From Plant
Resources of South-East Asia No 2: Edible fruits and nuts, PROSEA
Foundation
by F. S. P. Ng
Taxon
Diospyros digyna Jacq.
Protologue
Pl. hort. schoenbr. 3: 35 (1798).
Family
EBENACEAE
Chromosome
Numbers
2n = unknown
Synonyms
Diospyros
nigra (J.F. Gmelin) Perrottet (1825), Diospyros ebenaster
Hiern (non Retz.) (1873).
Vernacular
Names
Black persimmon, black sapote (En). Philippines: zapote negro (Tagalog).
Origin and
Geographic Distribution
Black persimmon is believed to be native to Central America, especially
Mexico and Guatemala, and to have been taken by the Spanish colonizers
to the Philippines. It has, to some extent, become naturalized in the
Moluccas and Sulawesi. Its most important area of cultivation is Mexico
and Guatemala; elsewhere in the tropics it is a minor fruit, known to
relatively few people.
Uses
The
fruits are eaten when fully ripe and soft. The pulp, which is contained
within a thin skin, is soft, sweet, smooth, and pale brown in colour.
When scooped out and stirred, the colour changes to chocolate brown.
Apart from being eaten fresh, the pulp may be made into a drink by
blending with citrus, vanilla, or other flavours. It is also used in
ice-cream, cakes, and liqueurs. Unripe fruits are inedible; they are
hard, astringent because of the high tannin content, caustic and
bitter, and have been used as fish poison in the Philippines and the
West Indies.
The wood is yellowish to deep-yellow with black markings near the heart
of old trunks; it is compact and suitable for cabinetwork, but is
little used. Various preparations of bark and leaves have been used
medicinally against fever and skin disease.
Properties
Per 100 g edible portion the fruit contains approximately: water 82 g,
protein 0.7 g, fat 0.01 g, carbohydrates 15 g, ash 0.6 g, Ca 22 mg, P
23 mg, vitamin C 192 mg.
Botany
Evergreen tree, 10(—25) m tall, with a dominant trunk, bearing
pseudo-whorled tiers of slender spreading applanate branches (Massart's
architectural model). Leaves alternate, elliptic-oblong to
oblong—lanceolate, 10—30 cm long, leathery. Flowers axillary, unisexual
or hermaphrodite, male flowers usually in clusters of 3(—7), female
ones usually solitary; it is not clear whether the different types of
flowers are mixed or restricted to different trees; flowers white,
tubular, calyx green and persistent, ovary 8-, 10- or 12-celled, 1
ovule per cell. Fruit a flattened globose to slightly lobed berry, 5—15
cm in diameter, dark olive-green, seated on a persistent 4—6-lobed
calyx which reflexes at maturity; pulp soft, brown to black. Seeds
0—12, flat, ca. 2 cm long, smooth, brown.
Seeds germinate in about 30 days; seedlings grow slowly but later on
the tree becomes a vigorous grower. The juvenile phase can be as short
as 3—4 years. Flowers are borne on the new shoots; hence the crop cycle
is linked to flushing. In the subtropics certain trees seem to flower
on the spring flush, others on the summer flush, corresponding to fruit
maturing in late summer and in winter respectively. The trees are said
to flower in March in the Philippines; this suggests that they flush
and flower during the dry season.
Some trees bear flowers that are self-incompatible, so it is not
advisable to plant a solitary tree. Fruit on cultivated trees is often
seedless or nearly so. Introduced selections and outstanding seedlings
are now being cloned in Australia, where nurseries offer a gradually
increasing range of cultivars, including 'Bernecker' and 'Maher'.
Ecology
The altitudinal range for the cultivation of the black persimmon is
quite astonishing. In Mexico, it is cultivated from sea level to 1800
m. However, it is normally found below 600 m and, as it does not
tolerate frost, it is successful only in the tropics and subtropics.
The tree adapts to different soil types and survives flooding, but it
is rather sensitive to drought, requiring abundant irrigation in dry
areas.
Agronomy
Black persimmon is commonly propagated from seed, which remains viable
for several months if stored dry. Clonal propagation by budding or
grafting on seedling rootstocks is also possible; it is the way to
propagate seedless types. Trees grow vigorously and should be spaced
10—12 m apart.
There is no information on husbandry, crop protection or yield;
apparently the trees can bear sizeable crops each year with little
attention. The fruit turns a duller colour when ripe and the persistent
calyx at the base, which is pressed against the developing fruit,
becomes reflexed. At this stage the fruits are still firm. They soften
3—14 days after harvesting, and must be distributed beforehand because
soft ripe fruits are difficult to handle. Individual fruits ripen
suddenly and unpredictably within 24 hours. Harvested fruits can be
stored for several months at 10°C. When removed from cold storage and
placed at tropical room temperature (about 29°C), they will soften
within 48 hours.
Prospects
Black persimmon is said to have 4 times the vitamin C content of sweet
oranges, and to be a good source of calcium and phosphorus. Response to
the taste varies greatly between people, and the dark chocolate colour
of the pulp is considered to be unattractive. Nevertheless, because the
tree is robust, well-adapted to the tropics, and heavy-bearing, a close
re-examination of its potential is merited.
Literature
George, A.P., 1984. Ebenaceae. In: Page, P.E. (Compiler): Tropical tree
fruits for Australia. Queensland Department of Primary Industries
Information Series QI 83018. pp. 58—60.
Howard, R.A., 1961. The correct name for Diospyros ebenaster.
Journal of the Arnold Arboretum, Harvard University 42: 430—435.
Moncur, H.W., 1988. Floral development of tropical and subtropical
fruit and nut species. CSIRO National Resources Series No 8, Melbourne.
pp. 50—52.
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