Food is a primary need of living organisms. It
provides adequate energy to do the biological and physical work. The early man
explored his surroundings to locate the materials of natural origin for food.
Still they continued their search in the plant and animal kingdoms to expand
his food basket, but due to pontification in few crops and limited land for
agricultural, a important problem has been created in last few years i.e.
providing appropriate food for increasing populace at alarming rate of the world.
Researchers are working day-night for achieving the appropriate food
requirement at root level, still need appropriate plan/policies to get the
optional food in near future. There are about 1500 wild edible plants available
in the world and many of them are found in Nigeria, whereas only very few crops
are cultivated as crop and frequently used as food. In, Nigeria, numbers of
wild/ underutilized crops is used by the rural and tribal communities. They
cultivated in home garden/ near to forest / collect from the forest, store and
they used as food staples in day-to-day
as well as in critical periods. Those wild / underutilized crops are
rich in nutrients and secondary metabolites. There are many important food crops are found in Nigeria. Among them, Plectranthus esculentus is important wild tuber crops belonging to
family Lamiaceae. It is indigenous tropical crop to Africa and easily available
in Nigeria and others Sub-Saharan African countries (Ukpabi, 2009).
It is
very popular as “Livingstone potato”. Plant was first cultivated in the upper
Niger valley of the Hausaland in Nigeria and in the Central African Republic;
although it is seen as a lost crop of Africa and it was cultivated since
pre-historic times. It is a crop that is still relevant today. Tubers of the P. esculentus are quite important as
rich of nutritious components and eaten as a substitute for potato (Solanum tuberosum). Tubers covered with
thin layer as well as small size which make it difficult peeling. For this
reason, difficult to get reasonable amount of yield. The farmers or gathers,
who are mostly rural women use traditional systems for peeling i. e. applying
friction with or without sharp sand in a flowing streams. The system is known
as abrasion method of peeling (Ap). Botanically it is Plectranthus esculentus is a perennial dicot herb that is a member of the mint family . This
herb can grow to be as tall as 2 metres. Some of the branches on the base bend
down and grow into the ground that then can form oblong tubers, which are the
fleshy underground stems. These tubers are edible and nutritious, often eaten
as a substitute for potato or sweet potato. Although they are rarely seen
because the vegetative reproduction is predominant, the plant also has yellow
flowers. These flowers are two-lipped, and are on the short and crowded
branches. While the plant is in flower the stems are leafless. Plectranthus
esculentus has fleshy leaves, on angular stems. These leaves have brown
gland-dots underneath and toothed edges. The tubers of this plant are quite
important since that is the part of the crop that is used for sale, and farmer
exchange.
Food, medicinal and economic values
The tubers of Plectranthus
esculentus are often used as a substitute for a potato or sweet potato. Directly after cultivation
it can be boiled or roasted. The stems have been used to sweeten gruel
(porridge). The leaves can be cooked in saucers as well. Plectranthus
esculentus has been said to help with digestive problems also used to treat
stomach ache and abdominal pain. It has also been used as anthelminthics. The
fleshy underground stems, the tubers are the part of the plant that is
consumed. This tuber crop is considered to be superior to other tuber crops in
terms of its food value. In 100g there is:
- Crude protein level: 13 g
- Total lipids: 0.6 g
- Total carbohydrates 80 g
- Calcium 140 mg
- Iron 50 mg
- Vitamin A 0.17 mg
It is rich in carbohydrates, vitamin
A, minerals, and essential amino acids. Plectranthus esculentus has contributed
significantly to rural diets. In 2001-2002 farmers were able sell 250 g of this
crop for up to Rand 5 (US$1), which is higher than the price of an Irish potato.
Communities can also sell the cooked leaves for Rand 7 (US$1.30). There is this
cash demand for Plectranthus esculentus but it is typically exchanged between
neighbours and friends. Women have high knowledge of this crop including
nutritious value and cultivation practices because it is indigenous. This is an
advantage for farmers since they have the initial knowledge to grow this crop
and the potential to be successful in the first season of harvest.
Research
needs
Collecting and evaluation of Tsenza varieties would be the first step in germplasm research and development for improved production of the Livingstone Potato. This would be followed by development of techniques for rapid multiplication and distribution of improved varieties. Research on agronomic practices, pest and disease control, nutritional studies, post-production handling and processing will also be done. A project on Tsenza has been initiated at the Horticultural Research Centre, Marondera, Zimbabwe to improve food security and income-generation for rural communities through the maximum utilization and conservation of P. esculentus. More research activities will follow the germplasm-collecting exercise which has already been undertaken in Seke, Nyanga and Makoni some of the major production districts in the eastern regions of Zimbabwe. Similar activities are being undertaken in Malawi and South Africa, countries that together with Zimbabwe form a network whose vision is to have P. esculentus recognized as a valuable food crop. Through this network and in close collaboration with other countries, the vision on the Livingstone Potato may be realized and P. esculentus will attain the merit and status it deserves.
Collecting and evaluation of Tsenza varieties would be the first step in germplasm research and development for improved production of the Livingstone Potato. This would be followed by development of techniques for rapid multiplication and distribution of improved varieties. Research on agronomic practices, pest and disease control, nutritional studies, post-production handling and processing will also be done. A project on Tsenza has been initiated at the Horticultural Research Centre, Marondera, Zimbabwe to improve food security and income-generation for rural communities through the maximum utilization and conservation of P. esculentus. More research activities will follow the germplasm-collecting exercise which has already been undertaken in Seke, Nyanga and Makoni some of the major production districts in the eastern regions of Zimbabwe. Similar activities are being undertaken in Malawi and South Africa, countries that together with Zimbabwe form a network whose vision is to have P. esculentus recognized as a valuable food crop. Through this network and in close collaboration with other countries, the vision on the Livingstone Potato may be realized and P. esculentus will attain the merit and status it deserves.