Naranjilla: Favourite Fruit of the Andes
Scientific Name: Solanum quitoense
Family: Solanaceae
The Naranjilla, botanically known as Solanum quitoense,
belongs to the same family as the potato, tomato and tamarillo. It is
one of those exotic fruits one hears about but rarely encounter in this
country.
To those who know this fruit, they are generally
well-liked, although a first encounter with the fruit may lead to
disappointment, as the fruit tends to be very acid or almost bitter
when eaten before maturity.
Like so many 'new' exotic fruits,
the Naranjilla is native to the mountainous regions of Ecuador and
Colombia in South America. Wild forms of the Naranjilla are found in
mountain forests from 1200 to 2000m altitude in the Andes. The plant
itself can be immediately recognised by its spectacular large, velvety,
purple-veined leaves.
The plant is multistemmed, the stems being
pale green and spiny and reaching a height of about 2m. The round,
orange, golfball-sized fruits are carried on short stalks on the stem.
The green unripe fruits are covered in dense fine hair which rubs off
easily when the fruit matures. The Naranjilla plant is a perennial,
usually lasting about five years under favourable conditions.
Naranjilla
is a Spanish word meaning 'little orange'. The fruit does somewhat
resemble an orange in shape and colour, but there the resemblance
stops. The skin is thin but leathery. The juicy pulp has the
consistency of tomato pulp, moss-green in colour, embedded with flaky
seeds.
Our experience is to wait to harvest the fruit until they
fall off, usually between the months of October to December. Often the
fruit splits open when they ripen. At this stage the fruit is in
optimum condition for consumption. The colouration of the fruit from
green to yellow-orange takes place several months before maturity.
During this stage, the fruit is too immature to eat, although by
appearance alone one would be tempted to eat it.
The fruit of
the Naranjilla is most popular in Ecuador where it is used widely -
commonly made into juice, used in sorbets, and made into ice cream. The
juice may be diluted and sugar added to make a very refreshing drink of
unique flavour. Although not commercially exploited on a large scale,
Naranjilla can be bought at most market places in South American towns
and cities.
The Naranjilla has been tried in many countries of
the world without a great deal of success. The plant has exacting
climate requirements. It does not tolerate frosts nor temperatures
above 28°C. It prefers humid constant temperatures between 10 to 25°C
throughout the year. These conditions are hard to find, and New Zealand
can only partly satisfy these requirements.
Our winters are too
cool for the Naranjilla, yet the plant survives our climate. During the
winter months the plant is set back, losing most of its leaves.
Greatest tree losses occur during the cold months as root rot diseases
and various stem rots take their toll. Surviving plants are either
genetically stronger or a superior microclimate helps in their survival
through winter.
The Naranjilla was first introduced in this
country in 1956 by Dr. Harold Mouat of DSIR. Plants were grown at the
Mount Albert Research centre and some were sent to Kerikeri
orchardists. Nothing has ever been reported about what became of these
trees.
The writer introduced some Naranjilla seeds in 1968 from
Costa Rica. These plants produced fruit and continued to survive for
about three years, with the exception of one plant which has survived
to this day. The longevity of the latter is probably due to its growing
site, semi-shade under an old Puriri tree. Subsequently seeds have been
imported by different people over a number of years. No one seems to
have yet tackled commercial production of the fruit.
The seed
can be extracted from the fruit and sown straight away. Seedlings
emerge in about a month and can be pricked out when large enough to
handle. The plants are difficult to handle in pots or containers, as
they are very water-demanding. Young plants may be lined out in the
field when quite small, during the late spring.
Growth is rapid.
Under favourable conditions, flowers and fruitset occurs about six
months from planting out. Spacing in the field would need to be 1.8m
each way.
Interplanting with leguminous crops such as beans,
alfalfa or the like helps to maintain the ground cover and mulch which
the plant requires.
The main problem of growing Naranjilla is
the susceptibility of the plant to numerous diseases and pests, in
particular, Phytophthora root rot and nematode insects in the roots.
Both of these limit the life of the plant.
A well-drained soil
does help, but is no answer in itself. Stem rots caused by bacteria
cause dieback of the stems. The use of copper-based sprays may reduce
the problem.
It has been shown that the Naranjilla prefers
semi-shade, a soil rich in organic matter with ample moisture during
the summer. During the winter soil should not become waterlogged.
Naranjilla
grown under the protection of trees which provide fertile litter, such
as the Puriri, but not pine trees, and should be ideal for growing in
this country.
What does the future hold? Naranjilla can be grown
in New Zealand. Some plants have shown that economic results can be
achieved. It seems a matter of plant selection to aim for a more
disease-resistant type of plant.
Over the years, it has already
been observed that the more spiny type (on leaves and stem) are more
resistant to disease than those with smooth leaves. Recent
introductions from Ecuador are under trial at the writer's farm.
A
sweeter fruit type originally found in the Baeza area in Ecuador is now
growing here. Other selections from higher altitudes in the Andes might
hold a better future. Hybrid plants of Solanum quitoense x Solanum vestissimum may result in some interesting fruits.
Growing Naranjilla is one thing. The real challenge will lie in finding a market for the fruit.
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