 Solanum betaceum (syn. Cyphomandra betacea) is a small tree or shrub
in the flowering plant family Solanaceae. It is best known as the
species that bears the tamarillo, an egg-shaped edible fruit. Other
names include tree tomato and tomate de árbol.
Description
Plant origin and regions of cultivation
The tamarillo is native to the Andes of Peru, Chile, Ecuador,
Colombia and Bolivia. Today, it is still cultivated in gardens and
small orchards for local production, and it is one of the most
popular fruits in these regions. Other regions of cultivation are
the subtropical areas throughout the world, such as South Africa,
India, Hong Kong, China, United States, Australia, and New Zealand.
The first internationally marketed crop of tamarillos in
Australia was produced around 1996, although permaculture and exotic
fruit enthusiasts had increasingly grown the fruit around the
country from the mid nineteen seventies on.
In New Zealand, about 2000 tons are produced on 200 hectars of
land and exported to the United States, Japan and Europe. For the
export, the existing marketing channels developed for the kiwifruit
are used. Original Entry about origin of Name.
The tamarillo is also successfully grown at higher elevations of
Malaysia and the Philippines, and in Puerto Rico. In the hot
tropical lowlands, it develops only small fruits and fruit setting
is seldom.
Prior to 1967, the tamarillo was known as the "tree tomato" in
New Zealand, but a new name was chosen by the New Zealand Tree
Tomato Promotions Council in order to distinguish it from the
ordinary garden tomato and increase its exotic appeal. The choice is
variously explained by similarity to the word "tomato", the Spanish
word "amarillo", meaning yellow, and a variation on the Maori word
"tama", for "leadership". It is called Tree Tomato in most of the
world.
Plant
The plant is a fast-growing tree that grows up to teters. Peak
production is reached after 4 years, and the life expectancy is
about 12 years. The tree usually forms a single upright trunk with
lateral branches. The flowers and fruits hang from the lateral
branches. The leaves are large, simple and perennial, and have a
strong pungent smell. The flowers are pink-white, and form clusters
of 10 to 50 flowers. They produce 1 to 6 fruits per cluster. Plants
can set fruit without cross-pollination, but the flowers are
fragrant and attract insects. Cross-polination seems to improve
fruit set. The roots are shallow and not very pronounced, therefore
the plant is not tolerant to drought stress. Tamarillos will
hybridize with many other cyphomandra solanaceae, though the hybrid
fruits will be sterile.
Fruit
The fruits are egg shaped and about 4-10 centimeters long. Their
color varies from yellow and orange to red and almost purple.
Sometimes they have dark, longitudinal stripes. Red fruits are more
acetous, yellow and orange fruits are sweeter. The flesh has a firm
texture and contains more and larger seeds than a common tomato. The
fruits are very high in vitamin and iron and low in calories (only
about 40 calories per fruit).
Fruit composition, some important componentsComponent [g/100g]
Range Component [mg/100g] Range
Water content 81-87 Vitamin A 0.32-1.48
Proteins 1.5-2.5 Vitamin C 19.7-57.8
Fat 0.05-1.28 Calcium 3.9-11.3
Fiber 1.4-6.0 Magnesium 19.7-22.3
Total acidity 1.0-2.4 Iron 0.4-0.94
Cultivation
Soil and climate requirements
The tamarillo prefers subtropical climate, with rainfall between
600 and 4000 millimeters and annual temperatures between 15 and 20
°C. It is intolerant to frost (below -2 °C) and drought stress. It
is assumed that fruit set is affected by night temperatures. Areas
where citrus are cultivated provide good conditions for tamarillos
as well, such as in the Mediterranean climate. Tamarillo plants grow
best in light, deep, fertile soils, although they are not very
demanding. However, soils must be permeable since the plants are not
tolerant to water-logging[1]. They grow naturally on soils with a pH
of 5 to 8.5.
[edit] Growth
Propagation is possible by both using seeds or cuttings.
Seedlings first develop a straight, about 1.5 to 1.8 meters tall
trunk, before they branch out. Propagation by seeds is easy and
ideal in protected environments. However, in orchards with different
cultivars, cross-pollination will occur and characteristics of the
cultivars get mixed up. Seedlings should be kept in the nursery
until they reach a height of 1 to 1.5 meters, as they are very
frost-sensitive.
Plants grown from cuttings branch out earlier and result in more
shrub-like plants that are more suitable for exposed sites. Cuttings
should be made from basal and aerial shoots, and should be free of
pathogenic viruses. Plants grown from cuttings should be kept in the
nursery until they reach a height of 0.5 to 1 meter.
The tree grows very quickly and is able to carry fruits after 1.5
to 2 years[2]. The plant is daylength-insensitive. The fruits do not
mature simultaneously, unless the tree has been pruned. A single
tree can produce more than 20 kg fruits per year, an orchard yields
in 15 to 17 tons per hectare[3]. One single mature tree in good soil
will bear more fruit than a normal family can eat in about 3 months.
Tamarillos are suitable for growing as indoor container plants,
though their swift growth, their light, water and humidity
requirements and their large leaves can pose a challenge to those
with limited space.
Plant management
Tamarillo Tree
The tamarillo trees are adaptable and very easy to grow. However,
some plant management strategies can help to stabilize and improve
plant performance.
Planting
Planting distances depend on the growing system. In New Zealand,
with mechanized production, single row planting distances of 1 to
1.5 meters between plants and 4.5 to 5 meters between rows are
recomended. In traditional growing regions such as the Andean
region, plantations are much more dense, with 1.2 to 1.5 meters
between plants. Dense planting can be a strategy to protect plants
against wind[1]. On poorly drained soils, plants should be planted
on ridges.
[edit] Pruning
Pruning can help to control fruit size, plant size, harvest date
and to simplify the harvest of fruits[1]. Cutting the tip of young
plants leads to the desired branch height. Once the tree shape has
been formed, pruning is reduced to the removal of old or dead wood
and previously fruited branches, since branches that have already
carried fruits will produce smaller fruits with lower quality the
next time. Light pruning leads to medium sized, heavy pruning to
large sized fruits. Basal shoots should be removed. When plants are
grown in greenhouses, pruning prevents excessive vegetative growth.
When the tree is about 1 to 1.5 metres in height, it is advisable
to cut the roots on one side and lean the tree to the other (in the
direction of the midday sun at about 30 to 45 degrees). This allows
fruiting branches to grow all along the trunk rather than just at
the top.
Mulching
Since the plants are sensitive to drought stress, mulching can
help to preserve moisture in the soil[3]. It can also be a strategy
to suppress weeds, as other soil management techniques such as
plowing is not possible due to the shallow and sensitive root
system.
Shelter
The plants have to be protected from wind. Their shallow root
system does not provide enough stability, and the lateral branches
are fragile and break easily when carrying fruits.
Harvest
Ripening of fruits is not simultaneous. Several harvests are
necessary. In climates with little annual variation, tamarillo trees
can flower and set fruit throughout the year. In climates with
pronounced seasons (such as New Zealand), fruits ripen in fall.
Premature harvest and ethylene induced ripening in
controlled-atmosphere chambers is possible with minimal loss of
fruit quality. The fragile lateral branches can break easily when
loaded with fruits, so premature harvest helps to reduce this risk
and allows storage of fruits up to 20 days at room temperature. A
cold water dipping process, developed by the New Zealand Department
of Scientific and Industrial Research also allows further storage of
6-10 weeks.
Usage
Culinary use
The fruit is eaten by scooping the flesh from a halved fruit.
When lightly sugared and cooled, the flesh is used for a breakfast
dish. Yellow-fruited cultivars have a sweeter flavor, occasionally
compared to mango or apricot. The red-fruited variety, which is much
more widely cultivated is more tart, and the savory aftertaste is
far more pronounced. In the Northern Hemisphere, tamarillos are most
frequently available from July until November, and fruits early in
the season tend to be sweeter and less astringent.
They can be made into compotes, or added to stews (e.g. Boeuf
Bourguignon), hollandaise, chutneys and curries. Desserts using this
fruit include bavarois and, combined with apples, a strudel.
In Colombia, Ecuador and parts of Indonesia (including Sumatra
and Sulawesi), fresh tamarillos are frequently blended together with
water and sugar to make a juice. It is also available as a
commercially pasteurized purée.
The flesh of the tamarillo is tangy and variably sweet, with a
bold and complex flavor, and may be compared to kiwifruit, tomato,
guava, or passion fruit. The skin and the flesh near it have a
bitter taste and are not usually eaten raw.
The tamarillo has been described as having a taste similar to
that of a passion fruit and a piquant tomato combined.
The red and purple types of fruits are prefered in import
countries of Europe: Even though they taste more acidic, their color
is favoured by consumers.
Industrial use
The fruits are high in pectin and therefore have good properties
for preserves. However, they oxidize and loose color when not
treated. Yellow fruit types are better applicable for industrial
use.
Prospects |
