Wednesday, 25 September 2013

Relevance of Cassava in the Agricultural Policy of Nigeria

Classification of Cassava
Kingdom                Plantae
Phylum                  Angiosperm
Order                     Malpighlales
Family                   Euphorbiaceae
Sub Family            Crotonoideae
Genus                    Manihot
Species                  esculenta

Nigeria is the largest producers of cassava in the world but less processor of cassava and largest importer of wheat flow in the world.  The government under the administration of President Goodluck Jonathan made the following policies early in the year 2012.
  • The tax of importing wheat flour should be increased to 65%.
  • Production of more cassava for :Food security
  • 40% cassava flour input
  • Export crop for government revenue
  • Cassava for bread baking
  • Creating employment
Processing and Utilization of CassavaCassava is a very variable commodity with numerous uses and by products.  Each component of the plant can be valuable to it’s cultivators. The leaves may be consumed as a vegetable, or cooked as a soup ingredient or dried and fed to livestock as a protein feed supplement. The stem is used for plant propagation and grafting. The root are typically processed for human and industrial consumption. 
Below is an order of importance of Cassava Products being consumed in different zones.

Zone                          Order of importance (Below are the local names of cassava processed foods)
South West                Gari, Lafun, Fufu/Akpu
South South               Gari, Akpu
South East                 Gari, Fufu/Akpu
North Central            Gari, Fufu/Akpu, Starch
North East                 Fufu/Akpu, Gari, Abacha

Cassava Usage
Domestis usage
  • It is used to produce Gari
  • It leaf can be used for soup
  • It is used to make Fufu
  • It is also used for Akpu
  • It is medicinal
Industrially cassava is used:
  • For Biofuel
  • Cassava flour (for bread baking, biscuit making etc.)
  • It is also used in the production of starch
  • It is used in the production of ethanol.
  • It is used in drugs production
  • Cassava serve Animal feeding:
  • Cassava is use in the production of chips
  • It leaf can serves as sow of protein for animals
Stem usage
  • The step is use for further propagation
  • It can serves as fire wood for the villagers instead of deforestation.
Sources of income and revenue
  • Cassava can serves as source of income for farmers.
  • It can serves as source of foreign revenue for government.
Generally, cassava can be used for these products: Food confectionery, Sweeteners, Glues, Plywood, textile, paper, biodegradable products, monosodium, glutamate, and drugs malt drink cassava chips and pallets used in animal feeds and alcohol production. And lastly, cassava can be a source of foreign revenue if it is being used as one of the export goods by government of Nigeria.

The task to be faced now is how to develop successful long-term relationships between members of the cassava supply chain (farmer to agribusiness entrepreneurs) to address and resolve the problems faced by everyone from ineffectual market, low levels of technology used and inadequate policy and regulatory systems. I therefore recommend that the Government and private sector should help in providing large-scale enterprises where operation would provide employment and the large tonnage processing with marketing opportunities. Government should also provide credit facilities and fertilizers where necessary to the farmers. Roads in rural areas should be in good condition for easy transportation. I therefore challenge us all to rise and be self employed in the area of cassava planting which can increase the standard of living of the people. The greatness of a man is not in his wealth but his contribution to the society.

References for further reading
  • Brautlechet, C.D.  (1953). Starch: is sources, production Uses. Reinhold, New York. Pp 60-75.
  • IITA (2002). Competitiveness workshop.  Opportunities for Cassava in Nigeria.  Bokanga, IITA-Ibadan (2002).8-14.
  • Imo State Agricultural Development Programmed (ADP). 2O03. Report on the State Agro-Processing and Market Expansion Group (SAMEG), (2003).2:39.
  • Kormawa, P. and Akoroda, M.O. (2003). Cassava Supply Chain Arrangements for Industrial Utilization in Nigeria.  Ibadan: IITA.
  • RTEP. 1995.  Roots and Tubers Expansion Programme: Formulation Report (Vol. 2), 91/95 IF AS-NIR 64. IFAD, Rome. 
  • Scott.  G.J., Rose, G. and Ringler, C.(2000). Roots and tubers for the 21st Century: Trends, projections, and policy for developing countries.  Washington, D.C. IFPRI.
  • Shaib, B., Adamu A. and Bakshi, J. (1997).  Nigeria National Agricultural Research Strategy Plan: 1996-2010.  Ibadan, Nigeria:  Intec Printers Limited.

Economic Importance of Cassava

Brief history of Cassava
Cassava, Manihot esculenta Crantz  (also known as yuca, manioc, tapioca, mandioc etc.) is native to the South American Country of Brazil, where wild population of subspecies (flabellifolia) shown to be the progenitor of domesticated cassava are centered in West Central Brazil, where it was likely first domesticated more than 10,000 years before the present time. Cassava was introduced to the African region by Portuguese traders in the sixteenth century and has since become one of the most important staple food crops in the African continent (Jones, 1959).

Initially, cassava was grown in the forest areas but since the turn of the century, it has become a common food crop in Northern Guinea and Sudan savannah, in areas of high population density. In 1949, Pierre Marty wrote that the “poisonous roots” of a yuca were used in the preparation of bread. Also in 1854, Livingstone described the use of cassava in preparation of flour in Angola. Subsequently, Stanley described its use in Congo. Cassava cultivation increased after 1850 in the Eastern Africa sub region as a result of the efforts of  the Arabs and Europeans who recognized the value of cassava as a safeguard during the period of famine. Cassava is now grown far and wide as a food crop or for industrial purposes as more scientists, agriculturist and Plant Biologists have become aware of its importance mostly in developing countries, where it is most commonly produced.

Cassava plant is a woody herb or shrub, that could grow to a height of 1-3m or more. Leaves are green, palmate and may have 5-7 lobes. Flowers are green in colour, unisexual and lack petals. Tubers are somehow globose in shape, tapered and are composed of a homogenous flesh encased in a rind 1mm thick, which is rough and brown at the outer surface. Tubers grow in cluster of 4-8 at the stem base

Cassava can be planted as stand alone crop or cultivated along side other crops like maize, vegetables and cover crops like potato. Cultivation of cassava cuts across the tropical and Sub tropical regions of the World. The major cassava producers in the World are Nigeria, Brazil, Thailand, Indonesia, DR Congo, Ghana, Tanzania, Mozambique, Uganda, Madagascar and a host of other countries. According to the Food and Agriculture Organization of United Nations, Nigeria is largest producer of cassava in the World. In Nigeria the North Central, the South-South, the South-East, and the South West are major producers of cassava.

Cassava requires a warm humid climate, but can thrive in hot and dry conditions with a marked degree for drought tolerance. Cassava grows best on light sandy loams or loamy sands with PH of 4-8 which are moist, fertile and deep. In practice, it is grown on a wide range of soil provided the texture is friable enough to allow the development of cassava roots. Production of cassava is best when rainfall is fairly abundant, but can be grown where annual rainfall is as low as 500mm or as high as 5000mm. This plant can withstand prolong periods of drought. All growth stop below a temperature of 10 degree Celsius, an optimum temperature condition for cassava growth and development is between 25-29 degree Celsius. Yields are usually reduced at a temperature above 29 degree Celsius. Cassava is a short day plant, which makes its roots less tuberous in day lengths greater
than 10-12 hours.

Considering the fact that cassava is a very cheap and important food crop that requires little skill to cultivate, with moderate requirement for soil nutrient, climatic condition and water, its cultivation should be highly encouraged mostly in rural areas, so as to bring sustainable growth and development to such areas. Furthermore, Nigeria could get huge revenue from the exportation of cassava and it's products like starch in full capacity which will in turn boost her reputation globally not only as the largest producer of cassava in the World, but also as one of the major exporters.

References for further reading
  • Baumer, G.W. (1962). Processing of garri and tapioca in rural industries. Report to the Federal Government of Nigeria. Report No. 1486, pp 154.
  • Brautlecht, C.D. (1953). Starch: Its sources, production and Uses. Reinhold, New York. Pp 67-72.
  • A review of cassava in Africa with country case studies on Ghana, Nigeria, United Republic of Tanzania, Uganda and Benin. Retrieved on 14th Nov., 2012.
  • www.goarticle,com. Non food uses of cassava. Retrieved on 15th Nov., 2012.
  • Cassava- History and uses. Retrieved on 14th Nov., 2012. 
  • Medicinal importance of cassava. Retrieved on 15th Nov., 2012. 
  • Cassava based dishes and list of cassava diseases. Retrieved on 15th Nov., 2012.
  • Cassava origin, crop status and traditional medicine uses. Retrieved on 15th Nov., 2012.

Economic Importance of Cashew

Distribution Of Cashew
Cashew is native to Central and South America, with Eastern Brazil as its primary centre of diversity. Early Portuguese and Spanish explorers were responsible for introducing the tree into Southeast Asia, East Africa, and West Indies in the 16th century. Their primary purpose then was to combat soil erosion along the coastline. The word cashew is, in fact, derived from Portuguese name for the nut (‘caju’) which in turn was adopted from its Brazilian native name (‘acaju’). Today, cashew is an important cash crop and foreign exchange earner for many countries, including India, Nigeria, Mozambique, Tanzania, Kenya, Brazil, and Portugal. It could account for as much as 3.5-20 percent of total exports in such countries. In Nigeria, cashew is grown mostly in the middle-belt states (Kwara, Benue, and Plateau) and some of the southern states such as Oyo, Edo, Anambra and Imo. It is called 'kaju' or'kasu' in yoruba land.

The cashew tree (Anacardium occidentale L.) belongs to the Anacardium family, the same family with mango (Mangifera indica). Cashew is a sprawling evergreen tree whose canopy, at full maturity, may spread up to 12 meter in diameter. It is hardy and drought-tolerant, probably because its root system penetrates not only vertically to a considerable depth, but also literally to almost twice the canopy spread. The position of the inflorescence at branch tips suggests that cashew tree bear their fruits at the periphery of the canopy. Hence, the branches of trees spaced too closely tend to overlap and may disturb fruiting. Cross pollination is mainly by insects and wind. Field studies in Tanzania have shown that although flowers are formed profusely, only about ten percent blossoms produces fruits. This may be due to substantial fruit abortion and immature fruit drop. Insect attack and heavy rains and storm during flowering also affect the fruit percentage. Following pollination, a period of two- three months may elapse between fruit set and maturity, the nut being faster in reaching its maximum size than the apple.

The colour and the size of the apple, the size of the nuts, and the colour of the young leaves distinguish cashew varieties and hybrids, which may be yellow, red, or purple. Generally, the apple and the nuts considerable variation in yield and size provide ample scope for the selection of genotypes for use in breeding programmes. The selection of cashew trees with desirable characteristics is still the dominant method of breeding in some countries. In recent times, however, India assumed forefront position in efforts to evolve high-yielding hybrids with greatly improved production of nuts and apples. The plant traits emphasized are enhanced number of inflorescence per tree, increased ratio of hermaphrodite to male flower and extended duration of flowering. Others include large apple and nuts sizes, large kernels, and high yield nut per tree.

Cashew is essentially a tropical crop, grows best in the warm, moist and typically tropical climate. The distribution of cashew is restricted to altitudes below 700 m, although it may be found growing at elevation up to 1200 m. It is best adopted to the coastal regions. Cashew is grown in areas with rainfall ranging from 600 – 4500 mm per annum. Fruit setting in cashew will be good if rains are not abundant during flowering and nuts mature in a dry period. Cashew is a sun loving tree and does not tolerate excessive shade. It can tolerate temperature of more than 36°C for a shorter period but the most favourable temperature lies between 24°C to 28°C. Cloudy weather during flowering enhances scorching of flowers due to tea mosquito infestation. Well drained red, sandy and laterite soils are ideal for good growth and yield of cashew. More than 30 varieties which are having exportable grade of cashew kernels are released from different research institutes in India and details are furnished separately.

Uses of Cashew
  • The cashew tree has been cultivated for food and medicine for over 400 years. Cashews have served nutritional, medicinal, and wartime food. More recently, they have been used in the manufacture of adhesive, resins and natural insecticides. During world war II, the cashew tree became highly prized as the source of valuable oil drawn for the shell. 
  • The cashew kernel is a rich source of fat (46% and protein 18%) and is a good source of calcium, phosphorus and iron. It has a high percentage of polyunsaturated fatty acids, in particular, the essential fatty acid, inoleic acid. 
  • The fat apple is a source of vitamin C, calcium and iron. The bark, leaves, gum are commonly use to relieve toothache and sore gum and the baled water extract of the leaves or bark is used as mouth wash.
  • A paste of bark, grounded in water is used in a tropical applications for the cure of ringworm, in this form it can however act as irritant and should not be applied to sensitive skin or to children. 
  • The root can be used as purgative. 
  • Fibres from the leaves can be used to strengthen fishing lines and nets and as folk remedies for calcium deficiency and intestinal colic, as well as a vitamin supplement.
  • The water resistant wood is used for boats and furies, while the resin, in addition to having industrial uses, is used as an expectorant (cough remedy) and insect repellent.
Uses of Cashew Nuts
The cashew nuts kernel is constituted of three different portions namely: the shell, the kernel and the adhering testa. The primary product of cashew nuts is the kernel, which is the edible portion of the nuts and is consumed in three ways:
  • Directly by the consumers.
  • As roasted and salted nuts
  • In confectionery and bakery products, for example, finely chopped kernel are used in the production of sweets, ice cream, cake and chocolates, both at home and industrially and as paste to spread on bread.
The relative importance of these uses varies from year and country to country, but it is estimated that at least 60 percent of cashew kernels are consumed as salted nuts. Separately packed cashew nuts are a good selling line, mainly as an appetizer to cocktail drinks. Salted cashews are part of the snack food market. They compete mainly with other nuts, although chips, salted popcorn and other savoury snacks can impinge on the nuts market. The price of cashew nuts is much higher than the price of peanuts or other snacks so those sales must be based on a strong taste of preference by consumer. Cashew nuts are generally considered a luxury product and an element of their appeal may lie in this status.

Uses of Cashew Apple
In cashew producing countries, the nut is only one of the products enjoyed by the local populations. The cashew apple or false fruit is an edible food rich in Vitamin C. It can be squeezed for fresh juice, which can then be fermented into cashew wine, which is a very popular drink in West Africa. In parts of India, it is used to distil cashew liquor referred to as feni. In Brazil, the apple is used to manufacture jams and soft and alcoholic drinks. The cashew tree bears a false fruit known as cashew apple from which the nut protrudes. The cashew apple is between three and five inches long and has a smooth, shiny skin that turns from green to bright red, orange or yellow in colour as it matures. It has a pulpy, juicy structure, with a pleasant but strong astringent flavour.

The cashew apple is very rich in Vitamin C (262mg/100ml of juice) and contains five times more Vitamin C than orange. A glass of cashew apple juice meets an adult individual daily vitamin C (30mg) requirement. The cashew apple is also rich in sugars and contains considerable amount of tannins and minerals, mainly calcium, iron and phosphorous. Furthermore, the fruit has medicinal properties, it is used for curing scurvy and diarrhoea as it is effective in medicinal properties. It is also effective in preventing cholera. It is applied for neurological pain and rheumatism. It is also regarded as first- class source of energy.

In conclusion, cashew cultivation has become the subject of widespread development by agencies, producer, governments and advocates of sustainable economies. Cashew also offers environmental benefits in the fight to combat deforestation and erosion. The tree and its by-product offer medicinal benefits from traditional malaria treatment to a rich source of nutrition to the body as it contain more vitamin than orange. Cashew has also become a crop of high economy and attained the status of an export oriented commodity bringing considered foreign exchange to the country. I therefore advise us to take cashew as a good source of vitamin C.

References for further reading
  • Awareness of Cashew Product Potentials and Market Information (2012) Http://
  • Cashew nuts (seeds) and Production. (2012)
  • Gibbon. (2001). Upgrading primary production: A Global Commodity Chain Approach. World Development.29(2):18-21
  • Granastein, D. G. (2004). Biointensive Management Of Orchard Understorey http://organnic
  • Mayer, A.A. (1917). Integrated Production and Protection practices of Cashew. African journal of biotechnology.3(2):7-13
  • Ohler, D. (1979). Orchard management of cashew disease.ABC-CLIO Inc. Quebec.202pp

Monday, 23 September 2013

Medicinal Importance of Shea Butter

Shea butter, botanically called Vitellaria paradoxa is a tree of a sapotaceae family. It is a small to medium sized deciduous tree which is 10-15m high (min 7m and max 24m), branched, dense and spreading round. The bark is conspicuously thick and corky, it protects older trees against bush fires. It secretes white latex as do broken twigs or petioles. Leaves are in dense clusters, spirally arranged at the end of stout twigs, leaves are oblong. Leaf margin are wavy and bent. Petioles are 5-15cm long. The flowers develop in the axils of scale leaves, at the extremities of dormant twigs, from buds formed two years previously. The flowers are white or creamy white. In Nigeria, it is locally known as 'ORI' among the yorubas and 'OKWUMA' among the Igbos.

Natural Habitat
The Shea butter tree is light demanding specie of open site, parkland and savannah; swampy areas that are liable to flooding for any length of time are avoided. The extensive root system is essential for survival in the five to seven months dry season of savannah climate and can withstand quite severe fires. The Shea butter tree can be found in Mali, Cameroon, Congo, Cote d’Ivoire, Ghana, Togo, Senegal, Sudan, Burkina Faso, Uganda and Nigeria.

Medicinal importance
The bark: Extracts of the bark of Vitellaria  paradoxa possess anti-fungal activities against some group of fungi such as Aspergillus niger, Aspergillus flavus, Epidermophyton floccosum, Microsporum audouinii and Trichophyton mentagrophyte. Fresh materials of plants were collected and air dried for a period of two weeks and they were pre-crushed in a mortar after which they were pulverized into fine powder using electric blender. Extraction was done with cold and hot water, and ethanol. l.5g of the powdered sample was separately suspended in each 25ml of the extract ants. The cold water and ethanol extraction were done in a rotatory shaker at 60rpm for 24hrs, while the hot water was carried out in water bath at 700C for 48hrs. The mixtures were further filtered through sterile 0.45┬Ám Millipore filter. The filtrates were evaporated to semi-solid mass and subsequently dried in a beaker on water bath to give a dark brown resinous mass.

The dry extracts were later reconstituted with their respective extractants to give a concentration of 200mg/ml for the antimicrobial activity evaluation (Banso and Ayodele, 2001). The fungi used were obtained from the stock culture collection of the department of microbiology, University of Ilorin, Nigeria. After the experiment the extracts exhibited greater inhibitory effect against the dermatophytes (E. floccosum, M. audouinii and T. metagrophyte) than the Aspergillus species and the ethanolic extracts exerted the greatest inhibitory activity, followed by the hot aqueous extracts while cold aqueous extract exhibited the least.  This is because ethanol is known to dissolve multivariable compounds polar or non- polar. The bark of V.paradoxa would be fungicidal against Aspergillus spp only at higher concentration than the dermatophytes.

However, this work has shown that ethanol is the extractant of choice because the bioactive substance in the bark of V. paradoxa tested is less soluble in cold water than in ethanol. Therefore using appropriate extractants, the bark of V. paradoxa could be purified and manufactured as an antiseptic agent for the treatment of infections caused by these groups of fungi. Phytochemical screening of the stem bark extracts of V. paradoxa revealed the presence of carbohydrates, alkaloids, saponins, tannins and glycosides (E-mahmood, 2008). This study was designed to asses the toxicological effect of the ethanol extracts and the antibacterial activities of both ethanol and aqueous extracts of the stem bark of V. paradoxa against Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Enterococus faecalis, Staphylococcus aureus, Pseudomonas aeruginosa and Streptococcus pyogenes.

All the bacteria were susceptible except Pseudomonas aeruginosa and Streptococcus pyogenes that showed resistance to aqueous and ethanol extracts. A bark decoction is used in a bath to facilitate child birth in cote d’Ivore. It is drunk to encourage lactation after delivery, although in northern Nigeria such a concoction is said to be lethal. A bark infusion is used as an eyewash, a foot bath to help extract jiggers and to neutralize the venom of the spitting cobra . Infusion have also been taken for the treatment of cough, leprosy in Guinea-Bissau and for gastric problems as well as diarrhea and dysentery.

The Roots: Roots and root bark are grounded into a paste and taken orally to cure jaundice, or are boiled and pounded to treat chronic sores and girth sores in horses. They are also used for the treatment of diarrhea and stomach ache. The roots of V. paradoxa when used as chewing stick has been found to be useful in the treatment of oral infection (Ndukwe, 2005). Dried roots of V. paradoxa when chopped and milled, a pinch of three fingers is added to porridge and taken twice daily for 15 days to treat urinary schistosomiasis (Paulsen, 2006).

Shea butter nuts: Shea butter extracted from the nuts protects the skin against sun burns, so it is a useful ingredient in sun-protection or post-sun-exposure products. It also encourages wound healing and soothes skin irritation. It is stable and permits the fast release of medicaments; it can therefore be used as a base for suppositories and ointments. Shea butter is traditionally used in medicines particularly for the preparation of skin ointment which is used to treat inflammation, rashes in children, dermatitis, sunburn, chapping, irritation and as rub for rheumatism

Certified Organic Shea Nut Oil: Beautiful oil with a deep golden color which is gotten from cold pressing the nut seed of the Shea Tree. Shea oil is a byproduct of Shea butter production where the pressing of the seeds produces fractionated oil.

The leaves: leaf decoction is used for stomach ache, headache and eye lotion. Decoction of leaves of V. paradoxa is taken twice daily for 30days for the treatment of urinary schistosomiasis (Paulsen, 2006).

In conclusion the discussion above had shown that Shea butter has a high content of important chemicals such alkaloids, saponins, glycosides and carbohydrates which are useful in the production of drugs for the treatment of infectious diseases and therefore shea butter tree has proven to be an important plant species in our world today.

References for further reading   
  • Banso, A. and Ayodele, O.P. (2001). Activities of extracts of Vitellaria paradoxa against Escherichia coli and Aspergillus niger. Journal of Applied Science and Management, 5:58-65
  • Cowan, M.M. (1999). Plant products as antimicrobial agents. Clinical Microbiology Review, 12 (4):564-582.
  • Dalziel, J.M. (1968). The useful plants of west tropical Africa. Nigeria National Press Ltd, Apapa, Lagos, :232-233.
  • Emeruwa, A. L. (1982). Antibacterial substance from Vitellaria paradoxa extracts. Journal of natural products. 45(2): 123-127.
  • Etejere, E.O., Oladipo, V.T. and Bhat, R.B. (1990). Ethnobotanical studies from central Nigeria. Economic Botany, 44(3):382-390

Saturday, 21 September 2013

Wood and it's Industrial Uses

Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers (which are strong in tension), embedded in a matrix of lignin which resists compression. Majorly there are two types of wood namely; Soft wood and Hard wood. Wood is provided as secondary xylem in the stem of trees (and other woody plants). In a living tree it performs a supportive function enabling woody plants to grow larger or to stand up for themselves. It also mediates the transfer of water and nutrients to the leaves and other growing tissue. Wood may also refer to the plant material with comparable properties, and to material engineered from wood or wood chips or fiber. (Hickey, 2001).

Processes of wood formation
Wood is yielded by trees, which increase in diameter by the formation between the existing wood and inner bark of new woody layers which envelope the entire stem, living branches and roots. This process is known as Secondary growth, this originates from the activities of lateral meristem, which are of two types namely: vascular cambium and cork cambium. Between the primary phloem and primary xylem is a narrow strips of undifferentiated and meristematic procambial cells referred to as the Fascicular cambium, together with primary xylem forms the vascular bundle. At the early stages of secondary growth the parenchyma cells become meristematic becoming the Inter-fascicular cambium. Both the fascicular cambium and inter-fascicular cambium forms the vascular cambium which is the origin of secondary tissues i.e. the secondary plant body which essentially comprises the secondary xylem or wood and secondary phloem.

Types of wood
Generally there are two types of wood, depending on the type of plants from which wood is obtained. These are:
  • Softwood: the gymnosperms especially the conifers are termed softwoods. They originate from needle-like leaved trees. Softwood is homogenous in structure with predominant long straight elements. It is highly suitable for paper making.
  • Hardwood: The dicot woods are termed hardwoods. They originate from broad-leaved tress. Many commercial dicot woods (hardwood) are heterogeneous, strong, dense and heavy with high proportion of fibre tracheids and libriform fibres.
Both types of wood are widely different in density and hardness. Moreover they are identified on the basis of:
  1. Absence or presence of vessels (or pores)
  2. Axial parenchyma
  3. Rays or radial parenchyma
  4. TylosesTrees grow in thickness from their centre by adding layer of cellular rings at the outside of the tree. As they grow and age, the cells closer to the inside of tree stop conducting sap and die. The dead cells become the heartwood and the newer cells that still conduct sap form the sapwood. In many woods, the softwood is often much lighter in colour.
Properties of wood
  1. Density: one of the most important physical properties of wood is its density (which is the mass of a unit volume of wood. The mass can be determined by weighing the wood and the volume by multiplying the length and breadth.
  2. Moisture Content: This is the ratio of the mass of water content in the wood to the mass of the same sample of dried wood. Wood is hygroscopic i.e. it has affinity for water. 
  3. Shrinkage and Swelling: Loss of water in wood results in shrinkage and gain of water in swelling. The higher the moisture content the greater the swelling and vice-versa.
  4. Mechanical or strength properties: This is the ability of the wood to resist applied force or stress that might tend to change its shape and size.
  5. Thermal properties: Wood has low heat conductivity and high insulating property; hence it is suitable for building construction.
  6. Electrical properties:  Very dry especially oven-dry wood is an excellent insulator i.e. it has low electric conductivity which however increases with moisture content. (Samuel, 2000).
  7. Acoustic properties: Wood may produce sound when struck directly or may amplify or absorb sound waves; hence it is useful material for musical and other acoustic instruments.
Assessment of wood quality
Wood may be of high, medium, or low quality depending on such parameters as color, texture, grain, figure, defects, luster, odour and taste. This is used for selecting wood for various kinds of uses or application.
  • Colour: This varies from light to dark, depending on whether the material is sourced from the sapwood or heartwood. It may be light-yellow, deep-yellow, yellowish-brown, pale brown, reddish-brown, deep-brown, red or black. This is due to some chemical substance deposited in the wood tissues. For example, ebony is the black wood of many trees in the Family Ebenaceae especially the genus Diospyros. The wood is darkened by deposition of gum resin in the heartwood of the timber.
  • Texture: This refers to the surface characteristic of the wood as determined by the relative size and degree of uniformity of cells and tissues in the wood. It may be fine, coarse, even or uneven.
  • Grain: This refers to the structural arrangement, orientation and alignment of cells relative to the longitudinal axis of the board or timber.
  • Figure: This refers to the surface designs or patterns as determined by such factors as the grains, annual rings, parenchyma, chemical deposits and plane of cutting.
  • Defects: These are irregularities and faults which tend to lower the strength, durability and quality of wood. They include: checks (or shakes), knots, holes, pitch, pockets, wares, decay, blemish and reaction wood.
  • Lustre: This is the surface sheen or gloss, arising from light reflection from wood surface. Occurrence of oils and gums may enhance the luster of wood.
  • Odour and Taste: Wood from different species has their characteristic and distinctive odour and taste. The wood may be strongly aromatic or sweet- smelling as in sandal wood (Santalum album in the family Santalaceae). It may be odourless or weakly aromatic. Wood may be bitter or sweet or peppery to taste, depending on the chemical constituent of the wood.
Industrial Uses of wood
Wood has a wide array of industrial uses in pulp and paper making, match-making, boards and timber industry (furniture and construction industries.

Pulp and Paper making
  • Pulp production: Pulping in pulp production is a process of digestion or grinding of wood to free and/or delignify the fibres from their compact, lignify state thus reducing the wood to a small mass called PULP. Wood normally contains 40-50% cellulose, 10-30%, hemicelluloses, 20-30% lignin and about 10% extractives (resins, proteins, tannins, mineral salts etc).There are 3 principal types of pulping: Mechanical, chemical and semi-chemical pulping.
  1. Chemical pulping: This is the process involving the use of chemical reagents to digest, separate and delignify the fibres in the wood. the result is called CHEMICAL PULPING. There are several methods of chemical pulping methods, e.g. The sulphate or kraft process, sulphite process, soda process and the neutral sulphite process. Of which kraft process is the dominant chemical pulping method. The name, kraft process is derived from the German word ‘Kraft’ meaning ‘Strong’ because the fibre obtained from this process is very stong. This is produced by combining wood chips and chemicals In large vessels known as digesters,(sodium sulphate, sodium sulpide and sodium hydroxide) the sulphur chemicals accounts for the rotten egg smell of many pulp mills. The sulphur is used to get the fibre out of trees where heat and chemicals breakdown the lignin and binds the cellulose fibres together. kraft pulping uses less than 50% of the trees and the rest ends up as sludge which is burned, spread on land. A bonus of kraft process is that the chemicals can be recycled and re-used in the mill. Magazines, printing and graphic papers, grocery bags are examples of products made with kraft pulp. Kraft pulp is usually dark and is often bleached with chlorine compounds.
  2. Mechanical pulping: This is the process of grinding or reducing the wood into fibrous, pulpy state by purely mechanical means. This is done by physically shredding trees into pulp with grindstones  embedded with silicon carbide and aluminium oxide acting as an abrasives and/or heat. The logs must be parallel to the stone and held firmly against its surface by means of Hydraulic Arms. The surface of the stone consists of grits or ridges which tear the fibre out as the stone turns. This process use about 90% of the tree, unlike chemical pulping, mechanical pulping has weaker fibres, tends to discolour overtime and the process uses a lot of water and energy. Mechanical pulping is commonly used for newspapers and is often bleached with hydrogen peroxide chlorine.
  3. Semi-chemical pulping: This process consists of a mild chemical treatment of wood to remove partially or attack partially the fibres, followed by a mechanical grinding to separates the fibres completely to form the pulp. (Christopher, 1999).
  • Paper making: This process is achieved by means of paper-making machines, the most common model being FOURDRINIER. The paper pulp is fed into the paper-making machine (fourdrinier). A pump sprays a thin layer of the liquid paper pulp onto a moving wire screen, as the pulp is carried along the screen, the water in it drops away, and the cellulose fibers become matted together, forming paper. While the paper is still damp, it is fed into a series of rollers which press it and dries it. The paper is then spooled into huge rolls, cut into various sizes and converted into paper products.
  • Environment-friendly paper making: This is achieved by using some thermophilic(organisms that grow in extremely hot conditions) or heat loving bacteria such as Thermus aquaticus. These bacteria have ability to breakdown wood fibers to make pulp and turn the wood pulp white or bleach the pulp. The wood chips and the bacteria are incubated in the digester at high temperatures. The product is referred to as microbial pulp or organic pulp. (Abdulrahaman, 2011).
  • Manufacture of matches: There are 2 major types of matches namely: Safety matches and Non-safety matches. Safety matchstick is prepared using wood through the following phases:
I. Reduction of wood to sticks of standard shape and size: 2mmx2mmx45mm.
II. Immersion of matchstick in 2% solution of ammonium phosphate in 1% phosphoric acid. This is to prevent the matchstick from glowing after it has been burnt out (to prevent persistent afterglow).
III. dipping the tips of matchsticks in a solution of paraffin in benzene t facilitate instant combustion of wood at ignition
IV. Tipping or application of Emulsion on the tips of matchsticks.(Jaime, 2005).
  • Manufacture of particle boards or chipboards: These are boards made from wood chips or particles which are bonded or squeezed together under pressure using synthetic resin glue e.g urea formaldehyde or phenol-formaldehyde. Kitchen manufactures and flooring. There are 3 major kinds: Plain chipboard, Sandwich chipboard and Veneered chipboard
  • Manufacture of Fibreboard: A board made up of wood pulp and some additives, hardened by drying into panel. Cupboards and shelves. There are 2 kinds: Insulating board and Hardboard
  • Manufacture of Sawnwood boards: These are boards obtained from logs or timbers using saws.
  • Tangent cut-board: These are boards obtained when cut is parallel to the timber or log’s surface. There are two subtypes namely: Sash-sawn or plain and Billet-sawn boards
  • Radial cut board: These are boards obtained when the plane of cut is parallel to the medullar rays i.e. the radii of the logs.
Boards in making building industry
  • Roofing Boards
  1. Beam: A long heavy piece of wood used with others to support the roof of a building.
  2.  Rafter: the sloping beam forming part of the roof framework.
  3. Truss: a supporting framework for a roof 
  4. Purlin: a horizontal beam supported by the principles of a roof and itself supporting the rafters.
  5. Fascia: these are boards that form the perimeter of the roof.
  • Boards for window and door frames: Plywood is used for flush doors. Outside doors consist of wood planks.
  • Blockboard: This consists of a core of softwood strips glued together and covered by 2 face veneers
  • Laminboards: This consists of a core of hardwood strips glued together and covered by 2 face veneers.
Some Important timber species in Nigeria
1 Tectona  grandis  (Teak): Telephone, electric poles and Furnitures
2. Gmelina  arborea (short- fibre plant)
3. Pinus spp. (long fibre plant) used for pulp and paper-making.
4. Khaya  ivorensis (lagos mahogany/Gedu)
5. Albizia  ferruginea (Ayinre-ogo)
6. Terminalia  superb (Afara)
7. Milicia  excelsa (iroko/African oak)
8. Triplochiton  scleroxylon (African maple/obech (ebony)
10. Entandrophragma utile (mahogany)    

References for further reading
  • Adam, K.A. and Krampah, E.O. (2005). Wood anatomy of a dicotyledon  stem. The Paleobotanist. 3rd ed. 26: 199-205.
  • Allan, P.A. and Dave, O.A. (2007). Wood anatomy of trees. Geophytology. 2nd ed. 18: 217-218.
  • Bentum, M.O. (2001). Commercial timbers of West Africa. Smithsonian Contribution to Botany, pp.69
  • Christopher, J.B. (1999). Handbook of pulping and paper making. San Diego : Academic Press.
  • Hickey, M.M. and King, C.A. (2002). The Cambridge illustrated glossary of botanical terms. Cambridge University Press, Cambridge.
  • Jaime, W.O. (2005). Matches - The manufacture of fire. Indian journal of chemical technology, 12 (3): 369 – 380.
  • Samuel , J.A. (2000). The mechanical properties of wood. J. willey and Sons, pp.165.