Manilkara (PROSEA)

Plant Resources of South-East Asia
Introduction

Protologue: Fam. pl. 2: 166 (1763).

Family: Sapotaceae

Chromosome number: x= unknown

Trade groups

Manilkara: heavy hardwood, e.g. Manilkara fasciculata (Warb.) H.J. Lam & Maas Geest., M. kanosiensis H.J. Lam & B.J.D. Meeuse, M. kauki (L.) Dubard.

Vernacular names

Manilkara

Indonesia: sawo
Malaysia: sawah
Philippines: duyok-duyok
Papua New Guinea: sner
Burma: khayay-rgn
Thailand: lamut-thai, lamut-sida, ket (central)
Vietnam: găng néo, viết.

Origin and geographic distribution

The genus Manilkara consists of about 65 species, of which about 30 occur in tropical America, about 20 in tropical Africa and about 15 in tropical Asia, Australia and the Pacific. In Malesia 4 species occur naturally, and one other species is found in India, Sri Lanka, Burma, Thailand and Indo-China. M. kauki has the largest distribution area in South-East Asia. M. zapota (L.) P. v. Royen (sapodilla or ciku) from South America has been introduced and is commonly planted as a fruit tree in South-East Asia.

Uses

Manilkara timber is used for heavy construction, also in contact with the ground or exposed to the weather: for house and bridge building, railway sleepers and telephone poles. It is also used for flooring and furniture. The wood of M. kauki has a good reputation in Indonesia for use in furniture and fine carving (particularly in Bali). The timber is also suitable for turnery, and has been used particularly for mills. The wood shows excellent properties for the production of charcoal.

The fruits of M. kauki are edible but without much flavour. Fruits of M. duplicata Dubard and M. hexandra are edible as well. M. kauki is also used successfully as rootstock for sapodilla fruit trees, and flowers and seeds of this species are applied in local medicine.

Trees of M. kauki have been planted near palaces and temples, often during ceremonial events.

Production and international trade

Manilkara timber has no economic importance for export, although small amounts of timber from M. kanosiensis are exported from Papua New Guinea to Japan. Carvings made from M. kauki wood are highly prized, and sold on a fairly small scale in shops and markets in Indonesia.

Properties

Manilkara timber is heavy and hard. The heartwood is brown, dark brown or reddish-brown, sometimes with reddish streaks, and more or less lustrous. The sapwood is lighter brown, and distinctly demarcated from the heartwood, especially in freshly cut trees. The density is 900-1150 kg/m³at 12% moisture content. The grain is straight to interlocked, texture fine to very fine.

At 12% moisture content the modulus of rupture (of M. kanosiensis timber) is 164 N/mm², modulus of elasticity 21 200 N/mm², compression parallel to grain 83 N/mm², shear 19 N/mm², cleavage 109 N/mm tangential, and Janka side hardness 12 640 N.

The rates of shrinkage are high. Timber of M. fasciculata from Irian Jaya showed a shrinkage from green to 15% moisture content of 2.5% radial and 8.7% tangential, and from green to oven dry of 4.8% radial and 12.2% tangential. The timber air dries slowly, and end checking during drying is common. Drying should therefore be done very slowly and carefully. Rapid drying of boards at 100°C shows much checking and deformation, but may be done in about 5 days. Using a reasonable drying schedule, it takes more than 3 weeks to dry from green to air dry. A 30% solution of polyethylene glycol can minimize shrinkage.

Although Manilkara timber is very hard, working properties when using modern equipment are usually good. It contains little or no silica. It gives a very fine and smooth polish due to its fine texture, and this, in combination with the unusual colour, makes the wood an attractive medium for fine carvings. The wood should be pre-bored for nailing and screwing, as it is hard and splits easily.

The timber is rated as durable in contact with the ground or weather; it is resistant to fungal and insect attack. However, it is not resistant to teredos, and should only be used in water free of teredos. For most applications, preservative treatment is not needed.

The fine dust of air-dried wood may cause irritation to nose, throat and eyes.

The seeds contain saponins (seed kernels of M. hexandra contain more than 10%).

Description

Usually medium-sized, but sometimes fairly large trees up to 40 m tall, with straight cylindrical or twisted bole, sometimes free of branches for over 30 m and up to over 100 cm in diameter, but often less, buttresses to 1.5 m high or lacking; outer bark cracked to deeply fissured, greyish-brown to dark brown, inner bark soft and fibrous, pinkish or reddish, exuding latex; crown often rounded and dense.
Leaves arranged spirally, simple and entire, leathery, usually obovate with rounded tip, with parallel secondary and tertiary veins; petioles often slender; stipules small and caducous or absent.
Inflorescences in axils of leaves or leaf scars, 1-many-flowered.
Flowers bisexual or rarely unisexual, pedicellate; calyx consisting of 2 whorls of (2-)3(-4) free or shortly united sepals; corolla 6(-9)-lobed, each lobe usually divided to the base into 3 segments with median segment clasping a stamen, glabrous; stamens 6(-12), epipetalous and inserted at the top of the corolla tube, alternating with (0-)6(-12) staminodes; pistil 1, with 6-14-locular, hairy or glabrous ovary and exserted style.
Fruit a fleshy berry, 1-6-seeded.
Seed ellipsoid or obovoid, usually strongly laterally compressed, with a hard and shining testa and narrowly elongate scar, basi-ventral or extending along most of the adaxial surface; cotyledons foliaceous, endosperm copious.
Seedling (of M. kauki) with epigeal germination; hypocotyl erect and straight; cotyledons shortly petiolate; leaves arranged spirally; latex present.

Wood anatomy

Macroscopic characters

Heartwood brown, dark brown to reddish-brown, sometimes with red-brown streaks, distinctly demarcated from the light brown sapwood, especially in freshly cut trees.
Grain straight to interlocked.
Texture fine to very fine; wood more or less lustrous.
Growth rings indistinct to vague; radial vessel files sometimes visible as white lines to the naked eye, solitary vessels only in the sapwood just visible to the naked eye; parenchyma and rays not distinct without a hand lens.

Microscopic characters

Growth rings indistinct, sometimes vaguely present by differences in spacing of tangential parenchyma lines.
Vessels diffuse, 10-20(-24)/mm², in radial multiples of 2-4(-16), round to oval, average tangential diameter 60-150μm; perforations simple; intervessel pits alternate, round, 3-7μm; vessel-ray pits mainly confined to the upright and square cells, mostly large and simple, horizontally to vertically elongated or round, partly half-bordered, scarce in procumbent cells; helical thickenings absent; red gum-like deposits and thin-walled, rarely sclerotic tyloses present in heartwood.
Fibres c. 1200-1900μm long, non-septate, very thick-walled with simple to minutely bordered pits mainly confined to the radial walls.
Parenchyma abundant, diffuse, diffuse-in-aggregates or in fine discontinuous 1(-2)-seriate very wavy to straight bands sometimes forming a reticulate pattern, 4-8 bands per radial mm, in strands of 5-8(-12) cells.
Rays 8-14/mm, (1-)2(-4)-seriate with uniseriate tails, up to 1 mm high, heterocellular with 2-4(-5) rows of upright to square marginal cells and procumbent body cells.
Prismatic crystals present in chambered axial parenchyma cells, in chains of 4-6(-10) chambers, rare in ray cells.
Silica bodies recorded in ray cells and parenchyma.

Species studied: M. fasciculata, M. hexandra, M. kauki, M. littoralis (Kurz) Dubard, M. zapota.

Growth and development

Flowering and fruiting of M. kauki is reported to occur throughout the year in Indonesia, differing per region. In Bali, ripe fruits are found from April to July. The trees are considered slow growers. Trees of M. kauki reach a trunk diameter of 2-6 cm after 8 years. The architecture of the tree is according to Aubréville's model.

Other botanical information

The timber of M. bidentata (A.DC.) A. Chev. (synonym: M. balata (Pierre) Dubard) is traded from South and Central America as bullet-wood. Manilkara shows much variation in the division of the corolla lobes and number of staminodes, but is otherwise a remarkably consistent genus.

Ecology

Manilkara trees occur in lowlands, sometimes in hills up to 500 m altitude. They are often more or less confined to coastal areas, and are particularly found in the drier regions of South-East Asia. M. kauki grows especially on regosols; it prefers sandy loam soils, often at banks of small seasonal streams and on coral beaches, and is commonly associated with Drypetes spp., Eugenia spp., Schoutenia ovata Korth., Pterospermum diversifolium Blume, Pongamia pinnata (L.) Pierre and Diospyros maritima Blume.

Propagation and planting

Seeds should be sown in the shade. Germination starts 2.5-5 weeks after sowing. Experiments with M. kauki showed that the position of the seed in the soil is important for successful germination. Germination occurs most rapidly when the longitudinal axis of the seed is in a horizontal position. A germination percentage of 80% may be reached, although germination of M. hexandra seeds in nurseries in India is reported to be much lower. When seeds are soaked in an ethephon or chlormequat chloride solution for 24 hours, 55-66% of the seeds germinate. Seedlings of M. kauki are transplanted into the field when they are about 45 cm tall. Experiments with M. kauki seedlings showed that growth is promoted by applying 50 mg per kg potting medium of NPK fertilizer.

Silviculture and management

Seedlings of M. kauki are planted into the field at spacings of 2 m × 1 m. Plantations tend to become very dense after about 8 years, and thinning is then necessary.

Harvesting

Logs of M. kauki to be used for carving are usually not debarked directly, and are not treated with preservatives. The logs can be stacked for a long time without any risk of serious damage. Resin lacquer (shellac) can be used as a cheap material for stabilizing craft products made of M. kauki wood for the tourist industry.

Genetic resources

M. kauki has become rare, particularly in areas where the wood is much used for carving, e.g. in Java and Bali. In situ conservation is done through the establishment of nature reserves, ex situ conservation is practised by encouraging establishment of plantations, especially in Bali.

M. fasciculata and M. kanosiensis are locally common, particularly in New Guinea. Large-scale exploitation of forest may, however, seriously threaten the stands of these species, as the trees are slow growers and not planted.

Prospects

The establishment of plantations of M. kauki might be profitable economically. Carvings made of the wood of this species are in great demand and fetch high prices.

Literature

Alrasjid, H., 1971. Keterangan tentang silvikultur sawokecik (Manilkara kauki Dubard, Sapotaceae) [Information on the silviculture of sawokecik (Manilkara kauki Dubard, Sapotaceae)]. Laporan No 127. Lembaga Penelitian Hutan, Bogor. 7 pp.
Bolza, E. & Kloot, N.H., 1966. The mechanical properties of 81 New Guinea Timbers. Technological Paper No 41. Division of Forest Products, CSIRO, Melbourne. pp. 24-27.
Daryono, H., 1983. Pengaruh posisi penyemaian dan skarifikasi benih sawo kecik (Manilkara kauki Dubard) terhadap perkecambahan dan pertumbuhan bibitnya [Effect of seed position and scarification of sawo kecik (Manilkara kauki Dubard) on the germination and growth of seedlings]. Buletin Penelitian Hutan No 419: 11-12.
Eiseman, F. & Eiseman, M., 1988. Woodcarvings of Bali. Periplus Editions, Berkeley, Singapore. 88 pp.
Fundter, J.M. & Wisse, J.H., 1977. 40 belangrijke houtsoorten uit Indonesisch Nieuw Guinea (Irian Jaya) met de anatomische en technische kenmerken [40 important timber species from Indonesian New Guinea (Irian Jaya) with their anatomical and technical characteristics]. Mededelingen Landbouwhogeschool Wageningen 77-9: 167-172.
Kasmudjo & Joesoef, M., 1981. Utilization of resin lacquer as stabilization material for wood dimension. Duta Rimba 7(44): 3-9.
Sidiyasa, K., 1988. Beberapa aspek ekologi sawokecik (Manilkara kauki (L.) Dubard) di Purwo Barat, Banyuwangi Selatan, Jawa Timur [Some ecological aspects of sawokecik (Manilkara kauki (L.) Dubard) at Purwo Barat, Southern Banyuwangi, East Java]. Buletin Penelitian Hutan No 495: 1-19.
van Royen, P., 1953. Revision of the Sapotaceae of the Malaysian area in a wider sense 5. Manilkara Adanson em. Gilly in the Far East. Blumea 12: 401-412.
Wardani, M., 1989. Response of Manilkara kauki (L.) Dubard seedlings to dosage and frequency of nitrogen phosphorus potassium 13 13 20 fertilizer. Buletin Penelitian Hutan No 506: 11-18.
Yong, D.L. et al., 1985. Studies on the end-use development of lesser-known tropical timber (4). Properties and utilization of five lesser-known species grown in Irian Jaya District, Indonesia. Research Reports of the Forest Research Institute Korea No 32: 111-134.

Selection of species

Authors

I.G.M. Tantra (general part),
N. Tonanon (properties),
R.H.M.J. Lemmens (properties, selection of species),
R. Klaassen (wood anatomy)