Abstract
A systematic study was conducted on Phyllostachys pubescens by analyzing the chemical constituents of its rhizome and culm at different ages. Our results indicated that the ash contents of the rhizome and culm of P. pubescens at different ages showed the largest coefficient of variation (CV), followed by alcohol benzene extractives. The CVs of acid-insoluble lignin, holocellulose, HNO3-C2H5OH cellulose, and pentosan were relatively small. Analysis of t-tests indicated that significant differences were found in the contents of extractives, acid-insoluble lignin, holocellulose, and ash of rhizome and culm (p < 0.05). The differences in contents of HNO3-C2H5OH cellulose and pentosan were not significant. Analysis of multiplicity showed that the contents of HNO3-C2H5OH cellulose, pentosan, and ash were not significantly different in bamboos at the ages examined. Likewise, the contents of lignin, alcohol benzene extractives, and holocellulose exhibited no significant difference between one-year-old and three-year-old bamboos. However, the differences in these parameters between five-year-old bamboos and one- and three-year-old bamboos were all statistically significant. Our results suggest that three-year-old P. pubescens is suitable for use as a raw material for papermaking. In addition, our findings provide a theoretical basis for effective utilization of P. pubescens and enhancement of its value.
Download PDF
Full Article
Comparison of Variations in the Chemical Constituents of the Rhizome and Culm of Phyllostachys pubescens at Different Ages
Bin Xu,a,* Shuai Liu,a and Tao Zhu b
A systematic study was conducted on Phyllostachys pubescens by analyzing the chemical constituents of its rhizome and culm at different ages. Our results indicated that the ash contents of the rhizome and culm of P. pubescens at different ages showed the largest coefficient of variation (CV), followed by alcohol benzene extractives. The CVs of acid-insoluble lignin, holocellulose, HNO3-C2H5OH cellulose, and pentosan were relatively small. Analysis of t-tests indicated that significant differences were found in the contents of extractives, acid-insoluble lignin, holocellulose, and ash of rhizome and culm (p < 0.05). The differences in contents of HNO3-C2H5OH cellulose and pentosan were not significant. Analysis of multiplicity showed that the contents of HNO3-C2H5OH cellulose, pentosan, and ash were not significantly different in bamboos at the ages examined. Likewise, the contents of lignin, alcohol benzene extractives, and holocellulose exhibited no significant difference between one-year-old and three-year-old bamboos. However, the differences in these parameters between five-year-old bamboos and one- and three-year-old bamboos were all statistically significant. Our results suggest that three-year-old P. pubescens is suitable for use as a raw material for papermaking. In addition, our findings provide a theoretical basis for effective utilization of P. pubescens and enhancement of its value.
Keywords: Phyllostachys pubescens; Rhizome; Culm; Bamboo age; Chemical constituent; Axial variation
Contact information: a: School of Forestry and Landscape Architecture, AnHui Agricultural University, Hefei,230036 ,China; b: Wood Carving and Antique Furniture Products Quality Supervision and Testing Center of Fujian Province, Xianyou, Fujian ,351200 , China; *Corresponding author: xubin@ahau.edu.cn
INTRODUCTION
As a commercial bamboo species in China, Phyllostachys pubescensis cultivated over a large region, mostly in subtropical areas such as the Qinling Mountains, and between the Hanjiang River Basin and the Yangtze River Basin (Jiang 2007; Geng and Wang 2008). The underground portion of P. pubescens is composed of rhizome, root, and bud, while the aboveground part consists of culm, branch, and leaf. The bamboo rhizome, or underground stem, is an important component of P. pubescens, with a huge potential for exploitation and utilization. It is well known the removal of rhizome appropriately is beneficial to the bamboo forest restoration and refreshment of soil, which can enhance the quality of afforestation (Mao et al. 2011). Also, the rational use of rhizome can improve the comprehensive utilization and high-added value of residue. The utilization of rhizome has a long history, and it is widely used in bamboo charcoal, bamboo pipe, and bamboo carvings. Nevertheless, existing research on the wood properties of P. pubescens has focused mostly on bamboo culm. With increasing demand for bamboo resources, more scholars have begun to study ways to promote effective utilization of rhizome resources (Chen et al. 2001; Wang 2001; Li et al. 2002; Wang and Wei 2002; Han 2007; Zhang et al. 2007; Shi et al. 2008), However the properties and utilization of rhizome have been reported rarely. Two important factors, the resistance to insects and decay, affect the use of bamboos, and these in turn are determined by the chemical properties of the bamboo (Zheng 2001; Pu et al. 2002; Chilako et al. 2004; Guo et al. 2005; Lu et al. 2008; Fang et al. 2009; Yang et al. 2009; Fan et al. 2010; Dinesh et al. 2012). Accordingly, the chemical constituents of rhizome were compared with the culm of P. pubescens. The research focused mostly on the rhizome at different ages. Differences of chemical constituents were analyzed, and the variation features in the axial direction were identified to provide a basis for the utilization of whole bamboo and to increase the value derived from rhizome’s utilization.
EXPERIMENTAL
Materials
Phyllostachys pubescens samples were collected from a northern slope (gradient 30° to 40°), where the east longitude and northern latitude were 118o01’22’’and 30o12’55’’, respectively on 27th Sept, 2012 in Tangjiacun village, (Taiping) Jiaocunzhen town in Huangshan City, Anhui Province. The bamboos were II operation level with healthy growth and development status, but without the topping treatment (Liu and Zeng 2010). The average heights of culm and clear bole were 16.5 m and 7.1 m, respectively, and the average diameter at eyebrow was 10.96 cm. Bamboo age was determined based on the integrity or degree of decay of the surviving bamboo shoot’s shell from mother bamboo, age marker of branchlet, and culm colour. One-year-old, three-year-old, and five-year-old P. pubescenssamples including rhizome parts (30 cm each) were collected with three replicates each, and preserved indoors using pigsty stacking in a ventilated corridor for three months before the tests.
Methods
Sampling (30 cm) was carried out on different parts of the rhizome and culm (1.5 m, 3.5 m, 5.5 m, and 7.5 m) of bamboo. Culm top segments were taken from the top 2 m with culm diameter more than 4 cm (Wang and Pu 2000) following guidelines in GB/T 15780-1995 (1996). Three samples were taken from every part (rhizome, 1.5 m, 3.5 m, 5.5 m, 7.5 m, and the top) of bamboo at each age. For example, in the case of rhizome, three segments (5 cm each) were sampled, as shown in Fig. 1. Fresh samples were dried naturally until they reached air-dried moisture content, then sliced into thin sections (the size as match) by an axe, after which they were ground using a TL2020 high-speed pulverizer (Beijing DHS Life Science and Technology Co., Ltd.; Beijing). Sample powder was obtained that could pass through a 0.38-mm aperture (40 mesh), but failed to pass through a 0.25-mm aperture (60 mesh). Six indicators of chemical composition of bamboos, selected based on TAPPI standards (T 258 om-02 2004; T 211 om-02 2004; T 204 om-88 2004;T 222 om-02 2004; T 9 wd-75 2004) and on the work of Qu (1990) comprising alcohol benzene extractives, holocellulose, acid-insoluble lignin, cellulose (extracted by the HNO3-C2H5OH method; Qu 1990), pentosan, and ash, were assayed. The extractives and the pentosan were detected by the alcohol-benzene extraction method (GB/T 2677.6 1995) and the dibromination method (Qu 1990), respectively.
Analysis of multiplicity is widely used for comparison between two groups of all independent multi-samples. Thereby the difference of the specific chemical constituent between different ages of bamboo can be obtained easily. A t-test was used to determine differences between rhizome and culm due to analysis of t-test can reflect the mean difference between two groups with independent sample.
Using analysis methods, i.e. variance, t-test, and multiplicity, the experimental data were analyzed with SPSS software (International Business 90 Machines Corp., New York), version 21.0.
Fig. 1. Schematic diagram of sampling
RESULTS AND DISCUSSION
Analysis of Chemical Constituents of Rhizome and Culm of P. pubescens
The major chemical constituents of bamboo include cellulose, lignin, and hemicellulose, which are the structural materials of cell walls and used as the main parts for processing and utilization. Although extractives and ash are minor constituents, they also have an impact on the properties of the wood, as well as processing and utilization (Xu et al. 2013). As shown in Table 1, statistical analysis of six chemical parameters indicated that the contents of ash in the rhizome and culm of P. pubescens of different ages showed the largest coefficient of variation (CV), followed by the alcohol benzene extractives; the CVs of the contents of acid-insoluble lignin, holocellulose, HNO3-C2H5OH cellulose, and pentosan were relatively small. The results supported the operative conclusion raised by the previous study that major chemical constituents, i.e. cellulose, hemicellulose and lignin of P. pubescens at six different locations, were less variable, while the extractives and ash showed relatively large fluctuation (Lin et al. 2010). This indicates that the major chemical constituents of the bamboos were relatively stable. However, the minor constituents, which affect insect prevention and decay resistance fluctuated, may be influenced by bamboo age, sampling segment, and growth status. Generally, the raw materials will perform better for pulping when several conditions are met, i.e.with higher content of cellulose and pentosan but lower content of extractives and ash (Cui 2010), as well as the fiber length more than 0.3 mm, the ratio of fiber length to width more than 35, and the content of mixed cells less than 50% (Guo 1989). So along with our previous study about the fiber characteristics of rhizome (Liu et al.2014), we can conclude that the three-year-old rhizome is the most suitable for use as raw materials for papermaking.
Table 1. Descriptive Statistics of Chemical Composition of P. pubescens from Rhizome to Top at Different Ages
Differences in Chemical Constituents of Rhizome & Culm of P. pubescens
To determine differences between the rhizome and the aboveground part of P. pubescens, the chemical constituents of the rhizome were compared with those of the segment at diameter eye-height (1.5 m of culm above the ground, abbr. D.E.H). The results are listed in Table 2. The contents of extractives, acid-insoluble lignin, holocellulose, and ash in rhizome and culm were significantly different (p < 0.05). In contrast, the contents of HNO3-C2H5OH cellulose and pentosan showed no significant difference (p > 0.05). These differences may affect the process change of pulp and paper (Guo et al. 2005). So this result could reflect the material heterogeneity between the rhizome and the aboveground part of bamboo.
Analysis of the Significance of Variance in Chemical Constituents of P. pubescens
Table 3 shows the variability of chemical constituents at different bamboo ages. The contents of acid-insoluble lignin at different bamboo ages showed the largest variability (F > F0.01, P < 0.01). Variation of the contents of extractives and holocellulose were also significantly different (F > F0.05, p < 0.05). Alternatively, variations in the contents of HNO3-C2H5OH cellulose, pentosan, and ash were relatively small, with no significant differences across bamboo ages (F < 1 p > 0.05). The result indicated that chemical constituents (especially in lignin, extractives and holocellulose) of bamboo have variability among different ages. The results agreed with the literature about influence of bamboo ages on the pulping performance of P. pubescens (Cui 2010; Dong 2010).
Table 2. Analysis of T-test on Differences in the Chemical Constituents of Rhizome and Culm of P. pubescens
Note: The statistical significance was at the 95% confidence level.
Table 3. Analysis of Variance on Chemical Constituents of P. pubescens
Note: F0.05 (18, 36) = 1.90; F0.01 (18, 36) = 2.48, Sample ID represents total test sample numbers.
Analysis of Axial Variation and Multiplicity of Chemical Constituents of P. pubescens
Because P. pubescens is a monocotyledon, it grows mostly in the longitudinal direction, and less radially. The variation curves in Fig. 2 show that the chemical constituents of P. pubescens vary with bamboo age and from the underground rhizome to different segments of culm.
As shown in Fig. 2, with increasing bamboo age, the contents of HNO3-C2H5OH cellulose, lignin, and extractives increased gradually, while the contents of pentosan, holocellulose, and ash decreased.
Fig. 2. Plots showing axial variation in chemical constituents of P. pubescens at different ages
Note: the number 1, 3, and 5 indicates one-year-old, three-year-old, and five-year-old bamboo, respectively
Along the axial direction from the rhizome to the top, the contents of HNO3-C2H5OH cellulose, holocellulose, and extractives of bamboo increased at first, and then declined; this was observed across all ages. The pentosan content showed an increasing trend along the same axis. Furthermore, differences were observed in lignin contents at different bamboo ages. The lignin content decreased at first, and then increased from the rhizome to the top in one-year-old and three-year-old bamboos, while it fluctuated in five-year-old bamboos. For different ages of bamboos, the ash contents first decreased from the rhizome to the top, and tended to remain stable thereafter. In Table 4 the analysis of multiplicity indicated no significant differences in the contents of HNO3-C2H5OH cellulose and pentosan of P. pubescens at different ages (p > 0.05).
Table 4. Multiplicity Analysis of Major Chemical Constituents of P. pubescens at Different Ages
- Denotes statistical significance at the 95% confidence level
Likewise, no significant difference was found between the lignin contents of one-year-old and three-year-old bamboos (p>0.05). However, lignin content was significantly different between one-year-old and five-year-old bamboos, as well as between three-year-old and five-year-old bamboos (p<0.05). Although the difference in holocellulose contents between one-year-old and three-year-old bamboos was not significant (p>0.05), the differences between three-year-old and five-year-old bamboos and between one-year-old and five-year-old bamboos were statistically significant (p<0.05). As given in Table 5, analysis of multiplicity indicated that ash content did not differ across bamboos of different ages. Likewise, no significant difference was found in the contents of alcohol benzene extractives between one-year-old and three-year-old bamboos (p>0.05). However, the differences between one-year-old and five-year-old and between three-year-old and five-year-old bamboos were significant (p<0.05). Consistent with the previous study (Cui 2010; Dong 2010), also our results indicate the difference exist among different ages of bamboo regarding the chemical constituents of culms or rhizomes.
Table 5. Multiplicity Analysis of Minor Chemical Constituents of P. pubescens at Different Ages
* Denotes statistical significance at the 95% confidence level
CONCLUSIONS
- With increasing age of bamboo, the contents of HNO3-C2H5OH cellulose, lignin, and extractives gradually increased, while the contents of pentosan, holocellulose, and ash decreased.
- Along the axial direction from the rhizome to the top, the contents of HNO3-C2H5OH cellulose, holocellulose, and extractives of bamboos all increased initially and then declined across all ages. Interestingly, the contents of pentosan showed an increasing trend.
- Significant differences in the lignin contents of bamboos at different ages indicated that it decreased initially, but increased from the rhizome to the top in one-year-old and three-year-old bamboos; however, the lignin contents from five-year-old bamboos fluctuated. Also, with age increasing, the ash contents first decreased from the rhizome to the top, and tended to remain stable thereafter.
- Analysis of a T-test to investigate differences between the rhizome and the aboveground part of P. pubescens found that extractives, acid-insoluble lignin, holocellulose, and ash in the rhizome and the culm (D.E.H.) all showed significant differences, while HNO3-C2H5OH cellulose and pentosan contents showed no significant difference.
- Multiplicity analysis found that there were no significant differences (p > 0.05) in the contents of HNO3-C2H5OH cellulose, pentosan, and ash in bamboos at the ages examined. Also, other contents including lignin, alcohol benzene extractives, and holocellulose exhibited no significant difference between one-year-old and three-year-old bamboos. However, the differences in these parameters between five-year-old bamboos and one- and three-year-old bamboos were all statistically significant.
- Along with our previous study on the fiber characteristic of rhizome at different ages (Liu et al. 2014), the related results obtained in this paper show that the three-year-old rhizome is most suitable for use as a good raw material for papermaking. Also to some extent, the finding provide a theoretical basis for effective utilization of rhizome as well as enhancement of its value.
ACKNOWLEDGMENTS
This study was supported by the Laboratory of Chemistry of Anhui Agricultural University in China under “The twelfth five-year plan of the national science and technology in rural areas” “solid waste utilization technology in the process of bamboo pulping and papermaking,” No. 2012BAD23B0204.
REFERENCES CITED
Chen, C. J., Qiu, E. F., and Liang, Y. C. (2001). “Research on geological variation rule and selection of bamboo resource,” Journal of Bamboo Research 20(3), 20-28. DOI: 10.3969/j.issn.1000-6567.2001.03.004
Chilako, A., Yoshitoshi, N., and Fumihisa, K. (2005). “Waste reduction system for production of useful materials from un-utilized bamboo using steam explosion followed by various conversion methods,” Biochemical Engineering Journal 23(2), 131-137. DOI: 10.1016/j.bej.2004.11.004
Cui, M. (2010). Influence for Bamboo Pulping Performance at Different Ages, M.S. thesis, Beijing Forestry University, Beijing, China.
Dinesh, B., Li, L., and Yong, H. K. (2012). “Gas chromatography-mass spectrometry analysis and chemical composition of the bamboo-carbonized liquid,” Food Analytical Methods 5(1), 109-112. DOI: 10.1007/s12161-011-9194-4
Dong, R. Y. (2010). “Chemical analysis of Phyllostachys nigramaterials and the skin pigment,” M.S. thesis, Zhejiang Agriculture and Forestry University, Zhejiang, China.
Fang, K., Yang, Q. P., Shi, J. M., Wu, L. S., Guo, Q. R., Li, J., and Yang, G. Y. (2009). “A primary study on chemical characteristics’ variation of moso bamboo wood from subtropical zone,” Acta Agriculturae Universitatis Jiangxiensis 31(4), 679-683. DOI: 10.3969/j.issn.1000-2286.2009.04.019
Fan, Y. H., Cai, Y. P., Hu, W., Chen, J. Z., and Chen, C. Q. (2010). “Study of chemical compositions of Phyllostachys pubescens in Yiyang, Hunan Province,” Journal of Central South University of Forestry and Technology 30, 155-158. DOI: 10.3969/j.issn.1673-923X.2010.03.029
Geng, B. J, and Wang, Z. P. (1996). Flora of China, Science Press, Beijing.
GB/T 15780-1995. (1996). Testing methods for Physical and Mechanical Properties of Bamboos, China Standard Press, Beijing.
Guo, S. X. (1989). “On suitability of shirt-rotation culture of Poplar Hybrids for wood fiber production,” Journal of Beijing Forestry University 11(4), 66-73.
Guo, X. J., Li, X. W., Zhang, J., Fan, C., and Xue, B. (2005). “Studies on variation of main chemical constituents of wood in pulpwood plantation of Eucalyptus grandis,” Journal of Sichuan Agricultural University 23(3), 305-312. DOI: 10.3969/j.issn.1000-2650. 2005.03.011
Han, J. (2007). “Constructing resources saving bamboo industry through raising the level of the comprehensive utilization,” China Forest Products Industry 34(1), 12- 15. DOI: 10.3969/j.issn.1001-5299.2007.01.003
Jiang, Z. H. (2007). Bamboo and Rattan in the World, First Edition, China Forestry Publishing House, Beijing.
Li, Z. C., Fu, M. Y., Jiang, J. M., Yang X. S., and Xiao, J. H. (2002). “Geographic pattern of phenotypic features of Phyllostachys pubescens in natural stands,” Forest Research 15(6), 654- 659. DOI: 10.3321/j.issn:1001-1498.2002.06.004
Liu, S., Xu, B., Wang, C. G., and Zhu, T. (2014). “Comparative study on morphological characters and differences of fiber in Phyllostachys pubescens coming parts of rhizomes among different growth ages,” Journal of Beijing Forestry University 36(3), 121-124. DOI: 10.13332 /j.cnki.jbfu.2014.03.019
Lin, J. G., Chen, J. M., Wang, S. Y., and Liu, Z. H. (2010). “Variation of fiber morphology and chemical composition of moso bamboo from different provenances,” Journal of Bamboo Research 29(1), 54-57. DOI: 10.3969/j.issn.1000-6567.2010.01.012
Liu, Z. K., and Zeng, Z. Q. (2010). “Verification and assessment on assets of Phyllostachys pubescens forests,” Jiangxi Forestry Science and Technology (3), 42-43. DOI: 10.3969/j.issn.1006-2505.2010.03.014
Lu, S. B., Ding, G. J., and Peng, J. S. (2008). “Influence of site conditions upon the chemical properties of Phyllostachys pubescensculm-wood,” Journal of Central South University of Forestry and Technology 28(1), 79- 83. DOI: 10.3969/j.issn.1673-923X.2008.01.002
Mao, D. M., Lu,Y. Y., Zheng, L. S., Li, T. C., and Wu, L. D. (2011). “Growth of bamboo running rhizomes after digging up bamboo rhizome shoots,” Journal of Zhejiang Forestry College 28(5), 833-836.DOI: 10.3969/j.issn.2095-0756.2011.05.026
Pu, J. W., Song, J. L., and Yao, C. L. (2002). “Studies on variation of chemical constituents of Populus tomentosa Carr. triploid clones,”Paper Science and Technology 21(3), 1-3. DOI: 10.3969/j.issn.1671-4571.2002.03.001
Qu, W. J. (1990). Pulping and Paper Making Experiment, China Light Industry Press, Beijing.
Shi, J. M., Yang, G. Y., Guo, Q .R., Fan, G. R., Zhong, A. Y., Zhang, W., Wu, L. S., He, G. F., and Xia, F. (2008). “A study on geographic phenotypic variation of Phyllostachys edulis in Jiangxi province,” Acta Agriculturae Universitatis Jiangxiensis 30(5), 824-828. DOI: 10.3969/j.issn.1000-2286.2008.05.014
T 258 om-02. (2004). “Basic density and moisture content of pulpwood,” Technical Association of the Pulp and Paper Industry, U.S.A.
T 211 om-02. (2004). “Ash in wood, pulp, paper, and paperboard: Combustion at 525 °C,” Technical Association of the Pulp and Paper Industry, U.S.A.
T 204 om-88. (2004). “Solvent extractives of wood and pulp,” Technical Association of the Pulp and Paper Industry, U.S.A.
T 222 om-02. (2004). “Acid-insoluble lignin in wood and pulp,”Technical Association of the Pulp and Paper Industry, U.S.A.
T 9 wd-75. (2004). “Holocellulose in wood,” Technical Association of the Pulp and Paper Industry, U.S.A.
Wang, Y. D. (2001). “The effect of management on the growing and form of moso bamboo culms,” Forest Research 14(3), 245-250. DOI: 10.3321/j.issn:1001- 1498.2001.03.002
Wang, Y. D., and Wei, D. H. (2002). “The effect of weather factors on the culm growth of moso bamboo,” Journal of Bamboo Research21(1), 46-52. DOI: 10.3969/j.issn.1000-6567.2002.01.010
Wang, K. H., and Pu, S. Y. (2000). Bamboo Wood Identification and Inspection, First Edition, China Forestry Publishing House, Beijing.
Xu, B., Zhu, T., Li, J. Y., and Liu, S. (2013). “Identification of wood between Phoebe zhennan and Machilus pingii using the gas chromatography-mass spectrometry direct injection technique,” European Journal of Mass Spectrometry 19(3), 187-193. DOI: 10.1255/ejms.1226
Yang, X. Y., Fu, M. Y., Xie, J. Z., and Li, Z. C. (2009). “Geographic variation and provenance selection for bamboo wood properties in Bambusa chungii,” Journal of Forestry Research 20(3), 261-267. DOI: 10.1007/s11676-009-0045-8
Zhang, S. F., Ma, Q. X., and Ding, Y. L. (2007). “Genetic diversity analysis of moso bamboo based on morphological characterization,” Journal of Bamboo Research 26(3), 16-21. DOI: 10.3969/j.issn.1000-6567.2007.03.004
Zheng, R. (2001). “Analysis of chemical content of bamboo wood of Phllostachys heterocycle cv.pubescens of different altitude,” Journal of Zhengjiang for Science and Technology 21(1), 17-20. DOI: 10.3969/j.issn.1001-3776.2001.01.005
Article submitted: June 26, 2014; Peer review completed: August 28, 2014; Revised version received and accepted; September 18, 2014; Published: September 23, 2014.