From Neglected
crops: 1492 from a different perspective
by the Food and Agriculture Organization of the United Nations
Annona
scleroderma Saff.
Excerpt from Custard Apples (Annona spp.)
Common
Names: English: poshte; Spanish. chirimoya, anona del
monte; other: cawesh, cahuex, poshté
Family:
Annonaceae
A.
scleroderma is one
of the least-known fruit trees of the genus; it is grown mainly in
southwestern Guatemala and is notable for the structure of its fruit
which, unlike the other cultivated species, has a very tough skin,
allowing it to be handled much more easily and making it resistant to
insect attack. The fruit may be cut and the flesh removed with a spoon.
Its potential value is in its high-quality flesh, hard skin and high
yield. It could become an export item and a product for wide local
consumption.
However, the height of the tree (which does not
facilitate fruit harvesting), the fact that the fruit is attacked by
birds and the defoliation caused by wind are an obstacle to
exploitation of this species.
Botanical
description
A.
scleroderma
is a tall tree which reaches 15 to 20 m and has tough, lanceolate
leaves measuring 10 to 25 x 5 to 8 cm. They are shiny on the upper
side, slightly pubescent on the underside and have fragile, 3 cm long
petioles. The flowers are greenish yellow, the outer petals have a
longitudinal prominence which arises in the small branches or in groups
in the old part of the thick branches. The fruit occurs in compact
spherical groups, is 5 to 10 cm in diameter and generally falls off
when ripe, without a noticeable colour change. The cream-coloured flesh
has a bittersweet flavour and a soft texture.
Ecology and
phytogeography
This
species apparently grows wild on the Atlantic slope from Campeche to
Honduras but is only grown in southwestern Guatemala between 300 and
1000 m on the Pacific slope. In this area. which is called the
Bocacosta and has very fertile volcanic soils, there is a short dry
season and an annual rainfall of around 4000 mm. The plant fruits
between late December and April, with a maximum yield around the
beginning of February.
Genetic
diversity
The
most visible characteristic of variability is in the fruit's surface.
The areoles are generally marked by raised edges which form a hexagon.
In some varieties, the edges are reduced to a crisscross of brown lines
on a smooth, green surface; in other varieties, there is a central
prominence on each areole; in some varieties there are well developed
edges and prominences, while still others have an irregular, corrugated
surface.
The fruit also seems to vary in the thickness of its
skin, which is on average 3 mm, but slightly thicker and tougher in the
smooth-skinned varieties. The Pacific varieties are green or green with
brown spots, while those from the Atlantic side have a thicker, reddish
green skin.
No cultivars are known to be established by
vegetative propagation. Genetic erosion is evident, since it is a crop
with a restricted area in a highly populated region where land is
required for building or cultivating coffee. Trees which were sown on
coffee plantations have been destroyed or deformed because they produce
too much shade or because they were damaged by children picking their
fruit.
Genetic erosion is very pronounced in A. scleroderma;
there are no gene banks and a few plants have been introduced into
Australia and the United States ( Florida). For this reason, material
urgently needs to be collected in southwestern Guatemala (from San
Felipe, San Andrés Villa Seca, San Sebastián, Colomba, El
Tumbador, etc.).
Cultivation
practices
Fresh
seeds take about a month to germinate. whether they are collected and
dried on the same day or stored in bags for a week or two. They do not
need to be soaked or treated in any other way. Seeds that have been
stored for two to three months need about six months to germinate.
In Australia, A.
scleroderma grows well when grafted on to stocks of A. muricata and Rollinia mucosa.
When grafted material is planted. it must be borne in mind that the
trees should be pruned so that a wide crown remains to facilitate fruit
harvesting. This also reduces exposure to wind and bird damage.
The
shade requirements of young plants—shade seems to promote
growth—need to be studied. However, trees located in sunny
positions would have a lower, more compact habit. Trees grown from seed
begin to produce at around tour years when they reach a height of 4 to
6 m.
Prospects for
improvement
The advantages of A.
scleroderma
as a fruit for local consumption and export are its high productivity
and the fact that the flavour and aroma of its flesh are not as strong
as in other Annona
species,
but are different and pleasant. The abundant, cream-coloured or creamy
grey flesh separates easily from the seeds and it does not have sandy
grains or fibres that adhere to the seed membrane. The thick, leathery
skin does not split and is very resistant to insect attack and ordinary
packaging and transport.
Activities
that merit close attention regarding A. scleroderma are:
The
collection and evaluation of genetic material; propagation through
grafting on to stock of the same species or related species to obtain
low trees with an open crown, which facilitate fruit harvesting:
Running small market gardens or interplanted crops; marketing, since it
is a "new" fruit even for Guatemalan markets;
Packaging and transport technology to prolong the good condition of the
fruit and its acceptance on the market.
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© FAO
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Bibliography
Mahdeem, H. "Custard Apples."
Neglected crops: 1492 from a different perspective, FAO Plant Production and Protection Series, no. 26, Food
and Agriculture Organization of the United Nations, 1994, FAO, fao.org. Accessed 13
Feb. 2016.
Published 9 Apr. 2015 LR. Last update 13 Feb. 2016 LR
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