Syzygium jambos (PROSEA)

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Plant Resources of South-East Asia
Introduction
List of species


Syzygium jambos (L.) Alston


Protologue: Trimen, Handb. Fl. Ceylon 6, Suppl.: 116 (1931).
Family: Myrtaceae
Chromosome number: 2n= variously recorded as 28, 33,42, 44, 46,54, 66.

Synonyms

  • Eugenia jambos L. (1753).

Vernacular names

  • Roseapple, Malabar plum (En)
  • Pome rose, jambosier (Fr)
  • Indonesia: jambu air mawar, jambu mawar, jambu kraton
  • Malaysia: jambu kelampok, jambu mawer
  • Philippines: tampoy (Tagalog), bunlaun (Bisaya), yambo
  • Cambodia: châm'-puu
  • Laos: chièng, kièng
  • Thailand: chomphu-namdokmai (central), manomhom (northern), yamu-panawa (Malay-Yala)
  • Vietnam: ly, bô dào, roi.

Origin and geographic distribution

Roseapple originates in South-East Asia, its centre of origin being Malesia. From there it has been spread throughout the tropics. It has now become naturalized in many tropical countries. It is not a crop for commercial orchards, but the trees are widely grown in home gardens.

Uses

The fresh fruit is somewhat insipid and often left for the children to pick. The fruit is also cooked or preserved in various ways for home use. It can be distilled to yield a rosewater that is said to be equal to the best obtained from rose petals.

A yellow-coloured essential oil, important in the perfume industry, is derived from the leaves by distillation. The heartwood is heavy and hard and is suitable for use as construction timber. However, the wood is very susceptible to termite attack and not durable in the soil. The bark contains 7% tannin on a dry weight basis and is used for tanning and dyeing purposes. The plant is a useful melliferous and ornamental species; with its regular shape, attractive foliage and striking appearance in bloom, it is a useful avenue tree along driveways, etc. Several parts are used medicinally as a tonic or a diuretic.

Properties

The fruit contains per 100 g edible portion: water 84-89 g, protein 0.5-0.8 g, fat 0.2-0.3 g, carbohydrates 9.7-14.2 g, fibre 1-2 g, ash 0.3-0.4 g, carotene 123-235 IU, vitamin B complex 0.55-1.04 mg and vitamin C 3-37 mg. The energy value is 234 kJ/100 g. The pulp has a high pectin content, making it suitable for use as a settling agent.

The essential oil extracted from the leaves contains 27% d l-α-pinene and 24% l-limonene, two cyclic monoterpenes, responsible for the pleasant smell of the oil.

Several parts of the plant - i.e. the seeds, the leaves, the stems, the roots and the bark - are poisonous due to the presence of the alkaloid jambosine and hydrocyanic acid.

Botany

  • Evergreen tree, up to 10 m tall and 50 cm trunk diameter, often low branching and with a dense crown of wide-spreading branches; stem terete, sometimes quadrangular when young, generally twisted at the base, with brown, furrowed, smooth bark.
  • Leaves opposite, oblong-lanceolate, 9-26 cm × 1.5-6 cm, thinly coriaceous, cuneate at base, acuminate at apex, glossy dark-green above, lighter green and obscurely glandular punctate beneath, petiole 5-6(-13) mm.
  • Inflorescences short terminal or axillary corymbs, 5-10 cm long, 4-5(-10)-flowered.
  • Flowers large, 5-10 cm wide, white to greenish-white; calyx lobes 4, suborbicular, up to 10 mm × 7 mm; petals 4, suborbicular, 15-18 mm diameter, white to greenish-white; stamens about 400, up to 4 cm long; style up to 4 cm long; pedicel up to 1.5 cm long.
  • Fruit a drupe, globose to ovoid, 2.5-5 cm diameter, crowned by persistent calyx and style, whitish-yellow, sometimes pink-blushed, fragrant; pericarp fleshy, yellow-pink.
  • Seeds 1-2(-4), subglobose, 1-1.6 cm diameter, brown, rough coated, polyembryonic.

The tree grows in more or less synchronous flushes, one of which brings on bloom. Bloom occurs after a quiescent period, e.g. in spring in the subtropics, late in the dry season in East Java. The fruit ripens 3 months after bloom. The rosewater smell of the fruit is distinctive for the species.

Ecology

Roseapple is a tree of the tropics which has penetrated into the subtropics. It thrives up to about 1200 m above sea level. At much higher elevations and towards its limits in the subtropics it bears no fruit. It withstands minimum temperatures down to 0°C.

Young plants require a shady and moist environment, but established trees are rather hardy. The tree prefers a wet climate but also grows in monsoon climates with a taxing dry season. It is not clear whether flowering and/or fruiting are set back under dry conditions; recommendations to ensure access to soil moisture and the observation that trees do not shed their leaves easily suggest that the tree is not really drought-resistant. On the other hand, the trees are said to tolerate wind and salt.

There are virtually no limitations on soil conditions; the tree copes with poor drainage as well as flooding and grows on various soil types. The recommended pH is between 5.5-7.0.

Agronomy

Roseapple is normally propagated by seed. The seeds have no dormancy and germinate well. A single seed often gives rise to 3-8 seedlings, most of which are true to type. Other methods of propagation include air layering, budding and grafting. Air layering is commonly done in India and Bangladesh during the quiescent season. The layers are planted after half a year. Roseapple can be budded on 10-12-month-old rootstocks using the modified Forkert method; Syzygium pycnanthum Merr. & Perry and Syzygium samarangense (Blume) Merr. & Perry can also serve as rootstocks. The spacing is about 5 m × 6 m. Initially shade is provided. The juvenile phase lasts 4-5 years; air layered trees bear fruit within 4 years. The tree is hardly ever given any special attention.

Roseapple does not seem to suffer much from any insect pests, but it is a host to most fruit flies (Anastrepha and Ceratitis spp. as well as Dacus spp.). It is attacked by several fungi, causing leaf spots, anthracnose and root rot.

The only indication of yield level is from India: 2 kg per tree per year. This is quite low, even taking into account that the fruit is not heavy. The fruits, if meant to be consumed fresh, should be handled with care and marketed as quickly as possible. The fruits bruise easily and rapidly lose their crispness. The fruit is non-climacteric. Three days after harvest, respiration and ethylene production decline to respectively 50% and 10% of their initial values. The colour does not change during storage.

Genetic resources and breeding

Whereas some authors maintain that the trees are rather variable, others do not mention this aspect. There are no cultivars. For successful selection or breeding work, a better insight into yield, yield-limiting factors, and variability of characteristics is necessary. Such work may also be directed towards enhancing the production of essential oils or the ornamental value. However, germplasm collections have yet to be established.

Prospects

There have always been advocates who claim that roseapple is one of the best if not the best Syzygium fruit. However, the marketplace has never vindicated these claims. Low yield, susceptibility to bruising and short shelf life are serious handicaps. Therefore, it is to be expected that roseapple will remain a home garden tree, appreciated for its ornamental value as much as for its fruit.

Perhaps there is scope for the roseapple as an agroforestry species in denuded areas where soil conservation is important. In addition to producing timber, the stand might be used for the essential oil in the leaves, the pectin in the fruit, or as forage for bees.

Literature

  • Akamine, E.K. & Goo, T., 1979. Respiration and ethylene production in fruits of species and cultivars of Psidium and species of Eugenia. Journal of the American Society for Horticultural Science 104 (5): 632-635.
  • FAO-SIDA, 1982. Fruit-bearing forest trees. FAO Forestry Paper 34. Rome. pp. 71-73.
  • Fish, B.E., 1976. The roseapple. Californian Rare Fruit Growers Yearbook 8: 100-111.
  • Morton, J.F., 1987. Fruits of warm climates. Creative Resource Systems Inc., Winterville, USA. pp. 383-386.
  • Whistler, W.A., 1988. A revision of Syzygium (Myrtaceae) in Samoa. Journal of the Arnold Arboretum 69: 167-192.

Authors

T.G. van Lingen