Bamboo Culms Research Articles

The use of newly isolated fungal cultures for the selective delignification of bamboo culms.

The screening of ligninolytic enzyme-producing fungal species in samples led to the identification of Paracremonium sp. LCB1, Clonostachys compactiuscula LCD1 and C. compactiuscula LCN1. Both these strains produced high levels of hemicellulase and ligninolytic enzyme production over a relatively short fermentation period of 3-5days while exhibiting very low levels of cellulase activity. The results of the tests indicated that co-culturing LCB1 and LCN1 enhanced the ability to degrade lignin, and the ideal degrading circumstances and internal degrading mechanism of combined fungi were examined. The results showed that under conditions of temperature (30°C), pH (5), culture time (40 d), solid-liquid ratio (1:2.5), the pretreatment of bamboo culms with a co-culture of LCB1 and LCN1 resulted in a pronounced 76.37% drop in lignin weight and a high lignin/cellulose loss ratio (>10). Fourier transform infrared spectroscopy, X-ray diffractometry, and scanning electron microscopy were used to characterize the physicochemical properties of these bio-pretreated bamboo culms, further confirming that LCB1 and LCN1 co-culture represents an effective approach to bamboo delignification.

Mechanical behavior of round bamboo under transverse local compression

Bamboo is a material with low transverse mechanical properties. To study the mechanical behavior of round bamboo under transverse local compression, 60 round bamboo culms were subjected to three-point bending tests. The effects of different parameters on the transverse local compressive behavior were investigated experimentally. Finally, the transverse local compressive ultimate bearing capacity of round bamboo was estimated using prediction equations. The results indicated that under three load boundary conditions, axial cracks appeared on both sides of the specimens in the midspan region, dents of different sizes appeared at the loading points, and additional fractures occurred in the inner diaphragms of the specimens with the loading point at the node. The specimens subjected to point and line loads underwent brittle failure. Under the space-curve load, the specimens with a loading point at the internode exhibited ductile failure, whereas the specimens with a loading point at the node exhibited brittle failure. To obtain a favorable transverse local compressive ultimate bearing capacity, it was optimal to consider the space-curve load as the load boundary condition and position the transverse local compression at the bamboo node. The results of the prediction equations agreed well with the test results.

Comprehensive physiological, cytological, and transcriptional regulatory analyses reveal the coloration mechanism of culm yellow-slot mutation in moso bamboo (Phyllostachys edulis)

The green tissue in the culm of bamboo, engaging in photosynthesis, supplies carbohydrates to support the rapid growth of its shoots, yet the molecular basis for the chlorosis of bamboo culm tissue has not been elucidated. In contrast to the wild-type moso bamboo (Phyllostachys edulis f. pubescens, MB) with integral-green internodes at culms, the mutant one (P. edulis f. luteosulcata, YM) has typical bicolor internodes with yellow slot and green wall. By pigment quantification and chloroplast ultrastructure investigation, we found that the chlorosis in YM slot was caused by chlorophyll a deficiency, defective stroma thylakoids and misalignment of grana thylakoids. Based on transcriptomic comparisons across yellow and green tissues, the expression of plentiful genes involved in chloroplast components were significantly deceased in the tissue of YM slot, including genes associated with chloroplast development and chlorophyll metabolism. Analysis of differentially expressed genes and a multilayered hierarchical gene regulatory network both suggest that the decreased expression of BBX15s (B-BOX ZINC FINGER PROTEIN 15s) is likely the underlying cause of thylakoid dysgenesis and chlorophyll deficiency in the YM slot. This was further corroborated by Yeast one-hybrid (Y1H) assays and transgenic validation experiments, which demonstrated that BBX15s can directly regulate the transcription of genes related to chloroplast development and chlorophyll synthesis. This study provides insight into the mechanism of moso bamboo culm chloroplast development and serves as a productive basis for further exploration of bamboo culm coloration.

Bamboo as a substitute for plastic: Underlying mechanisms of flexible deformation and flexural toughness of bamboo at multiple scales

To develop bamboo-based products by weaving, winding and molding for promoting "bamboo as a substitute for plastic", it is urgent to fully understand the underlying mechanisms of flexible deformation and flexural toughness of bamboo at multiple scales. In this study, we quantified the micro deformation and strain of bamboo cells at different curvatures by in situ high-resolution field emission scanning electron microscopy (FE-SEM) and X-ray micro-computed tomography (Micro-CT) to analyze its flexible deformation at cellular and nano scales. The toughening mechanism embodied in fracture morphology was quantitatively calculated using mathematical models at macro and cell-wall scales. Results showed that bamboo possessed both excellent flexible deformation and flexural toughness in the longitudinal direction with the variation of fiber contents in the radial direction of bamboo culm. Flexible deformation of bamboo was achieved through synergistic cellular deformation between tensile sclerenchyma fibers (SFs) and compressible parenchyma cells (PCs) adapted to external stress distribution. SFs with greater tensile strain (0.027) bore the load even after the PCs broke (0.019), while the PCs in the compression layer acted as a buffer through plastic deformation. Meanwhile, the cell-wall sublayer wound by microfibrils at different angles, demonstrated significantly different Young's modulus and fracture modes verified by a mathematical model. Multiwalled fiber pullout and crack deflection were the main toughening mechanisms in bamboo at macro- and cellular scales. Multiwalled fibers pullout energy contributed the most to fracture energy dissipation, accounting for 46.0∼77.5%, whereas the weak intercellular interface effectively promoted crack deflection, reduced the local stress and delayed bamboo failure.

Fiber Characteristics and Mechanical Properties of Oxytenanthera abyssinica.

Unlike the culm hollow structure of most bamboo species, Oxytenanthera abyssinica has a unique solid or semi-solid culm, which may endow it with superior mechanical performance. In this study, the variation in fiber morphology and micro-mechanical properties across the radial regions of bamboo culm was examined by optical microscopy, scanning electron microscopy, X-ray diffraction, and nanoindentation. Results showed that the mean values of vascular bundle frequency and fiber tissue proportion were 1.76 pcs/mm2 and 21.04%, respectively, both of which increased gradually from inner to outer. The mean length, diameter, and length-diameter ratio of the fiber were 2.10 mm, 21.54 μm, and 101.41 respectively. The mean indentation modulus of elasticity (IMOE) and hardness were 21.34 GPa and 545.88 MPa. The IMOE exhibited a significant increase from the inner to the middle region, and little change was observed from the middle to the outer region. There were slight fluctuations in hardness along the radial direction. The mean crystallinity and microfibril angle(MFA) of the fibers was 68.12% and 11.26 degrees, respectively. There is a positive correlation between cellulose crystallinity and the IMOE and hardness, while there is a negative correlation between the MFA and the IMOE and the hardness.

Description of two new species of Roussoella (Roussoellaceae, Pleosporales) associated with bamboo from Sichuan Province, China

The type genus of the Roussoellaceae family, Roussoella, is mainly known from monocotyledons, particularly on dead bamboo culms, mainly as a saprophyte. This study describes and illustrates two novel species of Roussoella viz. R. fusispora and R. sichuanensis associated with bamboo, collected from Sichuan Province, China. They were identified as new species based on morphology and phylogenetic analyses of a combined matrix of ITS, LSU, TEF1 and RPB2 gene regions. According to multi-gene phylogenetic analysis, R. sichuanensis represents a sister clade to R. multiloculata and R. verrucispora, whereas R. fusispora forms a sister clade to R. neopustulans. Roussoella fusispora exhibits distinct characteristics that differentiate it from R. neopustulans, specifically its relatively smaller asci and ascospores. Similarly, Roussoella sichuanensis can be distinguished from other closely related species primarily based on its comparatively smaller conidia and the presence of a white central ostiole opening on the conidiomata.

Determination of some physical and mechanical properties of parallel-strand lumber manufactured with bamboo (Phyllostachys bambusoides)

Parallel-strand lumber was manufactured with bamboo (Phyllostachys bambusodies). A polyol compound was added to modify the adhesive (pMDI). Bamboo culms were used to manufacture strands 3 mm thick, 19 mm wide, and 65 cm long. Adhesive was applied to the strands at 200 g/m2 with pressing at 110 °C, 15 kg/cm2, and 30 min. Panels were made with width 600 mm, length 600 mm, and thickness 20 mm. Some physical properties (oven-dry density, air-dry density, moisture content, thickness swelling, and water absorption percentage) and mechanical properties (bending resistance, modulus of elasticity, impact resistance, screw-holding capacity in tangential, radial, and transverse directions) of parallel-strand lumber for both adhesive types were determined. Both resin types improved some physical and mechanical properties of parallel-strand lumber. Additionally, the modulus of rupture and flexural modulus of elasticity of the test specimens using pMDI+5%MP adhesive were higher than those of the test specimens using pMDI. The average screw-holding capacity values of the test specimens were affected by the fiber aspect of the specimens rather than the adhesive type. Parallel-strand lumber produced from both pMDI and pMDI+5%MP adhesives can be used in structural applications, especially in places exposed to the disturbing effects of weather.

DESIGN-BUILT BAMBOO STRUCTURE USING MULTIPLE-MEMBER PRE-FABRICATED CONNECTORS

Bamboo as the structural material has become the trend to respond to sustainability, due to its outstanding structural properties and renewable aspect. Though bamboo architecture is seen throughout the world, but they are still varied from culture to culture, due to limited knowledge and advanced applications. In order to move this material forward for industrialization, standard system of creating bamboo structure should be established. The most challenge of bamboo structure is the connectors. Though the conventional style is elegant and crafty, but they require special skills and lengthy construction time. Using pre-fabricated connectors to expedite construction are not quite common. This potential to introduce pre-fabricated connectors and more complex bamboo structure is needed to explore further. This research then takes the design-built approach as the methodology. The process starts with designing a complex structure with multiple-member at column-foundation nodes. Pre-fabricated steel connectors are designed to host at least six members in a single node. Four nodes are designed in this 30 sq. m bamboo pavilion. Each member is made of two different bamboo formats; bundled bamboo culms and bundled bamboo splits. Pavilion frames then are assembled using designed connectors in actual construction site. The construction is carefully monitored and documented for their strength and feasibility. It is found that pre-fabricated connectors can simply put the construction together with simple tools and in efficient time. Multiple-member at column-foundation nodes is strong and possible for complex structure. They perform well and still hold the elegant integrity of bamboo architecture.

A Literature Review On the Use of Bamboo as A Truss Member and Fiber-Reinforced Polymer as A Truss Jointing Material

A truss is a structure that has a rigid configuration formed by an assembly of straight members connected by pins. Many roofing systems use trusses, but the wide variety of truss configurations in architecture is an advantage to creating vast arrays of aesthetics in buildings. Steel, mainly plain carbon steel designated A36, is the most used material for truss members and joint connectors. However, these members are both heavy and non-sustainable, soseveral kinds of literature recommend studying the potential of using lightweight and sustainable alternatives. This review focuses on using bamboo in truss and the potential of fiber-reinforced composite as a truss joint connector. Bamboo culms and glued-laminated bamboo (glubam) are the two types of bamboo commonly used in truss fabrication based on the review. Bamboo culms from Dendrocalamus asper exhibit a tensile strength of 340 MPa, while the glubam made of Yushania alpina has 364 MPa. Other mechanical properties of bamboo necessary for the truss analysis are not yet clearly defined, although studies used ASTM D143-09 to determine several mechanical properties of bamboo or glubam. Fiber-reinforced composite can exhibit an enormous array of varieties and still demonstrate a strength close to or even higher than steel. It is lightweight and can reach a tensile strength of 700 MPa. The researcher recommends synthesizing bamboo or glubam as truss members and fiber-reinforced composite as truss joint connectors.

Structural Grading and Characteristic Value of the Moso Bamboo Culm Based on Its Minimum External Diameter

Bamboo culm has been regarded as a traditional element in construction; meanwhile, it has great potential for the construction of rural houses to achieve green and low-carbon development. However, traditional bamboo houses are usually constructed according to previous experience, and it is hard to design bamboo houses in a standard way. Structural grading of the bamboo culm is an essential work to achieve standardization design. Grading the Moso bamboo culm (P. edulis) based on its minimum external diameter is proposed in this paper. The geometric, physical and mechanical properties of 883 Moso bamboo culms with three different treatment processes were measured and analyzed, namely untreated, with chemical preservatives and heat treatment. It was found that the external diameter of the Moso bamboo culm could be determined by the perimeter in practice. The treatment process has a great influence on the geometric, physical and mechanical properties. Bamboo culms with three different treatment processes could be divided into five, five and four grades, respectively. Meanwhile, based on measurement data, the characteristic values of each grade are presented, including the wall thickness, external and internal taper, linear mass, nominal density and compressive strength. The minimum chemical treatment factor is 0.785, 0.662 and 0.649, while the minimum heat treatment factor is 0.722, 0.644 and 0.877 for wall thickness, linear mass and nominal density, respectively. The treatment factor for compressive strength is 1.12 and 1.52 of chemical treatment and heat treatment, respectively. This study may aid establishing technical specifications and a standard design method for Moso bamboo structural building.

Characterization of Bamboo Culm as Potential Fibre for Composite Development.

This study aims to evaluate how age, harvesting seasons, and culm height affect the properties of various bamboo species. The properties of bamboo fibres for composite development in Ethiopia have not been investigated so far. In this study, the properties of Y. alpina and B. oldhamii were scientifically investigated for bamboo culm structural applications and bamboo fibre composite development based on age and the harvesting season. Y. alpina was collected at Injibara and Mekaneselam which are located in east Gojjam and south wollo, whereas B. oldhamii was collected at Kombolcha which is located in south Wollo, Ethiopia. Three representatives of bamboo plants were collected in the three regions, namely from three age groups, across two harvesting months. The highest and lowest moisture content and shrinkage were measured at the ages of one year and three years, respectively, whereas basic densities were measured at the ages of three years and one year. The harvest month of November yields higher moisture content and shrinkage but lower basic densities compared to February. Yushania alpina has a higher moisture content and shrinkage but lower basic densities compared to Bamusa oldhamii. The current research demonstrates that the three-year-old groups and the harvesting month of February produce yields more suited for construction and structural purposes due to the ensuing good dimensional stability after drying. From the highest to the lowest percentage of the degree of crystallinity of the yield, it is that derived from Inj., followed by Meka., and then Kombolcha, respectively. Bamboo fibres have high powder crystals and degradation temperatures which make them suitable for composite development at two year old. Yushania alpina has a higher degree of crystallinity and degradation temperature of cellulose compared to Bambusa oldhamii.

Uses of Bamboo for Sustainable Construction—A Structural and Durability Perspective—A Review

Bamboo is a natural biodegradable material used as a strength-bearing material that operates for system works, formwork supporting stands, structural members in low-rise houses, props, framing, bridges, laminated flooring, facades, walls, roofs, and trusses. Over recent years, there has been an increased demand for bamboo, considering sustainable construction practices. Exploring bamboo’s physical and mechanical behaviour is essential to develop innovative construction methods and design guidelines. Therefore, this paper aims to review the studies on bamboo culms’ material properties and physical behaviour, considering the load-bearing capacity and structural adequacy. This study summarises the physical and mechanical properties of a wide array of bamboo species grown worldwide. Mechanical properties such as compressive, tensile, flexural, shear, and bucking strengths are explored, highlighting the key findings in previous experimental works. Results have indicated a significant variability in bamboo’s material and mechanical properties considering the growth conditions, location along a culm, geometric imperfections and environmental conditions. In addition to material and mechanical properties, structural bamboo connections, engineered bamboo products, and preservative treatment of bamboo are also investigated. The construction industry can utilise the summary of the findings of this study to develop design guidelines for sustainable bamboo construction. Overall, this paper presents an overview of structural capability and drawbacks for future research and development using bamboo in modern construction.

Sources of carbon supporting the fast growth of developing immature moso bamboo (Phyllostachys edulis) culms: inference from carbon isotopes and anatomy.

Phyllostachys edulis is a spectacularly fast-growing species that completes its height growth within 2 months after the shoot emerges without producing leaves (fast-growing period, FGP). This phase was considered heterotrophic, with the carbon necessary for the growth being transferred from the mature culms via the rhizomes, although previous studies observed key enzymes and anatomical features related to C4-carbon fixation in developing culms. We tested whether C4-photosynthesis or dark-CO2 fixation through anaplerotic reactions significantly contributes to the FGP, resulting in differences in the natural abundance of δ13C in bulk organic matter and organic compounds. Further, pulse-13CO2-labelling was performed on developing culms, either from the surface or from the internal hollow, to ascertain whether significant CO2 fixation occurs in developing culms. δ13C of young shoots and developing culms were higher (-26.3 to -26.9 ‰) compared to all organs of mature bamboos (-28.4 to -30.1 ‰). Developing culms contained chlorophylls, most observed in the skin tissues. After pulse-13CO2-labelling, the polar fraction extracted from the skin tissues was slightly enriched in 13C, and only a weak 13C enrichment was observed in inner tissues. Main carbon source sustaining the FGP was not assimilated by the developing culm, while a limited anaplerotic fixation of respired CO2 cannot be excluded and is more likely than C4-photosynthetic carbon fixation.

Functional properties of flour substitute from bolo (Gigantochloa levis) bamboo shoots and culms

Functional properties of flour substitute from bolo (Gigantochloa levis) bamboo shoots and culms

Does monocarpic Phyllostachys nigra var. henonis regenerate after flowering in Japan? Insights from 3 years of observation after flowering.

Phyllostachys nigra var. henonis, a monocarpic bamboo with a 120-year flowering interval, is next predicted to flower in Japan in the 2020s. Because a huge area of the country is presently covered by stands of this species, post-flowering dieback of these stands and ensuing drastic changes in land cover may cause serious social and/or environmental problems. No study on the regeneration of this bamboo species was conducted during the last flowering event in the 1900s, and the regeneration process of this species is thus still unknown. In 2020, we encountered a localized flowering of P. nigra var. henonis in Japan and used this discovery as a rare opportunity to study the initial regeneration process of the species. Over 3 years, more than 80% of culms in the study site bloomed, but no seed was produced. In addition, no established seedlings were located. These facts strongly suggest that P. nigra var. henonis lacks the ability to produce seeds and cannot undergo sexual regeneration. Some bamboo culms were produced after flowering but died within 1 year of emergence. Small, weak culms (dwarf ramets) also appeared after flowering, but most died within 1 year as well. Three years after flowering, all culms had died, with no sign of regeneration detected. According to our 3 years of observation, this bamboo appears to be hard to regenerate-an idea completely contradicted by the fact that this species has long persisted in Japan. We thus considered other possible regeneration modes for P. nigra var. henonis.

Mathematical system based on taper functions for distribution by structural product of culms in three giant bamboo taxa

Aim of study: To generate a mathematical system to distribute structural products of bamboo culms.
 Study area: Northeastern region of the state of Puebla, Mexico.
 Materials and methods: Eighty-seven culms of Bambusa oldhamii Munro, Guadua aculeata Rupr. and Guadua angustifolia Kunth were collected in Puebla, Mexico. Four taper functions were evaluated, the one with the best predictive capacity was fitted to model the diameter over and under wall together with a wall thickness model. The fitting strategy consisted of a system of additive equations using Weighted-Nonlinear Seemingly Unrelated Regression (WNSUR) procedure with autocorrelation correction, in combination with the Dummy Variable technique.
 Main results: The Fang & Bailey case 1-a model was selected to describe the diameter over and under wall; the Cao and Papper model was used to model the wall thickness. The R2adj of the system fitted were 0.977, 0.944 and 0.918, and RMSE values 0.186 cm, 0.200 cm and 0.134 cm, for diameter over wall, diameter under wall, and wall thickness, respectively. G. angustifolia had the greatest taper and wall thickness, followed by G. aculeata. The highest proportion of primary product was presented by G. angustifolia. The system generated had parameters specific for each bamboo taxon.
 Research highlights: The diameter profile of bamboo culms can be modeled by taper functions. A mathematical system for distribution by structural product type was developed consisting of: (1) a taper model for the diameter over wall and, (2) a function to estimate the commercial height.

Effects of integrated process of flattening and densification on the gradient structure and properties of Moso Bamboo

Bamboo is an appealing source of engineering materials due to its renewability and sustainability. However, the traditional method of processing bamboo splits using four-side planing leads to a very low utilization rate of bamboo materials. Additionally, the non-uniform structure of the bamboo culm wall results in a concentration of higher density towards the outer part and a gradual decrease towards the inner part. To address these issues, this study proposes an effective and environmentally friendly method that combines flattening and densification to modify the heterogenous structure and enhance the properties of natural bamboo. Natural bamboo splits with a moisture content of 70 % were compressed by 44 % along the radial direction of culm wall for 20 min at temperatures of 170 °C and 190 °C, respectively. The gradient characteristics of modified bamboo including microstructure, density, and mechanical properties were investigated for the first time to explore the effect of flattening and densification on the heterogenous bamboo material. After modification, the parenchyma tissues were collapsed, the fiber bundle fraction increased, and the differences in lumen size and fiber fraction between the outer and the inner parts of bamboo splits decreased. The density of the inner part of bamboo splits was tremendously increased to over 1.0 g/cm3 and was consistent with that of the outer part. The tensile and bending properties across the gradient were significantly improved, and the weaker section was reinforced and possessed a strength equivalent to the sturdy part of natural bamboo. Furthermore, the tensile and bending properties of full-thickness bamboo splits were improved, and the change in stress distribution led to a stable structure replacing the previously vulnerable structure.

Determinants of the Market Outlet Choice of Bamboo Culms (Yushania alpine) Producers in Banja District, Western Ethiopia

Bamboo meets a growing and various bamboo product demand and generates revenue. The study is aimed at analyzing the critical variables that affect the choice of alternative bamboo market outlets. By using two stages sampling procedures, 114 bamboo producers were randomly and proportionally selected. The determinants that affect the choice of bamboo market outlet were analyzed by multivariate probit model. Based on the model result, the probability of bamboo producers to select wholesaler, retailer, processor, and local traders’ outlet were 16.8%, 46.2%, 60.8%, and 54.3%, respectively. The probability of success and failure to select four market outlets were 2.5% and 2.2%, respectively. The result of MVP revealed that family size, total land holding size, amount of culm production, farming experience, distance to the market, and silviculture management practice affected the probability of farmers’ market outlet choice. Therefore, improving the producers’ knowledge and skills through capacity building and creating framers’ organization for collective action can help producers select the right market to sell bamboo products.

Effect of Bamboo Culm Grading on the Properties of Flattened Bamboo Boards

As a natural biomass material, bamboo is subject to variations in culm size as well as in physical and mechanical properties that substantially influence processing and product quality. The diameter, thickness, and hardness of bamboo culms are critical factors for the output and quality of flattened bamboo board (FBB). In this study, the effects of different hardness modulus (HM) grades on the physical and mechanical properties of FBB were examined. The results showed that the HM of Moso bamboo (Phyllostachys pubescens) followed a normal distribution. Nine grades of HM could be divided by an interval of 5 KN/mm2. The physical and mechanical properties of FBB were positively correlated with the HM of bamboo culms. Compressive strength, tensile strength, and shear strength, as well as the bending properties of FBB, each increased with increasing HM. Furthermore, under the same conditions, the mechanical properties of FBB were superior to those of both bamboo strips and bamboo culms. The softening, flattening, and planing processes were beneficial in improving the performance of bamboo. The strong correlation between HM and the properties of FBB indicates that the HM grading of bamboo culms can be used in bamboo processing to produce high-quality FBB products with uniform performance.

Taxonomy and phylogeny of Hypoxylon zhaotongensis sp. nov. (Hypoxylaceae, Xylariales), a bambusicolous fungus from Yunnan, China

During a survey of bambusicolous fungi in Yunnan Province, southwestern China, several saprobic fungi associated with dead bamboo culms were collected and cursorily identified as species belonging to Xylariales (Sordariomycetes), based on a morphological approach. In this study, a new species, Hypoxylon zhaotongensis, from bamboo was established. In addition, molecular analyses based on multiple gene sequences (ITS, LSU, RPB2, β-tubulin) were carried out to determine the phylogenetic placement of the new isolates. The morphological characteristics show that our new taxon differs from the known Hypoxylon species in having broader asci and ascospores with conspicuously straight germ-slit, which is less than the spore length. Detailed description, photo-plate and a phylogenetic tree showing the taxonomic placement of the new species are provided in this paper.