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ABSTRACT Fertilization at the large bell stage of maize is the key to increasing maize yield and improving fertilizer use efficiency. To achieve fast and accurate recognition of maize stems by intelligent agricultural equipment in complex field environments, an improved YOLO v4 maize stem recognition model with an increased CBAM, which can achieve real-time identification and positioning of maize stems, is proposed. In this paper, first, we collected images of maize stems under different conditions in the field, expanded the maize stem images and produced a maize stem image dataset by adding Gaussian noise, changing the brightness and performing other data enhancement methods, and manually annotated the maize stem via LabelImg software. Second, a convolutional block attention module (CBAM) and SIoU loss function were added to the original YOLO v4 target detection network to obtain the CB-YOLO v4 target detection network. Last, this network was compared with the original YOLO v4, Faster-RCNN, SSD and YOLO v3 target detection networks, and it achieved 93.1%, 92.4% and 92.6% precision, recall and mAP (mean average precision), respectively, for maize root recognition, which is significantly better than the other algorithms and is suitable for practical maize interrow operation systems.

Plant vascular bundles are responsible for water and material transportation, and their quantitative and functional evaluation is desirable in plant research. At the single-plant level, the number, size, and distribution of vascular bundles vary widely, posing a challenge to automatically and accurately identifying and quantifying them. In this study, a deep learning-integrated phenotyping pipeline was developed to robustly and accurately detect vascular bundles in Computed Tomography (CT) images of stem internodes. Two semantic indicators were used to evaluate and identify a suitable feature extraction network for semantic segmentation models. The epidermis thickness of maize stem was evaluated for the first time and adjacent vascular bundles were improved using an adaptive watershed-based approach. The counting accuracy (R2) of vascular bundles was 0.997 for all types of stem internodes, and the measured accuracy of size traits was over 0.98. Combining sap flow experiments, multiscale traits of vascular bundles were evaluated at the single-plant level, which provided an insight into the water use efficiency of the maize plant.

Maize stem sculptures, produced during the 16th and 17th centuries in New Spain (today, Mexico) are a clear example of the convergence of the artistic traditions from the American indigenous populations and European influence. This typology of sculptures is not limited to the Americas, as the examples found in European countries have shown. Therefore, a detailed technological investigation is required to correctly classify them. This work presents the interdisciplinary and multianalytical investigation of a 16th-century sculpture made with a maize stem preserved in Guadalajara city, Mexico. We used a set of techniques, such as CT, SEM-EDX, μ-FTIR, and μ-Raman, to study, from a macro to a micro level, the structure, the polychromy, and the modification of the sculpture. The results showed the use of maize stems, paper, and wood in the construction of the sculpture and the use of the traditional polychromy, as well as the numerous modifications that changed its appearance considerably resulting in its misclassification. We were able to associate the statue with the Cortés workshop (Mexico City region), probably produced in the decade of 1580, and track its liturgical use and historical development through the centuries.

The proportion and composition of plant tissues in maize stems vary with genotype and agroclimatic factors and may impact the final biomass use. In this manuscript, we propose a quantitative histology approach without any section labelling to estimate the proportion of different tissues in maize stem sections as well as their chemical characteristics. Macroscopic imaging was chosen to observe the entire section of a stem. Darkfield illumination was retained to visualise the whole stem cellular structure. Multispectral autofluorescence images were acquired to detect cell wall phenolic compounds after UV and visible excitations. Image analysis was implemented to extract morphological features and autofluorescence pseudospectra. By assimilating the internode to a cylinder, the relative proportions of tissues in the internode were estimated from their relative areas in the sections. The approach was applied to study a series of 14 maize inbred lines. Considerable variability was revealed among the 14 inbred lines for both anatomical and chemical traits. The most discriminant morphological descriptors were the relative amount of rind and parenchyma tissues together with the density and size of the individual bundles, the area of stem and the parenchyma cell diameter. The rind, as the most lignified tissue, showed strong visible-induced fluorescence which was line-dependant. The relative amount of para-coumaric acid was associated with the UV-induced fluorescence intensity in the rind and in the parenchyma near the rind, while ferulic acid amount was significantly correlated mainly with the parenchyma near the rind. The correlation between lignin and the tissue pseudospectra showed that a global higher amount of lignin resulted in a higher level of lignin fluorescence whatever the tissues. We demonstrated here the potential of darkfield and autofluorescence imaging coupled with image analysis to quantify histology of maize stem and highlight variability between different lines. [ABSTRACT FROM AUTHOR]

Abstract Background Micro-computed tomography (μCT) bring a new opportunity to accurately quantify micro phenotypic traits of maize stem, also provide comparable benchmark to evaluate its dynamic development at the different growth stages. The progressive accumulation of stem biomass brings manifest structure changes of maize stem and vascular bundles, which are closely related with maize varietal characteristics and growth stages. Thus, micro-phenotyping (μPhenotyping) of maize stems is not only valuable to evaluate bio-mechanics and water-transport performance of maize, but also yield growth-based traits for quantitative traits loci (QTL) and functional genes location in molecular breeding. Result In this study, maize stems of 20 maize cultivars and two growth stages were imaged using μCT scanning technology. According to the observable differences of maize stems from the elongation and tasseling stages, function zones of maize stem were firstly defined to describe the substance accumulation of maize stems. And then a set of image-based μPhenotyping pipelines were implemented to quantify maize stem and vascular bundles at the two stages. The coefficient of determination (R2) of counting vascular bundles was higher than 0.95. Based on the uniform contour representation, intensity-related, geometry-related and distribution-related traits of vascular bundles were respectively evaluated in function zones and structure layers. And growth-related traits of the slice, epidermis, periphery and inner zones were also used to describe the dynamic growth of maize stem. Statistical analysis demonstrated the presented method was suitable to the phenotyping analysis of maize stem for multiple growth stages. Conclusions The novel descriptors of function zones provide effective phenotypic references to quantify the differences between growth stages; and the detection and identification of vascular bundles based on function zones are more robust to determine the adaptive image analysis pipeline. Developing robust and effective image-based phenotyping method to assess the traits of stem and vascular bundles, is highly relevant for understanding the relationship between maize phenomics and genomics.

The proportion and composition of plant tissues in maize stems vary with genotype and agroclimatic factors and may impact the final biomass use. In this manuscript, we propose a quantitative histology approach without any section labelling to estimate the proportion of different tissues in maize stem sections as well as their chemical characteristics. Macroscopic imaging was chosen to observe the entire section of a stem. Darkfield illumination was retained to visualise the whole stem cellular structure. Multispectral autofluorescence images were acquired to detect cell wall phenolic compounds after UV and visible excitations. Image analysis was implemented to extract morphological features and autofluorescence pseudospectra. By assimilating the internode to a cylinder, the relative proportions of tissues in the internode were estimated from their relative areas in the sections. The approach was applied to study a series of 14 maize inbred lines. Considerable variability was revealed among the 14 inbred lines for both anatomical and chemical traits. The most discriminant morphological descriptors were the relative amount of rind and parenchyma tissues together with the density and size of the individual bundles, the area of stem and the parenchyma cell diameter. The rind, as the most lignified tissue, showed strong visible-induced fluorescence which was line-dependant. The relative amount of para-coumaric acid was associated with the UV-induced fluorescence intensity in the rind and in the parenchyma near the rind, while ferulic acid amount was significantly correlated mainly with the parenchyma near the rind. The correlation between lignin and the tissue pseudospectra showed that a global higher amount of lignin resulted in a higher level of lignin fluorescence whatever the tissues. We demonstrated here the potential of darkfield and autofluorescence imaging coupled with image analysis to quantify histology of maize stem and highlight variability between different lines.

Maize stem sculptures, produced during the 16th and 17th centuries in New Spain (today, Mexico) are a clear example of the convergence of the artistic traditions from the American indigenous populations and European influence. This typology of sculptures is not limited to the Americas, as the examples found in European countries have shown. Therefore, a detailed technological investigation is required to correctly classify them. This work presents the interdisciplinary and multianalytical investigation of a 16th-century sculpture made with a maize stem preserved in Guadalajara city, Mexico. We used a set of techniques, such as CT, SEM-EDX, µ-FTIR, and µ-Raman, to study, from a macro to a micro level, the structure, the polychromy, and the modification of the sculpture. The results showed the use of maize stems, paper, and wood in the construction of the sculpture and the use of the traditional polychromy, as well as the numerous modifications that changed its appearance considerably resulting in its misclassification. We were able to associate the statue with the Cortés workshop (Mexico City region), probably produced in the decade of 1580, and track its liturgical use and historical development through the centuries. [ABSTRACT FROM AUTHOR]

Adsorption of heavy toxic metals by agricultural solid wastes has emerged as an alternative method of removal. Biosorption of Pb (II) has been studied by rice husk powder and maize stem powder at optimum pH, biosorbent doses, and contact time. Maximum percentage removal has been recorded at pH 7. With an increased dose of maize stem powder and rice husk powder, enhanced biosorption took place. A comparative study of biosorption by maize stem and rice husk powder revealed that maize stem powder had been found more suitable than rice husk powder at pH 7. Furthermore, the effect of contact time on the adsorption of Pb(II)has been studied both by maize stem and rice husk powder. The equilibrium concentration of Pb(II) has been attained in 60 minutes and showed the best fit in the first-order reaction and Langmuir adsorption model. SEM images before adsorption and after adsorption confirmed the insertion of Pb(II) ions onto the surface of biosorbents. [ABSTRACT FROM AUTHOR]

Summary: High‐throughput phenotyping is increasingly becoming an important tool for rapid advancement of genetic gain in breeding programmes. Manual phenotyping of vascular bundles is tedious and time‐consuming, which lags behind the rapid development of functional genomics in maize. More robust and automated techniques of phenotyping vascular bundles traits at high‐throughput are urgently needed for large crop populations. In this study, we developed a standard process for stem micro‐CT data acquisition and an automatic CT image process pipeline to obtain vascular bundle traits of stems including geometry‐related, morphology‐related and distribution‐related traits. Next, we analysed the phenotypic variation of stem vascular bundles between natural population subgroup (480 inbred lines) based on 48 comprehensively phenotypic information. Also, the first database for stem micro‐phenotypes, MaizeSPD, was established, storing 554 pieces of basic information of maize inbred lines, 523 pieces of experimental information, 1008 pieces of CT scanning images and processed images, and 24 192 pieces of phenotypic data. Combined with genome‐wide association studies (GWASs), a total of 1562 significant single nucleotide polymorphism (SNPs) were identified for 30 stem micro‐phenotypic traits, and 84 unique genes of 20 traits such as VBNum, VBAvArea and PZVBDensity were detected. Candidate genes identified by GWAS mainly encode enzymes involved in cell wall metabolism, transcription factors, protein kinase and protein related to plant signal transduction and stress response. The results presented here will advance our knowledge about phenotypic trait components of stem vascular bundles and provide useful information for understanding the genetic controls of vascular bundle formation and development. [ABSTRACT FROM AUTHOR]

Carbon allocation between vegetative and reproductive tissues impacts cereal grain production. Despite great agricultural importance, sink–source relationships have not been fully characterized at the early reproductive stages in maize. Here, we quantify the accumulation of non-structural carbohydrates and patterns of gene expression in the top internode of the stem and the female inflorescence of maize at the onset of grain filling (reproductive stage R1). Top internode stem and female inflorescence tissues of the Puma maize inbred line were collected at reproductive stage R1 (without pollination) and non-structural carbohydrates were quantified by spectrophotometry. The female inflorescence accumulated starch at higher levels than the top internode of the stem. Global mRNA transcript levels were then evaluated in both tissues by RNA sequencing. Gene expression analysis identified 491 genes differentially expressed between the female inflorescence and the top stem internode. Gene ontology classification of differentially expressed genes showed enrichment for sucrose synthesis, the light-dependent reactions of photosynthesis, and transmembrane transporters. Our results suggest that sugar transporters play a key role in sugar partitioning in the maize stem and reveal previously uncharacterized differences between the female inflorescence and the top internode of the stem at early reproductive stages.

Background: Micro-computed tomography (μCT) bring a new opportunity to accurately quantify micro phenotypic traits of maize stem, also provide comparable benchmark to evaluate its dynamic development at the different growth stages. The progressive accumulation of stem biomass brings manifest structure changes of maize stem and vascular bundles, which are closely related with maize varietal characteristics and growth stages. Thus, micro-phenotyping (μPhenotyping) of maize stems is not only valuable to evaluate bio-mechanics and water-transport performance of maize, but also yield growth-based traits for quantitative traits loci (QTL) and functional genes location in molecular breeding. Result: In this study, maize stems of 20 maize cultivars and two growth stages were imaged using μCT scanning technology. According to the observable differences of maize stems from the elongation and tasseling stages, function zones of maize stem were firstly defined to describe the substance accumulation of maize stems. And then a set of image-based μPhenotyping pipelines were implemented to quantify maize stem and vascular bundles at the two stages. The coefficient of determination (R2) of counting vascular bundles was higher than 0.95. Based on the uniform contour representation, intensity-related, geometry-related and distribution-related traits of vascular bundles were respectively evaluated in function zones and structure layers. And growth-related traits of the slice, epidermis, periphery and inner zones were also used to describe the dynamic growth of maize stem. Statistical analysis demonstrated the presented method was suitable to the phenotyping analysis of maize stem for multiple growth stages. Conclusions: The novel descriptors of function zones provide effective phenotypic references to quantify the differences between growth stages; and the detection and identification of vascular bundles based on function zones are more robust to determine the adaptive image analysis pipeline. Developing robust and effective image-based phenotyping method to assess the traits of stem and vascular bundles, is highly relevant for understanding the relationship between maize phenomics and genomics. [ABSTRACT FROM AUTHOR]

Continuous adsorption of methylene blue from aqueous solutions onto maize stem ground tissue in column mode was investigated. The study encompassed the effects of important parameters such as flow rate, initial concentration of methylene blue, and bed depth on methylene blue removal from model solutions. The maximum adsorption capacity of the maize stem was 45.9 mg/g at the initial methylene blue concentration of 20 mg/L, bed height of 6.5 cm and flow rate of 8 mL/min. It was found that the breakthrough time for reaching saturation increased with a decrease in the flow rate, and also occurred earlier for a higher influent concentration. The breakthrough times increased with the bed depth, thus allowing a larger volume to be treated. The Adams-Bohart, Yoon-Nelson, Clark and artificial neural network models were used to predict the breakthrough curves. These models gave excellent approximations of the experimental behavior.[Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172025]

BACKGROUND The relationship between the chemical and molecular properties - in particular the (acid detergent) lignin (ADL) content and composition expressed as the ratio between syringyl and guaiacyl compounds (S:G ratio) - of maize stems and in vitro gas production was studied in order to determine which is more important in the degradability of maize stem cell walls in the rumen of ruminants. Different internodes from two contrasting maize cultivars (Ambrosini and Aastar) were harvested during the growing season. RESULTS The ADL content decreased with greater internode number within the stem, whereas the ADL content fluctuated during the season for both cultivars. The S:G ratio was lower in younger tissue (greater internode number or earlier harvest date) in both cultivars. For the gas produced between 3 and 20 h, representing the fermentation of cell walls in rumen fluid, a stronger correlation ( R2 = 0.80) was found with the S:G ratio than with the ADL content ( R2 = 0.68). The relationship between ADL content or S:G ratio and 72-h gas production, representing total organic matter degradation, was weaker than that with gas produced between 3 and 20 h. CONCLUSION The S:G ratio plays a more dominant role than ADL content in maize stem cell wall degradation. © 2017 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The impact of ball milling on structural components of maize ( Zea mays L.) stem was investigated in relation to enzymatic hydrolysis of carbohydrates. Ball milling of extractive-free maize stem material was carried out with different milling times up to 12 h. Carbohydrate conversion from ball-milled maize stem material with cellulolytic preparation Onozuka R-10 increased to 79% with increasing ball milling time up to 4 h, but did not thereafter increase further. Ball milling caused drastic depolymerization of hemicelluloses as revealed by increasing amounts of monosaccharides released in absence of enzymes. Infrared spectroscopy showed that cellulose crystallinity decreased within the first 6 h milling thereafter reaching a plateau. Thioacidolysis of solid residue fractions obtained after treatment of ball-milled samples with Onozuka R-10 suggested that no extensive degradation of lignin occurred during the milling. The effect of lignin structure on enzymatic hydrolysis of associated carbohydrates was further studied independently of cellulose crystallinity. Two lignin-carbohydrate fractions comprising hemicellulose and lignin with either high or low amount of aryl ether linkages were used as model materials. Lignins abundant in aryl ether linkages appeared more detrimental than condensed lignins to enzymatic hydrolysis of associated carbohydrates. [ABSTRACT FROM AUTHOR]

Carbon allocation between vegetative and reproductive tissues impacts cereal grain production. Despite great agricultural importance, sink–source relationships have not been fully characterized at the early reproductive stages in maize. Here, we quantify the accumulation of non-structural carbohydrates and patterns of gene expression in the top internode of the stem and the female inflorescence of maize at the onset of grain filling (reproductive stage R1). Top internode stem and female inflorescence tissues of the Puma maize inbred line were collected at reproductive stage R1 (without pollination) and non-structural carbohydrates were quantified by spectrophotometry. The female inflorescence accumulated starch at higher levels than the top internode of the stem. Global mRNA transcript levels were then evaluated in both tissues by RNA sequencing. Gene expression analysis identified 491 genes differentially expressed between the female inflorescence and the top stem internode. Gene ontology classification of differentially expressed genes showed enrichment for sucrose synthesis, the light-dependent reactions of photosynthesis, and transmembrane transporters. Our results suggest that sugar transporters play a key role in sugar partitioning in the maize stem and reveal previously uncharacterized differences between the female inflorescence and the top internode of the stem at early reproductive stages. [ABSTRACT FROM AUTHOR]

Abstract: Sequential fractionation of extractive-free maize stems was carried out using two mild alkaline extractions (0.5 and 2M NaOH, 20°C, 24h) before and after endoglucanase treatment. This procedure provided two lignin–carbohydrate fractions (LC1 and LC2) recovered after each alkali treatment. LC1 and LC2 contained 39% and 8% of the total lignin amount, respectively. These two fractions contained structurally distinct lignin molecules. While the content of resistant interunit bonds in lignin was 77% in LC1, it was increased up to 98% in LC2. Not unexpectedly, both alkali-soluble fractions contained substantial amount of p-coumaric and ferulic acids ether-linked to lignins. These results outline heterogeneity of maize stem lignins related to fractionation of grass materials. [Copyright &y& Elsevier]

Abstract: The potential of by-products and intermediate products of sugar beet processing as raw materials for bioethanol production in Vojvodina region has a big scope in view of the demand of ethanol as an alternative for fossil fuels. Also, from ecological point of view, use of agricultural waste as carriers for cells immobilization is justifiable. The biocatalyst prepared by immobilization of Saccharomyces cerevisiae on maize stem ground tissue was used for batch fermentation of sugar beet molasses and thick juice under normal and very high gravity (VHG) conditions. Cell immobilization was observed by electron microscopy. The carrier was effective for cell immobilization and provided strength and stability to the yeast cell mass and functioned as a fortification against toxins and inhibitors, enabling efficient ethanol fermentation, particularly in VHG conditions. Three different initial glucose concentrations were tested: 100, 150 and 300g/l. The maximum ethanol concentration of 83.20g/l for molasses and 132.39g/l for thick juice were achieved in VHG fermentation by immobilized cells, whereas the free yeast cells were unsuccessful in the same media. Taking into consideration significant process parameters sugar beet thick juice was found to be economically favorable, compared to molasses, particularly in the VHG fermentation process. [Copyright &y& Elsevier]

Lignins were isolated from maize stem and sugarcane bagasse by using mild dioxane or acidic dioxane solution. The result of nitrobenzene oxidation of the isolated lignins shows that there is a high proportion of p-hydroxyphenyl alcohol in the lignins of maize stem and sugarcane bagasse. The lignins isolated from maize stem and sugarcane bagasse have relatively same value of the weight-average ( = 3405-3868 g mol) and number-average ( = 1411-1612 g mol) molecular weights, and polydispersity (/ = 2.24-2.51). Acidic dioxane treatment did attack the β-aryl ether structures in lignins, in particular for β-aryl syringyl ethers, and broke the ester bonds between arabinose and ferulic acid that etherified to lignins, and it also cleaved lots of bonds in hemicellulosic polymer. The proportion of β- O-4 (threo) guaiacyl units is higher than that of β- O-4 (erthreo) guaiacyl units. The phenyl glycoside and benzyl ether linkages between lignin and hemicelluloses are also demonstrated in NMR analysis. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

Abstract: Low cost and locally available maize stems and rice stems as potential biosorbents were tested for their effectiveness in removing nitrobenzene (NB) from aqueous solution. The sorption capacities of the biosorbents were evaluated using isotherm tests and other factors such as solution pH and ionic strength, biosorbent loading and particle size, contact time and initial NB concentration were also investigated. The sorption equilibration time of NB at 25°C was about 72h, and the optimal NB removal efficiency was achieved with biosorbent particle size of 80–100mesh, further decrease in biosorbent particle size contributed to little changes in NB removal efficiency. When the biosorbent dosage was 10gL−1, the NB removal efficiency approached to the optimization. Both biosorbents performed similarly and NB was completely removed when treated at pH>7. So the optimized biosorbent loading was 10gL−1 with optimum particle size of 80–100mesh. High pH conditions (pH>7) were found to improve NB removal, while increasing the ionic strength in solution was found to decrease NB removal efficiency. Maize and rice stems were shown to be capable in removing NB from solution and have demonstrated their potential use as biosorbents. [ABSTRACT FROM AUTHOR]

• Microwave thermochemical pretreatments efficiently decomposed hemicellulose. • Microwave thermochemical pretreatments produced high yields of monosaccharides. • Microwave thermochemical pretreatments removed 96.1 % lignin content from biomass. • Efficient microwave thermochemical pretreatment was completed within 5 min. • Microwave heating consumed 25–34 folds less energy than conventional heating. Microwave (MW) heating is attracting great attention in biorefinery processes, because of its special dipole rotation heating mechanism. In the current study, MW and conventional heating methods were employed to assist the thermochemical pretreatments (H 2 O, H 2 SO 4 or NaOH) of maize stem biomass. Their influences on sugar release and biomass compositions during pretreatments were comparably evaluated. Compared to conventional heating pretreatment, MW thermochemical pretreatments are highly efficient in sugar recovery, contributing to 4.3 times higher amount of sugar release (1.25 vs 0.30 μmol/mg biomass) with reaction time 8 times shorter (5 vs 40 min) and selectively producing glucose as the major constituent (0.75 μmol/mg biomass) using 0.2 M H 2 SO 4 as pretreatment media. MW thermochemical pretreatment also effectively removed lignin (up to 91.6 %) within 5 min, which was significantly higher than conventional heating pretreatment (51.2 %). Conventional heating pretreatment successfully removed hemicellulose and converted the crystalline cellulose into amorphous cellulose, which is probably due to its longer heating time. Rapid MW thermochemical pretreatments efficiently fractionated hemicellulose and removed lignin content while keeping the crystalline cellulose structure. MW and conventional heating pretreatments led to similar digestibility of biomass solid residues. Overall, MW thermochemical pretreatment represents an energy efficient alternative strategy, as it consumed 25–34 folds less energy than conventional heating pretreatment for effective biomass fractionation and value-added chemical production. [ABSTRACT FROM AUTHOR]