does not account for key geometric features of the stalk (e.g., diameter) which are more influential.…”

Section: Comparison Of Integrated Puncture Score To Empirical Modelmentioning

confidence: 99%

“…For example, repeated selection for rind penetration resistance has been shown to produce stalks with smaller diameters [6]. Stalks with smaller diameters are known to be structurally inferior to stalks with larger diameters [23,29,33]. Thus, using rind penetration resistance as a selective breeding metric can produce stalks with a structurally disadvantageous morphology.…”

Section: Introductionmentioning

confidence: 99%

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Integrated Puncture Score: Force-Displacement Weighted Rind Penetration Tests Improve Stalk Lodging Resistance Estimations in Maize

McMahan

Seegmiller

et al. 2020

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Background: Stalk lodging (breaking of agricultural plant stalks prior to harvest) is a multi-billion dollar a year problem. Rind penetration resistance tests have been used by plant scientists and breeders to estimate the stalk lodging resistance of maize for nearly a hundred years. However, the rind puncture method has two key limitations: (1) the predictive power of the test decreases significantly when measuring elite or pre-commercial hybrids, and (2) using rind penetration measurements as a breeding metric does not necessarily create stronger stalks. In this study, we present a new rind penetration method called the Integrated Puncture Score, which uses a modified rind penetration testing protocol and a physics-based model to provide a robust measure of stalk lodging resistance. Results: Two datasets, one with a diverse array of maize hybrids and one with only elite hybrids, were evaluated by comparing traditional rind penetration testing and the Integrated Puncture Score method to measurements of stalk bending strength. When evaluating the diverse set of hybrids, both methods were good predictors of stalk bending strength (R2 values of 0.67). However, when evaluating elite hybrids, the Integrated Puncture Score had an R2 value of 0.74 whereas the traditional method had an R2 value of 0.48. Additionally, the Integrated Puncture Score was able to differentiate between the strongest and weakest hybrids in the elite hybrid data set whereas the traditional rind penetration method was not. Additional experiments revealed strong evidence in favor of the data aggregation steps utilized to compute the Integrated Puncture Score. Conclusions: This study presents a new method for evaluating rind penetration resistance that highly correlates with stalk bending strength and can possibly be used as a breeding index for assessing stalk lodging resistance. This research lays the foundation required to develop a field-based high-throughput phenotyping device for stalk lodging resistance.