Next Article in Journal
The Effects of Sudden Freezing on the Biochemical Status of Bamboo Leaves: A Case Study on Nine Species on a Subtropical Plateau
Previous Article in Journal
Early Spring Broadleaved Weed Control during Seedling Dormancy in Regenerated Pedunculate Oak Forests
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Forests
Volume 14
Issue 12
10.3390/f14122288
forests-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Variations in the Vascular Bundle and Fiber Structure during the Stem Development of Rattan (Calamus caesius Blume)

by
Linpeng Yu
1,2,3,
Kangjian Zhang
1,2,3,
Fukuan Dai
1,2,
Zehui Jiang
1,2,
Yuxuan Chen
1,2,
Youhong Wang
3,* and
Genlin Tian
1,2,*
1
Institute of New Bamboo and Rattan Based Biomaterials, International Center for Bamboo and Rattan, Beijing 100102, China
2
Key Laboratory of National Forestry and Grassland Administration/Beijing for Bamboo & Rattan Science and Technology, Beijing 100102, China
3
School of Forestry and Landscape Architecture, Anhui Agricultural University, Hefei 230036, China
*
Authors to whom correspondence should be addressed.
Forests 2023, 14(12), 2288; https://doi.org/10.3390/f14122288
Submission received: 1 November 2023 / Revised: 15 November 2023 / Accepted: 21 November 2023 / Published: 22 November 2023
(This article belongs to the Section Wood Science and Forest Products)
Browse Figures
Versions Notes

Abstract

:
Calamus caesius is one of the most well-known commercial climbing palm species across the world. A comprehensive understanding of the growth-dependent variation in microstructure and polymer distribution can provide fundamental information to guide its end-use applications. In this study, we investigated the age-wise characteristics of rattan stems and the ultrastructure of fibers using electron microscopy, light microscopy, and FTIR. The results showed that the frequency of vascular bundles with a diameter of 0.55∼0.62 mm in C. caesius was 3.49∼3.97 pieces/mm 2 . The diameter and length of the metaxylem vessel were 0.32∼0.34 mm and 2.86∼3.00 mm, respectively. Cellulose, lignin, xylan, and HCA are mainly concentrated in the fiber sheath of vascular bundles. The distribution of major polymers in positions other than the top was relatively stable. The tissue proportion of parenchyma, xylem, and phloem did not differ significantly at different positions. The proportion of fibers from 22.27%∼25.33% showed significant differences. The fiber length was 1.43∼1.76 mm, and the diameter was 10.78∼12.63 μ m. During the growth process of the rattan stem, the secondary wall of fiber cells continued to accumulate inward towards the cell cavity from 2 to 6 layers. The unique fiber properties and stable vascular bundle composition of C. caesius may have potential in fields such as composite materials or renewable energy.

1. Introduction

Rattan is a widespread, important, and diverse group of plants found in tropical and subtropical regions [1]. Rattan stems can be used for a large variety of purposes, including the creation of furniture, baskets, ropes, and other traditional crafts. The bench made of multilayer composites reinforced with rattan and loosely woven hemp fibers showed high rigidity and elasticity, demonstrating high structural capabilities and potential for upscaling [2]. Rattan stems are also used to manufacture building materials, textiles, and woven materials [3]. In modern building design, it is suggested to use rattan palms for ceilings due to their heat-resistive potential, which is superior compared to many other wood-based heat-insulating materials [4]. Additionally, rattan stems have medicinal and pharmacological functions, which can be used to treat various ailments and enhance immunity [5]. The natural hierarchical and gradient pore structure of the vascular bundles in rattan stems can even be utilized to create solar evaporators [6]. In addition, the composites manufactured by combining woven rattan and glass fibers have the potential to be used in the automotive industry, e.g., as bumper parts [7].
There are 13 genera and more than 600 species of plants associated with the common name rattan [8,9,10]; Among them, the Calamus L. genus is the most abundant, with an estimated 374 species [11,12]. These plants possess strong climbing abilities, with some growing upright, which is an adaptation to various environments. Rattans with climbing habits usually have larger diameters or a higher frequency of vessels than rattan that grow upright [13,14]. The composition and properties of rattan stems are constantly influenced by the cell growth, differentiation stage, and environment during their growth process [15,16]. The polymers of the cell wall interact and change, and the resulting alteration in the wall properties may be related to the variation in its function [17]. To utilize the biomass feedstocks with dynamic compositional changes, it is imperative to better understand the distribution of the main components (cellulose, hemicellulose, and lignin) at different age stages.
It has been shown that rattan fibers have walls with multiple layers, similar to those found in bamboo and coconut stem fibers [18,19,20]. Additionally, fiber cells influence tensile strength [21]. Studies on the maturation pattern of stem fibers in C. tetradactylus Hance show that the sequence of thickening of fiber cell walls usually occurs from the bottom to the top of the rattan stem [11,22]. However, the changes that occur during the maturation process are not well understood. A full understanding of the changes in anatomical structure, polymer distribution, and fiber wall of rattan during each growth stage can help with the development of new rattan materials or help optimize the process to obtain chemicals with high selectivity.
Calamus caesius Blume is a member of the Calamus genus of the Arecaceae family and is listed as one of the 27 important economic rattan species in the world by the International Bamboo and Rattan Organization [11]. The stems of C. caesius are flexible from the base to the top, with a consistent and smooth yellowish-white outer epidermis. They have long internodes and little variation in diameter along their length [23,24]. This type of rattan is suitable for various types of binding or weaving in furniture and basketry [25]. This study, which was based on light, Fourier transform infrared spectroscopy (FTIR), and electron microscopic observations, was primarily concerned with anatomical features and polymer distribution at the tissue level. It aims to reveal the structure of vascular bundles, the distribution of polymers, the thickness of fiber cell walls, and the ultrastructure of fibers at different ages along the stem.

2. Materials and Methods

2.1. Materials

C. caesius was purchased from Deng Jinzhi Rattan Factory (Guangzhou, China) and originated from Indonesia in Southeast Asia (The imported material was dead and dried tissue). Randomly, three healthy rattans were chosen (Length: 8.54 ± 0.82 m. Diameter: 12.59 ± 1.70 mm. Internode length: 26.85 ± 3.41 cm). The sample had a moisture content of around 11%. To represent the different ages of the naturally grown rattans, which were difficult to precisely determine, BASE (old), 2-METER (internodes located at 2 m above the ground, mature), MIDDLE (intermediate), and TOP (young) internodes were selected for this investigation. Blocks of 1 cm in length were cut from the middle part of the selected internodes. For this investigation, the stem’s intermediate (between the central and periphery places) portions were used (Figure 1).

2.2. ImageJ Measurement

The samples (1 cm in length) were cut from the internode middle of four distinct components using a precision cutting saw (IsoMet4000; Buehler Corporation, Lake Bluff, IL, USA), and the cross-sectional surfaces were subsequently polished using 600-grit sandpaper. To create high-resolution photographs, the cross-sections were scanned using a high-resolution scanner (V850 pro, Seiko Epson Corporation, Beijing, China) at a high resolution of 9600 pixels per inch in 16 bit grayscale mode. The number of vascular bundles or metaxylem vessels located in the middle region of the cross-sections was measured from the images using ImageJ software. ImageJ was a software developed by Wayne Rasband at the Research Services Branch of the National Institutes of Health (NIH), located in Bethesda, MD, USA, with the version being 1.53e. The number of vascular bundles or metaxylem vessels that had more than 50% of their area within a randomly selected 1 mm 2 area was counted as one. The mean value was calculated after measuring more than 30 data points for each sample. Measurements were also made of the fiber, parenchyma, phloem, and xylem tissue proportions. The number of points falling on fiber, parenchyma, phloem, and xylem was counted using a 10 × 10 dot counting method [15]. The percentage of each tissue type was represented by the percentage of its counted points to the total number of points. Each sample was counted 10 times.

2.3. SEM Observation

Samples that were around 1 cm long were selected and placed in a water-filled beaker. Then, using a Galanz microwave (G80W23CSP-Z, Galanz Corporation, Foshan, China), they were heated for 15 min. The sample was then polished with a sliding microtome (SM2010R, Leica Corporation, Wetzlar, Germany). The samples were coated with gold using an E-1010 sputter coater (Quorum Technologies, Emsworth, UK) for 90 s prior to imaging. After that, a 3 kV environmental SEM (GeminiSEM 360, Carl Zeiss AG, Oberkochen, Germany) was used to investigate the polished cross-section [26].

2.4. TEM Observation

The samples were cut into matchstick-sized pieces and placed in glass vials containing a solution of 30% hydrogen peroxide and 50% glacial acetic acid in a 50:50 molar ratio. The glass vials were sealed and allowed to rest at room temperature for a week. The samples were taken out, cleaned with distilled water, embedded in Spurr’s epoxy resin, and then transverse ultra-thin sections (70 to 90 nm) were cut using a diamond knife and an ultramicrotome (Leica EM UC7). The portions were then exposed to 1% w/v KMnO4 for 2 min at 25 °C of the surrounding environment. Transmission electron microscopy (TEM, JEM-1200EX; Japan Electronics Technology Corporation, Tokyo, Japan), operating at an accelerating voltage of 80 kV, was then used to study the cell wall layering characteristics [27].

2.5. Maceration

The selected sample was cut into matchstick-sized pieces and placed into glass vials containing a solution of glacial acetic acid and 30% hydrogen peroxide in a 50:50 molar ratio. 30% H 2 O 2 and glacial acetic acid of analytical grade were bought from Nanjing Chemical Reagent in China. To soften the substance, the vials were cooked in an oven (DHG-9240A, Yiheng Technology, Guangzhou, China) at 60 °C for roughly 8 h. The samples were stored in glass test tubes filled with water once they became soft and white and were then rinsed with deionized water. A tiny droplet of cell suspension was placed on a microscope slide and examined using a microscope (Leica Microsystem, Wetzlar, Germany) [24]. The diameter and length of each sample were assessed after 30 whole fibers and metaxylem vessel components were randomly selected.

2.6. Transmission Mode FTIR Imaging

Cross-sectional slices of 10 μ m thickness were made from four different positions using a microtome (SM2010R, Leica Corporation, Wetzlar, Germany). The Spectra Spotlight 300 imaging FT-IR system (Perkin-Elmer Inc., Shelton, CT, USA) was used to scan the prepared transverse sections under transmission mode. Prior to scanning, the MCT detector was cooled with liquid nitrogen and the instrument was allowed to stabilize for more than 30 min. The IR spectra were recorded in the fingerprint region of biomass materials (the range of 750–1900 cm − 1 ), with a resolution of 4 cm − 1 , using a scanning area of 150 × 150 μ m and a resolution of 6.25 × 6.25 μ m. To enhance the signal-to-noise (S/N) ratio and eliminate the impact of background spectra, the scanning time was set to 24, and a background signal was obtained every hour [28].

2.7. Data Analysis

The data extracted from the acquired images were analyzed using ImageJ software. Excel 2021 (Microsoft Corporation, Redmond, WA, USA) was utilized for conducting the statistical analysis, while ANOVA analysis was performed using IBM SPSS Statistics 19 software (IBM, Armonk, NY, USA). Charts and diagrams were generated using Origin 2018 software (OriginLab Corporation, Northampton, MA, USA) and PowerPoint 2021 software (Microsoft Corporation, Redmond, WA, USA) as well. The MAGE-Spotlight 300 software (Perkin-Elmer, Inc, Waltham, MA, USA) was used for FTIR image processing. Unimodal imaging was employed to accurately depict the spatial distribution of the main cell wall polymers in rattan tissue.

3. Results and Discussion

3.1. Microstructures

Figure 2 showed the scanned images of the complete cross-sections of the rattan stems at four different positions. The diameters of the rattan stems at different age stages were consistent, and the macroscopic appearance of the cross sections was very similar. The stem anatomy matched the typical structure of the monocotyledons: a single layer of cells formed an epidermis that covered the stem [29]. Vascular bundles were scattered throughout the ground tissue to provide support for the stem. In the center and intermediate parts, the vascular bundles were diffusely scattered, and the size and frequency of the vascular bundles were observed to be very similar. In contrast, the vascular bundles located at the peripheral part became visibly smaller and denser in distribution near the epidermis. Except for the area very close to the epidermis, the vascular bundles were evenly distributed in the ground tissue, and their sizes appeared to be very similar. The diameter and frequency of the metaxylem vessels had the same variation pattern as the vascular bundles.
According to the SEM images of C. caesius (Figure 3), the microscopic characteristics of the rattan stem at different age stages were barely distinguished, appearing remarkably similar. Vascular bundles were distributed throughout the ground tissue for support of the stem. The xylem was composed of protoxylem elements with xylem parenchyma and a large metaxylem vessel. The interfascicular region, or space between the vascular bundles, was primarily made up of parenchyma cells. Both the vascular bundles and the interfascicular area had enormous parenchyma cells [30,31]. Sieve elements and their companion cells were distributed, exhibiting a serial arrangement on both sides of the secondary xylem, and surrounded by fibers. A bundle sheath was formed on the fiber surface, which was a protective layer of fibers surrounding the vascular bundle, shielding the phloem and xylem. The vascular bundle was significantly stiffer than the surrounding parenchymatous tissue, which not only largely accounted for the overall stiffness of the plant but also determined its local stiffness [32]. Therefore, the frequency of vascular bundles within the stem was intimately linked to the local densities and material properties.

3.2. Ultrastructure Study

According to ultrastructure (Figure 4), the secondary walls of the majority of the fibers at the TOP were two-layer structures, the secondary walls of the fibers in the MIDDLE and 2-METER had four layers, and the secondary walls of the majority of the fibers at the BASE had six layers. The secondary walls of fibers showed alternating thick and thin structures, with the innermost layer generally being a thick layer and the outermost layer being a thin layer. The number of layers in the secondary walls was related to the arrangement of cellulose microfibrils. Microfibrils with the same orientation constructed one layer, meaning that base fibers with six layers might have six different microfibril arrangements.
Rattan plants have characteristics of growth and development that are different from those of other woody plants, and they have no secondary growth. The tissues formed by primary growth remain active throughout the plant’s life until the plant dies, without being supplemented by new tissues [33,34]. Thus, in our experiment, fibers of C. caesius showed obviously different developmental characteristics as their position changed. Fibers at the TOP were the youngest and had only two layers in the secondary wall. As the years increased, cell wall layers continued to accumulate inward to the cell cavity until they reached six layers. The prolonged activity of the protoplasm in the fiber cells of the C. caesius stem facilitates the ongoing thickening of the secondary wall. This process supports the plant’s sustained growth and development needs. There was a very interesting phenomenon; that is, the number of layers in the secondary walls was usually even, and during the thickening process, cell wall layers also increased in even layers, increasing two layers each time until reaching maturity. The above situation indicated that the thickening of fiber cell walls was not random but had inherent regularity.
As fibers matured, new lamellae formed, leading to an increase in both wall thickness and tissue proportion. However, this process was less pronounced in ground parenchyma compared to fibers [35]. The fiber wall structure and tissue proportion seemed to be the main determinants of how the Calamus species’ stems behaved under tensile and bending stress [36,37]. In practical applications, the tensile strength and bending strength of different rattan stems could be indirectly compared based on the fiber wall structure and tissue proportion.

3.3. The Vascular Bundle and Metaxylem Vessel Frequency and Tissue Proportion

As shown in Table 1, longitudinally, the vascular bundles frequency in C. caesius was 3.49∼3.97 pcs/mm 2 ( “pcs” abbreviation as “pieces”), and the frequency of vascular bundles shifting from the BASE to the TOP did not show any clear trends. The frequency of vascular bundles in C. caesius was close to that of C. zollingeri Becc. (3.30 pcs/mm 2 ), and the diameter of the latter (18.62 mm) was much larger than that of the former [38,39]. However, the frequency of vascular bundles in Korthalsia laciniosa Mart (diameter 17.00 mm) was 5.4∼9.8 pcs/mm 2 , much larger than that of C. caesius (Table 2). The frequency of vascular bundles was 3.02 pcs/mm 2 in C. ornatus BI. (diameter 14.76 mm) [12], which was slightly lower than that of C. caesius. As a result, it was clear that there was no correlation between the frequency of stem vascular bundles and internode diameter. The frequencies of vascular bundles and metaxylem vessels were very close, due to the well-developed vascular bundles located in the intermediate, each of which had a huge metaxylem vessel. The frequency of vascular bundles in the intermediate of the stem from the BASE to the TOP did not differ significantly, according to a one-way analysis of variance (ANOVA) at a 0.05 significance level. The frequency of metaxylem vessels showed no significant difference longitudinally.
At different positions (BASE, 2-METER, MIDDLE, or TOP), there were some differences in the proportion of tissues (Table 3). The xylem was composed of primary and metaxylem xylem, with the latter occupying a much larger proportion than the former. Due to the presence of large metaxylem vessels, approximately 23.44%∼25.05% of the tissue proportion indicated that this rattan had an excellent porosity [6]. The proportion of fiber tissue was relatively high at the BASE and relatively low at the TOP. The proportion of fiber tissue decreased by 3.06% from the BASE to the TOP, with the largest change among the four tissues. The fiber proportion of C. caesius was around 4% greater at the same locations as that of C. simplicifolius C. F. Wei [15]. To a certain degree, the mechanical strength of the material exhibited a positive correlation with the proportion of fibers [40,41,42]. This indicated C. caesius could potentially have better mechanical properties compared to C. simplicifolius [43]. For C. caesius itself, the mechanical properties of the BASE may be better than those of the TOP. The density of rattan is heavily influenced by its anatomical structure, particularly the size, frequency, and composition of its vascular bundles. There are more vascular bundles with thicker-walled fibers at the base, making this part of the stem more dense. Conversely, the top regions have fewer and thinner-walled fibers, showing a tendency to decrease in density [44,45]. In addition, the proportion of primary phloem was the smallest in each of the four different positions. The proportion of parenchyma tissue was highest at each position, occupying almost half of the area at each position. However, the ANOVA test showed that only the fiber at the TOP had significant differences with those at the BASE, 2-METER, and MIDDLE. The differences in the other three tissues along the axial direction were not significant. In short, the proportion distribution of each tissue was relatively stable at different positions. C. caesius with the high-porosity and high-fiber proportion having advantages such as being lightweight, having good elasticity, easy to bend and shape, strong water absorption, quick drying, and water resistance [46]. These advantages made the stem of C. caesius suitable for making furniture, crafts, woven products, and other products.

3.4. The Anatomical Characteristics of The Vascular Constituents

Table 4 showed radial diameters and the tangential of the vascular bundle did not change significantly at different longitudinal positions (BASE, 2-METER, MIDDLE, or TOP), and the form factor (the ratio of tangential diameter to radial diameter) of the vascular bundle was also between 1.04 and 1.07, close to 1, indicating that the cross-section of the vascular bundles was approximately circular. The results of the ANOVA test indicated that there were no statistically significant differences in the radial diameter, tangential diameter, and form factor of the vascular bundle of C. caesius, and the form and size of the vascular bundle were relatively stable. The radial and tangential diameters of the vascular bundle in C. caesius were larger than those of C. insignis Griff. (radial diameter 0.34 mm, tangential diameter 0.30 mm), but the vascular bundle frequency of C. caesius closely resembled that of C. insignis (1∼4 per mm 2 ) [38,47]. In the same area, the number of vascular constituents in both C. caesius and C. insignis were the same, but the area occupied by vascular bundles in C. caesius was much larger than that in C. insignis, which could infer that the proportion of parenchyma cells in C. insignis might be much larger than that in C. caesius.
The metaxylem vessel’s length and length–diameter ratio were not significantly different, according to the results of the ANOVA test. The diameter of the metaxylem vessel had significant differences between the BASE and two positions (2-METER and TOP), as well as between the MIDDLE and TOP longitudinally. Some research results showed that the absolute maximum length of metaxylem vessels seemed to have an approximate range, and this upper limit of metaxylem vessel length was equal to the maximum length for the vascular bundle [13,14]. Therefore, according to the maximum length of metaxylem vessels, it could be estimated that the maximum length of vascular bundles was about 3 mm. The diameter of the vessels in C. caesius was larger than that in Plectocomiopsis geminiflora Becc. (0.31 mm) and Daemonorops micracantha Becc. (0.25 mm) [38]. In addition, research results have shown that there is a negative correlation between the frequency and diameter of metaxylem vessels [48]. And the frequency of metaxylem vessels in P. geminiflor and D. micracantha were both larger than that of C. caesius, which proved the accuracy of this view. According to Hagen–Poiseuille’s law, the diameter of metaxylem vessels would affect hydraulic efficiency, hydraulic efficiency would significantly decrease or rise even if there was a minimal change in the diameter of the metaxylem vessels [49,50,51]. This indicates that although the diameter of vessels in C. caesius is only slightly larger than that in P. geminiflora, the hydraulic transport efficiency of C. caesius would be much larger than that of P. geminiflora.
The length of the fiber was the shortest at the BASE, the longest in the MIDDLE, and was slightly shorter at the TOP than in the MIDDLE. The BASE position’s fiber length differed significantly from the other three places (2-METER, MIDDLE, and TOP), according to the results of the ANOVA test, although there was no variation in length between the other three positions. The diameter of the fiber was the smallest at the BASE, the largest at the TOP, and intermediate at the MIDDLE. The diameter of the fiber had significant differences between the TOP and the other three positions (BASE, 2-METER, MIDDLE), although the diameters of the other three positions did not differ noticeably. The length and diameter of fibers at different longitudinal positions varied slightly, but the magnitude of the variation was not large. The fibers’ length–diameter ratio was lowest at the BASE, highest in the MIDDLE, and just marginally lower at the TOP than in the middle. Fibers became thinner and longer from the BASE to the MIDDLE. The length of fibers in P. geminiflora (length 3.52 mm, diameter 18.10 μ m) was much longer than that of C. caesius, but the fiber diameter was only about 6 μ m larger than that of C. caesius. The length–diameter ratio was approximately 35.67 higher than C. caesius. The fiber length of C. exillis (length 1.96 mm, diameter 21.9 μ m) was close to that of C. caesius, but the diameter was about 10 μ m larger than that of C. caesius, and the length–diameter ratio was about 39.82 higher than C. caesius [38]. C. caesius is widely considered one of the highest-quality rattan species in the world, which is known for its excellent flexibility. The fiber size of C. caesius could be used as one of the standards for evaluating the quality of rattan products. In composites made from natural fibers, the shape and size of fibers can significantly impact the material performance of the composites [52,53]. Therefore, the size of fibers was one of the most important factors that needed to be considered before use.
Table 5 showed the double wall thickness (The double wall thickness refers to the fiber diameter minus the cavity diameter), cavity diameter, and wall–cavity ratio of fibers at different positions (The wall-cavity ratio represented the ratio between the double wall thickness and the cavity diameter). It could be seen that the double wall thickness of fibers did not vary significantly among different positions, with an average of between 4 and 5 μ m, and the fiber wall thickness increased slowly from the TOP to the BASE. The ANOVA test revealed a significant difference in the double wall thickness at the top compared to other positions. Bhat [54] found that fiber content, fiber wall thickness, wall-cavity ratio, and vessel diameter affected rattan density along the stem. Fiber wall thickness was the key anatomical factor determining rattan’s physical properties. The cavity diameter of fibers ranged from 6 to 8.5 mm at different positions. The ANOVA test indicated that the cavity diameter at the TOP was significantly different from the other three positions (BASE, 2-METER, MIDDLE), while there was no significant difference between the BASE and the MIDDLE.
During the growth cycle from the BASE to the TOP, the young fiber diameter was not much different from the mature fiber, but both double wall thickness and cavity diameter showed significant differences. The internal structure was significantly different while the diameter remained the same, which suggested that the internal structure of fibers changed with age. The cell wall gradually thickened inward, and the cell cavity gradually decreased under pressure to adapt to different functional demands. The wall–cavity ratio of fibers also ranged from 0.58 to 0.93 at different positions. From BASE to TOP, the wall–cavity ratio gradually decreased. The wall–cavity ratio at the TOP was about 0.35 lower than that at the BASE. There was not much difference in the wall–cavity ratio between the BASE, 2-METER, and the MIDDLE. The wall–cavity ratio reflected the strength and flexibility of fibers [55,56]. Generally, the higher the wall–cavity ratio, the thicker the cell wall, and the smaller the cavity diameter, the harder and less bendable the fiber; the lower the wall–cavity ratio, the thinner the cell wall, and the larger the cavity diameter, the softer and more bendable the fiber. This suggested that fibers might be harder at the BASE and MIDDLE and softer at the TOP. The wall–cavity ratio from the BASE to the TOP was less than one, suggesting that the internal space of fiber cells was larger than their wall thickness. During the growth process of C. caesius’s rattan stem, fibers with large cavity diameters not only undertake support functions but may also undertake material connection functions between vascular bundles and ground tissues. Researchers are investigating several types of natural fibers as components for high-performance composite materials as a result of sustainable development and ecological responsibility [57,58]. Fibers of C. caesius could be considered for making modified or composite materials that meet various needs.

3.5. Distribution of the Main Polymers at Different Positions on the Tissue Level

Lignocellulosic biomass was mainly composed of cellulose, hemicellulose, and lignin, which typically constituted about 85%–90% of the biomass; the remaining components were organic extractives and inorganic minerals [59]. The biomass materials were naturally occurring polymeric composites [60]. All polymers could be found in the examined FTIR spectra through their respective characteristic peaks using Fourier-transform infrared spectroscopy (FTIR). Figure 5 showed the distribution of total infrared absorption intensity on a transverse section of C. caesius. The FTIR imaging microscope successfully visualized the spatial distribution of polymers on the transverse section of rattan. The high infrared absorption intensity regions were located in the fiber sheath at the same position, while the parenchyma tissue was much lower than the fiber region except for the base. This was because the fiber sheath had a high density and thick fiber wall, resulting in a higher polymer content. At the base, the polymer content of the parenchyma tissue adjacent to the fiber sheath area was almost equal to that of the fiber sheath area, but their chemical distribution was not directly comparable because of the inherent cell wall substance difference between the fiber sheath and the parenchyma tissue. In the fiber sheath at the TOP, the distribution of polymers was not as uniform as in other positions. The polymer content of the rattan stem gradually increased from TOP to base, and these changes could be regulated by gene expression, stress signals, and plant hormones [61].
The FTIR spectra of rattan from different positions measured via transmission are shown in Figure 6. In this study, the three spectral peaks required were located at 1320 cm − 1 , 1506 cm − 1 , and 1733 cm − 1 , respectively, and were used to generate chemical images in cellulose, lignin, hemicellulose, and hydroxycinnamic acid (HCA) distribution [28]. The 1320 cm − 1 band was related to CH 2 and C-H oscillation and was associated with cellulose [62]. The IR band near 1506 cm − 1 was caused by the C=C stretching vibration of the aromatic ring in lignin [63]. The peak at 1733 cm − 1 was attributed to the C=O vibration and C-O stretching of acetyl and carboxyl groups in hemicellulose and HCA [64]. The difference in position resulted in a significant difference in FTIR absorption. For the fibers at the BASE, the strongest infrared absorption peaks were at 1320 cm − 1 and 1506 cm − 1 , while for the fibers at the MIDDLE, the strongest infrared absorption peak was at 1733 cm − 1 . This indicated that the fibers at the BASE had the highest content of cellulose and lignin, while the fibers at the TOP had weak infrared absorption and poor spectral quality due to the lack of cell wall substance, and thus did not show a clear peak at 1733 cm − 1 .
Chemical images can display the distribution of specific components at characteristic wavelengths. Figure 7 shows the distribution of cellulose, lignin, hemicellulose, and HCA in rattan. The distribution of cellulose, hemicellulose, and lignin in the fiber sheath area of the four parts can be reliably visualized. Cellulose, lignin, hemicellulose, and HCA at the tip seem to be concentrated in the fiber sheath near the phloem sieve tube (Figure 7(d1–d3). The distribution in the fiber sheath area is quite clear. This distribution is reasonable because it can enhance the anti-lodging ability of sieve tubes with thin walls and large cavities as early nutrient transport units [14], enabling them to maintain their three-dimensional structure and normal physiological functions. In all areas except for the TOP, the spatial distribution of cellulose, xylan and HCA, and lignin was similar, and they were concentrated in the fiber sheath near the xylem vessels. The unimodal imaging at 1320 cm − 1 and 1506 cm − 1 showed that the infrared absorption intensity of the fiber sheath at the BASE, 2-METER, and MIDDLE positions was very close, indicating that the cellulose and lignin content at these three positions was very close. The strength of the rattan stem was mainly controlled by the number of cellulose molecules in the cell wall [64], which meant that the mechanical properties of the three positions might also be very close. The color difference was the largest at 1733 cm − 1 for xylan and HCA. The infrared absorption intensity at the middle position was the highest. Xylan was the main component of hemicellulose, and the chemical composition and proportion of each hemicellulose depended on the plant species and developmental stage [65,66,67]. Affected by HCA, the unimodal imaging at 1733 cm − 1 could not strictly reflect the variation of hemicellulose at different positions.

4. Conclusions

From a macroscopic perspective, the stem diameter of C. caesius at different ages was found to be similar, and the frequency of vascular bundles within the cross-section was uniform. Imaging FTIR microscopy revealed the chemical composition of rattan stems. The distribution of cellulose, lignin, xylan, and HCA in different parts of rattan stems had a specific pattern, which was mainly concentrated in the fiber sheath area. When considering the characteristics of vascular bundles, metaxylem vessels, and fibers, it was observed that during the growth process of the rattan stem, once young tissues formed, they did not undergo significant microscopic structural cellulose and lignin content changes. The proportion of fiber, primary phloem, xylem, and parenchyma cell tissue was consistently similar across different positions within the material, rendering C. caesius a high-quality material with homogeneous properties. This may enable it to potentially exhibit excellent performance in load-bearing, without significant variations in strength.
The ultrastructure of C. caesius fibers revealed that the number of layers in the secondary wall varied depending on their position, with two layers at the TOP, four layers at the MIDDLE and 2-METER, and six layers at the BASE. As fibers aged, cell wall layers accumulated inward. This process was not random, but had inherent regularity.
Considering these findings, there was potential for utilizing C. caesius in a range of applications, particularly in areas such as furniture, crafts, or composite materials, where its unique fiber characteristics and stable vascular bundle structure could be advantageous. Furthermore, future research could explore innovative applications and further investigate the specific mechanical properties and performance of C. caesius in different contexts, enhancing its potential applications.

Author Contributions

L.Y. wrote the main manuscript, K.Z. and F.D. provided the study materials and analysis of partial data, Z.J. and Y.C. were responsible for data curation, and G.T. and Y.W. were responsible for funding acquisition, methodology, and project administration. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by Fundamental Research Funds for the International Center for Bamboo and Rattan (1632020027), the National Key R & D Program of China (2022YFD2200901), and the Basic Scientific Research Funds of the National Natural Science Foundation (Grant No. 31800476).

Data Availability Statement

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

Conflicts of Interest

We declare that we have no known competing financial interest or personal relationships that could have appeared to influence the work reported in this paper.

References

  1. Sastry, C. Rattan in the Twenty-First Century—An Overview; FAO: Rome, Italy, 2001; pp. 3–6. [Google Scholar]
  2. Nguyen, M.T.; Solueva, D.; Spyridonos, E.; Dahy, H. Mycomerge: Fabrication of mycelium-based natural fiber reinforced composites on a rattan framework. Biomimetics 2022, 7, 42. [Google Scholar] [CrossRef] [PubMed]
  3. Hameed, B.; Ahmad, A.; Latiff, K. Adsorption of basic dye (methylene blue) onto activated carbon prepared from rattan sawdust. Dye. Pigment. 2007, 75, 143–149. [Google Scholar] [CrossRef]
  4. Alausa, S.; Oyesiku, O.; Aderibigbe, J.; Akinola, O. Thermal properties of Calamus deërratus, Raphia hookeri and synthetic board in building design in Southwestern Nigeria. Afr. J. Plant Sci. 2011, 5, 281–283. [Google Scholar]
  5. Net-anong, S.; Prommee, N.; Dechayont, B.; Prajuabjinda, O.; Yangthaworn, K.; Chunthorng-Orn, J.; Phuaklee, P.; Dawson, P.W.; Juckmeta, T. Calamus caesius (Rattan) wood: Chemical constituents, biological activities’ relative medicinal properties from Thai medicinal scriptures, and in silico antioxidant activity. Arab. J. Chem. 2023, 16, 104990. [Google Scholar] [CrossRef]
  6. Yang, R.; Liu, F.; Xia, L.; Wu, X.; Zhang, X.; Guo, F.; Yu, Y. Rattan-based solar evaporator with natural hierarchical and gradient pore structure for synergetic salt resistance and stable freshwater generation. Sep. Purif. 2022, 286, 120412. [Google Scholar] [CrossRef]
  7. Irawan, A.P.; Anggarina, P.T.; Utama, D.W.; Najid, N.; Abdullah, M.Z.; Siregar, J.P.; Cionita, T.; Fitriyana, D.F.; Jaafar, J.; Hadi, A.E.; et al. An experimental investigation into mechanical and thermal properties of hybrid woven rattan/glass-fiber-reinforced epoxy composites. Polymers 2022, 14, 5562. [Google Scholar] [CrossRef]
  8. Afentina; McShane, P.; Wright, W. Ethnobotany, rattan agroforestry, and conservation of ecosystem services in Central Kalimantan, Indonesia. Agrofor. Syst. 2020, 94, 639–650. [Google Scholar] [CrossRef]
  9. Kumar, A.; Sastry, C.B. The International Network for Bamboo and Rattan; FAO: Rome, Italy, 1999; pp. 48–53. [Google Scholar]
  10. Wahab, R.; Mokhtar, N.; Mohd Ghani, R.S.; Sulaiman, M.S. An overview of rattan industry status and its economic aspect in setting up rattan-based industry in Malaysia. e-BANGI 2019, 16, 1–10. [Google Scholar]
  11. Jiang, Z. Main commercial rattan species. In Bamboo and Rattan in the World; China Forestry Publishing House: Beijing, China, 2007; pp. 574–606. [Google Scholar]
  12. Ahmed, S.A.; Hosseinpourpia, R.; Brischke, C.; Adamopoulos, S. Anatomical, physical, chemical, and biological durability properties of two rattan species of different diameter classes. Forests 2022, 13, 132. [Google Scholar] [CrossRef]
  13. Fisher, J.B.; Tan, H.T.; Toh, L.P. Xylem of rattans: Vessel dimensions in climbing palms. Am. J. Bot. 2002, 89, 196–202. [Google Scholar] [CrossRef]
  14. Tomlinson, P.B.; Fisher, J.B.; Spangler, R.E.; Richer, R.A. Stem vascular architecture in the rattan palm Calamus (Arecaceae–Calamoideae–Calaminae). Am. J. Bot. 2001, 88, 797–809. [Google Scholar] [CrossRef] [PubMed]
  15. Wang, K.; Liu, X.; Yang, S.; Ma, J.; Jin, K.; Tian, G. The deposition of carbohydrates and lignin in the cell walls of Calamus simplicifolius during development. Wood Sci. Technol. 2021, 55, 1765–1779. [Google Scholar] [CrossRef]
  16. Paul-Victor, C.; Rowe, N. Effect of mechanical perturbation on the biomechanics, primary growth and secondary tissue development of inflorescence stems of Arabidopsis thaliana. Ann. Bot. 2011, 107, 209–218. [Google Scholar] [CrossRef] [PubMed]
  17. Speck, T.; Burgert, I. Plant stems: Functional design and mechanics. Annu. Rev. Mater. Res. 2011, 41, 169–193. [Google Scholar] [CrossRef]
  18. Abasolo, W.; Yoshida, M.; Yamamoto, H.; Okuyama, T. Internal stress generation in rattan canes. IAWA J. 1999, 20, 45–58. [Google Scholar] [CrossRef]
  19. Liese, W. Anatomy and properties of bamboo. In Proceedings of the International Bamboo Workshop, Hangzhou, China, 6–14 October 1985; pp. 196–208. [Google Scholar]
  20. Nahar, S.; Hasan, M. Effect of chemical composition, anatomy and cell wall structure on tensile properties of bamboo fiber. Eng. J. 2013, 17, 61–68. [Google Scholar] [CrossRef]
  21. Fidelis, M.E.A.; Pereira, T.V.C.; Gomes, O.d.F.M.; de Andrade Silva, F.; Toledo Filho, R.D. The effect of fiber morphology on the tensile strength of natural fibers. J. Mater. Res. Technol. 2013, 2, 149–157. [Google Scholar] [CrossRef]
  22. Cai, Z. Distribution of vascular tissue in four rattan canes. Acta Bot. Sin. 1989, 31, 569–575. [Google Scholar]
  23. Sebayang, D.; King, T.I.; bin Wahab, R. The properties of rattan Calamus caesius (Rattan Sega) and its application in spring form. J. Sains Mater. Indones. 2018, 5, 21–26. [Google Scholar]
  24. Yu, L.; Dai, F.; Zhang, K.; Jiang, Z.; Tian, G.; Wang, Y. Anatomical and microstructural features of rattan (Calamus caesius). BioResources 2023, 18, 6013–6024. [Google Scholar] [CrossRef]
  25. Blažková, L.; Jeníček, V. Rattan production and trade. Agric. Trop. Subtrop. 2006, 39, 1. [Google Scholar]
  26. Rocky, B.P.; Thompson, A.J. Production of natural bamboo fibers-3: SEM and EDX analyses of structures and properties. AATCC J. Res. 2018, 5, 27–35. [Google Scholar] [CrossRef]
  27. Tang, D.M.; Ren, C.L.; Wei, X.; Wang, M.S.; Liu, C.; Bando, Y.; Golberg, D. Mechanical properties of bamboo-like boron nitride nanotubes by in situ TEM and MD simulations: Strengthening effect of interlocked joint interfaces. ACS Nano 2011, 5, 7362–7368. [Google Scholar] [CrossRef] [PubMed]
  28. Zhu, J.; Wang, H.; Guo, F.; Salmén, L.; Yu, Y. Cell wall polymer distribution in bamboo visualized with in situ imaging FTIR. Carbohydr. Polym. 2021, 274, 118653. [Google Scholar] [CrossRef] [PubMed]
  29. Weiner, G.; Liese, W. Ratians-stem anatomy and taxonomic implications. IAWA J. 1990, 11, 61–70. [Google Scholar] [CrossRef]
  30. Buchanan, B.B.; Gruissem, W.; Jones, R.L. Biochemistry & Molecular Biology of Plants; John Wiley & Sons: Hoboken, NJ, USA, 2015. [Google Scholar]
  31. Wink, M. The plant vacuole: A multifunctional compartment. J. Exp. Bot. 1993, 44, 231–246. [Google Scholar]
  32. Rüggeberg, M.; Speck, T.; Paris, O.; Lapierre, C.; Pollet, B.; Koch, G.; Burgert, I. Stiffness gradients in vascular bundles of the palm Washingtonia robusta. Proc. R. Soc. B 2008, 275, 2221–2229. [Google Scholar] [CrossRef]
  33. Rowe, N.; Isnard, S.; Speck, T. Diversity of mechanical architectures in climbing plants: An evolutionary perspective. J. Plant Growth Regul. 2004, 23, 108–128. [Google Scholar] [CrossRef]
  34. Tomlinson, P.B. The uniqueness of palms. Bot. J. Linn. Soc. 2006, 151, 5–14. [Google Scholar] [CrossRef]
  35. Zhai, S.; Horikawa, Y.; Imai, T.; Sugiyama, J. Cell wall ultrastructure of palm leaf fibers. IAWA J. 2014, 35, 127–137. [Google Scholar] [CrossRef]
  36. Bhat, K.; Thulasidas, P.; Mohamed, C. Strength properties of ten South Indian canes. J. Trop. For. Sci. 1992, 5, 26–34. [Google Scholar]
  37. Bhat, K.; Liese, W.; Schmitt, U. Structural variability of vascular bundles and cell wall in rattan stem. Wood Sci. Technol. 1990, 24, 211–224. [Google Scholar] [CrossRef]
  38. Krisdianto, K.; Jasni, J.; Tutiana, T. Anatomical properties of nine indigenous rattan species of Jambi, Indonesia. Indones. J. For. Res. 2018, 5, 147–161. [Google Scholar] [CrossRef]
  39. Mathew, A.; Bhat, K. Anatomical diversity of Indian rattan palms (Calamoideae) in relation to biogeography and systematic. Bot. J. Linn. Soc. 1997, 125, 71–86. [Google Scholar] [CrossRef]
  40. Yang, S.; Xiang, E.; Shang, L.; Liu, X.; Tian, G.; Ma, J. Comparison of physical and mechanical properties of four rattan species grown in China. J. Wood Sci. 2020, 66, 3. [Google Scholar] [CrossRef]
  41. Petroudy, S.D. Physical and mechanical properties of natural fibers. In Advanced High Strength Natural Fibre Composites in Construction; Elsevier: Amsterdam, The Netherlands, 2017; pp. 59–83. [Google Scholar]
  42. Le Guen, M.J.; Newman, R.H.; Fernyhough, A.; Hill, S.J.; Staiger, M.P. Correlations between the physiochemical characteristics of plant fibres and their mechanical properties. In Proceedings of the Natural Fibres: Advances in Science and Technology towards Industrial Applications: From Science To Market; Springer: Berlin/Heidelberg, Germany, 2016; pp. 35–47. [Google Scholar]
  43. Wang, C.; Xu, X.; Wang, Y.; Gao, L.; Zhou, X.; Zhang, L.; Wu, H.; Liu, X. Main physical and mechanical properties of Daemonorops margaritae and Calamus simplicifolius. J. Northeast For. Univ. 2011, 39, 132–136. [Google Scholar]
  44. Schmidt, O.; Bahmani, M.; Koch, G.; Potsch, T.; Brandt, K. Study of the fungal decay of oil palm wood using TEM and UV techniques. Int. Biodeterior. Biodegrad. 2016, 111, 37–44. [Google Scholar] [CrossRef]
  45. Fathi, L.; Frühwald, A.; Koch, G. Distribution of lignin in vascular bundles of coconut wood (Cocos nucifera) by cellular UV-spectroscopy and relationship between lignification and tensile strength in single vascular bundles. Holzforschung 2014, 68, 915–925. [Google Scholar] [CrossRef]
  46. Liu, H.; Jiang, J.; Zhai, W. Bubble freeze casting artificial rattan. Chem. Eng. J. 2022, 449, 137870. [Google Scholar] [CrossRef]
  47. Tellu, A.T. Cladistics of some rattans (Calamus spp.) from Central Sulawesi based on physical and mechanical characteristic of stems. Biodiversitas 2006, 7, 225–229. [Google Scholar] [CrossRef]
  48. Hacke, U.G.; Spicer, R.; Schreiber, S.G.; Plavcová, L. An ecophysiological and developmental perspective on variation in vessel diameter. Plant Cell Environ. 2017, 40, 831–845. [Google Scholar] [CrossRef] [PubMed]
  49. Smith, M.S.; Fridley, J.D.; Yin, J.; Bauerle, T.L. Contrasting xylem vessel constraints on hydraulic conductivity between native and non-native woody understory species. Front. Plant Sci. 2013, 4, 486. [Google Scholar] [CrossRef] [PubMed]
  50. Tomlinson, P.B. Stem anatomy of climbing palms in relation to long-distance water transport. Aliso 2006, 22, 265–277. [Google Scholar] [CrossRef]
  51. Tyree, M.T.; Zimmermann, M.; Tyree, M.T.; Zimmermann, M. Hydraulic architecture of whole plants and plant performance. In Xylem Structure and the Ascent of Sap; Springer: Berlin/Heidelberg, Germany, 2002; pp. 175–214. [Google Scholar]
  52. Rajeshkumar, G.; Hariharan, V.; Sathishkumar, T.; Fiore, V.; Scalici, T. Synergistic effect of fiber content and length on mechanical and water absorption behaviors of Phoenix sp. fiber-reinforced epoxy composites. J. Ind. Text. 2017, 47, 211–232. [Google Scholar] [CrossRef]
  53. Faruk, O.; Bledzki, A.K.; Fink, H.P.; Sain, M. Progress report on natural fiber reinforced composites. Macromol. Mater. Eng. 2014, 299, 9–26. [Google Scholar] [CrossRef]
  54. Bhat, K.; Nasser, K.M.; Thulasidas, P. Anatomy and identification of south Indian rattans (Calamus species). IAWA J. 1993, 14, 63–76. [Google Scholar] [CrossRef]
  55. He, X.; Wang, D. Tensile property of corn stalk rind based on analysis of fiber morphology. Trans. Chin. Soc. Agric. Eng. 2015, 31, 92–98. [Google Scholar]
  56. Regen, D.M. Effects of chamber shape and fiber orientation on relations between fiber dynamics and chamber dynamics. Ann. Biomed. Eng. 1988, 16, 589–607. [Google Scholar] [CrossRef]
  57. Han, X.; Ding, L.; Tian, Z.; Wu, W.; Jiang, S. Extraction and characterization of novel ultrastrong and tough natural cellulosic fiber bundles from manau rattan (Calamus manan). Ind. Crops Prod. 2021, 173, 114103. [Google Scholar] [CrossRef]
  58. Ding, L.; Han, X.; Cao, L.; Chen, Y.; Ling, Z.; Han, J.; He, S.; Jiang, S. Characterization of natural fiber from manau rattan (Calamus manan) as a potential reinforcement for polymer-based composites. J. Bioresour. Bioprod. 2022, 7, 190–200. [Google Scholar] [CrossRef]
  59. Pasangulapati, V.; Ramachandriya, K.D.; Kumar, A.; Wilkins, M.R.; Jones, C.L.; Huhnke, R.L. Effects of cellulose, hemicellulose and lignin on thermochemical conversion characteristics of the selected biomass. Bioresour. Tech. 2012, 114, 663–669. [Google Scholar] [CrossRef] [PubMed]
  60. Väisänen, T.; Das, O.; Tomppo, L. A review on new bio-based constituents for natural fiber-polymer composites. J. Clean. Prod. 2017, 149, 582–596. [Google Scholar] [CrossRef]
  61. Sakurai, N. Cell wall functions in growth and development—A physical and chemical point of view. Bot. Mag. 1991, 104, 235–251. [Google Scholar] [CrossRef]
  62. Yin, Y.; Berglund, L.; Salmén, L. Effect of steam treatment on the properties of wood cell walls. Biomacromolecules 2011, 12, 194–202. [Google Scholar] [CrossRef] [PubMed]
  63. Yu, P. Molecular chemistry imaging to reveal structural features of various plant feed tissues. J. Struct. Biol. 2005, 150, 81–89. [Google Scholar] [CrossRef] [PubMed]
  64. Heraud, P.; Caine, S.; Sanson, G.; Gleadow, R.; Wood, B.R.; McNaughton, D. Focal plane array infrared imaging: A new way to analyse leaf tissue. New Phytol. 2007, 173, 216–225. [Google Scholar] [CrossRef]
  65. Dwianto, W.; Damayanti, R.; Darmawan, T.; Sejati, P.S.; Akbar, F.; Adi, D.S.; Bahanawan, A.; Amin, Y.; Triwibowo, D. Bending strength of lignocellulosic materials in softening condition. Indones. J. For. Res. 2020, 7, 59–70. [Google Scholar] [CrossRef]
  66. Scheller, H.V.; Ulvskov, P. Hemicelluloses. Annu. Rev. Plant Biol. 2010, 61, 263–289. [Google Scholar] [CrossRef]
  67. Spiridon, I.; Popa, V.I. Hemicelluloses: Major sources, properties and applications. In Monomers, Polymers and Composites from Renewable Resources; Elsevier: Amsterdam, The Netherlands, 2008; pp. 289–304. [Google Scholar]
Forests 14 02288 g001
Figure 1. The sampling method of Calamus caesius. A, B, C, and D were the parts tested in this study.
Figure 1. The sampling method of Calamus caesius. A, B, C, and D were the parts tested in this study.
Forests 14 02288 g001
Forests 14 02288 g002
Figure 2. Images of the softened sample were obtained through a cross-sectional scan. (The white circular lines were added digitally.) (a–d), represent cross-sections of the stem located at the BASE, 2-METER, MIDDLE, and TOP respectively. The scale bar was 20 mm.
Figure 2. Images of the softened sample were obtained through a cross-sectional scan. (The white circular lines were added digitally.) (a–d), represent cross-sections of the stem located at the BASE, 2-METER, MIDDLE, and TOP respectively. The scale bar was 20 mm.
Forests 14 02288 g002
Forests 14 02288 g003
Figure 3. SEM images of C. caesius. (a–d), represent the intermediate cross-sections of the stem located at the BASE, 2-METER, MIDDLE, and TOP respectively. FB: fiber; MV: metaxylem vessel; PC: parenchyma; PV: protoxylem; ST: sieve tube. The scale bar was 100 μ m.
Figure 3. SEM images of C. caesius. (a–d), represent the intermediate cross-sections of the stem located at the BASE, 2-METER, MIDDLE, and TOP respectively. FB: fiber; MV: metaxylem vessel; PC: parenchyma; PV: protoxylem; ST: sieve tube. The scale bar was 100 μ m.
Forests 14 02288 g003
Forests 14 02288 g004
Figure 4. TEM images depicting the cross-sections of intermediate stem fibers from the base to the top. (a–d), represented the fiber wall layer characteristics at the BASE, 2-METER, MIDDLE, and TOP, respectively. S1∼S6 represented the number of secondary wall layers.
Figure 4. TEM images depicting the cross-sections of intermediate stem fibers from the base to the top. (a–d), represented the fiber wall layer characteristics at the BASE, 2-METER, MIDDLE, and TOP, respectively. S1∼S6 represented the number of secondary wall layers.
Forests 14 02288 g004
Forests 14 02288 g005
Figure 5. Distribution of total adsorption intensity of vascular bundles at different positions. (a–d), represent the intermediate cross-sections of the stem located at the BASE, 2-METER, MIDDLE, and TOP, respectively. The scale bar was 100 μ m.
Figure 5. Distribution of total adsorption intensity of vascular bundles at different positions. (a–d), represent the intermediate cross-sections of the stem located at the BASE, 2-METER, MIDDLE, and TOP, respectively. The scale bar was 100 μ m.
Forests 14 02288 g005
Forests 14 02288 g006
Figure 6. Co-added spectrum in the central region of the fiber sheath.
Figure 6. Co-added spectrum in the central region of the fiber sheath.
Forests 14 02288 g006
Forests 14 02288 g007
Figure 7. Unimodal imaging of C. caesius. (a–d), represent the BASE, 2-METER, MIDDLE, and TOP respectively. (a1–d1) represent the distribution of cellulose based on the infrared absorption rate at 1320 cm − 1 . (a2–d2) represent the distribution of lignin based on the infrared absorption at 1506 cm − 1 . (a3–d3) represent the distribution of xylan and HCA based on the infrared absorption rate at 1733 cm − 1 . The scale bar was 100 μ m.
Figure 7. Unimodal imaging of C. caesius. (a–d), represent the BASE, 2-METER, MIDDLE, and TOP respectively. (a1–d1) represent the distribution of cellulose based on the infrared absorption rate at 1320 cm − 1 . (a2–d2) represent the distribution of lignin based on the infrared absorption at 1506 cm − 1 . (a3–d3) represent the distribution of xylan and HCA based on the infrared absorption rate at 1733 cm − 1 . The scale bar was 100 μ m.
Forests 14 02288 g007
Table 1. Vascular bundle and metaxylem vessel frequency.
Table 1. Vascular bundle and metaxylem vessel frequency.
PositionVascular Bundle Frequency
(pcs/mm 2 )		Metaxylem Vessel Frequency
(pcs/mm 2 )
BASE3.97 ± 0.56 a3.88 ± 0.28 a
2-METER3.49 ± 0.89 a3.65 ± 0.44 a
MIDDLE3.69 ± 0.40 a3.61 ± 0.32 a
TOP3.59 ± 0.51 a3.87 ± 0.31 a
Mean values ± standard deviations of n = 90 per sample type. Different letters indicate significant differences among different regions (p < 0.05). LSD test was adopted to conduct multiple comparisons. Before the ANOVA analyses, all the variables were checked for normal distributions and homogeneity of variance, the same methodology was applied to all subsequent tables.
Table 2. Vascular bundle frequency and stem diameter of different varieties.
Table 2. Vascular bundle frequency and stem diameter of different varieties.
VarietiesVascular Bundle Frequency
(pcs/mm 2 )		Stem Diameter (mm)
C. zollingeri Becc.3.3018.62
Korthalsia laciniosa Mart5.4∼9.817.00
C. ornatus BI.3.0214.76
Table 3. The proportion of four tissues.
Table 3. The proportion of four tissues.
PositionXylem (%)Fiber (%)Primary Phloem
(%)		Parenchyma (%)
BASE23.44 ± 2.98 a25.33 ± 0.25 a1.94 ± 0.54 a49.28 ± 2.43 a
2-METER25.05 ± 5.24 a24.76 ± 0.33 a1.15 ± 0.39 a49.04 ± 5.55 a
MIDDLE23.80 ± 1.30 a24.76 ± 1.41 a1.13 ± 0.30 a50.29 ± 1.73 a
TOP24.74 ± 1.80 a22.27 ± 1.16 b1.49 ± 0.64 a51.49 ± 0.82 a
Mean values ± standard deviations of n = 30 per sample type. Different letters indicate significant differences among different regions (p < 0.05).
Table 4. The anatomical characteristics of the vascular constituents.
Table 4. The anatomical characteristics of the vascular constituents.
TissueAnatomical
Structures		BASE2-METERMIDDLETOP
Vascular BundleRadial Diameter
(mm)		0.57 ± 0.03 a0.62 ± 0.01 a0.61 ± 0.04 a0.58 ± 0.01 a
Tangential Diameter
(mm)		0.55 ± 0.01a0.58 ± 0.02 a0.59 ± 0.04 a0.56 ± 0.03 a
Form Factor1.04 ± 0.02 a1.07 ± 0.05 a1.04 ± 0.02 a1.05 ± 0.04 a
Metaxylem Vessel
Element		Length
(mm)		2.86 ± 0.17 a2.85 ± 0.30 a2.97 ± 0.25 a3.00 ± 0.44 a
Diameter
(mm)		0.32 ± 0.03 bc0.33 ± 0.03 ab0.32 ± 0.01 b0.34 ± 0.01 a
Length-Diameter
Ratio		9.18 ± 1.55 a8.65 ± 1.56 a9.25 ± 1.11 a8.83 ± 1.17 a
FiberLength
(mm)		1.43 ± 0.30 b1.69 ± 0.33 a1.72 ± 0.30 a1.76 ± 0.31 a
Diameter
(µm)		11.05 ± 1.05 b11.39 ± 0.25 b10.78 ± 0.73 b12.63 ± 1.46 a
Length-Diameter
Ratio		129.32 ± 20.18 b148.53 ± 31.61 a159.89 ± 30.67 a142.76 ± 42.90 a
Mean values ± standard deviations of n = 90 per sample type. Different letters indicate significant differences among different regions (p < 0.05).
Table 5. Wall thickness, lumen diameter, and wall–cavity ratio of fibers.
Table 5. Wall thickness, lumen diameter, and wall–cavity ratio of fibers.
PositionDouble Wall
Thickness (µm)		Cavity Diameter
(µm)		Wall-Cavity Ratio
BASE5.00 ± 2.35 a6.05 ± 1.71 b0.93 ± 0.61 a
2-METER5.06 ± 1.83 a6.34 ± 2.00 b0.93 ± 0.66 a
MIDDLE4.37 ± 1.30 a6.41 ± 1.99 b0.80 ± 0.57 a
TOP4.13 ± 1.38 b8.51 ± 2.83 a0.58 ± 0.44 a
Mean values ± standard deviations of n = 90 per sample type. Different letters indicate significant differences among different regions (p < 0.05).
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Yu, L.; Zhang, K.; Dai, F.; Jiang, Z.; Chen, Y.; Wang, Y.; Tian, G. Variations in the Vascular Bundle and Fiber Structure during the Stem Development of Rattan (Calamus caesius Blume). Forests 2023, 14, 2288. https://doi.org/10.3390/f14122288

AMA Style

Yu L, Zhang K, Dai F, Jiang Z, Chen Y, Wang Y, Tian G. Variations in the Vascular Bundle and Fiber Structure during the Stem Development of Rattan (Calamus caesius Blume). Forests. 2023; 14(12):2288. https://doi.org/10.3390/f14122288

Chicago/Turabian Style

Yu, Linpeng, Kangjian Zhang, Fukuan Dai, Zehui Jiang, Yuxuan Chen, Youhong Wang, and Genlin Tian. 2023. "Variations in the Vascular Bundle and Fiber Structure during the Stem Development of Rattan (Calamus caesius Blume)" Forests 14, no. 12: 2288. https://doi.org/10.3390/f14122288

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop