Vetiveria zizanioides (PROSEA)
Vetiveria zizanioides (L.) Nash
- Protologue: in: Small, Fl. south-eastern U.S.: 67 (1903).
- Family: Gramineae
- Chromosome number: 2n= 20 (diploid); 40 (tetraploid)
- Phalaris zizanioides L. (1771),
- Andropogon muricatus Retzius (1783),
- A. zizanioides (L.) Urban (1903).
- Vetiver (grass), khus, khus-khus (En).
- Vétyver, chiendent odorant (Fr)
- Indonesia: akar wangi (general), larasetu (Javanese), usar (Sundanese)
- Malaysia: nara wastu, akar wangi, kusu-kusu
- Philippines: moras (Tagalog), amora (Cebu), anis de moro (Ilokano)
- Thailand: faek, ya-faekhom, ya-faeklum
- Vietnam: cò hương bài, hương bài.
Origin and geographic distribution
V. zizanioides grows naturally in swamp areas of northern India, Bangladesh, Burma (Myanmar) and occurs probably naturalized in many parts of South-East Asia. It has been in cultivation in India for centuries and is now found throughout the tropics and in many subtropical areas. It is grown for its oil mainly in Haiti, West Java, India, Réunion, China and Brazil. To a very limited extent it is grown commercially as far north as Texas. The use of vetiver in erosion control spread first from India to the Caribbean and Fiji and later to many tropical areas, including all countries of South-East Asia.
From the rhizome and roots of vetiver an essential oil, vetiver oil, is steam-distilled, which is used in perfumes, deodorants, soaps and other toilet articles. Its scent is heavy and woody. In perfumery, the essential oil and vetiveryl acetate, synthesized by acetylation of vetiver oil, are important fixatives for more volatile fragrance materials. The chemical stability of vetiver oil under alkaline conditions makes it a suitable scent compound for soaps. In certain canned foods e.g. asparagus and peas, fractions of vetiver oil are used to reinforce the natural odour and taste. The roots are used for making mats, fans or "pamaypay" in the Philippines and cooling screens named "tatties" in India. These give a pleasant smell to a room, especially when dampened. Dried roots or sachets of powdered roots are stored between clothes to give them a pleasant smell and to repel insects. Vetiver oil and roots have insecticidal and insect-repellant properties about which little is known. The oil is used medicinally as a carminative, diaphoretic, diuretic, emmenagogue, refrigerant, stomachic, tonic, antispasmodic and sudorific. A stimulant drink is made from fresh rhizomes in India. The plants are used as an anthelmintic in Madya Pradesh (India).
Young leaves of V. zizanioides are eaten by cattle and goats, though older clumps are left alone when other fodder is available. Stems and old leaves are an excellent, long lasting thatch and can be processed into a coarse paper-pulp.
Traditionally, V. zizanioides is planted in southern India in strips as permanent field boundaries and occasionally in contour strips to control erosion, while in Java it is planted to protect sloping drains. Its use as an erosion-control plant spread throughout the tropics, but for a long time remained restricted to small areas. Recent interest started in Fiji, where it was grown in contour strips in sugar-cane plantations on steep slopes. Since the late 1980s, its planting for erosion control has been promoted strongly, not only around fields, but also to protect terraces and road shoulders. Strips of densely packed, stiff and tough grass stems break the speed of run-off water and divide it evenly, reducing the risk of formation of run-off streams and gully erosion. The very dense root system has a strong tendency to grow downwards and effectively anchors strips of plants and soil behind it.
Production and international trade
Indonesia and Haiti export the largest quantities of vetiver oil, about 50-100 t/year each, while China exports about 20 t/year. The largest area of production in Indonesia is in Garut Regency in West Java where it is grown on about 20 000 ha. The best quality, called Bourbon oil, comes from Réunion. Production in Réunion declined from 50 t in 1960 to only 6 t in 1989. World production is estimated at about 250 t of oil per year. The main importing countries are the United States and western Europe (each with 100 t/year), and Japan (10 t/year). No statistics are available for India, which produces and uses considerable quantities.
The price of vetiver oil varies between years and sources. In the 1990s, Bourbon oil was valued at about US$ 135-155/kg, oil from Haiti at US$ 90-100/kg and oil from Indonesia at US$ 54-62/kg; vetiveryl acetate at US$ 160/kg.
Roots of V. zizanioides contain 1-3% vetiver oil, a light to reddish brown, sometimes greenish, viscous liquid. Its aroma has a sweet earthy woody top note; a heavy earthy woody body; and a similar dry-out lasting for several days. The oil is a mixture of over 300 components, mainly bi-cyclic and tri-cyclic sesquiterpene alcohols (about 50%) and ketones. The sesquiterpenesα-vetivone,β-vetivone and khusimol are the main constituents of the oil. They are considered fingerprints of the oil, although they do not possess the typical odour characteristics. The odour of vetiver oil is chiefly due to internal sesquiterpene ethers, such as epoxyeremophiladiene and epoxyspirovetivadiene. Several derivatives of khusimol are also important: zizanal and epi-zizanal and methyl esters. Other characteristic components of vetiver oil are vetivenic acid and vetivenyl vetivenate. In industry, the alcohols are often transformed to acetates, named vetiveryl acetate, which has a less intense, lighter, more floral scent than vetiver oil and is widely used as a fixative. The foreruns of vacuum distillation containing the more volatile components of the oil have an aroma strikingly reminiscent of asparagus.
Vetiver oil from northern India differs markedly from the oil from southern India and other production countries. The oil, called khus-khus, contains a large amount of khushilal, a C14-terpenoid, and has laevo-rotatory light-breaking characteristics, while oil from all other sources is dextro-rotatory. In India this oil fetches a higher price as its odour is preferred.
Vetiver resinoid is occasionally prepared by extracting the comminuted roots with benzene. In composition it is similar to vetiver oil but contains fewer components with a low boiling point and more truly represents the fragrance of the roots. The resinoid is a dark brown or dark amber semi-solid with a faint but extremely persistent odour reminiscent of the best vetiver oil: sweet woody, root-like, with a very rich, almost balsamic undertone. It is used in several perfumes and is unsurpassed as a fragrant fixative. Vetiver absolute has been prepared experimentally from the resinoid by alcohol extraction, but this product is not regularly available.
Vetiver oil is approved by the Food and Drug Administration of the United States under No 172.510 for use in alcoholic beverages only. The Research Institute for Fragrance Materials (RIFM) has published a monograph on the physiological properties of vetiver oil. See also: Composition of essential-oil samples and the Table on standard physical properties.
The nutritive value of the leaves varies with age and origin. Per 100 g dry material they contain: crude protein 5.5-6.7 g, ether extract 1.1-2.1 g, crude fibre 34.0-42.2 g, N-free extract 45-47 g, total ash 5-9 g, Ca 0.3 g, P 0.05-0.6 g. In vitro digestibility is 60%.
Adulterations and substitutes
Vetiver oil has been adulterated by adding cheap sesquiterpenes, such as caryophyllene and its derivatives (epoxide and acetate). A more sophisticated adulteration is carried out by the addition of nagarmotha oil from Cyperus spp.
- Coarse, perennial grass forming large, dense clumps with a stout, compact, aromatic, branched, spongy rhizome and fibrous root system up to a depth of 4 m.
- Culm erect, 1-1.5(-3) m tall, 2-8 mm in diameter, terete, solid, glabrous.
- Leaf sheaths laterally compressed, 10-20 cm long, keeled; ligule a very shallow fimbriate rim, 0.3-1.7 mm long; blade linear, flat or folded, stiff, 30-75(-90) cm × 4-10(-15) mm, glabrous below, puberulent in lower upper side, scabrous along the edges and back of the midrib.
- Inflorescence a well-exserted, terminal panicle, 15-40 cm long, with 6-10 whorls of up to 20 slender, articulating racemes up to 10 cm long; internodes of the racemes and pedicels filiform, slightly thickened apically; internode of spikelet bearing rachis slender, 5-6 mm long, glabrous or with short scattered hairs.
- Spikelets in pairs, 1 sessile and 1 pedicelled, 2-flowered, the pair falling as a unit; sessile spikelet 3.5-5.5 mm long, with well developed pointed, glabrous or pubescent callus, barren lower floret and perfect upper floret; glumes chartaceous, bearing papillose-based spicules or stiff hairs; lower glume lanceolate, folded about the mid-vein, as long as the spikelet, 7-veined; upper glume equal to or slightly shorter than lower glume, 3-veined; lower floret with hyaline, ciliate lemma and without palea; upper floret with lanceolate lemma, 3-4 mm long, 1-3-veined, with a short scabrid awn and palea oblong, 1.5-2.5 mm long, delicately hyaline, 1-veined, spinulose-hairy at the tip; stamens 3 with orange anthers about 2 mm long; pistil with glabrous ovary and 2 plumose, purple stigmas; lodicules 2, free, fleshy; caryopsis rarely formed, oblongoid to fusiform, apex slightly oblique; pedicelled spikelet more slender, 2.5-4.5 mm long; lower glume 3-7-veined, upper glume 3-veined; both florets staminate or with rudimentary stamens, anthers up to 2.5 mm long.
Growth and development
Under favourable field conditions vetiver clump cuttings (splits) start sprouting a week after transplanting, but growth is generally slow during the first 3 months. In one year the root system becomes well developed. Some roots may reach a depth of up to 4 m and about 90% of the roots are found within a radius of 20 cm from the plant. Mycorrhizal associations are formed with several fungi. V. zizanioides is not an aggressive colonizer, as it forms clumps and does not spread beyond the clumps via stolons or rhizomes. When soil builds up behind a plant, its crown rises and stays at the soil surface. Clumps that grow out intertwine with neighbouring plants, forming a dense sod. The centre of the clump rarely becomes empty with age.
Other botanical information
Two forms of V. zizanioides are sometimes recognized. One occurs in northern India, is smaller in size and has a different quality oil. It is rarely cultivated and mostly collected from wild stands. Under suitable, marshy conditions, it flowers regularly and sets fertile seed. The other form is widely cultivated and is probably a domesticated selection from southern India. Its plants are larger, rooting deeper, and yielding more oil. It very rarely flowers and produces virtually no viable seed and has to be propagated vegetatively. Neither form has been formally named and described, most probably because they are not distinguishable in herbarium material. The origin of V. zizanioides in Haiti is not fully understood: it spread naturally through the island and its oil differs somewhat from Javanese and South Indian oil, but is also dextro-rotatory.
"Monto", a sterile cultivar, has been released in Queensland (Australia). A few cultivars have been released in India: "Hybrid-8" and the artificial tetraploid "Sugandha" were developed from northern Indian plants, "Sunshine" and "Nilambore" are popular southern Indian cultivars.
The name Vetiveria zizanioides is sometimes erroneously attributed to Stapf and is often misspelled V. zizanoides . The taxonomy of the genus Vetiveria Bory is not yet well established. Although up to 10 species have been distinguished, it might appear that only one complex species exists in South-East Asia, V. zizanioides , with several varieties and cultivar groups. Most, if not all, so-called Vetiveria species are in fact Chrysopogon species, e.g. Chrysopogon ( Vetiveria ) nemoralis (Balansa) Holttum.
V. zizanioides is a hydrophyte, often dominant in fresh-water swamps, floodplains and on stream banks. It can only survive and spread naturally in swampy areas. It also exhibits, however, xerophytic properties and grows remarkably well under alternating very wet and very dry conditions with annual rainfall ranging from (300-)1000-2000(-3000) mm. Frost is not generally tolerated, but a few selections survive frequent frosts, with extremes as low as -9°C. The average maximum temperature required for good growth is 25-35°C; absolute maxima may be about 45°C. It should not be shaded permanently, although healthy hedges of vetiver can be maintained in sugar-cane plantations, as the plants recover quickly after the harvest of the cane. V. zizanioides is tolerant of very poor and adverse soil conditions. It is grown on heavy clays and on leached, poor sands. Soil reaction may range from very acid (pH 4.0) to very alkaline (pH 9.6). Mature plants are tolerant of saline soil; yield reductions of 50% (comparable to those of cotton and barley) have been found where salinity in the top 50 cm of the soil was 15-24 mS/cm. It can survive fire, rough trampling and grazing. For the production of vetiver oil, light sandy soils are required to facilitate harvesting of the smaller roots, which contain most oil.
Propagation and planting
V. zizanioides is propagated vegetatively by dividing clumps into splits consisting of one or a few shoots of 15-20 cm long with a portion of the roots. When large numbers of plants are needed, mother plants are heavily fertilized to promote tillering. Although it is cheaper to plant splits directly in the field, the use of splits allowed to regenerate roots in mist frames or raised in containers ensures maximum survival and fast establishment. When no containers are used, nurseries should be in light soil so that plants can be pulled up easily. Culms can also be used to produce large numbers of new shoots for propagation. They are cut, placed in a nursery on damp sand and lightly covered, keeping them under mist. Slitting the leaf sheath improves the success rate. After 2 months most nodes have produced roots and start forming leaves. Plant regeneration through somatic embryogenesis of callus in vitro is possible and plantlets from a tissue-cultured clone from Mauritius are available commercially. For oil production, splits are planted in well prepared soil, in rows spaced 50-60 cm apart and at 20-30 cm between plants. They are sometimes planted on ridges or on 2-row beds. Planting is done at the onset of the rainy season. To make contour hedges, a spacing of 20 cm between plants is used.
Two months after field planting of vetiver, the soil is earthed-up into ridges 30 cm wide and 20 cm high. To establish vetiver, early weeding is important. Weeding is done 3-4 times in the first year and a few times in the second. The final weeding is done just before harvesting to avoid roots of weeds in the harvested vetiver roots. V. zizanioides is tolerant of many herbicides, except those based on glyphosate. For good growth the use of manure or chemical fertilizer at a rate of 80 kg N and 30 kg each of P2O5and K2O is recommended. The N fertilizer should be applied in 3 equal doses, at planting, ridging and at about 8 months after planting. Intercropping with short-duration pulses can be done during the early stages of growth. Intercropping in coconut and areca palm plantations having a relatively open canopy is sometimes practised. Irrigation is sometimes economic. For erosion-control hedges it is essential to fill gaps between plants. When required, plants can be removed simply by cutting them off below the rhizome with a shovel, hoe or plough.
Diseases and pests
V. zizanioides has few disease and pest problems. Curvularia trifolii leaf blight may cause damage during the rainy season; it causes the leaves to turn pale-yellow and to eventually dry out. Fusarium spp. are also reported to cause damage. A number of parasitic fungi have been identified in Malaysia, which grow on vetiver without causing much damage. They may, however, become troublesome when susceptible crops are grown with vetiver. These fungi include Curvularia lunata and C. maculans , causing leaf spot in oil palm, and a number of Helminthosporium spp. causing leaf spot or blight in oil palm, coconut palm, maize and sugar cane. Larvae of Chilo moths are the most serious pest of vetiver and crops grown in association with it. The larvae feed on the fibrovascular bundles, resulting in wilting of the affected stems and leaves. They can possibly be controlled by burning. Other reported pests are white grubs ( Eupladia spp.) and rats. Under dry conditions, termites attack dead leaf and stem material, causing the centre of clumps to die. In extreme cases, plants are even killed. Resistance to some root-knot nematodes is effective. In trials in Brazil, vetiver was not affected by Meloidogyne incognita race 1 and Meloidogyne javanica .
Roots and rhizomes of vetiver are harvested 15-18 months after planting when their essential oil content is highest. In Java harvesting is sometimes done already after 12 months, elsewhere it is sometimes postponed until after 24 months, which results in lower yields, but higher quality oil, being heavier and darker coloured. A light irrigation is sometimes given prior to harvesting, to make it easier to digg up the roots manually. The use of a single-disk plough digging to 40 cm depth has been time efficient and effective in trials. On sloping land, harvesting can cause serious erosion.
The average yield of air-dried roots of vetiver varies from 1-2.4 t/ha, commonly yielding 12-17 kg oil. An excellent crop of vetiver in southern India and Réunion may yield 4 t/ha of roots, yielding over 40 kg vetiver oil.
Handling after harvest
The harvested roots of vetiver are cleaned of adhering earth by washing in running water and drying in the field for a few days; they are then separated and allowed to dry in the shade to 10-15% moisture content. Vetiver oil is obtained by steam distillation of fresh or stored roots; storing the roots for about 6 months has been reported to improve oil quality. Chopped roots are soaked in water for 10-20 hours to render them soft before being put into stills. The duration of distillation varies from place to place, depending on the provenance and age of the roots, and the quantity loaded. In southern India, a load of 125 kg is distilled for 72-96 hours. In Java, the process normally takes 12-36 hours, in Réunion 36-48 hours. The first fraction of the oil distilled over is lighter than water, the later fraction heavier. The fractions are collected in separating tanks, eventually combined and filtered warm in steam-jacketed filters or centrifuged to free the oil from water. A small amount of salt may be added to the roots to increase the recovery of the oil fraction heavier than water. A portion of the oil is water-soluble. To recover this fraction, distillation water is collected from the separators and re-used in the distillation still. The quality of the oil improves with storage, because it converts the harsh "green" earthy note of freshly distilled oil to a fuller, heavier and sweeter odour.
Several collections of vetiver germplasm are being maintained. In India, the National Bureau of Plant Genetic Resources maintains an extensive collection of both wild and cultivated material. The Essential Oils Research and Development Program of the Philippines has initiated collection of vetiver from different regions of the country, with the objective of identifying accessions which will produce a high yield and quality of essential oil. In Indonesia, about 150 accessions are being maintained by the Research Institute for Spice and Medicinal Crops with a similar objective. In Thailand, the Department of Land Development has embarked on germplasm collection of vetiver as part of an erosion control programme. Accessions have been obtained locally or introduced from India, Indonesia and Sri Lanka.
Most breeding work on vetiver is done in India by the Central Institute of Medicinal and Aromatic Plants in Lucknow, which has released several cultivars. Heritability estimates were found to be high for oil content and oil yield, but low for root yield. Genetic improvement has been tried through colchicine-induced polyploidy. Tetraploids yielding about 60% more than their parents and 40% more than the best available diploid were selected. The programme resulted in the release of the tetraploid cultivar "Sugandha".
The reputation of vetiver oil in the world market declined in the 1990s due to market distortions brought about by the highly regulated Haitian production and export system, the decline in production of Bourbon oil and the variability in the quality of Indonesian oil. These have prompted perfumers to look for other oils with a woody character. Consequently, world consumption has remained static. Since existing producers are more than capable of supplying any likely increase in demand in the future, prospects for new producers are not bright unless they can reliably produce a high quality oil.
Interest in Vetiveria spp. as erosion-control plants received a boost when the World Bank changed emphasis from bulldozer-built erosion control bunds to vetiver hedges. Experience in southern India and Fiji in large-scale commercial plantations and in subsistence farming show that vetiver can contribute to long-term erosion control, and initial experiences in South-East Asia are promising. Suggestions that vetiver can be used as an erosion-controlling crop under a wide range of conditions and with limited maintenance are exaggerated. Continuous strips without gaps can only be established where rainfall is adequate and when young plants are protected.
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C.C. de Guzman & L.P.A. Oyen