Dalbergia (PROSEA Timbers)
- Protologue: Suppl. pl. : 52 (1782).
- Family: Leguminosae
- Chromosome number: x= 10; D. latifolia, D. sissoo: 2n= 20
Sonokeling: medium-weight to heavy hardwood, D. latifolia Roxb.
Sonosissoo: medium-weight to heavy hardwood, D. sissoo Roxb. ex DC.
- (East) Indian rosewood, Bombay blackwood (En)
- Palissandre de l'Inde, Palissandre Asie (Fr)
- Indonesia: sonobrits, sonosungu (Java).
- Indonesia: sonowaseso (Java)
- Thailand: pradu-khaek (Lampang).
Origin and geographic distribution
Dalbergia includes about 100 species and is found in tropical and subtropical regions of all continents. Most species are found in Asia (70) from northern Pakistan to China, with the centre of diversity in the Himalayas. Most are shrubs or woody climbers. Some 18 species are trees with valuable timber. Only one tree species is indigenous to the Malesian region. Within Asia at least 7 species are valuable timber trees, most of them occurring in Assam and Burma. Both sonokeling and sonosissoo are amongst the most widely distributed species and are widely planted within and outside Asia.
Sonokeling is well known for its application in high-class furniture, cabinets and as a decorative timber used, for example, in passenger ships and for instrument cases. It is suitable for marine and aircraft grade plywood and, owing to its beautiful colour and figure, for decorative veneer. Because of its strength and durability it is suitable for all kinds of constructional work, for doors, window frames and wagon building. It is also used for heavy-duty striking tools such as hammers, felling axes and agricultural implements such as ploughs, harrows, rollers, etc. In cart and carriage building, it is used for felloes, spokes, poles, shafts, rims, etc.
Sonokeling is one of the most popular woods for carving and engraving. It is suitable for turnery and is an excellent timber for high-class bentwood furniture, walking-sticks, umbrella handles and other bentwood articles. It is also used for making musical instruments and sports equipment.
Sonosissoo is used for the same purposes, but it is a less decorative wood because it is lighter coloured than sonokeling and lacks the dark streaks. It is suitable for shoe lasts as a substitute for imported beech or maple wood. The root wood of sonosissoo has been used for tobacco pipes.
Both species are used as a shade tree in agroforestry systems in India (sonokeling is also used for this purpose in Java). Leaves of sonosissoo are used in India as fodder and the wood as firewood. They are both recommended for afforestation of eroded soils in Java.
Production and international trade
Sonokeling and sonosissoo are highly valued timbers for local processing in the furniture industry and for carving. The export of non-processed and semi-processed Dalbergia timber is not important in South-East Asia, and figures on production and trade are scanty. In 1990 a total of 16 750 m3 of Dalbergia timber was harvested in Java, the larger part of which was sonosissoo. The price of sonokeling wood from Java is comparable with that of teak wood.
Sonokeling is a medium-weight to heavy hardwood. The heartwood is dark purplish-brown with very dark brown to black streaks and is clearly demarcated from the 3-5 cm thick whitish to yellowish sapwood. The heartwood of sonosissoo is golden brown to deep brown with darker streaks, which are much less prominent than in sonokeling wood. The density of sonokeling wood is 770-860 kg/m3 at 15% moisture content. The grain is straight, sometimes wavy, texture moderately fine.
A test of sonokeling wood from Java gave the following results for mechanical properties (density at test 790 kg/m3, moisture content 12.5%): modulus of rupture 114 N/mm2, modulus of elasticity 11 270 N/mm2, compression parallel to grain 61 N/mm2, shear 8-9 N/mm2, cleavage 85 N/mm radial and 91 N/mm tangential, Janka side hardness 6970 N and Janka end hardness 8015 N.
The rate of shrinkage from green to oven dry is 2.9% radial and 6.4% tangential. Sonokeling splits easily at the end during drying, especially when green wood is kiln dried too fast. Pre-drying is recommended. The temperature during kiln drying should be 43-71°C and the corresponding relative humidity should decrease from 84% to 38%. Once dry, the wood is exceptionally stable in service.
Sonokeling is rather difficult to work with hand tools but it is quite easy to machine. It can be planed to a smooth surface. Turning, screwing, polishing and gluing give good results, and the wood can be peeled or sliced to make decorative veneer that can be glued satisfactorily to make plywood.
Sonokeling wood is durable; graveyard tests showed an average life in contact with the ground of 7.3 years under tropical conditions. Laboratory tests indicate that the wood is resistant to dry-wood termites and very resistant to wood-rotting fungi. It is difficult to treat with preservatives using the vacuum-pressure method.
Sonokeling wood contains 54% cellulose, 27% lignin, 10% pentosan, 1% ash and 0.6% silica. The solubility is 4.5% in alcohol-benzene, 1.8% in cold water, 5.2% in hot water and 15.9% in a 1% NaOH solution. The energy value is 19 180 kJ/kg.
- Small to large trees, shrubs or woody climbers, trees up to 43 m tall, with a straight or more crooked bole of up to 150(-180) cm in diameter and often only branchless for 3-10(-12) m; buttresses absent to prominent; root a taproot; outer bark whitish or grey.
- Leaves alternate, imparipinnate; leaflets alternate, reticulately veined, without stipels. Inflorescence a terminal or axillary cyme or panicle; bracts and bracteoles usually small and subpersistent.
- Flowers bisexual, papilionoid, small; calyx 5-merous, the teeth prominent with the upper 2 broader than the lower 3; standard glabrous, keel connate at the apex; disk absent; anthers small, globular, non-versatile, dehiscing with small, transverse slits; ovary stipitate, style short, incurved, glabrous, with a small stigma, ovules few or 1.
- Fruit an indehiscent pod, thin-walled, with 1 or rarely few central seeds, not winged.
- Seed reniform, compressed.
- Seedling with hypogeal germination.
- Heartwood deep red-brown, often with purplish streaks, distinctly demarcated from the whitish sapwood.
- Grain straight.
- Texture moderately fine.
- Growth rings usually distinct; in the inner, wider part of the growth ring, vessels more numerous and wider than in the outer, smaller part, in heartwood the latter dark brown, almost black; vessels just visible to the naked eye, in heartwood often filled with dark brown gum.
- Rays and axial parenchyma not distinct without a lens.
- Ripple marks distinct.
- Growth ring boundaries marked by marginal parenchyma bands; within a growth ring, the diameter of libriform fibres slightly decreases while the fibre wall thickness increases somewhat and the vessel frequency decreases towards the latewood.
- Vessels diffuse, where numerous about 10/mm2, solitary or occasionally mutually flattened in multiples, in radial multiples of usually 2(-3) vessels, usually completely surrounded by parenchyma, round to oval, average tangential diameter of solitary vessels 80-175μm, of vessels in multiples 100-155μm; perforations simple; intervessel pits alternate, distinctly vestured, hexagonal, 7μm, sometimes with coalescent apertures; vessel-ray and vessel-parenchyma pits similar but half-bordered.
- Fibres 600-800μm long, non-septate, thick-walled, with simple to minutely bordered pits almost entirely confined to the radial walls; gelatinous layers regularly present.
- Axial parenchyma rather abundant, paratracheal, banded and apotracheal diffuse; paratracheal parenchyma vasicentric to winged-aliform, vasicentric parenchyma one to several cell layers thick; banded parenchyma somewhat undulating, very variable in tangential length, 1-4 cells wide, also marginal, the tangentially longer bands less wide than the tangentially shorter ones, usually enclosing one, sometimes more vessels; apotracheal diffuse parenchyma scarce, usually near paratracheal and banded parenchyma; parenchyma strands not immediately bordering upon vessels, usually 2-celled, parenchyma rarely fusiform, when bordering upon vessels 3-4-celled.
- Rays 8-12/mm, 1-3(-4)-seriate (usually 2-3-seriate), up to 7-8(-17) cells high, mostly homocellular, almost entirely composed of procumbent parenchyma cells, only one row of marginal cells usually shorter in radial direction or sometimes even composed of upright parenchyma cells.
- Crystals prismatic, in chambered axial parenchyma cells, rarely in short procumbent or upright marginal ray cells.
- Deposits dark reddish-brown, rather often present in vessels, libriform fibres and procumbent ray parenchyma cells, sometimes in axial parenchyma.
- Vessel elements, axial parenchyma strands, fusiform parenchyma cells, rays and probably also libriform fibres distinctly storied.
Species studied: D. latifolia.
Growth and development
Seedlings of sonokeling have a strong taproot and are practically devoid of any secondary roots when young. Initial growth of seedlings is slow. Nodules which are the result of symbiotic nitrogen-fixing bacteria are already found on the roots of seedlings. Young trees are also relatively slow growing; reported growth rates differ considerably. In Java an annual height growth of 2 m and an annual volume increment of 15 m3/ha have been recorded for young plantations on favourable sites, but in India 10-year-old stands have an average height of 6 m with a trunk diameter of 4-5 cm. In India the average age of reaching a diameter of 60 cm has been estimated at no less than 240 years! Trees of over 200 years have also been recorded from Java.
Sonokeling seldom flowers in Java; the flowering periods are September - November and February - March. Pods are mature in December and May - June.
Sonosissoo trees grow fast; under exceptional conditions, they may reach 3.7 m in 1 year, 11 m in 5 years, and 15 m in 10 years.
Other botanical information
The genus Dalbergia belongs to the tribe Dalbergieae and is closely related to the mainly neotropical genus Machaerium . The genus is usually subdivided into 5 sections or subgenera. D. latifolia and D. sissoo both belong to the section Sissoa Benth. Some other tree species of the genus Dalbergia are used for timber, e.g. D. bariensis Pierre (in Indo-China and Thailand), D. cambodiana Pierre (Indo-China), D. cochinchinensis Pierre (Indo-China, Thailand), D. cultrata Graham ex Benth. (Burma, Indo-China, Thailand), D. oliveri Gamble (Indo-China, Thailand), D. melanoxylon Guillaumin & Perrottet (Africa), D. nigra Allemão ex Benth. (South America) and D. retusa Hemsl. (Central and South America).
Sonokeling occurs in Java in deciduous forest in periodically very dry localities. Older trees are very drought-resistant. Sonokeling thrives well in areas with up to 6 dry months with mean monthly rainfall of less than 40 mm. It tolerates maximum temperatures of 35-48°C and minimum temperatures of 0-6°C; it is only marginally frost hardy. It grows well on deep, permanently moist but well-drained soils and also attains large dimensions on vertisols. Growth is retarded on nutrient poor, dry and stony soils. In Java sonokeling grows naturally up to 600 m altitude, but it is successfully cultivated as high as 1000 m altitude.
Sonosissoo grows in its natural area of distribution on well-drained, colluvial and alluvial soils of pH 5.0-8.5, in areas with 750-2000 mm annual rainfall. In Java plantations of sonosissoo are successfully established on red-yellow grumusols and regosols in areas with annual rainfall of about 1900 mm and at about 250 m altitude.
Propagation and planting
Usually sonokeling is propagated from root suckers of 1-2.5 cm diameter (the tree is often surrounded by numerous suckers). Root and stem cuttings can also be used. The buds of root suckers and stem cuttings start to sprout about 9 days after planting, and those of root cuttings about 15 days after planting, but after 2 months all young plants are more or less the same height. Seeds have no dormancy, and the germination rate is often low (30-40%). The weight of 1000 seeds of sonokeling is approximately 50 g, that of sonosissooo approximately 30 g.
Sonosissoo is propagated successfully by air layering in India; application of growth regulators (auxins) enhances rooting and callus formation. In Nepal and India successful methods of tissue culture have been developed for both sonokeling and sonosissoo. In vitro mass multiplication of sonokeling is carried out in India from callus of shoot tips and shoot segments of over 50-year-old trees on a Murashige and Skoog medium containing naphthalene acetic acid and benzylaminopurine. For rooting, regenerated shoots from the calli are excised and first treated with a half-strength Murashige and Skoog medium, supplemented with indole-3-acetic acid, indole-3-butyric acid and naphthalene acetic acid for 48-72 hours. Then the plantlets are transferred to a hormone-free half-strength Murashige and Skoog medium. Rooted plantlets are transferred to pots and grown in the greenhouse.
Sonosissoo has been successfully propagated in Nepal by culturing cotyledons excised from seedlings on a Murashige and Skoog medium with the addition of benzylaminopurine (1.0 mg/l), naphthalene acetic acid (0.1 mg/l) and casein hydrolysate (1000 mg/l). Under these conditions 2-5 shoots developed from the nodal region of the cotyledon after 7 days. Multiple shoot formation was obtained by transferring these shoots to a medium supplemented with 0.25 mg/l benzylaminopurine and 1000 mg/l casein hydrolysate. The shoots continued to proliferate at a sustained rate of 10-15 microshoots per explant after 4 weeks of culture. They were subcultured for 2 years without any loss of multiplication potential. The microshoots root easily in non-sterile sand beds. Young plants are planted into the field at a spacing varying from 1 m × 2 m to 3 m × 3 m. Sonosissoo is planted in agroforestry systems in India with a spacing of 4.5 m × 4.5 m, and wheat is cultivated under the trees.
Silviculture and management In Java sonokeling is only planted on sites which are not sufficiently productive for teak (Tectona grandis L.f.). It is generally grown in pure stands, but sometimes mixed with mahogany (Swietenia sp.). Pruning and thinning are recommended 5-10 years after planting.
Diseases and pests
In East Java Fusarium solani caused widespread damage to sonokeling plantations over 15 years old. The symptoms are inward rolling of young leaves, dieback and discoloration of other leaves, and red streaks formed on outer layers of the sapwood. Root suckers of affected trees should not be used for propagation. Wilt disease caused by Fusarium spp. is a common and serious problem of sonosissoo. Greenhouse experiments in India showed that compared with non-inoculated plants, plants pre-inoculated with vesicular-arbuscular mycorrhizae (VAM, Glomus fasciculatus and G. tenuis) showed better growth and were less susceptible to wilt disease. Physiological stress caused by inferior site conditions increases the susceptibility of the trees to this disease.
Sonokeling seedlings often suffer seriously from damping-off; the mortality rate may be up to 60%. Up to 12 years old, sonokeling is susceptible to fungi of the genus Phytophthora. In nurseries leaf rusts (Uredo sissoo and Maravalia achroa) may be pathogenic to sonosissoo. In Java the trees are attacked by various insects such as leafminers, defoliators and stem-borers, but this causes no real problems for trees grown under favourable conditions. Phanerogamous parasites are widely found on trees in Java, e.g. Dendrophthoe falcata (L.f.) Ettingsh. and Scurrula philippensis (Cham. & Schlecht.) G. Don (both Loranthaceae).
Stands of Dalbergia trees have been depleted considerably all over the world. The decorative wood has been imported in Europe for several centuries for furniture and interior finishing. In many areas, large Dalbergia trees have become rare. In Java, for instance, it is now difficult to find an old and large sonokeling tree. However, sonokeling and sonosissoo are planted on a considerable scale in agroforestry systems in India, and, on a much smaller scale, in Java.
In general, rosewood (wood of a dark red or purplish colour streaked and variegated with black, particularly but not exclusively obtained from Dalbergia species) is one of the most expensive woods. Natural stands of Dalbergia, however, need urgent protection. Loggers should take full account of the fact that the trees are usually slow growers, and that therefore cutting cycles should be very long. Sonokeling and sonosissoo are suitable for incorporation in agroforestry systems, but to obtain straight boles, close spacing is desirable and this means establishing monoculture plantations. Sonokeling seems to offer good prospects for timber production in plantations in Java, but more research is needed on silvicultural aspects. Comparison of Javanese provenances of sonokeling with those from India appears to be useful, particularly concerning botany, growth and propagation.
- Chakravarty, P. & Mishra, R.R., 1986. The influence of VA mycorrhizae on the wilting of Albizia procera and Dalbergia sissoo. European Journal of Forest Pathology 16(2): 91-97.
- Dahms, K.-G., 1989. Das Holzportrait: Palisander [Portraits of wood: rosewood]. Holz als Roh- und Werkstoff 47: 337-342.
- Lamprecht, H., 1989. Silviculture in the tropics. Deutsche Gesellschaft für Technische Zusammenarbeit, Eschborn. pp. 236-238.
- Martawijaya, A., Kartasujana, I., Kadir, K. & Prawira, S.A., 1986. Indonesian wood atlas. Vol. 1. Forest Products Research and Development Centre, Bogor. pp. 133-137.
- National Academy of Sciences, 1979. Tropical legumes: resources for the future. National Academic Press, Washington, D.C., pp. 199-200, 231-238.
- Rai, S.N., 1978. Rate of growth of Dalbergia latifolia and Xylia dolabriformis. Malaysian Forester 41: 241-252.
- Ravishankar Rai, V. & Jagadish Chandra, K.S., 1988. In vitro regeneration of plantlets from shoot callus of mature trees of Dalbergia latifolia. Plant Cell, Tissue and Organ Culture 13: 77-83.
- Soekeri, 1979. A possibility on modification of the "sonokeling" planting technique. Duta Rimba 5(35): 20-26.
- Suharti, M. & Hadi, S., 1974. Wilt disease of Dalbergia latifolia in Malang forest district, E. Java. Laporan No 194. Lembaga Penelitian Hutan, Bogor. ii + 9 pp.
- Suwal, B., Karki, A. & Rajbhandary, S.B., 1988. The in vitro proliferation of forest trees 1. Dalbergia sissoo Roxb. ex DC. Silvae Genetica 37: 26-28.
Selection of species
- S. Prawirohatmodjo (general part),
- J. Suranto (general part),
- A. Martawijaya (properties),
- R.W. den Outer (wood anatomy),
- M.S.M. Sosef (selection of species)