PROSEA, Introduction to Fibres
- 1 Definitions and choice of species
- 2 Role of fibre plants
- 3 Properties
- 4 Botany
- 5 Ecology
- 6 Agronomy
- 7 Harvesting and processing
- 7.1 Harvesting
- 7.2 Post-harvest handling and processing
- 7.3 Pulping
- 7.4 Boards
- 7.5 Artificial fibres
- 8 Genetic resources and breeding
- 9 Research and development
- 10 Prospects
- 11 Authors
Definitions and choice of species
Fibres in general are defined as "slender strands of natural or man-made material usually having a length of at least 100 times their diameter and characterized by flexibility, cohesiveness and strength" (Lipton, 1995). The Textile Institute (Manchester, United Kingdom) has defined fibres as: "units of matter characterized by flexibility, fineness, and a high ratio of length to thickness" (Morton & Hearle, 1993).
Definitions of plant fibres vary from very simple, such as "a type of plant cell in which the wall has been thickened to perform a structural role" (Allaby, 1992), or "the thick-walled cells giving strength to plant tissue" (Lipton, 1995), to more comprehensive, such as "an elongate tapering cell that has at maturity a small lumen and no protoplasm content, that is found in many plant organs and is especially well developed in the xylem and phloem of the vascular system, and that imparts elasticity, flexibility, and tensile strength to the plant or organ" (after Webster's New International Dictionary).
Fibre plants are plants grown or collected for their fibres. They are often defined in a narrow sense, i.e. to include those plants from which fibres are extracted and used to make textiles, cordage, and sometimes also paper (Lipton, 1995; Wood, 1997). The present volume follows the commodity grouping adopted for the Prosea Handbook as presented in Jansen et al. (1991) and uses a wider definition of fibre plants, which are considered to comprise:
- Fibre plants in a narrow sense, used for textiles, cordage and paper (including those used for toothbrushes, sponges and cork).
- Plants used for making baskets, mats and wickerwork (including brooms).
- Plants used for packing and thatching (including leaves used as platters, for garments and as sandpaper).
Choice of species
In the present Prosea volume 72 species are described in detail in the 45 major treatments of Chapter 2. Brief descriptions of 129 minor species are given in Chapter 3. About 450 plant species whose use as fibre plants is secondary to other uses are listed in Chapter 4. An overview of the 72 major fibre plants is presented in Table 1. These include species producing the well-known plant fibres of international trade such as cotton (Gossypium spp.), jute (Corchorus spp.) and flax (Linum usitatissimum L.), and also lesser-known species used for weaving (e.g. Donax canniformis (G. Forster) K. Schumann, Fimbristylis umbellaris (Lamk) Vahl), thatching (e.g. Eugeissona triste Griff.) and packing (e.g. Heliconia indica Lamk). Of the 72 fibre plants, 39 are mainly used for cordage or tying, 28 for plaiting and weaving, 13 for thatching, 11 for textiles (including sacks), 10 for paper making, 3 for brushes and mats, 3 for miscellaneous uses (packing), 2 for natural fabrics and 1 for filling (stuffing). Species also used as fibre plants in addition to their primary use are treated in other Prosea volumes, for instance pineapple (Ananas comosus (L.) Merrill) in Prosea 2 (Edible fruits and nuts), Talipariti tiliaceum (L.) Fryxell (syn. Hibiscus tiliaceus L.) in Prosea 5 (Timber trees), toddy palm (Borassus flabellifer L.), sago palm (Metroxylon sagu Rottboell) and nipa palm (Nypa fruticans Wurmb) in Prosea 9 (Plants yielding non-seed carbohydrates), hemp (Cannabis sativa L.) in Prosea 12 (Medicinal and poisonous plants), and coir (Cocos nucifera L.) in Prosea 14 (Vegetable oils and fats). Rattans and bamboos are dealt with in Prosea 6 (Rattans) and Prosea 7 (Bamboos). Many trees used to supply pulp for paper making, including Acacia auriculiformis A. Cunn. ex Benth., A. mangium Willd., Eucalyptus camaldulensis Dehnh., E. deglupta Blume and Paraserianthes falcataria (L.) Nielsen (syn. Albizia falcataria (L.) Fosb.) are treated in Prosea 5 (Timber trees). Wheat, rice and sorghum, from which residues are used for paper making, are treated in Prosea 10 (Cereals). An overview of important fibre plants with other primary use is presented in Table 2.
Role of fibre plants
The use of plant and animal fibres for clothing dates back to the earliest civilizations. Wool became the main fibre for clothing in western and southern Europe, and hemp in northern Europe. Cotton was the ancient national textile of India and also a source of fibre for indigenous peoples in the Americas. Flax was probably first cultivated before 1000 BC, and linen from flax was used by the ancient Egyptians, Greeks and Romans. Ramie has been used since prehistoric times in China, India and Indonesia, and silk was important in China. Thus, the major textile fibres found today have all been in use for a very long time. Fibres have long been spun into yarns that were woven or knitted into fabrics for clothing. Over the centuries, the extraction of fibres and their processing into woven products developed into a highly skilled art, and fibres and fabrics became important items of commerce. Textile fibres were also used to produce articles such as sail cloth, furnishings, table linen and canvas. In addition, plant fibres were widely used for making rope, twine and fishing nets. The advent of steamships in the 19th Century, however, greatly reduced the demand for rope. The development of nylon and other synthetic fibres, with their excellent strength and durability, further reduced the demand for cordage produced from natural fibres. For example, leaf fibres from sisal (Agave sisalana Perrine) and henequen (A. fourcroydes Lem.) were long made into binder twine for the tying of hay bales, but they have now been largely replaced by synthetic fibres (Wood, 1997).
Old hemp clothing was one of the earliest materials to be used for paper making (Wood, 1997). The oldest surviving paper, made from hemp, was discovered in a tomb in China dating back to between 140 and 87 BC (Clarke, 1999). Paper making spread from China to India, Persia and Arabia, and from there through Spain into Europe in the 12th Century (Hill, 1952; Simpson & Conner Ogorzaly, 1995). Hemp, ramie, cotton, and rag fibres from plant or animal origin have been used for paper making for almost 2000 years (Croon, 1995; McDougall et al., 1993). In the 19th Century, straw and hardwood fibres began to be used as supplements, as technical and chemical knowledge increased (McDougall et al., 1993). Straw remained a major source of fibre in Europe and North America until the wood-based industry became fully established during the latter part of the 19th century (Moore, 1996). Softwood fibres became dominant with the advent of the sulphite pulping process, developed in 1857 (McDougall et al., 1993; Simpson & Conner Ogorzaly, 1995).
The end uses of fibre plants have been grouped in various ways, also depending on the definition of fibre plants applied (Hill, 1952; Kirby, 1963; Kochhar, 1986; Lewington, 1990; Schery, 1972; Simpson & Conner Ogorzaly, 1995). Fibre plants in a broad sense, as defined for the present volume, can be tentatively divided into 11 main groups: textiles, cordage and tying, brushes, filling, plaiting and weaving, thatching, natural fabrics, artificial fibres, paper, building and construction material, and miscellaneous uses.
The most important use of non-wood plant fibres is for textiles. Fibres are first spun into thread or yarn and then woven or knitted into fabrics. Fabrics include cloth for clothing and domestic use, and also coarser materials such as burlap for sacking. By far the most important fabric fibre is cotton; other fabric fibres include flax, hemp and ramie. Jute is the most important fibre for coarse fabrics for sacking. Netting fibres are used for lace, hammocks and all forms of nets. They include most commercial textile fibres and many local fibres such as Colona javanica (Blume) Burret, Curculigo spp. and Enhalus acoroides (L.f.) Royle in South-East Asia.
Cordage and tying
In the process of cordage production, individual fibres are twisted together but not woven. Many kinds of cordage exist, including rope, twine, binder twine and fish lines. The most important cordage fibres are abaca (Musa textilis Née), sisal and hemp; lesser-known but nevertheless widely distributed cordage plants include Abroma augusta (L.) L.f., Helicteres isora L., Malachra capitata (L.) L., Sansevieria spp. and Thespesia lampas (Cav.) Dalzell & A. Gibson. Many other species are of local importance only, such as Curculigo spp. in South-East Asia. Rough cordage is obtained by simply twisting together bast ribbons, e.g. of Anodendron and Colona spp. Many plant species are traditionally used for tying without much processing, for instance the stems and branches of lianas such as Bauhinia and Gnetum spp.
An important application of plant fibres is found in the manufacture of brushes, brooms and whisks. For these products fibres must be strong and stiff, but also flexible. Sometimes whole twigs, fine stems or roots are utilized; fibres are also obtained from leaf stalks of palms. The brush fibres include African piassava (from Raphia hookeri G. Mann & H. Wendl. and R. palma-pinus (Gaertn.) Hutch.), Bahia piassava (from Attalea funifera Mart.) and Para piassava (from Leopoldinia piassaba Wallace).
Filling fibres are used for stuffing (pillows, cushions, mattresses etc.), caulking (seams between planks, barrels etc.) and packing. The most valuable of all stuffing materials is kapok (Ceiba pentandra (L.) Gaertn.), but many other plant fibres are useful as filling material, such as Bombax anceps Pierre, B. ceiba L., the straw of cereals and other grasses, and the husks of maize.
Plaiting and weaving
Plaits are wide, flat, pliable, fibrous strands that are interlaced to make hats, sandals, baskets, chair seats, mats, etc. Non textile weaving encompasses a number of different techniques such as plaiting, twining, coiling and wickerwork. Usually older or otherwise tougher, less supple strands are used for mats, whereas more supple strands are used for baskets, chairs and other forms of wickerwork. Hat fibres are obtained from the leaves of the Panama hat palm (Carludovica palmata Ruiz & Pav.) and many Cyperaceae, Palmae and Pandanaceae. Fibres for mats are obtained from many plants, including a range of Cyperaceae, Palmae and Pandanaceae. Numerous species of rattan and bamboo are used in basketry, as are many Cyperaceae, Palmae and Pandanaceae.
Thatches are roof coverings made from non-wood plant material such as leaves, straw and reeds. They are widely used in South-East Asia, despite the growing popularity of zinc roofs. Zinc lasts longer, but requires cash outlay and gives a hotter indoor climate. For plant thatch, if locally available, usually no cash is required and it is cooler. It needs to be replaced more often than zinc, but this also depends on species used and construction technique. Thatched roofs are sometimes desirable in tourism, but also sometimes considered lower class and therefore avoided by people climbing the socio economic ladder. The choice of material for thatching depends on local availability: cogon grass (Imperata cylindrica (L.) Raeuschel) is widespread and is often used. Rice straw is used in rice-growing areas such as Bali (Indonesia). Often palm leaves are applied, either harvested from wild trees, e.g. Eugeissona triste, or as by-products from homesteads or plantations, e.g. from Borassus flabellifer, Cocos nucifera, Metroxylon sagu and Nypa fruticans.
Natural fabrics are often made from tree basts that are extracted from the bark in layers or sheets and pounded into rough cloth ("barkcloth"). Probably the best known of these barkcloths is "tapa cloth", obtained from the bark of paper mulberry (Broussonetia papyrifera (L.) L'Hér. ex Vent.). Other sources of barkcloth in South-East Asia include Artocarpus elasticus Reinw. ex Blume and Antiaris toxicaria Lesch.
Artificial fibres such as viscose, acetate and tri-acetate are obtained from cellulose contained in living plants. For a long time, cotton was the only source of the cellulose used in the production of artificial fibres and other cellulose products. Developments in wood technology have enabled the production of high-grade cellulose from wood. When certain woods are treated with concentrated acids or alkalis, the bond between the wood fibres and the lignin that cements them together is broken, and the fibres can be removed. These fibres may then be reorganized as paper or they may be further treated with chemicals. If this chemical treatment merely causes the fibre to dissolve into its component molecules, these molecules may be resynthesized into artificial fibres or converted into cellulose plastics.
Paper can be made from any natural fibrous material, including wood fibres, cereal straw, bamboo and textile fibres used in either the raw or manufactured state. Where wood-based fibres dominate, non-wood fibres usually only occupy small niche markets providing specialist properties to a range of high added-value products. However, where wood-based fibres are not sufficiently available, non-wood fibres are used across the spectrum of paper and paperboard products (Moore, 1996). Mills in Africa and Latin America mainly use wood, whereas in Asia non-wood raw materials predominate, due to (Moore, 1996):
- Lack of timber resources in some countries with a large population and consequently a high demand for paper, such as China, India, Bangladesh, Pakistan and Iran.
- Lower capital investment requirements for non-wood pulp and paper mills, due to smaller size and fewer technical problems.
- Less stringent pollution requirements from governments, in an attempt to promote investment in domestic paper manufacture.
Non-wood materials used for the production of pulp can be divided into 2 categories (Wood, 1997):
- Crop residues left after the primary product has been harvested or extracted. Examples are cereal straw residues (wheat, rice, sorghum) and bagasse left after the extraction of sugar from sugar cane (Saccharum officinarum L.). This group also includes waste fibres recovered from crops grown primarily for the manufacture of textile, sacking and cordage fibres. These waste fibres, referred to as tow, are recovered from the scutching and combing operations that form the initial operations prior to spinning.
- Crops specifically grown for paper production. Examples are bamboo, and textile and cordage fibres, e.g. abaca, hemp, jute, kenaf, New Zealand flax (Phormium tenax J.R. Forster & G. Forster), ramie and sisal. Hemp, jute, and ramie have specific applications in the manufacture of cigarette paper, tea bags, sack paper and saturating papers (Biermann, 1993). Traditional bast fibres such as kenaf (Hibiscus cannabinus L.) are removed from the stem and can be used to produce high-quality writing and specialty papers. Alternatively, the whole stems or the separated bark and core fractions can be used to produce pulps with properties comparable to those of wood. The bast fibres provide strength to the pulp, whereas the shorter core fibres provide good surface characteristics. Pulping of the whole stem rather than the separated bast and core fibres has the advantage of saving considerably on the costs of labour involved in retting and decorticating.
In temperate climates the most important source of non-wood fibre for pulping is wheat straw; in Asia, rice and wheat straws and bamboo are important sources; and in Latin America sugar-cane bagasse is by far the main non-wood fibre (Moore, 1996). Sugar-cane bagasse has been considered as a source of raw material in various Asian countries, including Thailand and India. However, bagasse is also an important source of fuel for boilers of sugar mills, and for that reason in short supply for alternative applications (Moore, 1996).
Building and construction material
Current applications of non-wood plant fibres in building material include particle board, fibreboard, especially medium density fibreboard (MDF), and inorganic matrix composites (IMCs). Boards are mainly used indoors as insulation material. IMCs find application in plaster boards, tiles, concrete, mortars and plasters. Softwoods are the preferred raw material for particle boards and MDF; jute and kenaf sticks are used as well. Smaller quantities of hardwood are also used, especially for particle board, but generally not preferred, because the higher dust levels associated with their processing can increase resin consumption and processing costs, and can increase the risk of fire and explosion in the factory (Hague, 1997). Straw and bagasse are quite widely used for the production of low- and medium-density particle board. The use of timber for construction purposes has been dealt with in the Prosea volumes on timber trees.
Jute and similar fibres are traditionally used for carpet backing, carpet underlays and for the manufacture of felt. Other potential uses include geotextiles for erosion control on slopes and for agricultural mulching. Fibres from coir, sisal, jute and flax are made into biodegradable plant pots, e.g. in Germany (Groot, 1996). A relatively new and increasingly popular use of plant fibres is found in the automotive industry, where they are used to make press-moulded composites for door panels, hat racks and trunk liners. In Germany, for instance, the use of plant fibres in the automotive industry grew from 4000 t in 1996 to about 14 000 t in 1999. The main fibre used in 1999 was flax (11 000 t), but kenaf (1100 t), hemp (1100 t), jute (700 t) and sisal (500 t) were also used (Karus & Kaup, 1999).
Various developments during the 20th Century have led to a decline in the importance of non-wood fibres other than cotton: the mechanization of production and thus increased market share of cotton, the development of synthetic fibres from petroleum (nylon, acrylic, terylene, polyester) or from cellulose contained in living plants (viscose, acetate, tri-acetate), and a decline in the use of sacking for the transport of agricultural products due to the advent of transport in containers (Lewington, 1990; Wood, 1997). Although many species are or have been used as fibre plants, only a few are grown at present on a large enough scale to be of importance in international trade. Most fibre plants are indigenous species collected or cultivated for local use only. Table 3 presents statistics on the production and trade of the most important fibre crops (excluding woods for paper making) from 1996 to 2000. Separate statistics for kenaf and roselle are not available. They are usually included in the "jute-like fibres", a group also including China jute (Abutilon theophrasti Medik., synonym: A. avicennae Gaertn.), Congo jute (Urena lobata L.), other Malvaceae, and sunn hemp (Crotalaria juncea L.). Kenaf is estimated to make up about 90% of the total, and roselle about 10%.
Table 3 shows that cotton is by far the most important fibre crop in terms of area under cultivation, production, and export value, followed by jute and flax. Across all countries, the export fraction does not exceed 35% of total production; this means that the largest proportion of the fibres produced worldwide is consumed domestically. When fibre plants are defined in a broad sense, by far the most important fibre plants on a world scale are woody species used for paper making, with an estimated annual production in the early 1990s of about 1750 million t (Bolton, 1995).
The estimated production of the major fibre crops in South-East Asia (except woods for paper making) is presented in Table 4, which shows that for most of these crops South-East Asia plays only a minor role in world production, the exceptions being kapok and abaca. Statistics on the production of flax and hemp in South-East Asia are not available, but fibre production of these crops is limited in the region.
In 1994 the annual world production of paper pulp was 170 million t, of which only 12.5 million t (8%) were produced from non-wood materials, including bamboo and bagasse (Croon, 1995; Wood, 1997). The explanation for the popularity of wood is its low cost and high fibre quality. To be successful, alternative sources must have both these characteristics (Clarke, 1999). China produces about half of the world's non-wood pulp (Croon, 1995; Wood, 1997). The pulp and paper industries in industrialized countries have generally shown little interest in non-wood fibre crops, partly because it is felt that enough forest resources are available and that non-wood fibre crops are not cost-competitive.
The main morphological properties determining the suitability of fibres for different uses, such as textile or paper, are the length and width of the individual fibre cells ("ultimate fibres") which form the skeleton of the fibres (Maiti, 1997; McDougall et al., 1993). Cell wall thickness and lumen diameter are generally less important (McDougall et al., 1993). In Table 5 the dimensions of selected plant fibres are presented.
The fibre cells of ramie are the longest of all the vegetable fibres, followed by cotton, flax and hemp. For the industrial production of fine textiles, e.g. for clothing, a length:width ratio of over 1000 is generally required (McDougall et al., 1993). Cotton, flax and ramie generally have a length:width ratio of 1000 or higher. The length:width ratio of abaca, jute, kenaf, roselle and sisal is well below 1000, and these fibres can only be used for coarser textiles. Kapok has a length:width ratio of about 1000, but the fibre cells are normally too smooth to be spun into yarns, and thus not suitable for the production of textiles. For the production of burlap bags jute is superior in quality to kenaf, because it possesses fibre cells with more uniform morphology. Some other fibre crops have desirable qualities for burlap bags. Among these, Sida rhombifolia L. and Urena lobata are of good quality, associated with a high length:width ratio of the fibre cell.
For cordage, rough fibres are used in general, such as abaca and sisal. The fibres of these plants are uniform on the surface and the cell tips, and the fibre cells have an intermediate length:width ratio. Rough fibres such as those of Furcraea spp., Abelmoschus esculentus (L.) Moench and Hibiscus radiatus Cav., as well as several other Agave spp., also have the desirable qualities (Maiti, 1997).
Fibres used for brushes normally have thick filaments, with orderly cells very compactly arranged in the fibre bundle, a low length:width ratio of fibre cells, and thick fibre walls. Coir and the leaf stalks of Cocos nucifera and Borassus flabellifer, for instance, possess fibres characterized by low length:width ratio of fibre cells and thick cell walls (Maiti, 1997).
The properties of paper-based products are to a large extent determined by the types of pulp from which they are manufactured, whereas the properties of the pulp are determined by the properties of the raw material (fibre dimensions, chemical composition) and the pulping process used (Hague, 1997). The length:width ratio is important, because it affects the paper's flexibility and resistance to rupture. Softwood ultimate fibres are 2.7-4.6 mm long and hardwood ultimate fibres have a length of 0.7-1.6 mm (Karakus et al., 2001). Softwood fibres are ideal for paper making, because their long, thin, flexible structure allows them to pack closely together into non-porous, tightly bonded sheets. Hardwood fibres do not pack as tightly together, because they are shorter and less flexible (McDougall et al., 1993).
Plant fibres consist of primary and secondary cell walls (Figure 1). The main components of plant fibres are cellulose, non-cellulosic polysaccharides (NCP), often subdivided into hemicelluloses (mainly composed of neutral sugar residues) and pectin (characterized by a high content of D-galacturonic acid residues), and lignin (Biermann, 1993; McDougall et al., 1993). The term holocellulose refers to the entire carbohydrate fraction of the material, i.e. cellulose plus hemicelluloses, whereas α-cellulose is the fraction isolated by a caustic extraction procedure. It is generally considered to be pure cellulose, but it actually is 96-98% cellulose (Biermann, 1993). The ratio of the different constituents and the chemical nature of the lignin and hemicelluloses varies widely between plant types and species (McDougall et al., 1993; Moore, 1996). Table 6 presents the chemical properties of selected plant fibres.
In contrast to plant fibres, animal fibres such as wool mainly consist of protein. This difference in chemical composition affects properties such as the resistance to washing in hot water and the acceptance of dyes. In general, plant fibres are less elastic than animal fibres, but they have a higher affinity for water and are thus more absorbent than animal fibres. Animal fibres are susceptible to animal pests such as moths and silverfish, to which plant fibres are usually immune, whereas plant fibres are readily attacked by fungi and termites (Simpson & Conner Ogorzaly, 1995).
The primary structure of all celluloses is a β-1,4-linked polymer of D-glucopyranose residues (Figure 1). All evidence indicates that cellulose is a homopolymer, not covalently bonded to other constituents of the cell wall. Every D-glucose residue is inverted at an angle of 180° to the next residue, which means that the repeating unit is cellobiose. The cellobiose chains are mutually connected by hydrogen bonds (McDougall et al., 1993). The cellulose molecule of purified cotton consists of at least 2000-3000 simple glucose sugar molecule residues, joined end to end in the form of a long chain (Kirby, 1963).
The higher the cellulose content of a fibre, the greater its value (Kirby, 1963). Cotton contains 88-96% α-cellulose, ramie 69-91%, hemp 62-67%, sisal 54-66% and jute 45-64% (Table 6).
Hemicelluloses consist of short, highly branched chains of sugars. In contrast to cellulose, which is a polymer of only glucose, hemicelluloses are polymers of different sugars. They are built up from pentoses (usually D-xylose and L-arabinose), hexoses (D-galactose, D-glucose, and D-mannose) and uronic acid residues (Biermann, 1993). The polymerized pentoses are called pentosans. Hemicelluloses form, together with lignin, the cementing material of the middle lamella between the ultimate fibre cells. The branched nature of hemicelluloses makes them amorphous and easier to hydrolyse into their constituent sugars than in the case of cellulose. Hemicelluloses are soluble in 18.5% NaOH and this is the basis for their measurement in TAPPI test methods (Biermann, 1993). When hydrolysed, the hemicelluloses from hardwoods release products high in xylose, whereas the hemicelluloses contained in softwoods yield more hexoses.
The presence of hemicelluloses in material for paper making increases the pulp yield and the strength of the resulting paper. Hemicelluloses are not wanted in dissolving pulps for cellulose-based plastics (Biermann, 1993).
Lignin is a complex aromatic polymer, often present in the middle lamella and the mature secondary wall (Biermann, 1993; McDougall et al., 1993). Lignification increases the rigidity of the cell wall, makes it less susceptible to predation and less permeable to water (McDougall et al., 1993). The structure of naturally occurring lignins is not yet well known, but they are formed by the radical-induced polymerization of phenylpropenoid monomers. These monomers are based on coumaryl alcohol and may have 1 or 2 methoxyl groups at C-3 and/or C-5 on the benzenoid ring (McDougall et al., 1993; Palit et al., 2001). Many types of linkages between the monomers have been found, but the β-O-4 aryl ether is the most common. Sometimes ferulic and p-coumaric esters are found (McDougall et al., 1993).
High-quality fibres like cotton, ramie, flax and hemp contain very little (less than 5%) lignin, whereas jute, kenaf and roselle generally contain 10-20% lignin, making them inferior for fine fabrics (Palit et al., 2001). In paper making, removal or modification of lignin is essential for the production of pulp for quality papers (McDougall et al., 1993).
Pectin is a material that binds fibre cells together (Kirby, 1963). Pectic acid is defined as a polysaccharide containing more than 90% D-galacturonic acid. However, some "pectins" have only 20% galacturonic acid and 80% neutral sugar residues, which is one of the reasons for combining them with hemicelluloses in the non cellulosic polysaccharides. The D-galacturonic acid residues are connected by α-1,4-linkages, but α-1.2-linked L-rhamnose residues also occur in the main chain. Methyl and acetyl esters are additional constituents of the polymer, whereas complex arabinans and 2 types of arabinogalactan are linked to the rhamnogalacturan backbone. Very little pectin is typically present in cell walls, but in some fibre plants, for instance flax, considerable amounts of pectin are present in the middle lamellae between fibre cells and other cells (McDougall et al., 1993). The pectin content of important fibres is for unretted flax 4%, retted flax 2%, ramie 2%, sisal 1%, hemp 0.8% and jute 0.2% (Table 6).
The physical properties of plant fibres are a function of the properties of the individual fibre cells and those of the matrix of intercellular cementing materials in which the fibre cells are embedded (Mukherjee & Radhakrishnan, 1972). Important physical properties of plant fibres include strength, durability, cohesiveness (the ability of individual fibres to stick together when spun into yarn), pliability (the quality enabling the filaments to be wrapped around each other during spinning), and colour (Weindling, 1947). These characteristics usually vary widely within species, even between fibre strands within the same plant. They also depend on a range of other factors, including temperature, moisture content and test methods. Weindling (1947) has made an attempt to rank some bast and leaf fibres with respect to these properties (Table 7).
The strength of plant fibres can be expressed in various ways. Strength or tenacity is a measure of resistance to steady forces, and is the appropriate quantity to consider when material is subject to a steady pull, for instance in the case of a rope used for hoisting heavy weights (Morton & Hearle, 1993). The strength may be given by the breaking load, which can be measured by hanging weights on to a fibre strand to determine at what weight the fibre breaks. As the breaking load depends on the cross-sectional area of the fibre, a more useful characteristic is the tensile strength: the breaking load or force per unit area of cross-section, usually expressed in N/mm2 (106 Pa) or in kg/mm2. An older method of expression is the breaking length: the length at which the material, when hung up, will break under its own weight. It is usually expressed in km. Another useful characteristic is the elongation at break, which is a measure of the resistance of material to elongation. It is defined as the amount of extension when the fibre breaks, expressed as a percentage of the original length of the fibre. The elasticity is the degree to which the fibre recovers its original length after extension. The Young’s modulus or modulus of elasticity is the ratio of the stress (force per unit area) or applied load to the strain or deformation produced in a material that is elastically deformed; the higher the value, the stiffer the material. Its reciprocal is the coefficient of elasticity. Table 8 presents typical values of the tensile strength, elongation at break and Young's modulus of selected plant fibres.
Taxonomy and morphology
In general the most important textile and cordage fibre-yielding families are the Malvaceae (cotton, kenaf, roselle) and Tiliaceae (jute). Plants used for basketry are primarily found in the Cyperaceae, Gramineae, Palmae and Pandanaceae. Material for thatching is often obtained from Gramineae (Imperata spp., Miscanthus spp.), Palmae (Borassus flabellifer, Cocos nucifera, Corypha utan Lamk, Eugeissona triste, Nypa fruticans) and Pandanaceae (Pandanus spp.). Paper is mainly obtained from trees in the Pinaceae (Pinus spp.) and Myrtaceae (Eucalyptus spp.). The main non-wood sources of paper are Gramineae (bamboos, cereal straw).
The major South-East Asian fibre plants treated in Chapter 2 comprise 72 species belonging to 25 plant families. Families with the greatest number of species are the Cyperaceae (11 species), Malvaceae (10 species), Palmae and Pandanaceae (5 species each), Tiliaceae, Gramineae, and Thymelaeaceae (4 species each) and Agavaceae (3 species) (Table 9). All the 11 Cyperaceae are perennial herbs, whereas the 10 Malvaceae are herbs, shrubs or trees (Table 9). The 129 minor fibre plants treated in Chapter 3 belong to 37 plant families, with the greatest number of species in the Pandanaceae (23 species), Cyperaceae (14 species), Moraceae (12 species), Malvaceae (10 species), Tiliaceae (8 species), Urticaceae and Palmae (7 species each) and Leguminosae (6 species).
Fibres and fibrous material are obtained from various plant parts, mainly from the stems, leaves and fruits or seeds.
Fibrous material from the stem can be classified into:
- Bast fibres ("soft fibres"): the soft and flexible fibres extending through the inner bark ("bast") of stems of dicotyledonous plants. The fibre strands of commerce usually consist of bundles of individual sclerenchyma fibre cells, the exception being ramie, where commercial fibres are single fibre cells. This group includes the fibres from jute, flax, hemp, sunn hemp, ramie, kenaf, roselle and Congo jute (Urena lobata).
- Bast: sometimes the bast fibres are not separated, but the bast is used entirely or in ribbons, often for rough cordage (e.g. Colona spp.). Formerly, bast sheets of Artocarpus elasticus and Broussonetia papyrifera were widely used in South-East Asia for the production of barkcloth.
- Wood fibres: the fibres occurring inside the vascular cambium of softwood or hardwood stems. Softwoods yield tracheids and xylem fibres, and hardwoods produce a mixture of tracheids, vessel elements and xylem fibres. Both softwoods and hardwoods are used in a wide range of papers. Examples of softwoods are Pinus spp., examples of hardwoods are Eucalyptus spp.
- Fibres from monocotyledonous stems: consisting mainly of vascular tissues and their sclerenchymatous bundle sheaths, and used for paper making and the production of building boards. Examples are cereal straw, bamboo, bagasse from sugar cane, and the stems of reeds such as Phragmites spp. Pulps from these materials typically have low strengths but can be blended with high-strength bark pulps to produce pulps with good paper-making characteristics.
- Entire or split stems: used for plaiting and weaving (many Cyperaceae), for thatching (many Gramineae), or for tying (e.g. Bauhinia spp. and Nepenthes spp.)
- Pith: sometimes used for paper making, e.g. in the production of ricepaper from Tetrapanax papyriferus (Hook.) K. Koch. The pith of the stem of Cyperus papyrus L. was used by early civilizations to make a primitive form of paper.
Fibrous material from the leaves can be distinguished into:
- Leaf fibres: fibres separated from the non-fibrous leaf tissue. The main leaf fibres are the "hard fibres" of commerce: the fibres extending lengthwise through the pulpy tissues of long leaves of monocotyledonous plants, with the fibres being characteristically hard and stiff in texture. The "hard fibres" include fibres from the vascular bundles in the leaves of Agavaceae such as sisal, henequen, cantala (Agave cantala Roxb.), the leaf-sheaths in the pseudostems of abaca, and the petioles of Raphia spp.
- Entire leaves or leaf strips: used for plaiting and weaving (Palmae and Pandanaceae), thatching (many Palmae and Pandanaceae), as platters (e.g. Heliconia indica), and for packing (e.g. the leaf blades of Musa spp.).
Seed and fruit fibres include cotton, formed by elongation of individual epidermal hair cells of the seed, kapok, a fruit hair fibre, and coir, the fibre comprising the mesocarp of the coconut.
Of the 72 major fibre plants treated in this volume, 44 mainly yield stem material, 25 are mainly exploited for their leaves (including leaf sheaths), and 5 provide seed or fruit fibres (Table 9). The plants yielding stem fibres include 23 species yielding bast material, 20 species of which entire or split stems are used, and 1 species of which the pith of the stems is used. The plants yielding leaf fibres include 18 species of which the entire leaf or leaf strips are used, and 13 of which leaf fibres are separated. The plants yielding seed or fruit fibres are 4 species yielding seed fibres and 1 species yielding fruit fibres.
Growth and development
Most fibre plants treated in this volume are perennials (Table 9). Many of those that are harvested for leaf fibres are monocarpic: they flower only once after a certain number of leaves have formed, and die after flowering. Examples are the perennial herbs Agave cantala, A. sisalana, Furcraea foetida (L.) Haw., Musa textilis, Phormium tenax, Sansevieria roxburghiana J.A. Schultes & J.H. Schultes and S. trifasciata Prain, and the palms Corypha utan Lamk, Eugeissona triste, Raphia farinifera (Gaertn.) Hylander, R. hookeri and R. vinifera P. Beauv. In sisal, for instance, 200-250 leaves are formed before the plant flowers. As the leaf emergence rate depends on ecological conditions (mainly temperature and rainfall) the lifespan of a sisal plant may vary from 3 to 20 years.
Annual bast fibre plants such as jute, kenaf, roselle and flax are usually not allowed to complete their life cycle, because the fibres are located in the vegetative parts, and optimum fibre quality is obtained by harvesting immature plants. Seed and fruit fibre plants such as cotton and kapok, on the other hand, are harvested after completion of a generative phase. Cotton is basically a perennial plant with an indeterminate growth habit, but it is usually grown as an annual, with the formation of nodes on the main stem arrested by fruit load, temperature, soil moisture, photoperiod, or a combination of these factors.
Day length influences growth and development of several fibre plants, indirectly affecting growth and yield. Hemp, jute, kenaf, roselle and ramie, for instance, are short-day plants, requiring photoperiods of less than about 12.5 hours for flower induction. When days are longer than the critical photoperiod (in practice often around 12.5 h, but this depends on species, cultivar and temperature), flowering is delayed, which is desirable for bast-fibre producing crops. Flax, on the other hand, is a long-day plant. Modern cotton cultivars are generally photoperiod-insensitive. The variation in photoperiod-sensitivity among cultivars can be exploited by choosing sowing dates and cultivars in such a way that the duration of the vegetative period and yield are optimal.
The majority of the fibre plants treated in this volume, including abaca, cantala, coir, Congo jute, cotton, jute, kapok, roselle and sisal, grow best at average temperatures of about 25 °C. Several species, such as kenaf, ramie and paper mulberry, also grow well at somewhat lower temperatures. Fibre hemp, flax, Juncus effusus, Miscanthus spp., Phormium tenax and Tetrapanax papyriferus (Hook.) K. Koch require a temperate climate; in South-East Asia they can usually only be grown successfully at higher altitudes. Most fibre plants treated in this volume are not frost-hardy, but mature P. tenax is tolerant to frost and T. papyriferus may also survive light frost.
Rainfall requirements vary widely. Among the perennial fibre plants, the minimum annual requirements of Sansevieria spp. (250 mm), P. tenax (500 mm) and sisal (< 1000 mm) are low, but these crops are also found in areas with much higher rainfall, for instance 3500 mm for P. tenax. Cantala also prefers semi-arid conditions, though it can be grown in higher rainfall areas as well. Abaca, on the other hand, needs 2000-3000 mm of rainfall per year. Perennials with intermediate annual requirements include kapok and Thespesia lampas (1500-1700 mm). Monocarpic perennials such as sisal and cantala form fewer leaves per year and have a longer life cycle under dry conditions or at low average temperatures. For annual fibre crops, the rainfall during the growing season is more important than the total annual rainfall, with cotton, for instance, needing at least 500 mm during the growing season. In general, jute and kenaf require about 100-125 mm per month, flax 150-200 mm, Congo jute 160-210 and roselle 150-270 mm.
Some fibre plants tolerate a wide range of ecological conditions. As such, they are easy to grow and in fact behave as weeds in many instances. Arundo donax L., for example, grows at average annual temperatures between 9 and 29 °C and an annual rainfall of 300-4000 mm.
The soil requirements of fibre plants vary, but rich alluvial, sandy loams, loams and clayey soils are generally preferred. The pH affects the efficient utilization of soil nutrients; generally, soils which are slightly acidic are suitable for most of the species treated, though cantala prefers limestone soils. Most textile and cordage fibre plants, including abaca, cantala, kenaf, ramie, roselle and sisal, need well-drained soils, as they do not tolerate waterlogging, but white jute (Corchorus capsularis L.) is relatively tolerant to inundation in later development stages. Many plants used for weaving, on the other hand, grow in swampy or inundated locations: Donax canniformis, Juncus effusus, Phragmites vallatoria (Pluk. ex L.) J.F. Veldkamp, Typha spp. and Cyperaceae such as Actinoscirpus grossus (L.f.) Goetgh. & D.A. Simpson, Cyperus spp., Fimbristylis umbellaris, Lepironia articulata (Retz.) Domin, Scirpodendron ghaeri (Gaertn.) Merr. and Schoenoplectus spp. A special case is Enhalus acoroides, which is subaquatic.
Although naturally occurring plants have been important sources of fibre since the beginning of history, it is desirable for a viable industry to be able to obtain raw material from sustainable and well-managed farmers' plots or industrial plantations. Supply from the wild may be sufficient for the local needs of communities in the immediate vicinity. Species collected from the wild are sometimes over-exploited and may be threatened with extinction, especially those with restricted and endemic distribution such as some Pandanus spp. In the Philippines, for example, gatherers of fibre plants collect and sell fibre plants from the wild for their livelihood and a shortage of some wild species has already arisen, for example, various rattan species. Nevertheless, many species treated in this volume are collected from the wild and some have become important raw materials for local use and small-scale cottage and handicraft industries. Sometimes propagules are collected from the wild and planted in home gardens or fields, either as sole crops or as components of intercropping systems. Many of the perennial species intended for domestic and local uses are intercropped, whereas annual herbs are mostly grown as sole crops. Industrial plantations of major crops in South-East Asia include those of cotton, abaca, ramie, kenaf, roselle, jute, cantala and sisal, the extent of which differs from country to country and depends on the requirements of domestic and export needs. The stiff competition offered by fibre crop producing countries outside South-East Asia limits the scope for industrial plantations in the region.
Propagation and planting
Many fibre plants are propagated by seed but a range of vegetative methods are employed as well (Table 10). The disadvantage of seed propagation for cross-pollinating species is the genetic variation of the resulting progeny that may express undesirable fibre characteristics, and extensive use may sometimes rapidly decrease seed viability. Most fibre plants in Table 10 show no seed dormancy but Pandanus spp. possess a hard exocarp which should be soaked in water first for faster germination. Methods of vegetative propagation include the use of stolons, rhizomes, bulbils and suckers, whereas stem and branch cuttings are also common. The desired fibre characteristics can be maintained by vegetative propagation. Rooting is easily stimulated by application of growth regulators.
Though most species can be propagated in several ways, often one specific method is practised. Most annual fibre plants, including cotton, flax, hemp, jute, kenaf, roselle and sunn hemp, are propagated by seed. The preferred propagation methods for perennial fibre plants are mostly vegetative, for example using rhizome cuttings (ramie), suckers (cantala), bulbils (sisal, Furcraea foetida) and corms (abaca). Kapok is propagated by either seed or cuttings, and in Indonesia seedlings are grafted with high-yielding clones.
Although commonly used in other major crops, in vitro propagation techniques are rarely used in fibre crops, though they have been developed for abaca, cantala, sisal, paper mulberry, Juncus effusus, Raphia spp. and Wikstroemia spp. The application of in vitro propagation techniques may prove beneficial in the near future, as this may be a way to provide disease-free and homogeneous plant material in sufficient quantities. At present, the only mass-propagation of fibre plants through in vitro culture in South-East Asia is with abaca in the Philippines, where tissue-cultured plants are used in replanting programmes.
Many fibre plants, especially those with small seeds, are broadcast directly in the previously prepared field, but other crops are raised first in nursery seedbeds before being planted out. Adequate spacing between plants is required to allow for weeding and harvesting. Close planting is observed, for instance in jute, kenaf, roselle and Helicteres isora, to avoid branching which would lower the quantity and quality of the fibre obtained. Sisal is sometimes planted in a double-row system ("twin-row planting"), in which pairs of rows are alternated by wider spaces ("lanes"); the plants in the rows nearest to each other are staggered, so that they are as far apart as possible (Lock, 1969). Table 11 presents an overview of commonly applied plant spacings and densities for the most important fibre crops.
Cropping techniques for fibre plants differ little from those of other annual and perennial crops. Weed control is a primary concern as weeds may reduce the quantity and quality of the fibre. It is especially important in plants with little competitive ability (e.g. flax), and during the early stages of development for most crops. Furthermore, weeds sometimes harbour diseases and pests that may be detrimental to the crop.
Irrigation of fibre crops in industrial plantations occurs in Indonesia for roselle, but most fibre plants are planted at the onset of the rainy season and grown under rainfed conditions. Cotton, however, may be grown under irrigated or rainfed conditions.
Fertilizer recommendations depend on soil characteristics and nutrient uptake of the fibre crop. The nutrient uptake of flax, for instance, is relatively low: for a crop yielding 5-6 t straw and 0.6-0.8 t seed per ha it is 50-75 kg N, 10-16 kg P and 40-60 kg K. Cotton and jute have moderate nutrient uptake. For a yield of about 1.7 t/ha seed cotton, the uptake is about 105 kg N, 18 kg P and 66 kg K per ha (Halevy & Bazelet, 1989). The uptake by 1 ha of Corchorus capsularis producing 2 t dry retted fibre is about 63 kg N, 14 kg P and 132 kg K (Dempsey, 1975). An example of a fibre plant with a high nutrient uptake is Congo jute: for a typical production of about 2.2 t dry retted fibre per ha, the nutrient uptake is 190 kg N, 24 kg P and 175 kg K per ha (Dempsey, 1975). The nutrient removal may be less than the nutrient uptake, because plant parts containing absorbed nutrients, such as leaves, are sometimes returned to the field. In flax, kenaf and roselle, for instance, stems are left to defoliate in the field after harvesting. In cotton, however, the destruction of harvested plants is prescribed to control pests and soil-borne diseases. Crop rotation and the use of organic fertilizers may also be applied to maintain soil fertility.
Diseases and pests of fibre crops in South-East Asia include fungi, bacteria, viruses, nematodes, insects and parasitic plants. Important fungal diseases of fibre plants include seedling and stem rot (Macrophomina phaseolina) on jute and kenaf, white fungus disease (Rosellinia necatrix) on ramie, collar rot (Phytophthora nicotianae var. parasitica) on kenaf and roselle, Fusarium wilt on cotton, abaca, kenaf and roselle, and Verticillium wilt on cotton. An important bacterial disease is bacterial blight (Xanthomonas campestris pv. malvacearum) on cotton. Important virus diseases are bunchy top and abaca mosaic on abaca. Nematode problems are often caused by root-knot nematodes (Meloidogyne spp.), for example on cotton and kenaf. Important pests include various bollworms on cotton, the jassid leaf hopper (Amrasca biguttula) on roselle, and the Mexican sisal weevil (Scyphophorus interstitialis) on sisal. Parasitic plants include Loranthaceae, which damage kapok, and Orobanche ramosa L. on hemp (Wulijarni-Soetjipto et al., 1999). For many lesser-known species there is little or no information available on diseases and pests.
Control of diseases and pests includes cultural, chemical and biological methods. Cultural methods include field sanitation by destroying crop residues, eradication of affected plants or plant parts, destruction of weeds that serve as alternate or collateral hosts, the use of resistant genotypes and clean planting material, crop rotation, harvesting in the dry season, application of appropriate tillage practices and manual removal of pests. Cultural methods may be sufficient in small-scale agriculture, but they are often uneconomic in large-scale industrial plantations. Here, diseases and pests are usually controlled by chemicals, but care should be taken to reduce toxic side-effects. Chemical control is effective only if the timing is correct and often supplementary cultural methods are necessary. Cotton is notoriously sensitive to pests, which has led to excessive spraying of insecticides. Resistance breeding and approaches such as Integrated Pest Management (IPM), comprising a range of techniques including the use of specific cultivars, a short planting period, adequate fertilization, planting of trap crops, weekly pest monitoring, spraying with Bacillus thuringiensis at an early growth stage, the release of natural enemies (e.g. Trichogramma chilonis) and the use of synthetic insecticides when the pest population reaches a critical level, are applied to reduce pesticide use in cotton (Pascua et al., 1997).
Harvesting and processing
The time from planting to first harvest ranges from a few months in annual herbs such as jute and kenaf to several years in perennials such as abaca and sisal.
The time of harvest for annual bast fibre plants such as jute, flax, kenaf and roselle involves a trade-off between fibre yield and quality, and these plants are usually harvested at a specific developmental stage. Jute, for instance, is harvested at mid-flowering; earlier harvesting results in lower yields of fine fibre, whereas later harvesting results in higher yields, but a coarser and lower-quality fibre. Annual bast fibre plants are usually harvested manually, by cutting or pulling. Often bundles of harvested material are left for some days in the field to accelerate defoliation and desiccation.
In perennial fibre crops such as sisal the leaves are also cut manually. Care must be taken to leave sufficient leaf area at each cutting to enable the plant to continue optimal growth. In sisal, for instance, about 20-25 leaves are left on the plant at the first cutting, which is usually decreased to 15-20 leaves at subsequent cuttings.
Post-harvest handling and processing
Various basic procedures are used to separate fibres from the surrounding plant tissues. The main processes are retting, scutching, chemical treatment, decorticating and ginning (Simpson & Conner Ogorzaly, 1995; Wood, 1997). Excessive processing, whether microbial, chemical or mechanical, results in degradation of the cellulose fibrils and a decrease in fibre quality (McDougall et al., 1993).
Retting is the usual extraction procedure for bast fibres. It is a microbiological process in which the combined action of water and microbial (mainly bacterial) enzymes decomposes the pectic material around the fibre bundles so freeing the fibre bundles, which can then be extracted manually (McDougall et al., 1993; Wood, 1997). It normally involves the immersion of bundles of stems in ponds or streams. The time required depends on temperature and varies widely. Where temperature and humidity are high and there is little wind, stems can be dew-retted in the field. In this case, the active organisms are fungi that break down the pectic substances in the bark (Wood, 1997).
The retted stems of flax and hemp are dried, after which they are passed through fluted rollers to break the core into pieces of woody matter called "shiv" that remain attached to the fibre. The material is then passed through a "scutching" machine, which removes the shiv from the fibre by beating and scraping. The fibre is subjected to a special combing operation ("hackling") prior to spinning (Simpson & Conner Ogorzaly, 1995; Wood, 1997).
Fibres extracted by retting are still encrusted with lignins and hemicelluloses, affecting the fibre quality. Fibres to be used for textile production are often subjected to additional chemical treatment to remove these compounds. Ramie, for instance, contains a gummy pectinous material that is not broken down by retting, and separation of the fibre requires a chemical treatment. This is usually done in the spinning mill prior to the spinning operation. The treatment involves soaking the separated bark in weak alkali baths for a given period at a given temperature. The chemical most often used is caustic soda, but other sodium-based alkalis are also used. The specific combination of treatment time, temperature, the alkali type and its concentration, are usually proprietary information (McDougall et al., 1993; Wood, 1997).
Decortication is used primarily for hard leaf fibres such as sisal, cantala and henequen. It involves crushing the plant material and scraping the non-fibrous material from the fibres. In this process, the leaves are trimmed to remove the spines and subsequently passed through decorticating machines that crush them between rollers and scrape them against a bladed drum. During scraping, water is sprayed onto the leaves to help separate the fleshy waste material from the fibre. Wet decorticated fibre is usually washed before being dried. After drying, the fibres are brushed mechanically to remove dust and other matter and to increase the lustre.
Ginning is applied to seed fibres such as those from cotton. It is a process during which seeds are pulled free from the fibres covering them, in the case of cotton followed by extensive further cleaning and combing of the fibres (Simpson & Conner Ogorzaly, 1995). The invention and development of the saw gin in the 1790s largely contributed to a rapid expansion of cotton production (Smith, 1995).
Other mechanical procedures
Bast fibres can also be extracted from green or dried stem material by mechanical means without being retted first. A simple method is to pass dried stems through a sloping rotating cylinder with bars that abrade the material as it passes through the cylinder. The core material is broken down and screened out, whereas the fibre bundles remain intact and pass through the length of the cylinder. Machines of this type have been developed for kenaf in the United States.
Ribboning machines are used for green stem material, in which the bark separates easily from the stem. The stems are fed through the machine, with the bark being recovered. The bark ribbons may subsequently be retted in the usual way (Wood, 1997).
Spinning is the process in which a partly tangled mass of fibres is combed or carded, and separated into a parallelized rope form known as a "sliver". This sliver is drawn out to a certain thickness so that it can be twisted into a yarn. In the course of these operations the fibres are combed with steel pins and made to bend around various fluted rollers moving at fast speeds. If the fibres are not sufficiently strong they will not be able to withstand such treatment and the strength of the final yarn will be unsatisfactory. To soften and lubricate the fibres, they may be sprayed with a lubricant or batching oil before processing (Kirby, 1963). Fibre filaments of good spinning quality have a small diameter, high intrinsic resistance and uniform surface structure (Maiti, 1997). In the ancient form of spinning, employed by cultures in both hemispheres and still in use in some cultures, a spinning stick (also called "spindle") is rotated by one hand to take up the yarn produced by twisting the fibres between the thumb and forefinger of the other hand. The spinning wheel was probably invented in India between 500 and 1000 AD. In early versions the wheel, rotating the spindle by means of a band or belt, was turned by hand. Later additions were foot pedals for turning the wheel and a distaff to hold the unwoven fibre mass, thus freeing both hands for twisting. In response to the rising demand for cotton yarn, the first spinning machines were developed in England in the middle of the 18th Century (Smith, 1995).
Weaving is the process of producing fabric by interlacing one set of yarn with another set at right angles, usually by means of a loom. The yarns running the length of the fabric are termed warp (or warp yarns), whereas the crosswise yarns are called filling or weft (or weft yarns) (Smith, 1995). In the manufacture of rope, lengths of fibre are spun into yarns, which are twisted together into strands. The strands are twisted in the opposite direction to the yarns to form a rope. Most rope consists of 3 strands twisted in a right-hand direction.
The primary aim of pulping is to separate fibres and to produce a fibre surface suitable for bonding in the process of paper making (Moore, 1996). Many pulping processes have been developed to convert raw materials into separated fibres suitable for use in paper making. The pulping methods can be divided into three main processes: chemical, mechanical and semi-chemical. The processes differ in their nature and the pulp yield obtained. The chemical processes separate the cellulose from the lignin, whereas the mechanical processes convert all the constituents present. As a consequence, chemical processes give pulp yields of only 30-50%, whereas mechanical processes give yields of over 80%. The choice of the appropriate pulping process depends on the raw material to be pulped and the grade of paper or board product to be made from it (Moore, 1996).
Chemical pulping processes
Chemical processes involve the use of chemicals to separate the lignin fraction of raw materials. The processes rely on the action of one or more radicals acting on the lignin compounds. Chemical separation causes little or no damage to the fibre length. Recovery of the active chemicals is an important environmental and economic consideration.
Chemical pulping processes are applied to both hardwoods and softwoods. The yield of fibre for paper making from wood is typically 40-50%. Chemical pulps from softwoods have high tear, tensile and burst strengths and are particularly suitable for sacking and wrapping papers. Pulps from hardwood generally have lower strength, but have properties making them more suitable for printing and writing papers. Often hardwood and softwood pulps are blended to make a particular product (Hague, 1997). So-called "woodfree paper" contains at least 90% chemical pulp.
Chemical pulping processes include:
- Sulphite process: one of the earliest chemical processes (Moore, 1996), normally involving the heating of raw material with a solution of NaHSO3 and/or Na2SO3 (McDougall et al., 1993). This process is less applied nowadays, because of the imperfect recovery of the chemicals (Moore, 1996). It is, however, still used for the production of papers with specific properties, such as sanitary and tissue papers which must be soft, absorbent and of moderate strength (McDougall et al., 1993).
- Kraft or sulphate process: the most widely used chemical pulping process, in which the raw material is treated with a solution of NaOH and Na2S, forming the reactive anions S2- and HS- (McDougall et al., 1993). A disadvantage is the occurrence of sulphur-based air emissions. The kraft process is well established for wood-based materials, but too severe for most non-wood materials, where lignin is less strongly bonded to the cellulose.
- Soda process: based on sodium hydroxide and widely used in the processing of non-wood fibres. Chemical recovery is straightforward and the virtual absence of reduced sulphur compounds in the process means that there are few emission problems. Yield improvements have been obtained by using additives such as anthraquinone.
- Organosolv process: an organic solvent or mixture of organic chemicals is used. This makes the recovery possible of all the components of the raw material (cellulose, hemicelluloses, lignin) and the solvent itself. The advantages over other chemical processes are higher pulp yields, easy bleaching, lower costs and less environmental stress. However, only an alcohol-based system has been developed into a commercial operation (Hague, 1997; Moore, 1996).
Mechanical pulping processes
In mechanical pulping processes the whole material or large part of it is converted into pulp by mechanical action. These processes are characterized by high yields. The resulting pulp contains cellulose, hemicelluloses and lignin. Mechanical processes are cheaper than chemical processes, with higher yields and less pollution (Sabharwal et al., 1995). Disadvantages of mechanical processes are the high energy demand and the damage caused to the fibres; they generally cause severe shortening of fibre length (Moore, 1996; Sabharwal et al., 1995). Mechanical pulping is mainly applied for softwoods such as spruce. The pulps are usually used for short-life, low-cost products such as newsprint (Hague, 1997; Hill, 1952).
Mechanical pulping processes include:
- Stone groundwood (SGW) process: the earliest mechanical process, in which raw material is ground by means of a rotating stone. Resulting pulps have a short fibre length. The addition of long-fibre chemical pulp is often necessary to give the required strength to the final paper sheet.
- Pressurized groundwood (PGW) process: developed from the SGW process to produce pulps with better strength properties and using less energy. The process is basically the same except that the pulp is prepared at a steam pressure of 1-2 bar.
- Refiner mechanical pulping (RMP) process: chips of raw material are fed into a rotating disc refiner, which breaks them into single whole fibres. Subsequently some of the whole fibres are fibrillized (converted into fibrils and cell wall fragments), which enhances the bonding characteristics of the pulp. RMP production is usually a multi-stage process involving a primary and a secondary refiner. The energy consumption of RMP can be reduced by pretreatment of the raw material by chemicals before or during refining (chemi-refiner mechanical pulping, CRMP) or fungal treatment before mechanical refining (bio-refiner mechanical pulping, BRMP) (Sabharwal et al., 1995).
- Thermo-mechanical pulping (TMP) process: heat in the form of steam is applied to the raw material prior to fibre separation by means of disc refiners. Heating has a softening effect on the chips and reduces fibre damage during the mechanical action. TMP production is more energy intensive than SGW or RMP, but the pulp has better strength properties. Newsprint, for instance, can be manufactured from 100% TMP (Moore, 1996; Hague, 1997).
A range of mechanical processes have been developed involving chemical pretreatment (mostly with sodium sulphite), either alone or in combination with a temperature pretreatment. Examples are the chemi-mechanical pulping (CMP) process, the chemi-thermo-mechanical pulping (CTMP) process and the thermo-chemi-mechanical pulping (TCMP) process. Of these, CTMP, using a pretreatment with 1-4% sodium sulphite, has become the most widely used. Most chemical pretreatments do not affect pulp yields, but only soften the chips prior to fibre separation. These essentially mechanically based processes are often difficult to distinguish from semi-chemical processes (Moore, 1996). Promising results have been obtained with CTMP and TMP for kenaf bark and comparable results may be obtained with other bast fibre crops (Wood, 1997).
Processes with biological pretreatments (biomechanical pulping) are mainly based on the use of fast-growing lignin-degrading white rot fungi (Phanerochaete chrysosporium and Phlebia tremellosa). The pretreatment involves inoculation of the material followed by an incubation period of up to 4 weeks at 39 °C prior to fibre separation. Reductions in energy use and enhancement of strength properties of the pulp have been achieved (Moore, 1996).
Semi-chemical pulping processes
Semi-chemical pulping processes consist of a chemical and a mechanical pulping stage. Wood chips are initially cooked in a digester, and then defibrated with disc refiners. Pulp yields are typically in the range of 65-85% (Hague, 1997). The principal semi-chemical pulping process is the neutral sulphite semi-chemical process (NSSC), which involves chemical pretreatment followed by refining (Hague, 1997; Moore, 1996). The major differences between this and chemically pretreated mechanical processes are the concentration of the chemicals used and the conditions under which the pretreatment takes place. The chemical treatment typically involves the use of up to 15% sodium sulphite by mass of material, and approximately 4-5% sodium carbonate by mass. The process has been used extensively for the production of pulps for corrugating media, as NSSC pulps have the necessary stiffness characteristics required. Other semi-chemical processes include the sodium bisulphite, cold soda, and neutral sulphite-anthraquinone (NS-AQ) processes (Moore, 1996).
Hardwoods are commonly pulped using the NSSC process, with the pulps particularly suitable for use in packaging grades of paper, e.g. corrugating medium (Hague, 1997).
Bleaching is used to remove or inactivate chromophores, and techniques used in paper making are similar to those used in textile industries. Most methods remove lignin not removed through pulping, though some techniques remove chromophores without degrading the residual lignin. Most bleaching techniques use Cl2, NaOCl or ClO2 as active agent. Chlorinated bleaching methods are efficient, but produce toxic and mutagenic effluents (McDougall et al., 1993; Nezamoleslami et al., 1998). Therefore, non-chlorinated bleaching agents, producing less toxic waste, are very much in demand nowadays. Examples are oxygenated agents such as O2/OH-, H2O2 and O3. However, the alkaline conditions used in oxygen bleaching cause swelling of the fibres, reducing their strength and hemicelluloses content, thereby reducing the ability of the fibres to bond together (McDougall et al., 1993). Another possibility is to replace chlorine-based bleaching of wood and non-wood pulps with biological bleaching using ligninolytic white-rot fungi, such as Phanerochaete chrysosporium and Trametes versicolor (Nezamoleslami et al., 1998).
For electrical insulating papers the fibre must be free from ions, and therefore unbleached pulps, washed with purified water, are used (McDougall et al., 1993).
Once bleached, paper pulp, while still hydrated, may be beaten to give a fluffy, highly absorbent fibre suitable for sanitary products (McDougall et al., 1993).
Particle board is manufactured by hot-pressing pre-formed mattresses consisting of fibrous particles blended with resin and wax. Medium density fibreboard (MDF) is manufactured by defiberizing softened wood chips at elevated temperatures (170 °C) using disc refiners, blending the resulting fibres with resin and wax, followed by drying, mattress forming and hot-pressing. The resin most commonly used to bind particles together in particle board and MDF is urea formaldehyde (UF). Melamine reinforced UFs (MUF) are used where some moisture resistance is needed. For exterior use phenol formaldehyde (PF) or isocyanates (MDI) may be used. They are more expensive than UFs, but lower quantities are needed and formaldehyde release from finished boards is significantly reduced. Small amounts of wax are added to boards to improve their short-term resistance to thickness swelling in damp or wet environments (Hague, 1997).
The production of the artificial fibre rayon requires highly purified cellulose as raw material. Originally cotton was used, because of its high cellulose content, but it has almost entirely been replaced by wood fibres (McDougall et al., 1993). The cellulose is dissolved by soaking pulp in strong alkali (18% NaOH), after which hemicelluloses and degraded cellulose are removed with the excess alkali. The damp cellulose is shredded, aged in air, and made to react with CS2 to form cellulose xanthate. After dissolution in aqueous NaOH a solution is formed known as "viscose", which is filtered and extruded while spinning into an acid bath. The xanthate groups are hydrolysed and the cellulose structure is re-established. The physical properties of the resulting product are mainly determined by the spinning conditions (McDougall et al., 1993).
Genetic resources and breeding
Progress in crop improvement requires access to adequate resources of genetic variability. The collection, conservation and characterization of germplasm has developed into a highly specialized activity carried out in genebanks established by national and international agricultural research organizations (FAO, 1996). The International Plant Genetic Resources Institute (IPGRI) in Rome (Italy) has a mandate to advance the conservation and use of genetic diversity. It coordinates global genebank activities with emphasis on plant genetic resources in developing countries (IPGRI, 1999). In the case of fibre plants, active collection and conservation of genetic resources is limited to the economically most important crops. Table 12 presents an overview of genebanks with germplasm collections of 9 major fibre crops.
The cotton collection (COT) of the United States Department of Agriculture, Agricultural Research Service (USDA/ARS) at College Station in Texas, United States, is the world largest repository for cotton germplasm. This genebank holds seed samples of some 9000 accessions, including about 4600 of Gossypium hirsutum L., 2500 of G. arboreum L., 1200 of G. barbadense L., 200 of G. herbaceum L. and various numbers of accessions of a further 37 Gossypium spp. Another very important cotton genebank is that of CIRAD (Centre de Coopération Internationale en Recherche Agronomique pour le Développement) in Montpellier, France, with seed of 3600 accessions of the 4 main species and 31 other Gossypium spp. This latter collection is regularly evaluated and rejuvenated in grow-outs at a seed multiplication centre in Costa Rica (Hau, 1999). Smaller working collections of cotton germplasm are maintained by national agricultural research systems in China, India and several other cotton-producing countries. Molecular fingerprinting has contributed considerably to a better understanding of the genetic and genomic relationships between cotton varieties and species (Abdalla et al., 2001). Such information will facilitate more efficient utilization of cotton genetic resources in the future.
The Bangladesh Jute Research Institute (BJRI) in Dhaka is the mandated world repository for germplasm of jute and its allied fibre crops kenaf and roselle. This genebank stores and maintains about 6000 accessions, including some 4000 for jute alone (Corchorus capsularis, C. olitorius L. and other Corchorus spp.). A duplicate set of seed samples for these accessions is stored in the genebank of the Commonwealth Scientific and Industrial Research Organization (CSIRO) in Canberra, Australia.
Genetic resources for Linum usitatissimum (flax and linseed) totalling more than 3000 accessions, representing mostly landraces and cultivars, are conserved in genebanks of many countries including France (Institut National de la Recherche Agronomique (INRA), Versailles), the Netherlands (Centre for Genetic Resources (CGN), Wageningen), Germany (Bundesforschungsanstalt für Landwirtschaft (FAL), Braunschweig; Genebank, Institute for Plant Genetics and Crop Plant Research (IPK), Gatersleben), the Russian Federation (N.I. Vavilov Research Institute of Plant Industry, St Petersburg), United States (United States Department of Agriculture (USDA), Beltsville), Canada (Plant Gene Resources of Canada (PGRC), Saskatoon), India (National Bureau of Plant Genetic Resources (NBPGR), Akola Regional Station), China (Institute of Crop Germplasm Resources, Chinese Academy of Agricultural Sciences (CAAS), Beijing), Australia, eastern European countries and Argentina (Fu et al., 2002; IPGRI, no date; Marshall, 1989). Molecular fingerprinting is also applied here to establish genetic diversity in flax and linseed germplasm (Fu et al., 2002).
Germplasm collections are maintained by national agricultural research systems in the main producing countries for each of the remaining 4 fibre crops. Brazil (Instituto Agronômico de Campinas (IAC), Campinas, São Paulo) has collections of ramie and sisal, the Philippines (Institute of Plant Breeding (IBP), College, Laguna; National Abaca Research Centre (NARC), Baybay, Leyte) of ramie and abaca, China (Institute of Bast Fiber Crops of the Chinese Academy of Agricultural Sciences (IBF-CAAS), Yuanjiang) of ramie, Tanzania (Mlingano Agricultural Research Station) of sisal and Indonesia (Indonesian Tobacco and Fibre Crops Research Institute (ITOFCRI), Malang) of kapok.
The general objective of plant breeding is the development of cultivars with the potential to provide maximum economic benefits to the growers. This usually requires the simultaneous selection for plant type and vigour, ecological adaptation, yield, quality and other characters. Host resistance to diseases and pests may assume the highest priority in breeding, when these have become a threat to the profitability or even survival of the crop (Simmonds, 1979). The breeding plans applied to a particular crop species are very much determined by its life cycle (annual or perennial), mating system (self- or cross-pollinating) and methods of multiplication. These determinants are presented in Table 13 for major fibre crops with active breeding programmes and cultivar development.
The three most important fibre crops (cotton, jute and its allied fibres kenaf and roselle, flax) are predominantly self-pollinating annual species which are multiplied by seed. The breeding methods commonly applied include line and pedigree selection - starting from landraces, older cultivars, or segregating progenies after crossing and backcrossing - all leading to uniform, homozygous cultivars. These are true to type and can be multiplied in seed blocks with simple precautions such as guard-rows and minimum distances (specific for each crop) to avoid illegitimate outcrossing. F1 hybrid cultivars with considerable hybrid vigour for yield have been successfully developed during the past two decades for cotton. However, the available systems of cytoplasmic male sterility have been inadequate for large-scale production of hybrid seed, mainly due to incomplete expression of fertility restorer genes in the male parents. Current use of cotton hybrids is limited to South Asia and China, where seed production by manual emasculation and pollination is economically feasible due to low labour costs (Hau et al., 1997).
The perennial fibre crops sisal, ramie and abaca are cross-pollinating species. The cultivars are clones developed from single plants selected within open-pollinated seedling progenies of existing varieties, or populations following intra- and interspecific hybridization.
Breeding objectives for the most important fibre crops include, in addition to the general aim of higher yields:
- Cotton: photoperiod-insensitivity, early crop maturity, adaptation to mechanical harvesting (in industrialized countries), high quality lint fibre (length, fineness and strength), seed quality (oil content and low gossypol content by glandless plants), resistance to diseases (e.g. bacterial blight and Fusarium wilt) and pests (e.g. bollworms, jassids), and drought tolerance (Hau et al., 1997; Poehlman, 1987).
- Jute: early crop maturity and low photoperiod-sensitivity, finer and whiter fibre quality, resistance to diseases (Macrophomina phaseolina) and improved seed production (Dempsey, 1975).
- Flax: resistance to lodging, fibre quality (fineness, strength and homogeneity), disease resistance (anthracnose, Fusarium wilt, rust), oil content and fatty acid composition of the seed (Dempsey, 1975).
Plant biotechnology is providing powerful new tools for plant breeding with the potential to increase selection efficiency and creating new approaches to hitherto unattainable objectives. Molecular marker technology is applied in many crops for germplasm characterization and management, accelerating gene introgression from related species and for marker-assisted selection (MAS). MAS enables early selection of important major genes (e.g. disease resistance) with molecular markers closely linked to the genes controlling the trait. In the case of polygenic traits (e.g. components of yield and quality) a more complex quantitative trait loci (QTL) analysis is required for the identification of significantly linked markers. A prerequisite to such a QTL analysis is the availability of a saturated genetic linkage map (Mohan et al., 1997). Genetic modification (GM) is still limited to characters controlled by major genes for which gene isolation and transfer is relatively easy. It also requires the possibility of routine application of transformation technologies and regeneration of plants from in vitro explants or embryogenesis. Tolerance to herbicides (e.g. glyphosate or glufosinate) and insect resistance based on Bt genes (derived from Bacillus thuringiensis) are the main characters that have been successfully expressed and commercialized so far. Genetically modified soya bean, maize, cotton and rapeseed/canola crops were grown in 2001 on 52.6 million ha worldwide, with 96% of the area in North America and Argentina (James, 2001).
All the above-mentioned options of molecular breeding are being applied to cotton with considerable success (Hau, 1999; Kohel et al., 2001). Bt-cotton (GM cotton cultivars with resistance to bollworms based on Bt genes, partly in combination with herbicide tolerance) is already grown on 4.3 million ha, including 1.5 million ha in China alone. Bt-cotton was first released in Indonesia in 2001 and India is likely to follow soon (James, 2001). Cotton alone accounts for 25% of the world use of insecticides and Bt-cotton has proven to be a most effective way of reducing pesticide use, particularly because host resistance to bollworms and other important insect pests have not been detected so far in cotton germplasm. Risks of early breakdown of host resistance due to the occurrence of new biotypes of the pest appear lower than assumed initially (Tabashnik et al., 2000). Work is in progress to develop wide-spectrum insect resistance based on a combination of several Bt and proteinase-inhibitor genes (Hau, 1999). Flax is another fibre crop with numerous biotechnology applications in breeding (Friedt et al., 1989). These have already led to the release of GM cultivars with resistance to herbicides in Canada (Trouvé, 1996).
Research and development
The principal organizations and institutes conducting research and development on fibre plants in South-East Asia are the following:
- Indonesian Tobacco and Fibre Crops Research Institute, Malang: various aspects (agronomy, breeding, ecophysiology, plant protection), mainly of cotton, but also of jute, kapok, kenaf, ramie and roselle.
- Institute for Research and Development of Cellulose Industries, Bandung
- Forest Research Institute Malaysia (FRIM), Kepong: utilization of kenaf for pulp and paper and composite products.
- Malaysian Agricultural Research & Development Institute (MARDI), Serdang: utilization of kenaf for animal feed.
- Malaysian Institute for Nuclear Technology (MINT), Kajang: utilization of kenaf for pulp and paper and composite products.
- University Putra Malaysia (UPM), Serdang: utilization of kenaf for composite products.
- Cotton Development Authority (CODA), Pasig City: cotton (all aspects).
- Fibre Industry Development Authority (FIDA), Department of Agriculture (DA), Quezon City: all aspects: propagation, production, utilization, etc.
- Forest Products Research and Development Institute (FPRDI), Department of Science and Technology (DOST), College, Laguna: research and development on fibre crops for pulp and paper, composite boards, furniture and handicrafts.
- Institute of Plant Breeding (IPB), University of the Philippines Los Baños (UPLB), College of Agriculture (CA), College, Laguna: propagation and breeding.
- National Abaca Research Centre (NARC), Leyte State University, Baybay: all aspects of abaca, e.g. collection and characterization of abaca germplasm, production and processing.
- Philippine Council for Agriculture, Forestry and Natural Resources Research and Development (PCARRD), Department of Science and Technology (DOST), Los Baños, Laguna: evaluation, monitoring and funding of research and development projects on fibre crops.
- Philippine Industrial Crops Research Institute (PICRI), University of Southern Mindanao (USM), Kabacan, North Cotabato: propagation and breeding.
- Philippine Textile Research Institute (PTRI), Department of Science and Technology (DOST) Complex, Bicutan, Taguig, Metro Manila: production and processing of fibre crops for textiles.
- Department of Agriculture: research and development on cotton, jute and jute like fibre, kenaf; technology transfer to extensionists, farmers and companies.
- Department of Agricultural Extension: development and transfer of the fibre plant production practices to farmers.
- Department of Industrial Promotion: technology transfer with respect to the production of handicrafts and cloth from fibre plants such as jute, cotton and paper mulberry; promotion of the production of handicrafts from fibre plants.
Supply and demand
In South-East Asia, as in the rest of the world, many plants are available that produce fibres suitable for various end uses. However, apart from woody species for paper making, only a few of them, such as cotton, abaca, jute, kenaf, roselle, sisal and Wikstroemia spp. have reached the international market and persisted there. After the Second World War, demand for plant fibres was high, but since then the demand for natural fibres (except cotton) has gradually decreased due to the development of synthetic fibres which are often cheaper to produce, more durable and easily converted into attractive designs and colours. More recently, however, growing concerns about environmental issues and hazards to the environment brought about by synthetics has led to renewed interest in plant fibres. Markets where plant fibres such as jute, kenaf, roselle and sisal may gain terrain over synthetic fibres include those for insulation, packaging, geotextiles, composites, filters, sorbents and active surfaces (Bolton, 1995). Because of its excellent fibre characteristics, cotton will undoubtedly remain an important commodity in the world market, and an increased share of South-East Asia in world cotton production seems attainable.
The largest potential market for non-wood plant fibres is that of paper and paperboard; even a small percentage deficit in supply of wood fibre would create huge opportunities for non-wood plant fibres (Bolton, 1995). World paper consumption rose steadily from 40 million t in 1950 to 226 million t in 1988, an average increase of 4.7% per year. The 1994 world consumption of paper and paperboard was 268 million t. The increase in paper production has led to a decline in forest resources in some countries, and there is now a greater emphasis on the recycling of paper and the planting of plantations for future pulp production. Both recycling and plantation forestry can be expected to lead to increases in the cost of pulp, which in turn is expected to increase the competitiveness of non-wood fibre plants as a source of pulp and paper (Wood, 1997).
Some advantages of non-wood fibres over wood fibres are (Moore, 1996):
- They can be derived from annual crops, which can be grown as part of existing farming systems; the total area planted is easily adapted to changes in world demand.
- Low lignin content.
- Reduced chemical usage and effluent.
- Decreased use of forest resources and, where fibres are extracted from agricultural wastes, less emissions of carbon monoxide and carbon dioxide arising from the burning of these waste products).
Disadvantages of non-wood fibres compared to wood fibres include (Moore, 1996):
- Supply problems. Large stocks and adequate storage at constant quality by drying or ensilage may be necessary to service large-scale operations. Alternatively, where non-wood pulp mills are based on agricultural residues or annual crops that are grown in scattered locations, they must be kept small to minimize transport costs, which means they cannot benefit fully from the economies of scale enjoyed by wood-based mills.
- Difficult chemical recovery. Non-wood fibrous materials usually have higher ash and silica contents. Most of the silica dissolves during cooking and remains as an undesirable component in the spent pulping liquor. There are no commercial installations with operating recovery systems for use with non-wood fibrous materials. The size of operation also has an impact on the chemical recovery problem. If the technical problems of chemical recovery in non-wood pulping are solved along the lines of today's pulping process technology, the size and cost of chemical recovery, effluent treatment and other control measures will increase, which will reduce much of the financial advantage non-wood fibre pulping has had in some regions.
- Some annual plants have a low fibre content. Miscanthus spp. have only a 30% fibre fraction and flax a 20% usable bast fibre. In grasses, nodes are often unwanted and need to be separated out.
Potential paper-making species for South-East Asia include jute, kenaf, roselle, paper mulberry, Arundo donax, Helicteres isora, and Miscanthus spp. Abaca and Wikstroemia spp. have potential in the market for specialty papers.
Many of the species treated in this volume are important only at a very restricted or local level. Some remain as secondary species for substitution and are only utilized when the major ones are in short supply. Reasons for the comparatively low demand for these secondary species compared with that of the major ones include the following:
- Lower yields, partly because of the lack of research and development work on lesser-known species.
- Lower product quality and more difficult processing techniques needed for them, thereby increasing production costs.
- Environmental and ecological factors restricting massive production: some species are suited only for a specific region with specific environmental conditions.
- The weedy behaviour of many species such as Cyperus, Malachra and Miscanthus spp. discouraging cultivation.
- Unwanted morphological characters of species, such as the irritating hairs of Abroma augusta and the spines of Corypha utan, rendering them less attractive for mass production.
A decisive factor in the potential success of a fibre is the cost of production, because the cost is as important a factor as quality for many uses; any fibre of reasonable quality that can be produced more cheaply than others will find a market (Schery, 1972).
Priorities in research and development efforts to expand the fibre industry in South-East Asia may include the following:
- Development of germplasm collections for lesser-known species (cultivated or wild-harvested) with high potential. Germplasm collections will help conserve and preserve species that may be found suitable for production in the future, especially those with a limited distribution.
- Breeding programmes for lesser-known fibre plants, focusing on fibre yield and quality (homogeneity, degree of lignification, strength, fineness and water uptake characteristics), improved ecological adaptation and resistance to diseases and pests. For industrial fibres, e.g. for paper making, productivity is an important factor. In cases where conventional breeding methods are difficult to use, breeding programmes should be complemented with research and development on a range of biotechnological techniques.
- Establishment of industrial plantations for economic exploitation of potential species, e.g. Wikstroemia spp., to ensure a continuous supply of raw materials for various end-uses.
- Development of improved cropping practices and processing methods.
- Development of mechanical harvesting methods, preferably combined with fibre extraction.
- Product improvement, product diversification and waste utilization. In many cases, not only fibres but also other products can be obtained from the same crop, thus enhancing crop value, as multiple-use crops will give a higher return. Waste-material and by-products may also be useful, for instance sisal short fibres, poles and boles for pulping, and leaf waste for animal feed.
- Substitution of established products by those from lesser-known species; e.g. Donax canniformis is sometimes substituted for rattans, which are increasingly being over harvested from the wild.
M. Brink, R.P. Escobin & H.A.M. van der Vossen (genetic resources and breeding)
Table 1. Overview of the major fibre plants treated in this volume.
Scientific name Common name Main uses
Abroma augusta devil's cotton cordage
Actinoscirpus grossus giant bulrush weaving
Agave cantala cantala cordage
Agave sisalana sisal cordage
Anodendron candolleanum akar katam cordage
Anodendron oblongifolium kapi cordage, fishing gear
Anodendron paniculatum Andamanese bowstring plant cordage, fishing gear
Artocarpus elasticus wild breadfruit cordage, barkcloth
Arundo donax giant reed weaving
Boehmeria nivea ramie textile, cordage, fishing gear
Broussonetia papyrifera paper mulberry paper, barkcloth
Carludovica palmata Panama hat palm weaving
Ceiba pentandra kapok stuffing
Colona javanica sampora cordage, fishing nets
Colona serratifolia jelunut cordage
Corchorus capsularis white jute sacking, cordage
Corchorus olitorius tossa jute sacking, cordage
Corypha utan gebang palm thatching, weaving
Curculigo capitulata palm grass cordage, fishing nets, cloth, packing
Curculigo latifolia lemba cordage, fishing nets, cloth, packing
Cyperus elatus wlingi weaving
Cyperus malaccensis Chinese mat grass weaving, tying
Cyperus papyrus papyrus weaving
Cyperus procerus rumput adem tying
Donax canniformis bamban weaving
Enhalus acoroides eel grass fishing nets
Eugeissona triste bertam thatching
Fimbristylis umbellaris globular fimbristylis weaving
Furcraea foetida Mauritius hemp cordage
Gossypium arboreum tree cotton textile
Gossypium barbadense sea island cotton textile
Gossypium herbaceum Arabian cotton textile
Gossypium hirsutum upland cotton textile
Heliconia indica lobster-claw platters, packing
Helicteres isora red isora cordage, paper
Hibiscus cannabinus kenaf sacking, cordage, paper
Hibiscus sabdariffa roselle sacking, cordage, paper
Juncus effusus soft rush weaving
Lepironia articulata purun weaving
Linum usitatissimum flax textile, paper
Malachra capitata wild okra cordage
Malachra fasciata wild okra cordage
Miscanthus floridulus floret silvergrass thatching
Miscanthus sinensis eulalia thatching
Musa textilis abaca cordage, paper
Nepenthes ampullaria kantong teko tying
Nepenthes rafflesiana periuk kera tying
Pandanus atrocarpus mengkuang weaving, thatching
Pandanus furcatus bengkuang weaving
Pandanus kaida mengkuang weaving
Pandanus odoratissimus pandan laut weaving, thatching
Pandanus tectorius pandan pudak weaving, thatching
Phormium tenax New Zealand flax weaving, cordage
Phragmites vallatoria reed thatching, weaving, brooms
Raphia farinifera Madagascar raphia palm thatching, tying, weaving
Raphia hookeri wine palm brushes, thatching, tying, weaving
Raphia vinifera bamboo palm brushes, thatching, tying, weaving
Sansevieria roxburghiana Indian bowstring hemp cordage
Sansevieria trifasciata African bowstring hemp cordage
Schoenoplectus lacustris great bulrush weaving
Schoenoplectus litoralis endong weaving
Schoenoplectus mucronatus bog bulrush weaving, tying
Scirpodendron ghaeri rumbai weaving
Tetrapanax papyriferus ricepaper tree ricepaper
Thespesia lampas polompom cordage
Typha domingensis cattail weaving, thatching
Typha orientalis cattail weaving, thatching
Urena lobata Congo jute cordage, textiles
Wikstroemia indica small-leaf salago paper, cordage
Wikstroemia lanceolata lance-leaf salago paper, cordage
Wikstroemia meyeniana large-leaf salago paper, cordage
Wikstroemia ovata round-leaf salago paper, cordage
Table 2. Important fibre plants treated in other PROSEA volumes.
Scientific name Common name Main fibre uses
Ananas comosus pineapple cloth
Borassus flabellifer toddy palm thatching, weaving
Cannabis sativa hemp cordage, nets, paper
Cocos nucifera coir cordage, mats, brushes, thatching, weaving
Crotalaria juncea sunn hemp cordage, nets, paper
Metroxylon sagu sago palm thatching, cordage, weaving
Nypa fruticans nipa palm thatching
Table 3. Annual production and trade of the most important fibre crops (except woods for paper making) in the period 1996-2000 in the world.
Crop Area (×1000 ha) Production (×1000 t) Export (% of production) Export value (×million US$) Main producing countries (in order of importance) Main exporting countries (in order of importance) Main importing countries (in order of importance)
Abaca 132 98 34 32 Philippines Ecuador Philippines Ecuador United Kingdom United States Japan Spain
Coir n.a. 663 20 36 India Sri Lanka Malaysia Bangladesh Thailand Sri Lanka India Philippines China Germany Netherlands United States United Kingdom
Cotton (lint) 33 232 18 684 29 7873 China United States India Pakistan Uzbekistan United States Uzbekistan Australia Argentina Turkmenistan China Indonesia Brazil Turkey Italy
Flax (fibre + tow) 489
25 228 China France Spain Russian Federation Belarus France Belgium Belgium China Italy
Hemp (fibre + tow) 60 65 5 5 China Spain North Korea Romania Russian Federation Netherlands Romania
Jute 1494 2813 14 90 India Bangladesh China Bangladesh India Pakistan China
Jute-like fibres1 371 498 <1 <1 India China Thailand Russian Federation
Kapok n.a. 124 0 0 Indonesia Thailand
Ramie 89 141 2 10 China Brazil Philippines Laos China Japan
Sisal 300 283 25 40 Brazil China Kenya Tanzania Madagascar Brazil Kenya Tanzania Madagascar Portugal Spain 1 Including kenaf, roselle, Congo jute, China jute, other Malvaceae, and sunn hemp. Sources: FAO databases.
Table 4. Estimated annual production (× 1000 t) of major fibre crops in South-East Asia in the period 1996-2000 (no information available for Papua New Guinea).
Crop BUR1 CAM IND LAO MAL PHI THA VIE SE Asia % of world
Cotton (lint) 55.2 0.1 8.9 6.0
1.2 15.2 23.9 110.4 0.6
Jute 36.5 1.0
5.3 14.5 57.3 2.0
Jute-like fibres2 <0.1
0.5 0.2 1 BUR = Burma (Myanmar); CAM = Cambodia; IND = Indonesia; LAO = Laos; MAL = Malaysia; PHI = Philippines; THA = Thailand; VIE = Vietnam 2 Including kenaf, roselle, Congo jute, China jute, other Malvaceae, and sunn hemp. Sources: FAO databases; estimations by various authors.
Table 5. Dimensions of the ultimate fibres of selected fibre plants.
Fibre Length (mm) Width (μm) Length: width ratio
Abaca (2-)4-8(-12) (6-)13-29(-53) 250-350
Cotton 10-40(-64) (12-)18-28(-38) 1000-4000
Flax (1-)10-40(-85) (5-)10-30(-38) 1000-2000
Hemp (5-)20-25(-55) (10-)20-25(-60) 250-1000
Jute (0.5-)2-2.5(-6.5) (9-)15-20(-33) 40-400
Kapok (8-)19-22(-35) (10-)19-20(-30) 1000
Kenaf (1.5-)2-3(-12) (7-)15-25(-41) 40-130
Ramie (10-)40-250(-600) (10-)25-60(-100) 1000-3000
Roselle (1.2-)1.9-3.1(-6.3) (10-)12-25(-44) 40-130
Sisal (0.3-)1.5-4(-15) (8-)15-30(-50) 100-150
Sugar-cane bagasse (0.8-)1.2(-2.8) (10-)12(-34) 50-100
Sunn hemp (3.7-)7-8(-12) (19-)25-30(-50) 130-300
Wheat straw 1-3 8-40 30-100
Eucalyptus 1-2 18-30 30-80
Spruce 3-4 20-50 70-160 Various sources.
Table 6. Chemical properties of selected plant fibres.
Fibre α-Cellulose (%) Hemicelluloses (%) Lignin (%) Pectin (%)
Abaca 55-64 18-23 5-18 1
Bamboo 36-43 15-16 21-31
Cotton 88-96 3-6 1-2
Flax (unretted) 57 15 2 4
Flax (retted) 64 17
Hemp 62-67 8-16 3-4 0.8
Jute 45-64 12-26 11-26 0.2
Kapok 43 32 13-15
Kenaf 44-62 14-20 6-19 4-5
Ramie 69-91 5-13 1 2
Sisal 54-66 12-17 7-14 1
Sugar-cane bagasse 32-48 22-32 19-24
Wheat straw 29-54 26-30 16-21
Eucalyptus 49 15 28
Pine 42 24 27
Poplar 48 23 19
Table 7. Ranking of selected bast and leaf fibres according to various physical properties.
1 2 3 4
Tensile strength ramie hemp flax jute
Durability ramie flax hemp jute
Cohesiveness flax hemp jute ramie
Pliability flax ramie jute hemp
Colour ramie flax hemp jute
Tensile strength of fibre strands abaca sisal New Zealand flax Mauritius hemp
Durability abaca sisal New Zealand flax Mauritius hemp
Pliability Mauritius hemp New Zealand flax abaca sisal Source: Weindling, 1947.
Table 8. Physical properties of selected plant fibres.
Fibre Tensile strength
Elongation at break
Coir 175 30.0 4.0-6.0
Cotton 285-595 7.0-8.0 5.5-12.6
Flax 345-1035 2.7-3.2 27.6
Hemp 690 1.6 n.a.
Jute 395-775 1.5-1.8 26.5
Ramie 400-940 3.6-3.8 61.4-128.0
Sisal 510-635 2.0-2.5 9.4-22.0 Source: Eichhorn et al., 2001.
Table 9. Taxonomic and morphological data on the major fibre plants treated in this volume.
Family Scientific name Type of plant Main plant parts used
Agavaceae Agave cantala perennial herb leaf fibre
Agave sisalana perennial herb leaf fibre
Furcraea foetida perennial herb leaf fibre
Apocynaceae Anodendron candolleanum liana bast fibre
Anodendron oblongifolium liana bast fibre
Anodendron paniculatum liana bast fibre
Araliaceae Tetrapanax papyriferus shrub-tree pith
Bombacaceae Ceiba pentandra tree fruit fibre
Cyclanthaceae Carludovica palmata perennial herb leaf
Cyperaceae Actinoscirpus grossus perennial herb stem
Cyperus elatus perennial herb stem
Cyperus malaccensis perennial herb stem
Cyperus papyrus perennial herb stem
Cyperus procerus perennial herb stem
Fimbristylis umbellaris perennial herb stem
Lepironia articulata perennial herb stem
Schoenoplectus lacustris perennial herb stem
Schoenoplectus litoralis perennial herb stem
Schoenoplectus mucronatus perennial herb stem
Scirpodendron ghaeri perennial herb leaf
Dracaenaceae Sansevieria roxburghiana perennial herb leaf fibre
Sansevieria trifasciata perennial herb leaf fibre
Gramineae Arundo donax perennial grass stem
Miscanthus floridulus perennial grass stem
Miscanthus sinensis perennial grass stem
Phragmites vallatoria perennial grass stem
Hemerocallidaceae Phormium tenax perennial herb leaf, leaf fibre
Hydrocharitaceae Enhalus acoroides perennial herb leaf fibre
Hypoxidaceae Curculigo capitulata perennial herb leaf fibre, leaf
Curculigo latifolia perennial herb leaf fibre, leaf
Juncaceae Juncus effusus perennial herb stem
Linaceae Linum usitatissimum annual herb bast fibre
Malvaceae Gossypium arboreum annual or perennial shrub seed fibre
Gossypium barbadense annual or perennial (under)shrub or tree seed fibre
Gossypium herbaceum annual or perennial (sub)shrub seed fibre
Gossypium hirsutum annual herb or perennial shrub seed fibre
Hibiscus cannabinus annual herb bast fibre
Hibiscus sabdariffa annual herb bast fibre
Malachra capitata annual or perennial herb bast fibre
Malachra fasciata annual herb bast fibre
Thespesia lampas shrub-tree bast fibre
Urena lobata annual or perennial shrub bast fibre
Marantaceae Donax canniformis perennial herb (peel from) stem
Moraceae Artocarpus elasticus tree bast
Broussonetia papyrifera tree bast
Musaceae Heliconia indica perennial herb leaf
Musa textilis perennial herb fibre from leaf-sheath
Nepenthaceae Nepenthes ampullaria climber stem
Nepenthes rafflesiana climber stem
Palmae Corypha utan palm leaf
Eugeissona triste palm leaf
Raphia farinifera palm leaf, leaf fibre
Raphia hookeri palm leaf, leaf fibre
Raphia vinifera palm leaf, leaf fibre
Pandanaceae Pandanus atrocarpus tree leaf
Pandanus furcatus tree leaf
Pandanus kaida tree leaf
Pandanus odoratissimus tree leaf
Pandanus tectorius tree leaf
Sterculiaceae Abroma augusta shrub-tree bast fibre
Helicteres isora shrub-tree bast fibre
Thymelaeaceae Wikstroemia indica shrub bast fibre
Wikstroemia lanceolata shrub bast fibre
Wikstroemia meyeniana shrub bast fibre
Wikstroemia ovata shrub bast fibre
Tiliaceae Colona javanica tree bast
Colona serratifolia tree bast
Corchorus capsularis annual herb bast fibre
Corchorus olitorius annual herb bast fibre
Typhaceae Typha domingensis perennial herb stem, leaf
Typha orientalis perennial herb stem, leaf
Urticaceae Boehmeria nivea perennial herb or shrub bast fibre
Table 10. Propagation methods of the major fibre plants treated in this volume.
Abroma augusta seed, stem cuttings, suckers
Actinoscirpus grossus seed, stolons
Agave cantala suckers, bulbils, in vitro culture
Agave sisalana suckers, bulbils, in vitro culture
Anodendron spp. unknown
Artocarpus elasticus seed
Arundo donax division, suckers
Boehmeria nivea rhizome cuttings, seed, division, air layering, stem cuttings, in vitro culture
Broussonetia papyrifera seed, wood or root cuttings, suckers, layering, grafting, in vitro culture
Carludovica palmata seed, suckers, rhizomes
Ceiba pentandra seed, wood cuttings
Colona spp. unknown
Corchorus spp. seed, stem cuttings, in vitro culture
Corypha utan seed, in vitro culture
Curculigo spp. division, suckers, seed, in vitro culture
Cyperus spp. seed, division, cuttings
Donax canniformis unknown
Enhalus acoroides seed
Eugeissona triste seed
Fimbristylis umbellaris division, seed
Furcraea foetida bulbils
Gossypium spp. seed, in vitro culture
Heliconia indica division, seed
Helicteres isora seed, stem cuttings
Hibiscus cannabinus seed, stem cuttings
Hibiscus sabdariffa seed, stem cuttings
Juncus effusus division, rhizomes, seed, in vitro culture
Lepironia articulata division
Linum usitatissimum seed
Malachra spp. seed, cuttings
Miscanthus spp. division, rhizome cuttings, seed, in vitro culture
Musa textilis suckers, corms, seed, in vitro culture
Nepenthes spp. layering, cuttings, seed
Pandanus spp. sucker shoots, stem cuttings, seed
Phormium tenax division, seed
Phragmites vallatoria division, seed, in vitro culture
Raphia spp. seed, in vitro culture
Sansevieria spp. division, suckers, leaf cuttings, seed, in vitro culture
Schoenoplectus spp. seed, division
Scirpodendron ghaeri offsets
Tetrapanax papyriferus seed, suckers
Thespesia lampas seed, cuttings
Typha spp. division, seed
Urena lobata seed
Wikstroemia spp. seed, stem cuttings, in vitro culture Various sources.
Table 11. Common plant spacings and densities for selected fibre crops.
Crop Spacing (cm) Density (pockets/ha)
Cotton 50-120 × 20-60 14 000-100 000
Flax 6-15 (between rows) 18 000 000-33 000 000
Jute broadcast 30 × 7-8 330 000-440 000 420 000-440 000
Kenaf broadcast 20-30 × 5-10 400 000 330 000-1 000 000
Roselle 20-40 × 15-30 80 000-330 000
Abaca 200-300 × 200-300 1100-2500
Ramie 25-140 × 5-60 12 000-800 000
Sisal 200-250 × 80-100 (single rows) 270-400 × 75-100 (double rows; 90-100 cm between rows of each pair) 2500-5000 4000-7200 Various sources.
Table 12. Germplasm collections of selected fibre crops.
Crop Principal germplasm repository and/or coordinator1 Other important collections
Abaca NARC, Philippines Philippines (IPB)
Cotton USDA/ARS, United States CIRAD, France United States, China, India, Greece
Flax INRA, France CGN, Netherlands FAL, Germany VIR, Russia United States, Canada, India, China, Australia, Argentina
Jute and allied fibres BJRI, Bangladesh CSIRO, Australia India, Thailand, Indonesia
Kapok ITOFCRI, Indonesia
Ramie IBF CAAS, China Brazil, Philippines
Sisal IAC, Brazil Tanzania 1 IPGRI is the overall coordinator for most crops. Various sources.
Table 13. Life cycle, mating system and multiplication of selected fibre crops.
Crop Predominant mating system Multiplication
Cotton self-pollinating (70-95%) seed (lines, F1 hybrids)
Flax self-pollinating (97-100%) seed (lines)
C. capsularis C. olitorius
self-pollinating (95-100%) self-pollinating (88-100%)
seed (lines) seed (lines)
Kenaf self-pollinating (88-99%) seed (lines)
Roselle self-pollinating (99-100%) seed (lines)
Abaca cross-pollinating clones (suckers, corms), seed
Ramie cross-pollinating clones (rhizome cuttings)
Sisal cross-pollinating clones (suckers, bulbils) Various sources.