1509

2: Edible fruits and nuts

Garcinia mangostana L.

Sp. Pl. 1: 443 (1753).

GUTTIFERAE

2n = variously recorded as 56—76, 88—90, 96, and 120—130.

Mangostana garcinia Gaertner (1790).

Mangosteen (En). Mangoustan (Fr). Indonesia and Malaysia: manggis. Philippines: manggustan, manggis. Cambodia: mongkhut. Laos: mangkhud. Thailand: mang-khut. Vietnam: cay mang cut.

The mangosteen is only known as a cultivated species, although there have been occasional reports of wild specimens in Malaysia. It closely resembles Garcinia hombroniana Pierre and Garcinia malaccensis T. Anderson, which are indigenous in Malaysia (the former is also indigenous in the Nicobar Islands). The mangosteen may be an allotetraploid hybrid of these two species; if so, it originated in Peninsular Malaysia. Cultivation has long been limited to South-East Asia, ranging from Indonesia eastwards to New Guinea and Mindanao (the Philippines) and north via Peninsular Malaysia into the southern parts of Thailand, Burma and Vietnam, and to Cambodia. Only during the last two centuries has the crop spread to other tropical areas, including Sri Lanka, South India, Central America, Brazil and Queensland, where orchards now cover small areas.

The mangosteen is probably the most highly praised tropical fruit. It is mostly eaten fresh, since preserved forms are far less appealing. The fruit rind is used to tan leather and to dye black. Both the rind and the bark have several applications in traditional medicine.
The dark red wood is heavy, coarse and very strong; when available it is used in carpentry and to make rice pounders.

Production is highest in Thailand: 67 500 t in 1987, the total area being 15 000 ha, of which nearly 5000 ha had not yet begun to bear in 1987. Peninsular Malaysia reported 27 000 t in 1987 with a total area of 2200 ha. The Philippines produced 2270 t mangosteen on 1130 ha, of which only 25% was recorded as bearing in 1987. Mangosteen does not figure in statistical data from Indonesia. International trade is still of little importance, but the fruit travels well and is found in markets as far away as Europe (from South-East Asia) and the United States (from Central America).

The flesh amounts to ca. one-third of the whole fruit. Thai sources give the following composition per 100 g edible portion : water 79.2 g, protein 0.5 g, fat nil, carbohydrates 19.8 g, fibre 0.3 g, calcium 11 mg, phosphorus 17 mg, iron 0.9 mg, vitamin A 14 IU, vitamin C 66 mg. The energy value is 340 kJ/100 g. The rind is rich in pectin and contains catechin tannin, rosin and a black dye.

Dioecious tree, 6—25 m tall, with a straight trunk, symmetrically branched to form a regular pyramidal crown, in conformity with the architectural model of Attims. All parts of the plant exude a yellow latex when damaged. Leaves opposite, with short petioles clasping the shoot so that the apical pair conceals the terminal bud; blades oblong or elliptical, 15—25 cm x 7—13 cm, thickly leathery, entire, cuspidate at the apex, glabrous and olive-green above, yellow-green beneath with pale green central nerve, prominent on both sides and with many evenly spaced prominent side nerves. Flowers solitary or paired at apices of branchlets, with short and thick pedicels, ca. 5.5 cm in diameter; sepals 4, arranged in 2 pairs; petals 4, thick and fleshy, yellow-green with reddish edges; staminodes usually many, 1—2-seriate, ca. 0.5 cm long; ovary sessile, subglobose, 4—8-celled with prominent sessile 4—8-lobed stigma. Fruit a globose and smooth berry, 4—7 cm across, turning dark purple at ripening, with persistent sepals and still crowned by the stigma lobes; pericarp ca. 0.9 cm thick, purple; 0—3 of the cells containing a fully developed seed, enveloped by a white arillode.

Mangosteen has no true seed in the sense that it develops from cells of the inner carpel wall, sometimes leading to poly-embryony. Morphologically the seed has been described as a tuberculous hypocotyl; the embryo is underdeveloped. On germination a radicle emerges from one end and the plumule from the opposite end of the seed. Soon an adventitious root develops at the base of the young shoot, after which the first radicle dies. Germination and initial growth proceed very slowly. It has been shown that heavier seeds (up to 1 g) germinate better, whereas the survival of seedlings after one year is best for seeds weighing more than 1.3 g; the maximum seed weight is well over 2 g.
Slow seedling growth is attributed to a weak root system, characterized by the absence of root hairs and poor development of laterals. The evidence strongly suggests that initially the roots have properties similar to those growing in water cultures and thus function defectively in solid potting mixtures. Under favourable conditions plants reach a height of 25 cm and a leaf area of more than 200 cm² within one year.
Growth quickens after side shoots emerge. Since a pair of side shoots grow out from virtually every node, the symmetry in the architecture of the young tree is striking. Mangosteens growing in mixed stands between taller trees retain their pyramidal habit and have well-spaced laterals. In full light, growth in height is much reduced; the tiers of lateral branches are close together, resulting in a very dense canopy and a rounded profile.
Thai growers say that the juvenile phase ends when the trunk bears 16 pairs of laterals. They aim to obtain their first crop 5 years after planting, but usually have to wait 1 or 2 more years. Where no high growth rate is maintained, the juvenile phase may last 12—20 years.
Young trees make up to 6 flushes of shoot growth per year, bearing trees usually only 2 or a single one. The flowers are borne at the tip of mature shoots. Floral initiation manifests itself in considerable swelling of the tip. From that stage the bud takes about 25 days to reach anthesis; the fruit ripens 100—120 days later. In many areas the trees tend to flower twice a year, usually shortly after a flush. Trees can be productive up to a great age.

A 19th Century description of the male flowers is occasionally quoted in later publications, but in fact no functionally male flowers have since been found. The seed is apomictic; at anthesis it is already clear which segments of the fruit will be seeded. The far-reaching consequence is that all mangosteen trees may belong to a single clone. Some distinct forms have been reported, but the only distinction which has been made repeatedly, possibly related to differences in growing conditions, is between trees with small leaves and small fruits and trees with large leaves and fruits of variable size.

Mangosteen is a crop of the humid tropics, often found in association with the durian. It thrives in conditions of high temperature, high humidity, a short dry season to stimulate flowering and an uninterrupted water supply. Growth is slow below 20°C and the upper limit is 38—40°C; both leaves and fruit are susceptible to sunburn. Shade is required during the early years and shelter throughout life. Protection is offered by other trees in mixed orchards (Thailand) and in home gardens. Stress should be avoided; a tree which is visibly suffering seldom recovers. There is much confusion over rainfall and soil requirements, but an assured year-round supply of water is essential. In spite of the weak root system the tree tolerates heavy soils which impede water movement, provided transpiration is limited by a sheltered site and high humidity. Under dry conditions irrigation is needed at small soil moisture deficits, and thick mulches are very beneficial.
Traditional growing centres are largely within 10° from the equator, but orchards in Queensland, Madagascar, Honduras and Brazil indicate that the potential range of mangosteen extends to 18° latitude in warm frost-free areas. The tree is grown up to 1000 m elevation in the tropics, but the growth rate is higher in the lowlands.

Mangosteen is propagated from seed, the seedlings being true to type. The seed is short-lived, but sowing can be delayed a few weeks by leaving it in the fruit. Heavy bearing trees and fruit from the main crop are chosen and only the large seeds are sown.
It is not uncommon to find healthy seedlings growing spontaneously under bearing trees and these may meet the needs of most home gardeners. Nurseries with substantial numbers of seedlings are found in Thailand. Selected seeds are pregerminated and potted. Seedling growth, extremely slow in the beginning, gradually picks up and under favourable conditions, a 60 cm tall seedling with one or two pairs of laterals can be raised in about 2 years. During this period the plants are transferred 3 times to larger bags.
Important elements of nursery work are a freely draining growing medium with high moisture retention (mixtures including shredded coconut fibre, peat, sphagnum or pine bark), high humidity and shade (e.g. by covering the nursery beds with coloured polythene tunnels). Watering can be used to supply nutrients, for instance in the form of diluted cow dung; foliar nitrogen also accelerates seedling growth.
Initially it was found very difficult to raise mangosteen outside its area of origin, and attempts to overcome stagnation in the growth of seedlings dominate the literature of the first half of the 20th Century. The problems with seedling growth and survival also led to numerous trials with other propagation methods, particularly grafting on related species which all have strong root systems. Several workers report initial success with rootstocks of the genera Garcinia L., Platonia Mart., Pentadesma Sabine and Clusia L., but there has been no follow-up to confirm these findings. Of Garcinia species, Garcinia xanthochymus Hook.f. ex T. Anderson and Garcinia morella (Gaertner) Desr. showed promise in more than one trial; again these results have not been confirmed. Most budding and grafting methods have failed, positive results being limited to inarching, the traditional method of propagation in South-East Asia for all fruits that do not respond to simpler methods. Attempts to root mangosteen cuttings and layers have also failed; only mist propagation of cuttings using orthotropic shoots offers some hope. Grafting on mangosteen seedlings is not difficult. It does shorten the juvenile phase, but growth is even more slow and fruits tend to be small.
Field planting should be done quickly and neatly, without exposure of the plants or undue loss of roots, and with water and shading material ready at the planting site.
In South-East Asia trees are not often planted in pure stands, but either in home gardens or in mixed orchards with durian, rambutan or coconut as the dominant and mangosteen and langsat as the subsidiary species. The mixed stand affords the necessary shelter for the mangosteens which require an area of 40—80 m² per tree, depending on growing conditions.

Shade is maintained for 2—4 years and gradually reduced. The slow growth makes the plant very vulnerable to weeds, and as the shade screen may hide weeds, regular checks are needed. A heavy mulch around the tree is a good alternative to weeding.
There is no specific information on husbandry. Mangosteen benefits from supplementary irrigation, even in rather wet areas. Trickle irrigation or the use of small under-the-tree sprinklers may be ideal for this crop, which has exacting water requirements. Boosting the growth rate in the early years with water and nutrients (nitrogen) shortens the unproductive period.

The mangosteen does not suffer much from pests and diseases. Gamboge, the yellow exudate from burst latex vessels, frequently spoils fruit. If gamboge infiltrates the white fruit segments, these turn translucent and become bitter. Gamboge is often also found as yellow spots on the fruit skin. Any physical damage to the latex vessels brings the disorder about: excessive watering after drought, punctures by sucking insects (capsids), strong wind, rough harvesting and handling.
Several caterpillars feed on the young leaves, and damage by sucking insects may lead to fruit drop. Several fungus diseases have been identified, of which the red (Phellinus noxuis) and brown (Ganoderma pseudoferreum) root rots are sometimes serious. No control measures are known.

Ripe fruit eventually drops and if it falls on a layer of mulch it may still be marketable. Growers do not risk leaving the fruit on the tree so long and pick it when the colour changes. Top quality is obtained by picking every 2—3 days the fruit which have turned to a light red colour. The fruit ripens over a period of 6—12 weeks per crop, and the intervals between harvests are usually too long so that much of the fruit is either immature or overripe, leading to disappointed consumers. Bamboo poles with a V-shaped cut at the top which can hold a single fruit are used in Malaysia, but in Thai orchards youngsters climb the trees to pick the fruit. The high cost of picking — because of the long ripening season — appears to be a major constraint for the commercialization of the crop.
The main harvest season in Thailand is May, June and July; in Peninsular Malaysia it is June, July, August; and in Sarawak it is November, December, January. In the main production centres (e.g. Chantaburi District, Thailand; Kedah State, Malaysia; Western Mindanao, the Philippines) the season is fairly well defined; elsewhere there are often 2 or even 3 harvest seasons in a year, apparently related to flowering following dry periods. Timing of the harvest appears to be influenced considerably by altitude and shade too.

In Malaysia the yield of bearing trees varies from 200—2000 fruits per tree. The average yield in Thailand in 1987 was 4.5 t/ha. For an estimated mean weight of 75 g per fruit and 150 trees/ha, this equals 400 fruit per tree. Trees in two small orchards in the Nilgiri hills in southern India produced on average 360 fruit per year over a period of 18 years, the best trees yielding more consistently and so coming to 500 fruit per year.

Light red fruit ripens in 5 days, the colour becoming dark purple. Ripe fruit has a shelf life of about one week. The fruit is graded by size, and gamboge spots may be removed. Thailand exports large fruit, the smaller — often seedless — fruit being preferred in the home market. In South-East Asia the fruit is taken to market in baskets. In Indonesia and the Philippines one often sees the fruit for sale in long bundles of about 2 dozen fruits strung together.
In spite of the thick fruit wall which hardens as the fruit ripens, the fruit is very vulnerable: a fall of 20 cm damages freshly-picked fruit. Hence the fruit should be handled with care. It should lie still in transport baskets, and impact on the baskets (e.g. on a moving truck) or on the fruit (e.g. by pouring fruit from a bin) should be minimized. The fruit lends itself to transport by air, provided it can be offered in sufficient quantity and uniform quality to justify sales promotion campaigns in overseas markets.

The assumption that all mangosteen trees may belong to a single clone has discouraged collectors. Hence the only sizeable germplasm collections are in Thailand, in Chantaburi (the largest) and the Prince of Songkhla University, Songkhla.

The mangosteen, already far too scarce for such a delicious fruit, is losing ground in most of South-East Asia. Home gardeners — not to mention commercial growers — can no longer afford to wait 10—15 years for trees to come into bearing. The long harvest period and the resulting high picking cost also form major constraints.
Whereas research work has so far failed to solve these problems, the Thai growers must have at least some of the answers, because they continue to grow the crop commercially on a large scale. To turn the tide for the mangosteen in South-East Asia the research effort should be resumed with a thorough study of the Thai propagation and husbandry techniques, including quantitative data on precocity of bearing and harvesting efficiency. Irrigation might prove to shorten the harvest period if briefly interrupting the water supply helps to trigger synchronous flowering.

Ahmad, S., 1983. Past, present and future research on mangosteen with an example of research and production in Malaysia. Proceedings International Workshop for promoting research in tropical fruits, Jakarta. 20 pp.
Almeyda, N. & Martin, F.W., 1976. Cultivation of neglected tropical fruits with promise. Part 1. The mangosteen. USDA, Mayaguez, Puerto Rico, ARS-S-155. 18 pp.
Bourdeaut, J. & Moreuil, C., 1970. Le mangoustanier, ses possibilités de culture en Côte d'Ivoire et à Madagascar. Fruits 25: 223—245.
Campbell, C.W., 1966. Growing the mangosteen in southern Florida. Proceedings of the Florida State Horticultural Society 79: 399—400.
Horn, C.L., 1940. Stimulation of growth in young mangosteen plants. Journal of Agricultural Research 61: 397—400.
Hume, E.P. & Cobin, M., 1946. The relation of seed size to the germination and early growth of the mangosteen. Proceedings American Society of Horticultural Science 48: 298—302.
Krishnamurthi, S. & Madhava Rao, V.N.M., 1965. The mangosteen (Garcinia mangostana L.): its introduction and establishment in peninsular India. In: Krishnamurthi, S. (Editor): Advances in agricultural sciences and their application. Coimbatore, India. pp. 401— 420.
Molesworth Allen, B., 1967. Malayan fruits: an introduction to the cultivated species. Donald Moore Press, Singapore. pp. 66—71.
Oliver, G.W., 1911. The seedling inarch and nurse plant methods of propagation. Bulletin 201. United States Department of Agriculture, Bureau of Plant Industries. 43 pp.
Richards, A.J., 1990. Studies in Garcinia, dioecious tropical forest trees: the origin of the mangosteen (G. mangostana L.). Botanical Journal of the Linnean Society 103: 301—308.

E.W.M. Verheij

Verheij, E.W.M., 1991. Garcinia mangostana L.. In: Verheij, E.W.M. and Coronel, R.E. (Editors): Plant Resources of South-East Asia No 2: Edible fruits and nuts. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea