Stalk lodging (the structural failure of plant stems prior to harvest) remains a major constraint to global cereal crop production, reducing yields, impairing grain quality, and increasing harvest losses. Since cellulose microfibrils are the primary load-bearing components in plant cell walls, the microfibril angle is widely considered a critical determinant of stalk mechanical properties. X-ray diffraction is a common technique for microfibril angle measurement, yet its applicability to cereal crops has not been fully validated. This study assessed the utility of X-ray diffraction based microfibril angle measurements for maize (Zea mays) and sorghum (Sorghum bicolor) stalks using the T-parameter method. Rind tissue samples from multiple maize and sorghum genotypes were analyzed using two diffractometers with copper (Cu) and molybdenum (Mo) X-ray sources. Corresponding internodes were also evaluated for rind penetration resistance, material bending stiffness, and bending strength to test whether measured microfibril angles reflected biologically meaningful variation. Across all genotypes and internodes, including preliminary observations from phenotypic extremes in select groups, microfibril angle values were highly uniform, with maize averaging 24.6 degrees (Cu) and 29.1 degrees (Mo) and sorghum averaging 24.3 degrees (Cu) and 29.4 degrees (Mo). microfibril angles exhibited extremely low variability (coefficient of variation < 3.3%), in stark contrast to the much higher variability observed in mechanical properties (CV = 20.5-47.1%). Systematic differences of similar to 20% between Cu- and Mo-based measurements were consistent across sample groups. Correlations between microfibril angle and mechanical properties were weak or absent; only Cu-derived microfibril angle showed a marginal relationship with bending stiffness, while Mo-derived microfibril angle showed no significant correlations. Pooled analyses further confirmed that microfibril angle remained nearly constant despite a wide range of mechanical property values. Collectively, these findings demonstrate that X-ray diffraction based microfibril angle measurements using the T-parameter method have limited applicability to cereal stalk tissues, as the method failed to capture biologically relevant variation. The uniformity of measured angles, lack of correlation with mechanical properties, and dependence on X-ray source raise concerns about the suitability of this method for maize and sorghum. These results highlight the need for refined or alternative microfibril angle measurement techniques to better understand the role of cellulose microfibril orientation in stalk lodging resistance.

Stalk lodging causes global maize (Zea mays L.) yield losses exceeding $6 billion annually. The poorly resolved genetic architecture of stalk lodging resistance, a key determinant of the ability of a plant to remain upright, poses a major constraint for genetic improvement. Characterizing natural variation in plant traits that influence stalk strength across multiple biological scales, referred to as intermediate phenotypes, is critical for enhancing lodging resistance. Here, we present a high-density phenotypic dataset comprising 11 intermediate phenotypes measured on 31,260 stalks from a maize diversity panel of 566 inbred lines grown in four environments. The dataset captures variation in structural and geometric properties of stalks and provides a foundation for genetic mapping, predictive modeling, and machine learning analyses to dissect the genetic basis of stalk lodging resistance. Moreover, trait-level resolution across a genetically diverse panel enables evaluation of the relative contribution of individual phenotypes to stalk strength. Beyond maize improvement for grain and forage production, this dataset offers valuable opportunities for improving stalk lodging resistance in other grasses.

The world has food security needs that are currently not being met. Stalk lodging undermines crop productivity and incurs global yield losses of at least $6 billion in maize ( Zea mays L.). Genetic architecture of stalk lodging resistance, a measure of the ability of the stalk to withstand lodging, remains poorly resolved, creating a bottleneck for genetic improvement. Identification of diverse plant traits at multiple length scales of biological organizations that contribute to stalk lodging resistance and characterization of natural variation for these traits is critical for improving stalk lodging resistance. We identified and evaluated 11 intermediate phenotypes, traits associated with stalk lodging resistance, in a maize diversity panel of 566 inbred lines evaluated over four environments. The identity of each of the 31,260 stalks evaluated in the study was preserved throughout the phenotyping pipeline which enabled capturing variation at the individual plant level. This high-density phenotypic dataset provided a foundation for statistical genomics, predictive modeling, and machine learning analyses to identify genes and genetic elements underlying stalk lodging resistance. Additionally, phenotypic characterization of multiple intermediate phenotypes on a diverse set of inbred lines provided excellent opportunities to understand the relative contribution of these traits to stalk lodging resistance. Besides improvement of maize for grain and animal feedstock, the inferences from this data will be valuable for improvement of stalk lodging resistance in other grass species. ### Competing Interest Statement The authors have declared no competing interest. * ⁰C : degrees Celsius cm : Centimeter ex-PVP : Expired Plant Variety Protection Act certificate KY : Kentucky mm : Millimeter N : Newton Nm : Newton*meter PVC : Polyvinyl chloride RH : Relative humidity SC : South Carolina

Additive manufacturing of composites composed of wood residues and ecofriendly binders such as sodium silicate could reduce the carbon footprint of the construction industry. In this paper the spatially varying mechanical behavior of a single layer of a 3D-printed wood-sodium silicate composite with a 50:50 wt.% known as PrinTimber was investigated. Flexural testing revealed the outer edges of a single printed layer of composite material exhibited greater strength compared to the inner regions of the same sample. Furthermore, tensile tests demonstrated that the longitudinal modulus of elasticity of a single layer was lower than the transverse modulus of elasticity of the same layer. Optical images revealed the 3D printing process tended to arrange wood fibers in a particular manner. The unique fiber arrangement within the layer explains the observed directional dependent response of the sample.

Breeding for stalk lodging resistance is of paramount importance to maintain and improve maize (Zea mays L.) yield and quality and meet increasing food demand. The integration of environmental, phenotypic, and genotypic information offers the opportunity to develop genomic prediction strategies that can improve the genetic gain for complex traits such as stalk lodging. However, implementation of genomic predictions for stalk lodging resistance has been sparse primarily due to the lack of reliable and reproducible phenotyping strategies. In this study, we measured 10 traits related to stalk lodging resistance obtained from a novel phenotyping platform on approximately 31,000 individual stalks. These traits were combined with environmental information and whole-genome resequence data to investigate the predictive ability of different single and multi-environment genomic prediction models. In total, 555 maize inbred lines from the Wisconsin diversity panel were evaluated in four environments. The multi-environment models more than doubled the prediction accuracy compared to the single-environment model for most traits, particularly when predicting lines in a sparse testing design. Predictive correlations for stalk bending strength and stalk flexural stiffness, a nondestructive method for assessment of stalk lodging resistance, were moderately high and ranged between 0.32-0.89 and 0.26-0.88, respectively. In contrast, rind thickness was the most difficult trait to predict. Our results show that the use of multi-environmental data could improve genomic prediction accuracy for stalk lodging resistance and its intermediate phenotypes. This study will serve as a first step toward genetic improvement and the development of maize varieties resistant to stalk lodging.

Additive manufacturing of wood-sodium silicate composites could aid in mitigating the carbon footprint of the building and construction industry. However, the effect of postmanufacture conditioning on the mechanical and physical properties of additively manufactured wood-sodium silicate composites is not well understood. This study investigated eight different postmanufacture drying processes, including: ambient indoor and outdoor conditions, oven-drying at two different temperatures, microwave drying, alcohol-induced dehydration using ethanol and denatured alcohol, and desiccant drying. Each postmanufacture conditioning treatment was assessed in terms of total moisture extraction and moisture extraction rate as well as the flexural strength, flexural stiffness, and hardness of the wood-sodium silicate samples after drying. In addition, the water absorption and volumetric swelling properties of the additively manufactured wood-sodium silicate samples were assessed via water submersion tests. The postmanufacture conditioning treatments were found to significantly affect the mechanical and physical properties of the samples. A universal ranking system was established based on cumulative rankings of each evaluated characteristic. Samples dried in ambient outdoor conditions achieved the best overall ranking and had the smallest carbon footprint. However, ovendried samples had the best flexural properties. Future studies investigating hybrid approaches in which composites are sequentially subjected to different drying methods will likely provide the most desirable mechanical and physical properties of wood-sodium silicate composites.

Stalk lodging in the monocot Zea mays is an important agricultural issue that requires the development of a genome-to-phenome framework, mechanistically linking intermediate and high-level phenotypes. As part of that effort, tools are needed to enable better mechanistic understanding of the microstructure in herbaceous plants. A method was therefore developed to create finite element models using CT scan data for Zea mays. This method represents a pipeline for processing the image stacks and developing the finite element models. 2-dimensional finite element models, 3-dimensional watertight models, and 3-dimensional voxel-based finite element models were developed. The finite element models contain both the cell and cell wall structures that can be tested in silico for phenotypes such as structural stiffness and predicted tissue strength. This approach was shown to be successful, and a number of example analyses were presented to demonstrate its usefulness and versatility. This pipeline is important for two reasons: (1) it helps inform which microstructure phenotypes should be investigated to breed for more lodging-resistant stalks, and (2) represents an essential step in the development of a mechanistic hierarchical framework for the genome-to-phenome modeling of herbaceous plant stalk lodging.

Genomes are organised into DNA loops by the Structural Maintenance of Chromosomes (SMC) proteins. SMCs establish functional chromosomal sub-domains for DNA repair, gene expression and chromosome segregation, but how SMC activity is specifically targeted is unclear. Here, we define the molecular mechanism targeting the condensin SMC complex to specific chromosomal regions in budding yeast. A conserved pocket on the condensin HAWK subunit Ycg1 binds to chromosomal receptors carrying a related motif, CR1. In early mitosis, CR1 motifs in receptors Sgo1 and Lrs4 recruit condensin to pericentromeres and rDNA, to facilitate sister kinetochore biorientation and rDNA condensation, respectively. We additionally find that chromosome arm condensation begins as sister kinetochores come under tension, in a manner dependent on the Ycg1 pocket. We propose that multiple CR1-containing proteins recruit condensin to chromosomes and identify several additional candidates based on their sequence. Overall, we uncover the molecular mechanism that targets condensin to functionalise chromosomal domains to achieve accurate chromosome segregation during mitosis.

Centromeres are scaffolds for the assembly of kinetochores that ensure chromosome segregation during cell division. How vertebrate centromeres obtain a three-dimensional structure to accomplish their primary function is unclear. Using super-resolution imaging, capture-C, and polymer modeling, we show that vertebrate centromeres are partitioned by condensins into two subdomains during mitosis. The bipartite structure is found in human, mouse, and chicken cells and is therefore a fundamental feature of vertebrate centromeres. Super-resolution imaging and electron tomography reveal that bipartite centromeres assemble bipartite kinetochores, with each subdomain binding a distinct microtubule bundle. Cohesin links the centromere subdomains, limiting their separation in response to spindle forces and avoiding merotelic kinetochore-spindle attachments. Lagging chromosomes during cancer cell divisions frequently have merotelic attachments in which the centromere subdomains are separated and bioriented. Our work reveals a fundamental aspect of vertebrate centromere biology with implications for understanding the mechanisms that guarantee faithful chromosome segregation.

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 (Zea mays L.) 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.

BACKGROUND:Stalk lodging (the premature breaking of plant stalks or stems prior to harvest) is a persistent agricultural problem that causes billions of dollars in lost yield every year. Three-point bending tests, and rind puncture tests are common biomechanical measurements utilized to investigate crops susceptibility to lodging. However, the effect of testing rate on these biomechanical measurements is not well understood. In general, biological specimens (including plant stems) are well known to exhibit viscoelastic mechanical properties, thus their mechanical response is dependent upon the rate at which they are deflected. However, there is very little information in the literature regarding the effect of testing rate (aka displacement rate) on flexural stiffness, bending strength and rind puncture measurements of plant stems. RESULTS:Fully mature and senesced maize stems and wheat stems were tested in three-point bending at various rates. Maize stems were also subjected to rind penetration tests at various rates. Testing rate had a small effect on flexural stiffness and bending strength calculations obtained from three-point bending tests. Rind puncture measurements exhibited strong rate dependent effects. As puncture rate increased, puncture force decreased. This was unexpected as viscoelastic materials typically show an increase in resistive force when rate is increased. CONCLUSIONS:Testing rate influenced three-point bending test results and rind puncture measurements of fully mature and dry plant stems. In green stems these effects are expected to be even larger. When conducting biomechanical tests of plant stems it is important to utilize consistent span lengths and displacement rates within a study. Ideally samples should be tested at a rate similar to what they would experience in-vivo.

This study sought to better understand how time of day (ToD) or turgor pressure might affect the flexural stiffness of sweet sorghum stalks and potentially regulate stalk lodging resistance. Stalk flexural stiffness measured across a 48 h period in 2019 showed a significant diurnal association with leaf water potential and stalk flexural stiffness. While the correlation between stalk flexural stiffness and this proxy for internal turgor status was statistically significant, it only accounted for roughly 2% of the overall variance in stiffness. Given that turgor status is a dynamic rather than fixed physiological variable like the cellular structure, these data suggest that internal turgor plays a small yet significant role in influencing the flexural stiffness of fully mature stalks prior to a stalk lodging event. The association was assessed at earlier developmental stages across three distinct cultivars and found not to be significant. Panicle weight and stalk basal weight, but not stalk Brix or water content, were found to be better predictors of stalk flexural stiffness than either ToD or turgor status. Observation across three cultivars and four distinct developmental stages ranging from the vegetative to the hard-dough stages suggests that stalk flexural stiffness changes significantly as a function of time. However, neither ToD nor turgor status appear to meaningfully contribute to observed variations in stalk flexural stiffness in either individual stalks or across larger populations. As turgor status was not found to meaningfully influence stalk strength or flexural stiffness at any developmental time point examined in any of the three sweet sorghum cultivars under study, turgor pressure likely offers only inconsequential contributions to the biomechanics underlying sweet sorghum stalk lodging resistance.

Background Komagataella phaffii (Pichia pastoris ) is a methylotrophic commercially important non-conventional species of yeast that grows in a fermentor to exceptionally high densities on simple media and secretes recombinant proteins efficiently. Genetic engineering strategies are being explored in this organism to facilitate cost-effective biomanufacturing. Small, stable artificial chromosomes in K. phaffii could offer unique advantages by accommodating multiple integrations of extraneous genes and their promoters without accumulating perturbations of native chromosomes or exhausting the availability of selection markers. Results Here, we describe a linear “nano”chromosome (of 15–25 kb) that, according to whole-genome sequencing, persists in K. phaffii over many generations with a copy number per cell of one, provided non-homologous end joining is compromised (by KU70 -knockout). The nanochromosome includes a copy of the centromere from K. phaffii chromosome 3, a K. phaffii -derived autonomously replicating sequence on either side of the centromere, and a pair of K. phaffii -like telomeres. It contains, within its q arm, a landing zone in which genes of interest alternate with long (approx. 1-kb) non-coding DNA chosen to facilitate homologous recombination and serve as spacers. The landing zone can be extended along the nanochromosome, in an inch-worming mode of sequential gene integrations, accompanied by recycling of just two antibiotic-resistance markers. The nanochromosome was used to express PDI , a gene encoding protein disulfide isomerase. Co-expression with PDI allowed the production, from a genomically integrated gene, of secreted murine complement factor H, a plasma protein containing 40 disulfide bonds. As further proof-of-principle, we co-expressed, from a nanochromosome, both PDI and a gene for GFP-tagged human complement factor H under the control of P AOX1 and demonstrated that the secreted protein was active as a regulator of the complement system. Conclusions We have added K. phaffii to the list of organisms that can produce human proteins from genes carried on a stable, linear, artificial chromosome. We envisage using nanochromosomes as repositories for numerous extraneous genes, allowing intensive engineering of K. phaffii without compromising its genome or weakening the resulting strain.

Abstract Background: Meeting the global demand for grain is becoming increasingly difficult due to numerous factors including climate variability, urbanization, increasingly frequent extreme weather events and drought. Stalk lodging destroys between 5%-25% of grain crops annually. Developing crop varieties with improved lodging resistance will reduce the frequency and impact of stalk lodging and consequently reduce the yield gap. Field-phenotyping equipment is critical to develop lodging resistant crop varieties, but the effectiveness of current equipment is hindered by measurement error. Relatively little research has been done to identify and rectify sources of measurement error in biomechanical phenotyping platforms. This study specifically investigated sources of error in bending stiffness and bending strength measurements which are often acquired using field-phenotyping devices. Three specific sources of error in bending stiffness and bending strength measurements were evaluated: horizontal device placement, vertical device placement and incorrect recordings of load cell height. Results: Incorrect load cell heights introduced errors as large as 130% in bending stiffness and 50% in bending strength. Results indicated that errors on the order of 15%-25% in bending stiffness and 1–10% in bending strength are common in field-based measurements. Improving operating procedures and protocols can mitigate this error. Such improvements include emphasizing attention to detail while conducting tests and improving the design of phenotyping equipment. Conclusion: Reducing measurement error in field-phenotyping equipment is crucial for advancing the development of improved, lodging-resistant crop varieties. The study found that incorrect load cell height entry and incorrect device placement both significantly contributed to measurement error in bending stiffness and bending strength measurements. These findings have important implications for reducing the yield gap in staple crops and meeting the global demand for grain.

This study presents a methodology for a high-throughput digitization and quantification process of plant cell walls characterization, including the automated development of two-dimensional finite element models. Custom algorithms based on machine learning can also analyze the cellular microstructure for phenotypes such as cell size, cell wall curvature, and cell wall orientation. To demonstrate the utility of these models, a series of compound microscope images of both herbaceous and woody representatives were observed and processed. In addition, parametric analyses were performed on the resulting finite element models. Sensitivity analyses of the structural stiffness of the resulting tissue based on the cell wall elastic modulus and the cell wall thickness; demonstrated that the cell wall thickness has a three-fold larger impact of tissue stiffness than cell wall elastic modulus.

ABSTRACT Background Komagataella phaffii (Pichia pastoris ) is a methylotropic commercially important non-conventional species of yeast that grows in a fermentor to exceptionally high densities on simple media and secretes recombinant proteins efficiently. Genetic engineering strategies are being explored in this organism to facilitate cost-effective biomanufacturing. Small, stable artificial chromosomes in K. phaffii could offer unique advantages by accommodating multiple integrations of extraneous genes and their promoters without accumulating perturbations of native chromosomes or exhausting the availability of selection markers. Results Here, we describe a linear “nano”chromosome (of 15-25 kb) that, according to whole-genome sequencing, persists in K. phaffii over many generations with a copy number per cell of one, provided non-homologous end joining is compromised (by KU70 -knockout). The nanochromosome includes a copy of the centromere from K. phaffii chromosome 3, a K. phaffii -derived autonomously replicating sequence on either side of the centromere, and a pair of K. phaffii -like telomeres. It contains, within its q arm, a landing zone in which genes of interest alternate with long (approx. 1-kb) non-coding DNA chosen to facilitate homologous recombination and serve as spacers. The landing zone can be extended along the nanochromosome, in an inch-worming mode of sequential gene integrations, accompanied by recycling of just two antibiotic-resistance markers. The nanochromosome was used to express PDI , a gene encoding protein disulfide isomerase. Co-expression with PDI allowed the production, from a genomically integrated gene, of secreted murine complement factor H, a plasma protein containing 40 disulfide bonds. As further proof-of-principle, we co-expressed, from a nanochromosome, both PDI and a gene for GFP-tagged human complement factor H under the control of P AOX1 and demonstrated that the secreted protein was active as a regulator of the complement system. Conclusions We have added K. phaffii to the list of organisms that can produce human proteins from genes carried on a stable, linear, artificial chromosome. We envisage using nanochromosomes as repositories for numerous extraneous genes, allowing intensive engineering of K. phaffii without compromising its genome or weakening the resulting strain.

Context: Stalk lodging causes up to 43 % of yield losses in maize (Zea mays L.) worldwide, significantly worsening food and feed shortages. Stalk lodging resistance is a complex trait specified by several structural, material, and geometric phenotypes. However, the identity, relative contribution, and genetic tractability of these intermediate phenotypes remain unknown.Objective: The study is designed to identify and evaluate plant-, organ-, and tissue-level intermediate phenotypes associated with stalk lodging resistance following standardized phenotyping protocols and to understand the variation and genetic tractability of these intermediate phenotypes.Methods: We examined 16 diverse maize hybrids in two environments to identify and evaluate intermediate phenotypes associated with stalk flexural stiffness, a reliable indicator of stalk lodging resistance, at physiological maturity. Engineering-informed and machine learning models were employed to understand relationships among intermediate phenotypes and stalk flexural stiffness.Results: Stalk flexural stiffness showed significant genetic variation and high heritability (0.64) in the evaluated hybrids. Significant genetic variation and comparable heritability for the cross-sectional moment of inertia and Young's modulus indicated that geometric and material properties are under tight genetic control and play a combinatorial role in determining stalk lodging resistance. Among the twelve internode-level traits measured on the bottom and the ear internode, most traits exhibited significant genetic variation among hybrids, moderate to high heritability, and considerable effect of genotype x environment interaction. The marginal statistical model based on structural engineering beam theory revealed that 74-80 % of the phenotypic variation for flexural stiffness was explained by accounting for the major diameter, minor diameter, and rind thickness of the stalks. The machine learning model explained a relatively modest proportion (58-62 %) of the variation for flexural stiffness.Conclusions: Characterization of stalk and internode properties using standard phenotyping methods revealed tremendous variation for intermediate phenotypes underlying stalk lodging resistance. The intermediate phenotypes showed moderate to high heritability, indicating their genetic tractability for improving stalk lodging resistance. Stalk geometric and material properties showed complementarity in determining stalk flexural stiffness. Engineering-informed models outperformed machine learning approaches in explaining variation for flexural stiffness.Implications: Identification of genetically tractable intermediate phenotypes will boost efforts toward genetic improvement of stalk lodging resistance in maize. Discovering the genetic architecture of the intermediate traits will enhance our understanding of the biological underpinning of stalk lodging resistance.

Background: Stalk lodging is the structural failure of crops due to external loading such as wind. Short-stature (i. e., dwarf) varieties of wheat and rice have shown promise in reducing lodging rates. However, similar dwarfing in large gains like maize and sorghum has typically been accompanied by undesirable commercial characteris-tics, including significantly decreased grain yields. The purpose of this paper is to quantify the relationship between lodging resistance and plant height in maize to better understand the potential impact of short-stature varieties of maize on lodging resistance.Results: Results from both the engineering analysis and the experimental field study indicate a nearly 1:1 rela-tionship between plant height and plant lodging resistance. These data support the validity of the engineering analysis and suggest that there exists a nearly linear relationship between crop lodging incidence and plant height.Conclusions: Plant height has a direct and quantifiable impact on crop lodging resistance as it influences the bending stresses experienced in the plant stem. This study presents the engineering analysis, supported by field experiments, that explains the cause of this nearly linear 1:1 relationship.

Stalk lodging (structural failure crops prior to harvest) significantly reduces annual yields of vital grain crops. The lack of standardized, high throughput phenotyping methods capable of quantifying biomechanical plant traits prevents comprehensive understanding of the genetic architecture of stalk lodging resistance. A phenotyping pipeline developed to enable higher throughput biomechanical measurements of plant traits related to stalk lodging is presented. The methods were developed using principles from the fields of engineering mechanics and metrology and they enable retention of plant-specific data instead of averaging data across plots as is typical in most phenotyping studies. This pipeline was specifically designed to be implemented in large experimental studies and has been used to phenotype over 40,000 maize stalks. The pipeline includes both lab- and field-based phenotyping methodologies and enables the collection of metadata. Best practices learned by implementing this pipeline over the past three years are presented. The specific instruments (including model numbers and manufacturers) that work well for these methods are presented, however comparable instruments may be used in conjunction with these methods as seen fit. • Efficient methods to measure biomechanical traits and record metadata related to stalk lodging. • Can be used in studies with large sample sizes (i.e., > 1,000).

Background: Stalk lodging (breaking of agricultural plant stalks prior to harvest) is a multi-billion dollar a year problem. Stalk lodging occurs when high winds induce bending moments in the stalk which exceed the bending strength of the plant. Previous biomechanical models of plant stalks have investigated the effect of cross-sectional morphology on stalk lodging resistance (e.g., diameter and rind thickness). However, it is unclear if the location of stalk failure along the length of stem is determined by morphological or compositional factors. It is also unclear if the crops are structurally optimized, i.e., if the plants allocate structural biomass to create uniform and minimal bending stresses in the plant tissues. The purpose of this paper is twofold: (1) to investigate the relationship between bending stress and failure location of maize stalks, and (2) to investigate the potential of phenotyping for internode-level bending stresses to assess lodging resistance. Results: 868 maize specimens representing 16 maize hybrids were successfully tested in bending to failure. Internode morphology was measured, and bending stresses were calculated. It was found that bending stress is highly and positively associated with failure location. A user-friendly computational tool is presented to help plant breeders in phenotyping for internode-level bending stress. Phenotyping for internode-level bending stresses could potentially be used to breed for more biomechanically optimal stalks that are resistant to stalk lodging. Conclusions: Internode-level bending stress plays a potentially critical role in the structural integrity of plant stems. Equations and tools provided herein enable researchers to account for this phenotype, which has the potential to increase the bending strength of plants without increasing overall structural biomass.