2986

11: Auxiliary plants

Albizia chinensis (Osbeck) Merrill

Amer. Journ. Bot. 3: 575 (1916) (Albizzia chinensis).

LEGUMINOSAE - MIMOSOIDEAE

2n = 26

Mimosa chinensis Osbeck (1757), Albizia stipulata (DC.) Boivin (1838), Albizia marginata (Lamk) Merrill (1910).

Silk tree (En). Chinese albizia (Am). Indonesia: jeungjing (Sundanese), sengon (Javanese), keura (Eastern Sumba). Cambodia: kôôl. Laos: kha:ng (Xieng Khouang), kha:ng hu: (Vientiane). Thailand: kang luang, san-kham (Northern), khang hung (Khon Kaen). Vietnam: s[oos]ng r[aws]n t[af]u, cham (Ha Tuyên), chu m[ef] (Quang Ninh).

Albizia chinensis occurs naturally in India, Burma (Myanmar), Thailand, Indo-China, southern China, Java and the Lesser Sunda Islands (Bali and Nusa Tenggara). In Borneo and Sumatra, it is possibly only found in cultivation. It is cultivated in many tropical countries.

Albizia chinensis is commonly used as a shade tree in tea and coffee plantations, often in a mixture with other trees like Paraserianthes falcataria (L.) Nielsen and Erythrina spp. In China shade-tolerant herbs are sometimes planted under Albizia chinensis. It is planted for slope stabilization and soil improvement. In parks and gardens and along roads it is grown as an ornamental. The tree has shown some potential as a fodder: the leaves are readily eaten by goats but the bark of branchlets is hardly touched, possibly because of its high saponin content. Due to the light weight of its wood, timber use is limited to house building, light furniture, tea chests and veneers. In India, it is used in boat building. As a firewood it is of low quality.

Foliage of Albizia chinensis contains per 100 g dry matter: crude protein 21—28 g, fat 5 g, neutral detergent fibre 35—60 g, acid detergent fibre 25—35 g, lignin 15 g, tannins 23—33 g, and ash 5—15 g. In rumen degradation tests, digestibility of freeze-dried leaf dry matter was 39% after 48 hours, nitrogen digestibility was 27%. Drying leaves at 60°C in a forced-draught oven decreased total tannin content and increased N digestibility to 45%, while dry matter digestibility decreased to 30%. The bark of Albizia chinensis contains triterpenes with spermicidal activity. The trunk of the tree contains gum of low quality. It has been mixed with other gums to be used as extender.
Weight of 1000 seeds is about 20 g.
The wood of Albizia chinensis is soft and not very durable. Sapwood is white, while heartwood is light to dark brown. It is resistant to the European subterranean termite (Reticulitermes lucifugus) and somewhat resistant to attacks by Cryptotermes and other insects. An extract of the wood has a repellent property to subterranean termites.

Unarmed, deciduous or evergreen tree with flat, spreading crown, up to 30(—43) m tall and trunk up to 70(—140) cm in diameter; bark dark grey, rather smooth, densely hooped, lenticellate, thin; live bark 5 mm thick, pinkish-red. Branchlets slightly angular in the distal parts, terete, puberulous to tomentose, glabrescent. Leaves bipinnate; stipules auriculate, very prominent, 1—1.5 cm x 0.6—3 cm, caducous, pinkish-orange, pubescent, with filiform tail, base much dilated at one side; rachis stout, 10—25 cm long, lenticellate, sparsely and minutely tomentellous, glabrescent, with an elliptical, raised gland near the base of 2—3 mm x 1—1.5 mm; pinnae 4—14(—20) pairs, 4—14 cm long, puberulous to tomentose, glabrescent, with glands at the junctions of the 1 or 2 distal pairs of leaflets, narrowly elliptical to slit-like, concave, 1 mm long, glands sometimes absent; leaflets (10—)20—30(—45) pairs per pinna, opposite, sessile, thinly chartaceous, asymmetrically subulate, 6—10 mm x 1.5—3.0 mm, apex sharply acute, base obtuse, oblique, midrib close to the upper margin, sparsely sericeous or glabrous on either side. Inflorescence consisting of pedunculate glomerules (heads) aggregated into terminal, yellowish-green, tomentose to hirsute panicle; peduncle 1—3 cm long, up to 5 in clusters, often with auriculate stipules at base; glomerule composed of 10—20 flowers; flowers pentamerous, dimorphic; in a glomerule the central flower is male, the marginal flowers are bisexual; calyx tubular to narrowly funnel-shaped, 2.5—5.0 mm long, tomentose to hirsute, ending in small triangular teeth; corolla funnel-shaped, 6—10 mm long, puberulous to hirsute especially on the lobes, lobes triangular-ovate, acute; stamens numerous, 2 cm long, at the base united into a tube as long as or slightly longer than the corolla tube; ovary glabrous, sessile. Pod thin, flat, strap-shaped, 6—20 cm x 2—3 cm, often with slightly sinuate margins, indehiscent or breaking irregularly, reddish or yellowish-brown, glossy, 8—12-seeded. Seed flattened ellipsoid, 7(—10) mm x 4—6 mm x 0.5—1 mm, dull dark brown, areole nearly circular, 1 mm in diameter. Seedling with epigeal germination.

Albizia chinensis is evergreen or leafless for a short period. In South-East Asia trees flower between September and June, fruits ripen between October and August. In northern India old leaves fall in January—February, new ones appear in March—April; flowering takes place soon after the appearance of the leaves; while pods attain full size by about September and ripen during December—March. The pods remain on the tree for a very long time and eventually dehisce, but are sometimes blown away by the wind before dehiscence. Without seed treatment the germination rate is only 5—7%.
Growth is very rapid, to 1.5 m within the year of planting. In natural forest an annual diameter increment of 2.7 cm has been recorded.
Nodulation is abundant and effective, and the nodules, which are dichotomously branched, grow throughout the year.

Philippine specimens, formerly referred to this species, have been referred to Albizia philippinensis Nielsen. They differ from Albizia chinensis in having smaller stipules, petiolar glands and flowers, and seeds with a larger areole. The related American species Albizia carbonaria Britton (synonym Albizia sumatrana v. Steenis) is also occasionally used as a shade tree in tea in Java and Sumatra.

Albizia chinensis is a native of mixed deciduous forest and rain forest in humid tropical and subtropical monsoon climates with annual rainfall varying from 1000—5000 mm. It occurs in secondary forest, along river banks, and in savannas up to 1800 m altitude. Light frost is tolerated. It is adapted to poor soils, high pH, is fairly salt-tolerant and thrives on lateritic alluvial soil and sandy mining areas. In growth trials on poorly drained, infertile, gleyed, podzolic soils it had a survival rate of nearly 100%.

Albizia chinensis is mostly propagated by seed. Dormancy can be broken by scarification or soaking seed in concentrated sulphuric acid for 10 minutes, followed by washing and soaking in water for 18 hours. After 6—8 weeks, the seedlings can be transplanted into the field. In tea plantations in India Albizia chinensis is planted at a spacing of about 7—15 m; for fodder production, the trees are grown at a spacing of 3 m x 1 m. At planting a small amount of a mixture of 60% lime, 30% superphosphate and 10% urea is mixed with the soil in each planting hole, to promote early growth.

Weeds have to be controlled regularly after transplanting until the plants reach a height of 1 m. Trees grown for shade are left to grow to about 7 m tall and are then cut back to 4 m.
The trees can be harvested for fodder twice a year during the growing season by cutting the stem back to 1 m. Such cutting is well tolerated.

No serious diseases have been reported, though the risk of canker reduces the life expectancy in north-eastern India to about 20 years. Attacks by thrips sometimes prevent flower opening and young pods can be damaged by beetles and larvae of various bruchids.

In trials in south-eastern Queensland, with 1500 mm annual rainfall, the mean annual leaf dry matter yield was 454 g per tree with stem dry matter yield of 584 g per tree. In north-eastern Thailand with 1200 mm rainfall, annual yield per tree was 360 g leaf dry matter and 480 g stem dry matter.

It is unlikely that substantial germplasm collections exist and there are no known breeding programmes.

As a fast growing tree legume, Albizia chinensis remains important as a shade tree especially in tea and in the reforestation of degraded land. Because of its tolerance of frequent pruning during the growing season it deserves testing in alley cropping systems. The tree has shown some value as a source of fodder, warranting further testing. Breeding and selection for low tannin content may result in higher dry matter and nitrogen digestibility.

Ahn, J.H., Robertson, B.M., Elliot, R., Gutteridge, R.C. & Ford, C.W., 1989. Quality assessment of tropical browse legumes: tannin content and protein degradation. Animal Feed Science and Technology 27: 147-156.
Akkaseng, R., Gutteridge, R.C. & Wanapat, M., 1989. Evaluation of trees and shrubs for forage and fuelwood in Northeast Thailand. The International Tree Crops Journal 5: 209-220.
Dutta, A.C., 1977. Shade trees, green crop and cover plants in the tea estates of North East India. Memorandum 30, Tea Research Association, Tocklai Experimental Station, Jorhat, Assam, India. pp. 8-9.
Nielsen, I.C., 1992. Mimosaceae (Leguminosae - Mimosoideae). Albizia. In: de Wilde, W.J.J.O., Nooteboom, H.P. & Kalkman, C. (Editors): Flora Malesiana. Series 1, Vol. 11. Foundation Flora Malesiana, Leiden, the Netherlands. pp. 64-86, 212.
Shelton, H.M., Lowry, J.B., Gutteridge, R.C. & Bray, R.A., 1991. Sustaining productive pastures in the tropics. 7. Tree and shrub legumes in pastures. Tropical Grasslands 25: 119-128.
Supriana, N., 1989. Studies on the natural durability of tropical timbers to termite attack. International Biodeterioration 24: 337-341.

R. Akkasaeng & R.C. Gutteridge.

Akkasaeng, R. & Gutteridge, R.C., 1997. Albizia chinensis (Osbeck) Merrill. In: Faridah Hanum, I & van der Maesen, L.J.G. (Editors): Plant Resources of South-East Asia No 11: Auxiliary plants. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea