From Plant
Resources of South-East Asia No 2: Edible fruits and nuts, PROSEA
Foundation
by J. A. Samson
Taxon
Averrhoa L.
Protologue
Sp. Pl. 1: 428 (1743); Gen. Pl. ed. 5: 196
(1754).
Family
OXALIDACEAE
Chromosome
Numbers
2n = 22, 24
Major Taxa
and Synonyms
Major species
— Averrhoa bilimbi
L., Sp. Pl. 1: 428 (1753).
— Averrhoa carambola
L., Sp. Pl. 1: 428 (1753).
Vernacular
Names
— Averrhoa bilimbi:
Bilimbi, cucumber tree (En). Cornichonier (Fr). Indonesia, Malaysia:
belimbing asam, blimbing wuluh, belimbing buluk. Philippines: kamias,
iba (Tagalog). Cambodia: trâlông töng. Thailand: taling pling. Vietnam:
khê tau.
— Averrhoa carambola:
Carambola, star fruit (En). Carambolier (Fr). Indonesia, Malaysia:
belimbing manis. Philippines: balimbing. Cambodia: spö. Laos: füang.
Thailand: ma fueang. Vietnam: khê.
Origin and
Geographic Distribution
Some
authors seek the origin in tropical America (Brazil), from where it
supposedly was taken to the Philippines. However, most authors support
the South-East Asian origin, for instance because there is a Sanskrit
name for carambola. Moreover, the distribution of bilimbi in tropical
America can be traced to its introduction from Timor to Jamaica in
1793. Both crops are now grown all over the humid tropics, and
carambola also in the subtropics.
Uses
The
fruit of bilimbi is used
for pickles, curries, chutney and preserves in syrup. The fruit of
carambola is used fresh, in salads, punch bowls, juice, preserves, jam
and jelly. Both fruits are also used to clean metal and remove stains
and in various ways in traditional medicine (e.g. skin disorders,
fevers).
Properties
The sour taste of
bilimbi is largely determined by citric acid; oxalic acid dominates in
carambola, even in the sweet types. Both fruits are rich in potassium
and vitamin A; the vitamin C content is low in bilimbi and fair in
carambola.
Quantitative data for the composition of carambola per
100 g edible portion: water 90 g, protein 0.75 g, total sugars 3.5—11
g, fibre 0.7 g. Carambola fruit contains 60—75% juice, which may be
quite acid or sweet as indicated by the acidity range (1.9—13.1
m.eq./100 g) and Brix levels (5—13%).
Description
Small
trees, 6—9 m tall, carambola up to 15 m. Leaves imparipinnate with
entire, usually ovate leaflets. Flowers in axillary or cauliflorous
panicles, pentamerous, heterostylous, with petals much longer than
sepals, 10 stamens, of which 5 sometimes rudimentary, and a superior,
5-celled ovary with 5 styles. Fruit a large berry, (ob)ovoid to
ellipsoid in outline. Seeds ellipsoid; endosperm present.
Averrhoa
bilimbi:
Sparsely branched tree, branches stiff, thick, upright. Leaves
7—19-jugate. Flowers usually in cauliflorous panicles,
heterotristylous; petals free, 10—20 mm long, red-purple; short stamens
fertile. Fruit slightly lobed, up to 10 cm x 5 cm. Seeds lacking aril.
Averrhoa
carambola:
Much-branched, broad, bushy tree, branches usually drooping. Leaves
3—6-jugate. Flowers usually in axillary panicles, heterodistylous;
petals coherent, up to 8 mm long, light red with purple heart; short
stamens rudimentary, lacking anthers. Fruit with 5 pronounced ribs,
stellate in cross-section, up to 12.5 cm x 6 cm. Seeds with fleshy aril.
Growth and
Development
Clonal
trees bear in 2—3 years, seedlings after 5—6 years. Both species grow,
flower and fruit continuously, but usually there are one or two
pronounced harvest seasons, each lasting about 2 months. Trees flower
abundantly, and overbearing is common in carambola (for a good crop
only about 0.5% of the flowers need to be pollinated). Flowers open
from 8—10 a.m.; fruit set is usually good but later fruit fall tends to
limit the crop. Carambola flowers with long styles are self-fertile,
but trees with short-styled flowers as a rule require pollen from
long-styled flowers. Fruit ripens 90—110 days after anthesis.
Other
Botanical Information
Carambola
cultivars are 'Maha 66' and 'B1'...'B17', in particular 'B2', 'B10' and
'B11' (Malaysia), 'Fu'ang Tung' (Thailand), 'Dah Pon' and 'Tean Ma'
(Taiwan), 'Arkin', 'Kara' and 'Kary' (Florida), 'Icambola' (Colombia),
'Fwang Tung', 'Giant Siam', 'Kembangan', 'B1', 'B2', 'B4', 'B6', 'B10'
and 'B16' (Australia). Important cv. characters are: taste (sweet to
acid, but may be strongly influenced by oxalic acid and tannin
content), colour (green to yellow), and shape (thin and sharp-edged
wings to thick wings and rounded edges, important in transport).
Ecology
Both species prefer a climate with a dry season, thriving where teak (Tectona grandis
L.f.) is at home, but also do well in wetter climates. Carambola can be
extended to frost-free subtropics; it is grown to 30°S in Australia and
32°N in Israel. Bilimbi grows up to 500 m altitude on Java. Both
species have a high water requirement, but they need well-drained
soils, pH 5.5—6.5, and grow well on peat. Drought, flooding and
salinity are not tolerated. Wind breaks are recommended on exposed
sites.
Propagation
and planting
Bilimbi
is grown mainly from seed. Grafting and budding are successful in
carambola. Budwood should not be tender or brittle. Budding on
one-year-old rootstocks gives best results. Topworking of trees with
cultivars which gain favour is easy; such trees resume production
within 1—1.5 years. The standard spacing 6 m x 6 m, that is 277
trees/ha for both species. However, for carambola spacing should be
adjusted to growing conditions, ranging from 160 trees/ha in favourable
tropical areas to 500 trees/ha in the subtropics and at higher
elevations.
Husbandry
Cultivars
must be planted mixed for cross-pollination. Pruning, water
availability and nutrient supply affect the flowering flushes. In
Taiwan carambola trees are pruned to restrict tree size, but hard
pruning suppresses flowering. Mulching and irrigation limit water
stress. An NPKMg formula, e.g. 10-10-10-5, at about 100 g/tree, is
applied every 3 months on young trees; later on the quantity is adapted
to trunk girth. Deficiencies of Zn, Mn and Fe must be corrected
regularly. In Malaysia, carambola fruit is bagged and excess fruit
thinned for top quality.
Diseases and
Pests
Leaf spot (Cercospora
averrhoa) and pink disease (Corticium)
occur in South-East Asia, but post-harvest rots are more serious, at
least on carambola fruit; the slightest blemish invites infection by Ceratocystis, Colletotrichum,
Dothoriella and Phomopsis
fungi. Caterpillars (Pingasa,
Pseudoterpna, Diacotrichia) attack flowers and young
leaves. Carambola fruit suffers most from fruit fly maggots,
particularly Dacus
dorsalis (South-East Asia) and fruit piercing moth (Othreis spp.,
Australia); bagging prevents infestation.
Harvesting
Carambola
fruit is non-climacteric and is picked green or more mature, depending
on the cultivar and consumer preference for a specific taste. The fruit
should be gently picked by hand to limit post-harvest losses. Seasonal
harvest greatly facilitates commercialization, but for home consumption
year-round cropping is an asset.
Yield
From
50—300 kg/tree is reported for carambola. At 277 trees/ha, this means
14—80 t/ha per year, confirming that carambola is one of the very few
tropical fruits which is naturally prolific.
Handling
After Harvest
Carambola can be stored 4 weeks at 5—10°C in a room with high humidity,
if picked as soon as the fruit starts to turn yellow.
Prospects
Whereas no
developments are foreseen in the case of bilimbi, carambola is rapidly
developing into a more commercial crop and penetrating distant markets.
Spurred by increasing attention to fruit quality (specific cultivars
for different uses, fruit thinning and bagging, harvest on the basis of
maturity indices, careful handling of the fruit), the end of the
expansion is not yet in sight.
Literature
Coronel, R.E.,
1986. Promising fruits of the Philippines. 2nd ed. College of
Agriculture, University of the Philippines, Los Baños. pp. 51—60.
Morton, J.F., 1987. Fruits of warm climates. Creative Resource Systems,
Inc. Winterville, N.C., USA. pp. 125—129.
Popenoe, W., 1920. Manual of tropical and subtropical fruits.
MacMillan, New York. pp. 429—432.
Sedgley,
M., 1984. Oxalidaceae. In: Page, P.E. (Editor): Tropical tree fruits
for Australia. Queensland Department of Primary Industries, Brisbane.
pp. 125—128.
Watson, B.J., George, A.P., Nissen, R.J. & Brown,
B.I., 1985. Carambola: a star on the horizon. Queensland Agricultural
Journal 114: 45—51.
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