Subject: Agricultural Science
Topic: Production of Cassava (Manihot spp)
Lesson Objectives: At the end of the lesson, learners should be able to:
i. State the varieties of cassava that are planted,
ii. Explain the processes involved in cassava production,
iii. State the uses of cassava.

Discussions

The crop Manihot esculenta, commonly known as cassava, is a woody perennial shrub cultivated extensively as annual crop in tropical and subtropical regions.

Growing Cassava Plant

Origin: Cassava originated from South and Central America (Brazil, Mexico and Guatemala) and was introduced into Nigeria by the Portuguese. It is now popular in all tropical regions of the world.

Scientific Classification

Varieties: Two varieties of cassava are very common. They are;
(a) Bitter cassava – Manihot esculenta or utilissima
(b) Sweet cassava – Manihot palmata
Each of these species have many cultivars or cultivated varieties.

Charactersitics of the Cassava Varieties

Bitter cassava

i. Has high level of prussic acid
ii. The prussic acid is distributed throughout the tuber
iii. They are late maturing and can take up to 12 – 18 months to mature
iv. Have high keeping quality especially if not harvested immediately after maturity.

Sweet cassava

i. Prussic acid is confined mainly to the peel
ii. The level of the glucoside is low
iii. They are early maturing
iv. They deteriorate rapidly if not harvested soon after maturity. Some high yielding hybrid cultivars are CH125, CH28, 53010 and 55124. Dan warri is particularly suitable for cultivation in Northern Nigeria, Nwangoye has red petiole, is low yielding but is early maturing.

Uses of cassava:

i. It is used as staple human food in the tropics
ii. It is a livestock feed
iii. Cassava forms the raw material for so many industries such as starch, alcohol, drug etc manufacturing industries.

Ecological Requirements: Cassava grows in a wide range of soils provided the soils are not waterlogged. It does best in well drained sandy or light alluvial soils. Gravelly, stony and saline soils are unsuitable for cassava production. Cassava requires moderate temperature, high sunshine and humidity and performs poorly under cold conditions. Cassava is well adapted to cultivation under drought conditions and can grow where yearly rainfall is as low as 500mm but 1000 – 1500mm of evenly distributed rainfall per year is the optimum requirement.

Land preparation: Cassava is planted either on flat, on mounds or on ridges. Clear and burn the bush. Where land preparation is mechanized, ploughing is followed by harrowing or ridging but, traditionally, mounds, or ridges are prepared without ploughing.
Planting: In commercial production, mature stem cuttings are used in propagation. Mature stem cuttings of about 25cm in length is planted by either burying 0.75 of the cuttings at an angle of about 45° or placing them horizontally in the plough layer. Leaves on the cuttings are removed to reduce transpiration.
Period of planting: Cassava is propagated anytime there is enough soil moisture but generally it is planted in tge North between June and August while in the Southern Nigeria, it is between March – October for the early crop and November – December for late planting.

Spacing: The recommended spacing is 90 – 100cm and this gives about 10,000 stands/ha.

Seed Rate: Cassava bundle contains 50 stems and 4 – 5 cuttings are obtained from each stem. On the average, 50 bundles of cassava stems are required per hactare of land.

Fertilizer Application: Cassava demands a lot of potassium from the soil. Ideally, 10:10:20 of NPK is recommended but this is not always available. In its place therefore, apply 12 – 12 – 17 NPK at 250 – 500kg/ha. Excess nitrogen leads to undesirable vegetative growth and increases the level of linamarin in the tuber. Muriate of potash, if available, may also be applied.

Weeding: Weeding is manually done and involves weed removal and remoulding of ridges and mounds with hoes to prevent exposure of the tuber. The use of herbicides in weeding is currently increasing especially in modern farms.

Harvesting: Cassava matures in 9 – 18 months. This is manifested by shedding of old leaves without the new flush forming. This is when there is maximum starch content in the tuber. Cassava is harvested as need arises because the fresh tubers are highly perishable.

Harvested Cassava

Storage: Cassava tubers are processed into meal of retted cassava, tapioca, garri, starch, flakes, chips and flour. These processed forms except meal and tapioca can store for a fairly long time and may be kept in dry container and bags.

Marketing: Cassava and cassava products are sold locally in Nigeria

Harvested Cassava Sets For Marketing

Garri Processed From Cassava

Pests: Important cassava pests are grasshoppers, termites, whiteflies, mealy bugs, green and red spider mites, rodents and ruminant farm animals.

Diseases: The major diseases of cassava are cassava mosaic, bacterial blight, leaf spots, root root and root galls.

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  1. What are the different varieties of cassava that are planted
  2. Explain the processes involved in cassava production.
  3. State the uses of cassava.

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