From Plant Resources of South-East Asia No 2: Edible fruits and nuts, PROSEA Foundation
by R. Rajendran
Taxon
Artocarpus altilis (Parkinson) Fosberg
Protologue
J. Acad. Sci. Wash. 31:95 (1941).
Family
MORACEAE
Chromosome Numbers
2n = 27, 28, 56 (tetraploid)
Synonyms
Artocarpus communis J.R. & G. Forster (1776), Artocarpus camansi Blanco (1837).
Vernacular Names
Breadfruit
(En). Arbre à pain (Fr). Indonesia: sukun (seedless); kelur, timbul
(seeded). Malaysia: sukun (seedless), kelor (seeded). Papua New Guinea:
kapiak (Pidgin). Philippines: rimas (seedless), kamansi (seeded).
Cambodia: sakéé, khnaôr sâmloo. Thailand: sa-ke (seedless),
khanun-sampalor (central). Vietnam: sakê.
Origin and Geographic Distribution
The
exact origin of breadfruit is uncertain. The centre of genetic
diversity extends from Indonesia to Papua New Guinea. In a broad sense,
it is a native of the Pacific and tropical Asia. It has long been an
important staple food in Polynesia. Breadfruit is now widely
distributed throughout the humid tropics.
Uses
Immature as well as ripe fruits
and seeds are eaten after boiling, baking, roasting or frying. The
fruit may be cooked whole or after cutting it; thin slices are also
fried. A kind of biscuit is made by slicing the ripe cooked fruit and
drying in the sun or in an oven; thus prepared it can be kept until the
next fruiting season. On many Pacific islands breadfruit is preserved
in pits or by burying (Samoa). The stored fruit ferments and is
converted into a nutritious but disagreeably smelling cheese-like
paste, which is made into cakes and baked. Commercial processing is
limited to preserving the boiled cut fruit in brine. In the
Philippines, the mature seedless fruit is boiled and eaten with sugar
and grated coconut or coated with sugar and dehydrated; immature seeded
fruit is cooked as a vegetable with coconut milk.
Leaves and fallen fruits make good animal feed. The male flower spikes are blended with fibre of paper mulberry (Broussonetia papyrifera
(L.) Ventenat) to make elegant loincloths. The smooth, grey bark is
fibrous and was once a source of the native cloth 'tapa'. The milky sap
is used to caulk canoes, as a glue to catch birds and as a chewing gum.
Diluted with rain water, the latex from the trunk is used as a remedy
for diarrhoea. In Trinidad and the Bahamas a leaf decoction is believed
to lower blood pressure and to relieve asthma. Chewed young leaves are
said to counteract food poisoning. The light yet quite firm, nicely
grained wood is used to make canoes, surfboards, toys, boxes and
crates; it can also be used in light construction work.
Breadfruit trees are planted as windbreaks and sometimes as shade trees for coffee.
Production and International Trade
No
statistics are available on area and production. Though a staple food
in many tropical islands there is virtually no international trade.
Small consignments are exported to the United Kingdom, France and
Italy. Canned breadfruit in brine is available in many oriental stores.
Jamaican traders export partially roasted whole fruit to Europe and the
United States.
Properties
The seedless
breadfruit has 70% edible portion which contains per 100 g: water 65—85
g, protein 1.2—2.4 g, fat 0.2—0.5 g, carbohydrates 21.5—31.7 g, calcium
18—32 mg, phosphorus 52—88 mg, iron 0.4—1.5 mg, vitamin A 26—40 IU,
thiamine 0.10—0.14 mg, riboflavin 0.05—0.08 mg, niacin 0.7—1.5 mg and
vitamin C 17—35 mg. The energy value is 470—670 kJ/100 g.
Description
Monoecious
tree, up to 30 m tall, evergreen in the humid tropics, semi-deciduous
in monsoon climates. Trunk straight, 5—8 m tall, 0.6—1.8 m in diameter,
often buttressed; trunk of clonally propagated trees branched low;
twigs spreading, very thick, with pronounced leaf and stipule scars and
lenticels; buds 10—20 cm long, covered with big conical keeled
stipules. Leaves alternate, ovate to elliptical in outline, 20—60(—90)
cm x 20—40(—50) cm, undivided when young, older ones entire or deeply
pinnately cut into 5—11-pointed lobes, thick, leathery, dark green and
shiny above, pale green and rough below, petiole 3—5 cm long.
Inflorescences axillary, peduncles 4—8 cm long; male ones drooping,
club-shaped, 15—25 cm x 3—4 cm, spongy, yellow, flowers minute with
single stamen; female ones stiffly upright, globose or cylindrical,
8—10 cm x 5—7 cm, green, flowers numerous, embedded in receptacle,
calyx tubular, ovary 2-celled, style narrow, stigma 2-lobed. Fruit a
syncarp formed from the entire inflorescence, cylindrical to globose,
10—30 cm in diameter, rind yellow-green, reticulately marked with
4—6-sided faces, sometimes bearing short spines; a large central core
is surrounded by numerous abortive flowers which form a pale yellow
juicy pulp, the edible portion of the fruit.
Most cultivated
breadfruits are seedless, seeded ones are known as breadnuts. Breadnuts
bear fleshy prickles, the edible pulp is largely replaced by the seeds,
which are brownish, rounded or flattened, 2.5 cm long. All parts of the
tree are rich in white gummy latex.
Growth and Development
Seeds
germinate about 2 weeks after sowing. The seedlings tend to grow
slowly, but they respond well to better growing conditions and may
start flowering in 4—10 years. Asexually propagated seedless forms
start flowering after 3—4 years. Under stress the trees shed most of
their leaves, tufts of young leaves persisting at the tip of the twigs.
The flowering pattern appears to depend on the cultivar rather than the
climate, at least in the humid tropics. Most cultivars flower
throughout the year, but some flower and fruit seasonally. Further from
the equator, however, the seasons determine shoot growth and all
cultivars flower and fruit more or less simultaneously.
The male and
female inflorescences are produced in separate leaf axils of the
current season's growth. The proportion of male inflorescences on a
tree may vary from 60—80%. If tapped at anthesis they release clouds of
pollen, indicating that pollination is largely by wind. The male
inflorescences reach anthesis 10—15 days after emergence and well
before the female inflorescences on the same tree, thus limiting
self-pollination. The flowers in a female inflorescence are pollinated
and fertilized (in seeded cultivars) within a period of 3—6 days. About
75% of the inflorescences set fruit, but this is considerably reduced
during the rainy season, strengthening the impression that the seedless
fruits also depend on pollination to stimulate parthenocarpic growth.
The fruit matures 60—90(—110) days after the inflorescence emerges. In
the seeded form there is little pulp and each fruit contains 20—60
edible seeds.
Other Botanical Information
The
seeded breadfruit is considered to be the wild form, although both
seeded and seedless forms are cultivated. So-called seedless forms
occasionally produce fruit with some seeds.
Forms with entire leaves and with both seeds and edible pulp are sometimes classified as a separate species: Artocarpus mariannensis
Trécul. Based on leaf, fruit and seed characteristics, hundreds of
breadfruit cultivars have been described and named, particularly in the
Pacific islands. Usually the cultivars are poorly defined and only
grown in one or two localities, so that it is not easy to compare
cultivars.
Ecology
Breadfruit
is a species of the wet tropics, preferring a hot (temperature 20—40°C)
and humid (rainfall 2000—3000 mm, relative humidity 70—90%) climate.
The latitudinal limits are approximately 17°N and S; the maritime
climate of small islands allows growth to 20—23°N. Rain apparently
stimulates extension growth, flowering and the rate of growth of the
fruit. The tree is occasionally found in the highlands (even up to 1500
m) and at higher latitudes, but yield and fruit quality suffer in
cooler conditions and the tree is more at home in the equatorial
lowlands (below 600 m). Young trees grow better under shade but later
full sun is required.
Tree growth is best in deep, well-drained,
moist alluvial soils rich in humus. The trees also grow on shallow
coralline soils of the atolls, and in New Guinea they are found at the
forest edge in floodplains and swamps. Whereas the trees shed their
leaves under dry conditions, it is said that they shed their fruit when
the soil is excessively wet; so yield may be depressed on marginal
soils. Apparently cultivars differ greatly in their tolerance of
adverse conditions; there are cultivars that cope well with shallow
calcareous soils, brackish water and salt sprays, annual rainfall of
only 1500 or 1000 mm, etc.
Propagation and planting
The
seeded breadfruit is usually propagated by seed. Fresh seeds germinate
readily giving 90—95% germination. The seeds lose viability within a
few weeks and cannot be stored in a refrigerator. The seedless
breadfruit is traditionally propagated from root suckers, which can be
separated when adventitious roots have been formed. This method,
however, is laborious and plant losses in the field are high if the
plants are not nursed carefully. Root suckers can also be air layered,
which increases the multiplication rate as well as the survival rate.
The more common propagation method is by root cuttings. Sections of
roots 2.5 cm or more in diameter and 20—25 cm long are inserted — at an
angle, not upright — in a shaded nursery bed, maintaining a high
humidity until the cuttings form adventitious shoots and roots, which
may take many months. They are then potted in individual containers and
cared for under shade prior to planting in the field. Other propagation
methods, e.g. air layering, budding and grafting (using seedlings of
the seeded form as well as other Artocarpus species as rootstocks) have
given varying degrees of success.
Plants are set out in the field at
the onset of the rains at a distance of 6—12 m, depending on the
cultivar and growing conditions. Where vigorous growth is expected a
spacing of 12 m x 8 m (about 100 trees/ha) is recommended. Partial
shade is provided until the plants are well established.
Husbandry
As
the plants resume growth in the field, the shade is removed. For a year
or two supplementary irrigation is desirable to sustain growth. Weeding
around the trees may be replaced by generous mulching to conserve
moisture and initiate a slow but steady supply of nutrients. Nutrient
requirements have not been studied and mature trees are not normally
manured. However, the growth of young trees may be stepped up by
applying manure or fertilizers 2 or 3 times per year. The fertilizer
may be mixed with the mulch and covered with fresh mulching material.
For
tall, sparsely branched cultivars, formative pruning and bending of
branches of young trees may be beneficial in improving tree shape for
harvesting.
Diseases and Pests
In
the Pacific outbreaks of Pingelap disease have caused dieback and death
of trees on a large scale since the 1950s; it was estimated that only
20% of the trees survived an outbreak in Guam in 1964. The causal
organism is not known and there is no cure. Typically the top branches
die back first; after a while the lower branches also wilt and the tree
eventually dies. Other diseases of the breadfruit are dieback (Fusarium, Pythium and Rosellinia), pink disease (Corticium and Pseudocercospora) soft rot of fruit (Phytophthora palmivora), fruit rot (Phytophthora, Phyllosticta, Rhizopus), stem-end rot (Phomopsis, Dothiorella and Phylospora), leaf blotch (Phyllosticta artocarpicola), leaf spot (Pseudocercospora and Cercospora), leaf rust (Uredo artocarpi) and root rot (Phillinus noxius).
The common insect pests of breadfruit are mealybugs, scales, twig
borers and fruit flies. Little or no crop protection is practised.
Harvesting
Mature
fruits are harvested when they turn yellowish; at that stage drops of
latex are secreted on the surface. Fruit harvested green should be
handled with extra care since the slightest injury causes a flow of
latex. The fruit stalk is cut with a sharp knife by a person climbing
the tree, or twisted using a wedge attached to a long pole. The fruit
drops to the ground or is caught in a net as it falls. The fruit is
directly submerged in water or the stalk end is covered immediately to
stop the bleeding.
Yield
A
tree can produce up to 700 fruits per year, each weighing 400—1200 g.
In the South Pacific, the estimated average yield per tree is 50—150
fruits; in India 200 fruits. In Barbados production potential has been
estimated at 16—30 t/ha per year.
Handling After Harvest
Harvested
fruits are collected in baskets and kept in a cool, shaded place. Fresh
green fruit has a shelf life of 7—10 days which can be extended by
keeping the fruit in water; ripe fruit lasts for 3—7 days. Fruits
wrapped in polyethylene bags and kept at 12°C can be stored for about
20 days. Lower temperatures cause chilling injury. Fruit may be
preserved by cooking, fermentation in pits or pots, and dehydration in
the sun or in an oven; the products can be kept until the next harvest
season.
Genetic Resources and Breeding
The
genetic resources of breadfruit appear to be very rich. Cultivars not
only differ greatly in tree and fruit characters, but also in their
adaptation to specific environmental conditions. Certain cultivars are
preferred for specific purposes, e.g. for harvesting green, for various
forms of processing, for cattle feed, for timber.
Several attempts
have been made to collect cultivars from various regions and to test
them in comparative trials in a few locations (e.g Western Samoa,
Tahiti and Fiji). However, it is not clear what the outcome of these
trials was.
Prospects
For
a crop that is an important staple in vast archipelagos and has caught
the fancy of the western world in a compelling way, remarkably little
is known about yield levels, harvest seasons and other factors which
determine whether breadfruit can hold its own against competing staple
foods and fruits. For South-East Asia a much better insight into the
phenology and yield of trees in humid and monsoon climates is a
prerequisite to substantiate the often-heard claims that the prospects
for breadfruit are very bright indeed.
Literature
Barrau, J., 1976. Breadfruit and its relatives: Artocarpus spp. In: Simmonds, N.W. (Editor): Evolution of Crop Plants. Longman, London & New York. pp. 201—202.
Coenen, J. & Barrau, J., 1961. The breadfruit tree in Micronesia. South Pacific Bulletin 11(4): 31—39, 65—67.
Morton, J.F., 1987. Fruits of warm climates. Creative Resource Systems Inc., Winterville N.C. pp. 50—58.
Otanes, R.T. & Ruiz, T.P., 1956. Propagation of rimas root cuttings. Araneta Journal of Agriculture 3(2): 56—66.
Reeve, R.M., 1974. Histological structure and commercial dehydration potential of breadfruit. Economic Botany 28(1): 82—96.
Sinha, M.M. & Sinha, S.M., 1968. Breadfruit. Science and Culture 34: 271.
|
|