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Chemical characterization of pressed fibrous residues of four aquatic weeds
..lquatic Botany, 42 ( ! 991 ) 81-85
8I
Elsevier Science Publishers B.V., Amstcrdam
Short Communication
Chemical characterization of pressed fibrous residues of four aquatic weeds Sunanda Chanda ~, Swapan K. Bhaduri b and Dharmadas Sardar b ~Lea.fProtein Research Unit, Biological Sciences Division, Indie~ Statistical Institute, 203, B.T. Road, Calcutta--700 035, India hDepartment of Chemistl3, and Microbiolog); Jute Techno!ogical Research Laboratories, Indian Council of ..Igricultural Research, 12 Regent Park, Calcutta--700 040, India (Accepted 13 May 1991 )
ABSTRACT Chanda, S.. Bhaduri, S.K. and Sardar, D., 1991. Chemical characterization of pressed fibrous residue~ of four aquatic weeds. Aquat. Bat., 42:81-85. The pressed fibrous residues, generated as a by-product during the large-scale manufacture of leaf protein from four aquatic weeds, Pistia stratiotes L. vat. cuneata Engl. (Araceae), Nymphoides o'istatum ( Roxb. ) O. Kuntze (Gentianaceae), Lemna perpusilla Tort. (kemnaceae) and AIImania nod(llora (L.) R.Br. ex Hook. f. (Amaranthaceae), were analysed for their chemical and mineral coml;osition. They were found to consist of lignin, cellulose, pentosan, lipid, pectin and minerals, l'istia stratiotes is a rich source of a-cellulose (40.63%),.,1. nodtiflora and N. cristatum contain pentosan and pectin ( 19.75% and 14.49%, respectively), while L. perpusilla shows comparatively larger amounts of minerals (ash content 15%). All the values obtained were compared with those of other similar aquatic weeds and agricultural wastes such as rice and wheat straw, grass, bagasse, etc., which are usually used in the preparation ofsilage, compost, biogas and several other products.
INTRODUCTION
Although the noxious growth of aquatic weeds is a global problem, this is more acute in tropical countries due to warm :noist weather. Hence, commercial uses for these weeds have attracted the attention of scientists. Exploitation of aquatic weeds for leaf protein production has been carried out in our ~.aboratory (Matai et al., 1971; Matai, 1976; Bandyopadhyay, 1989; Banerjee et al., 1985 ). After the extraction of protein from aquatic weeds, a significant ~,mount of fibrous residue is left as a by-product. These residues ;yore chemically analysed and their yields noted. The values were compared with st, me agricultural wastes, such as rice and wheat straw, grass, bagasse, etc., which are already in commercial use. The fibres of four plants, viz. Pistia stratiotes L. var cuneata Engl., Nymphoides cristatum (Roxb.) O. Kuntze, Lcmna per pusilla Torr. and AIhnania nodiflora (L.) R.Br. e× Hook. f. were analysed. 0304-3770/9 !/$03,50 (O I q91 Elsevier Science Publishers B.V. All rights reserved.
82
S. CttANDA ET AL.
METHODS
The four aquatic plants were selected according to their availability and collected from sites in and around Calcutta. The plant materials were harvested in a lush green condition from different areas. Protein was extracted by an International Biological Programme pulper (Davys and Pirie, 1969) and press (Davys et al., 1969). The juice containing protein was pressed out and plant fibre was obtained as a by-product. This fibre was oven-dried at 105°C for 48 h. For chemical analysis, nitrogen was calculated as Kjeldahl nitrogen and crude fal was extracted with cholo':oform.methanol (2:1) in a Soxhlet apparatus. Ash values were obtained by heating the samples at 550°C for 4 h in a muffle furnace. Lignin, holocellulose, o~-cellulose, pemc, san and pectin content were determined with defatted samples using standard methods (Technical Association of Pulp and Paper Industries, 1971 ). The polysaccharides were hydrolysed according to the method described by Jeffery et al. (1960). The neutral sugars were analysed by gas liquid chromatography (GLC) of their alditol acetates (Sawardekar et al., 1965). For GLC, a Hewlett-Packard 5830 A gas chromatograph equipped with a flame ionizing detector (f.i.d.) was used with a stainless steel column ( 180 cm × 0.5 cm) containing 3% ECNSS-M on supelcoport (80-100 mesh) at 190°C using nitrogen as the carrier gas. Molar proportions of sugar were determined conventionally from peak areas. For mineral analysis, the samples were dried at 100°C for 4 h, kept in a desiccator for 3 h and then ground in a special Wiley TABLEI DD' yield and chemical composition (% dry matter) of pressed fibres from four aquatic weeds Family
Pistia stratiotes var.
..llhnania nod~flora
Lemna l~erlmsilla
Nyml~hoides cristatum
229.5 _+75 9.50_+0.75 3.62 + 0.51 7.25+0.95 16.15+2.85 49.45±3.50 10.9 _+0.63 27.53_+0.75 19.75± 5.05 28.83_+_4.15 36.73±3.87
i81.3 _+33 15.0 +3.60 3.62 + 0.72 4.70+0.70 I 1.96± 1 . 9 3 48.50±.~.50 6.40 ± 1.75 3397±2.45 10.67± 1.25 44.17±5.69 56.12±6.18
231 _+27 7.6 _+0.08 2.62_+ 0.08 10.00_+2.50 19.52_+4.16 48.20_+4.05 8.00_+ 2.02 20.05_+1.25 14.49-+ 1.23 36.26_+4.86 43.00+5.00
Clttlc'ala
Yield (dry weight, gkg-:) Ash Nitrogen Crude fat Lignin l-lolocellulose Pectin a-cellulose Pentosan ADF NDF
171.5 _+25 10.0 _.+1 . 2 5 3.37 + 0.15 9.75+__1.20 16.52-+ 1 . 2 5 57.20-+4.75 4.77_+ 0.38 40.63_+3.27 6.40+0.25 34.$7+3.10 42.12+_2.96
Values are the mean ± standard deviation (SD) of five replicates. ADF, acid detergent fibre. NDF, ne atral detergent fibre.
83
PRESSED FI BROUS RESIDUES OF AQUATIC WEEI)S
mill to minimize minor element contamination. The tissues were analysed for Na, K, Ca, Mg, Fe, Zn and Cu with a Perkin Elmer Model 372 atomic absorption spectrophotometer after digestion in a nitric-perchloric acid mixture. Phosphorus was determined as reduced phosphomolybdate. Modified acid detergent fibre (Anon., 1986) and neutral detergent fibre (van Soest, 1963) were also estimated. RESULTS
The yield and chemical and mineral characteristics of pressed fibres from
P. stratiotes var. euneata, N. cristatum, L. perpusilla and A. nodiflora are reported in Tables 1-3. The data indicate that Pistia fibre is a rich source of ce-cellulose, those of Alhnania and Nymphoides are good sources of pentosan and pectin, while Lemna fibres have a high level of minerals. TABLE 2 Amount of neutral sugars in pressed fibres from four aquatic weeds Weed
..lllmania nod(llora .~)mphoides cristatum
Rhamnose Arabinose
(%)
Xylose
(%)
(%)
4.93+_0.60 14.72+_2.82 19.90+_4.95 0.52_+0.03 0.52_+0.10 16.96_+1.83
Mannose
~%)
1.73_+0.52
Galactose
(%)
Glucose
(%)
3.36_+0.65 55.33_+6.68
19.61+_4.47 23.99_+4.33 38.35_+4.85
L('IIIIIa
perlmsilla 0.30_+0.00 3.93+_0.75 14.25+_2.80 12.92_+1.86 l'istia stratiotesvar. 0.05+_0.00 4.20_+1.08 6.31_+1.28 14.31+2.27
18.82+_3.18 50.07_+5.45 0.15+-0.05
74.89_+6.18
c'tlllCala
Values are the mean _+SD of five replicates. TABLE 3 Mineral content (% dry matter) of pressed fibres from four aquatic weeds
Na K Ca Mg P I-c Z,a Cu
Pistia stratiotes var. cuneata
..lllmania nod(flora
Lemna perpusilla
Nym,,hoidcs cristatum
1.05 _+0.25 1.68 _+0.16 1.90 _+0.05 0.61 +0.07 3.00 +0.35 Nil 0.0041 +0.0004 0.0016+0.0002
3.82 +0.10 2.05 _+0.75 2.11 _+0.17 0.66 -+0.22 1.50 +0.63 Nil 0.004~,-+0.0007 0.0011 -+0.0000
1.68 _+0.06 1.95 _+0.15 3.75 -+0.05 0.78 -+0.11 3.75 _+0.15 0.13 _+0.00 0.0060+_0.0010 0.0018+_0.0000
0.60 +0.07 1.25 +0.05 2.33 +0.87 0.61 +0.07 1.75 +0.05 0.11 +0.07 0.0059_+0.0007 0.0026+_0.0004
Values arc the mean +SD of five replicates.
84
S. CHAND& ET AL.
DISCUSSION Data in Tables I ::nd 3 reveal results similar to those found by Boyd and Blackburn (1970) and Muztar el al. ( 1978a, b) with other aquatic weeds McGovern (1967) characterized several agricultural residues and natural fibres, such as grass, rice sl.raw, sugar cane, jute, pineapple and sisal. Accordiilg to his report, rice straw and grass contain ash (6-20%), lignin ( 12-19% ), a-cellulose (28-36%) and pentosan (25-32%). Except for pentosan, all values seem to be quite close to the values exhibited in Table 1. Leaf fibres used in the textile and weaving industries are chemically quite different from fibres ofaquatic weeds, as shown by Bhadun et al, ( ! 983 ). The mineral content of aquatic plant fibres seems to be higl'., and a-cellulose and pentosan contents seem to be low when compared with ~hos~:ofterrestrial plar~ts (Go~izalez imd Alzueta, 1984; Pathak et al., 1986). The fibres of some aquatic weeds, e.g. species of Phragmites (in Romania), Typha (in Mexico) and Jtttlctts (in Japan) have rotund rise in the commercial production of paper pulp, for floor matting and silage (Rodewald-Rudescu, 1974; Bagnall et al., 1974; Morton, 1975 ). Biogas production from water hyacinth fibres is going on in India, China, Taiwan and Korea, although the process also requires some a;aimal manure (Wolverton et al., 1975). Water hyacinth fibres are used for mushroom production in tropical countries (Pal, 1983 ). The present results indicate that the fibres from the four plants under study may find similar uses. ACKNOWLEDGEMENTS The authors are grateful to R.K. Dey and S.R. Pyne of the Indian Statistical Institute, Calcutta, and the late K.P. Roy of the .lute Technological Research Laboratories, Calcutta, for their valuable assistance throughout the investigation.
REFERENCES Anonymous, 1986. Fibre, ModifiedAcid-Detergentin Plant Material, tile Analysisof Agricultural Materials. Minlstr3'of Agriculture,Fisheriesand Food, USA ReferenceBookNo. 427, pp. 93-94. Bagnall. L.O., Baldwin,J.A. and Hentges,J.F., Jr., 1974. Processinganti storage ofwaler hyacinth silage. Hyacinth Control J., 12: 73-79. P~andyopadhyay,A.. 1989. Utilization of aquatic weeds with stress on their nutritive value. i'hD. Thesis, Universityof Calcutta, Calcutta, pp. 59-89. Banerjce, A., Bagchi, D.K. and Matai, S., 1985.,,'~llmanianod(lloraR.Br. (Amaranthaceac!, a promisir,g sourceof leaf protein. Aquat. Bot., 22: 393-396. Bhaduri, S.K., Sen, S.K. and Dasgupta, P.C., 1983. Structural studies of an acidic polysa~cha:-
I'RESSLD FIBROUS RESIDUES OF AQUATIC WEEDS
85
ida isolaied from leaf fibre of pineapple (..lnana,s comosus Merr.) Carboh.vdr. Res.. 121: 211-220. Boyd. C.E. and Blackburn, R.D., 1970. Seasonal changes in the proximate composition ofsome common aquatic weeds. Hyacinth Control., J., 8: 42-44. Davys. M.N.G. and Piric. N.W., 1969. A laboratory scale pulper for lea~' plant material. Biotechnol. Biocng., I l : 517-528. Davys, M.N.G.. Pirie, N.W. and Street, G., 1969. A laboratory scale press for extracting juice from tcafpulp. Biotcchnol. Bioeng., I1: 529-538. Gonzalcz, G. and Alzueta, C., 1984. Yield, chemical composition and nulritive value ofpressed pea vines (Pisum sativum) after LPC extraction. In: N. Sin gh (Editor), Current Trends in Life Sciences. Vol. XI. Progress in Leaf Protein Resea~-;,n. Today and Tomorrows Printers and Publishers, New Delhi pp. 355-361. Jeffery, J.E., Partlow, E.V. and Polglase, W.J., 1960. Chromatographic estimation of sugars in wood cellulose hydrolyzalc. Anal. Chem.. 32:1774-1777. Malai, S., 1976. Protein from aquatic weeds. In: C.K. Varshney and J. Rzoska (Editors). Aquatic Wccds in South East Asia, Proceedings of a Regional Seminar on Noxious A,quatic Vcgetalion, at New Delhi. Junk, The Hague, pp. 369-373. Matai, S.. Bagchi, D.K. and Raychudhuri, S., 1971. L,'af protein from some plants in West ~engal. Sei. Eng., 24: 102-105. McGovecn, J.N., 1967. Bleaching of non-wood pulp. Tappi, 50: 63A. Morton, J.F., 1975. Cattails ( Typha spp. ) weed problem or potential crop? Econ. Bol., 29: 729. MuTtar, A.J., Slinger, S.J. and Burton, J.H., 1978a. Chemical composition of aquatic macrophytes, i. Investigation of organic constituents and nutritional potential. Can. J. Plant Sci., 58:829-841. Muztar, A.J., Slinger, S.J. and Burton, J.H., 1978b. Chemical composition of aquatic macrophytes. Ill. Mineral composition of fresh water macrophytes and ff.cir potential for mineral nutrient removal from lake water. Can. J. Plant Sci., 58: 851-862. Pal, A., 1983. Agronomy and cultivation management of Ibhwqelh: voh'acea (Bull. ex. Fr.) Sing. in the plains of West Bengal. In: S.K. Roy (Editor), Frontiers of Research in Agricullure. Proceedings of the Indian Stati:a~,,,d Institute Golden Jubilee International Conference. Indian Statistical Institute, Calcutta, pp. 637-647. Pathak, B.S., Jain, A.K. and Singh, A., ! 986. Characteristics of crop residues. Agric. Wastes, 16: 27-35. Rodewald-Rudescu, L., 1974. Das Schilfrohr, Phragmite~ Trinius. E. Schweizcrbart'sche Verlagsbuchhahdlung, Stuttgart, 302 pp. Sawardekar, J.S., Si,,neker, J.H. and Jeanes, A., 1965. Qualitative determination of monosaccharides as their alditol acetates by gas liquid chromatography. Anal. Chem., 37:1602-1604. Technical Association of Pulp and Paper Industries, 1971. Standard and Suggested Mefllods. TAPPI, New ~,ork, pp. T222, T13, '1"203 03-61, T9. Van Soest, P.J., 1963. Use of detergents in the analysis of fibrous feed. J. Assoc. Offic. Agric. Ch",m., 46: 829-835. Wolver~on, B.C., McDonald, R.C. and Gordon, K., 1975. Bioconversion of water hyacinth to methane gas. NASA Tech. Memo. No. X-72725, pp. 135-145.
8I
Elsevier Science Publishers B.V., Amstcrdam
Short Communication
Chemical characterization of pressed fibrous residues of four aquatic weeds Sunanda Chanda ~, Swapan K. Bhaduri b and Dharmadas Sardar b ~Lea.fProtein Research Unit, Biological Sciences Division, Indie~ Statistical Institute, 203, B.T. Road, Calcutta--700 035, India hDepartment of Chemistl3, and Microbiolog); Jute Techno!ogical Research Laboratories, Indian Council of ..Igricultural Research, 12 Regent Park, Calcutta--700 040, India (Accepted 13 May 1991 )
ABSTRACT Chanda, S.. Bhaduri, S.K. and Sardar, D., 1991. Chemical characterization of pressed fibrous residue~ of four aquatic weeds. Aquat. Bat., 42:81-85. The pressed fibrous residues, generated as a by-product during the large-scale manufacture of leaf protein from four aquatic weeds, Pistia stratiotes L. vat. cuneata Engl. (Araceae), Nymphoides o'istatum ( Roxb. ) O. Kuntze (Gentianaceae), Lemna perpusilla Tort. (kemnaceae) and AIImania nod(llora (L.) R.Br. ex Hook. f. (Amaranthaceae), were analysed for their chemical and mineral coml;osition. They were found to consist of lignin, cellulose, pentosan, lipid, pectin and minerals, l'istia stratiotes is a rich source of a-cellulose (40.63%),.,1. nodtiflora and N. cristatum contain pentosan and pectin ( 19.75% and 14.49%, respectively), while L. perpusilla shows comparatively larger amounts of minerals (ash content 15%). All the values obtained were compared with those of other similar aquatic weeds and agricultural wastes such as rice and wheat straw, grass, bagasse, etc., which are usually used in the preparation ofsilage, compost, biogas and several other products.
INTRODUCTION
Although the noxious growth of aquatic weeds is a global problem, this is more acute in tropical countries due to warm :noist weather. Hence, commercial uses for these weeds have attracted the attention of scientists. Exploitation of aquatic weeds for leaf protein production has been carried out in our ~.aboratory (Matai et al., 1971; Matai, 1976; Bandyopadhyay, 1989; Banerjee et al., 1985 ). After the extraction of protein from aquatic weeds, a significant ~,mount of fibrous residue is left as a by-product. These residues ;yore chemically analysed and their yields noted. The values were compared with st, me agricultural wastes, such as rice and wheat straw, grass, bagasse, etc., which are already in commercial use. The fibres of four plants, viz. Pistia stratiotes L. var cuneata Engl., Nymphoides cristatum (Roxb.) O. Kuntze, Lcmna per pusilla Torr. and AIhnania nodiflora (L.) R.Br. e× Hook. f. were analysed. 0304-3770/9 !/$03,50 (O I q91 Elsevier Science Publishers B.V. All rights reserved.
82
S. CttANDA ET AL.
METHODS
The four aquatic plants were selected according to their availability and collected from sites in and around Calcutta. The plant materials were harvested in a lush green condition from different areas. Protein was extracted by an International Biological Programme pulper (Davys and Pirie, 1969) and press (Davys et al., 1969). The juice containing protein was pressed out and plant fibre was obtained as a by-product. This fibre was oven-dried at 105°C for 48 h. For chemical analysis, nitrogen was calculated as Kjeldahl nitrogen and crude fal was extracted with cholo':oform.methanol (2:1) in a Soxhlet apparatus. Ash values were obtained by heating the samples at 550°C for 4 h in a muffle furnace. Lignin, holocellulose, o~-cellulose, pemc, san and pectin content were determined with defatted samples using standard methods (Technical Association of Pulp and Paper Industries, 1971 ). The polysaccharides were hydrolysed according to the method described by Jeffery et al. (1960). The neutral sugars were analysed by gas liquid chromatography (GLC) of their alditol acetates (Sawardekar et al., 1965). For GLC, a Hewlett-Packard 5830 A gas chromatograph equipped with a flame ionizing detector (f.i.d.) was used with a stainless steel column ( 180 cm × 0.5 cm) containing 3% ECNSS-M on supelcoport (80-100 mesh) at 190°C using nitrogen as the carrier gas. Molar proportions of sugar were determined conventionally from peak areas. For mineral analysis, the samples were dried at 100°C for 4 h, kept in a desiccator for 3 h and then ground in a special Wiley TABLEI DD' yield and chemical composition (% dry matter) of pressed fibres from four aquatic weeds Family
Pistia stratiotes var.
..llhnania nod~flora
Lemna l~erlmsilla
Nyml~hoides cristatum
229.5 _+75 9.50_+0.75 3.62 + 0.51 7.25+0.95 16.15+2.85 49.45±3.50 10.9 _+0.63 27.53_+0.75 19.75± 5.05 28.83_+_4.15 36.73±3.87
i81.3 _+33 15.0 +3.60 3.62 + 0.72 4.70+0.70 I 1.96± 1 . 9 3 48.50±.~.50 6.40 ± 1.75 3397±2.45 10.67± 1.25 44.17±5.69 56.12±6.18
231 _+27 7.6 _+0.08 2.62_+ 0.08 10.00_+2.50 19.52_+4.16 48.20_+4.05 8.00_+ 2.02 20.05_+1.25 14.49-+ 1.23 36.26_+4.86 43.00+5.00
Clttlc'ala
Yield (dry weight, gkg-:) Ash Nitrogen Crude fat Lignin l-lolocellulose Pectin a-cellulose Pentosan ADF NDF
171.5 _+25 10.0 _.+1 . 2 5 3.37 + 0.15 9.75+__1.20 16.52-+ 1 . 2 5 57.20-+4.75 4.77_+ 0.38 40.63_+3.27 6.40+0.25 34.$7+3.10 42.12+_2.96
Values are the mean ± standard deviation (SD) of five replicates. ADF, acid detergent fibre. NDF, ne atral detergent fibre.
83
PRESSED FI BROUS RESIDUES OF AQUATIC WEEI)S
mill to minimize minor element contamination. The tissues were analysed for Na, K, Ca, Mg, Fe, Zn and Cu with a Perkin Elmer Model 372 atomic absorption spectrophotometer after digestion in a nitric-perchloric acid mixture. Phosphorus was determined as reduced phosphomolybdate. Modified acid detergent fibre (Anon., 1986) and neutral detergent fibre (van Soest, 1963) were also estimated. RESULTS
The yield and chemical and mineral characteristics of pressed fibres from
P. stratiotes var. euneata, N. cristatum, L. perpusilla and A. nodiflora are reported in Tables 1-3. The data indicate that Pistia fibre is a rich source of ce-cellulose, those of Alhnania and Nymphoides are good sources of pentosan and pectin, while Lemna fibres have a high level of minerals. TABLE 2 Amount of neutral sugars in pressed fibres from four aquatic weeds Weed
..lllmania nod(llora .~)mphoides cristatum
Rhamnose Arabinose
(%)
Xylose
(%)
(%)
4.93+_0.60 14.72+_2.82 19.90+_4.95 0.52_+0.03 0.52_+0.10 16.96_+1.83
Mannose
~%)
1.73_+0.52
Galactose
(%)
Glucose
(%)
3.36_+0.65 55.33_+6.68
19.61+_4.47 23.99_+4.33 38.35_+4.85
L('IIIIIa
perlmsilla 0.30_+0.00 3.93+_0.75 14.25+_2.80 12.92_+1.86 l'istia stratiotesvar. 0.05+_0.00 4.20_+1.08 6.31_+1.28 14.31+2.27
18.82+_3.18 50.07_+5.45 0.15+-0.05
74.89_+6.18
c'tlllCala
Values are the mean _+SD of five replicates. TABLE 3 Mineral content (% dry matter) of pressed fibres from four aquatic weeds
Na K Ca Mg P I-c Z,a Cu
Pistia stratiotes var. cuneata
..lllmania nod(flora
Lemna perpusilla
Nym,,hoidcs cristatum
1.05 _+0.25 1.68 _+0.16 1.90 _+0.05 0.61 +0.07 3.00 +0.35 Nil 0.0041 +0.0004 0.0016+0.0002
3.82 +0.10 2.05 _+0.75 2.11 _+0.17 0.66 -+0.22 1.50 +0.63 Nil 0.004~,-+0.0007 0.0011 -+0.0000
1.68 _+0.06 1.95 _+0.15 3.75 -+0.05 0.78 -+0.11 3.75 _+0.15 0.13 _+0.00 0.0060+_0.0010 0.0018+_0.0000
0.60 +0.07 1.25 +0.05 2.33 +0.87 0.61 +0.07 1.75 +0.05 0.11 +0.07 0.0059_+0.0007 0.0026+_0.0004
Values arc the mean +SD of five replicates.
84
S. CHAND& ET AL.
DISCUSSION Data in Tables I ::nd 3 reveal results similar to those found by Boyd and Blackburn (1970) and Muztar el al. ( 1978a, b) with other aquatic weeds McGovern (1967) characterized several agricultural residues and natural fibres, such as grass, rice sl.raw, sugar cane, jute, pineapple and sisal. Accordiilg to his report, rice straw and grass contain ash (6-20%), lignin ( 12-19% ), a-cellulose (28-36%) and pentosan (25-32%). Except for pentosan, all values seem to be quite close to the values exhibited in Table 1. Leaf fibres used in the textile and weaving industries are chemically quite different from fibres ofaquatic weeds, as shown by Bhadun et al, ( ! 983 ). The mineral content of aquatic plant fibres seems to be higl'., and a-cellulose and pentosan contents seem to be low when compared with ~hos~:ofterrestrial plar~ts (Go~izalez imd Alzueta, 1984; Pathak et al., 1986). The fibres of some aquatic weeds, e.g. species of Phragmites (in Romania), Typha (in Mexico) and Jtttlctts (in Japan) have rotund rise in the commercial production of paper pulp, for floor matting and silage (Rodewald-Rudescu, 1974; Bagnall et al., 1974; Morton, 1975 ). Biogas production from water hyacinth fibres is going on in India, China, Taiwan and Korea, although the process also requires some a;aimal manure (Wolverton et al., 1975). Water hyacinth fibres are used for mushroom production in tropical countries (Pal, 1983 ). The present results indicate that the fibres from the four plants under study may find similar uses. ACKNOWLEDGEMENTS The authors are grateful to R.K. Dey and S.R. Pyne of the Indian Statistical Institute, Calcutta, and the late K.P. Roy of the .lute Technological Research Laboratories, Calcutta, for their valuable assistance throughout the investigation.
REFERENCES Anonymous, 1986. Fibre, ModifiedAcid-Detergentin Plant Material, tile Analysisof Agricultural Materials. Minlstr3'of Agriculture,Fisheriesand Food, USA ReferenceBookNo. 427, pp. 93-94. Bagnall. L.O., Baldwin,J.A. and Hentges,J.F., Jr., 1974. Processinganti storage ofwaler hyacinth silage. Hyacinth Control J., 12: 73-79. P~andyopadhyay,A.. 1989. Utilization of aquatic weeds with stress on their nutritive value. i'hD. Thesis, Universityof Calcutta, Calcutta, pp. 59-89. Banerjce, A., Bagchi, D.K. and Matai, S., 1985.,,'~llmanianod(lloraR.Br. (Amaranthaceac!, a promisir,g sourceof leaf protein. Aquat. Bot., 22: 393-396. Bhaduri, S.K., Sen, S.K. and Dasgupta, P.C., 1983. Structural studies of an acidic polysa~cha:-
I'RESSLD FIBROUS RESIDUES OF AQUATIC WEEDS
85
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