Explanation And It Examples Vegetables Crops


The range of vegetables grown in various parts of West Africa is varied since both indigenous and exotic crops are included under this general heading. Most of the local vegetables such as spinach, okra and vegetable jute are well adapted to the humid lowlands and many of the exotic or introduced temperate types can also grow under these conditions, if given good management. Many of these, however, will grow to a larger size and will mature more satisfactorily at elevations over 1,000m, due mainly to the lower temperatures and the day/night (diurnal) variation in temperature.

The main characteristics and requirements of selected vegetable crops are as follows. They are all propagated by seed, unless otherwise stated, and are mainly grown on raised beds or on ridges

Hot peppers: red pepper, bird's eye pepper (Cultural and environmental requirements)
This crop is popular in many parts of West Africa and is a short lived perennial which is tolerant to a wide range of rainfall and soil types. Fertile soils with a high organic content are most suitable and an NPK fertilizer application before planting, with later surface dressings, encourages high yields. Hoeing, weeding, mulching and irrigation during dry weather are necessary and fruits are harvested as they mature.

Rotational cropping is recommended to reduce losses due to diseases such as bacterial wilt and also nematodes.

Sweet peppers, bell peppers, bullnose peppers (Cultural and environmental requirements)
These are similar to those recommended for tomatoes although some cultivars may be particularly sensitive to wet soil conditions. Seeds are sown in containers and  transplanted to beds or ridges, but rarely require staking. Routine cultivations such as weeding, mulching, fertiliser application and spraying to control pests and diseases should be regularly carried out if high quality crops are required.

Carrots (Cultural and environmental requirements)
This crop is not widely grown, but is becoming popular in some areas. The short rooted cultivars are normally considered to give the best results but elevations over 1 000 m are necessary for the production of high yields since high temperatures affect both the quality and size of the swollen roots.

Well drained, sandy soils, with a good content of organic material are most suitable and fertiliser should be applied before sowing, and at intervals until the roots begin to swell. Seeds are sown broadcast or in drills and seedlings thinned to 5-8 cm apart; they may be earthed up when the roots begin to develop, to protect them from excessive sun. Pests and diseases may be controlled by spraying. The roots are lifted when mature and may be stored for several weeks if kept in cool conditions.

Okra, okro (Cultural and environmental requirements)
This popular vegetable is grown either on flat land or on beds and thrives well at low elevations although some cultivars are sensitive to wet soils. Both short and long duration types are grown, pods on both types may begin to mature in 8-10 weeks, but the long duration ones will continue to fruit for several months Tonger than the short season cultivars. Fertile soils promote rapid growth, the seeds are sown direct on beds or on the flat, 2-3 seeds per stand, later thinning to single plants. Crop rotation will reduce damage due to nematodes and the use of good quality seed will prevent the spread of mosaic virus.

African spinach, amaranth, bush greens
(Cultural and environmental requirements)
The various species of Amaranthus which are included under the general heading of 'spinach' include:
Amaranthus hybridus var. cruentus, A. gangeticus, and A. viridis.

African spinach is grown throughout West Africa and in many tropical regions, it has a high nutritional value and, due to the rapid growth rate, several crops per year can be grown. It is a lowland crop, rarely successful at elevations over 5-600 m. Well drained soils, of a high organic content are suitable for this crop, additions of NPK fertiliser and particularly potassium, stimulate rapid and vigorous growth.

Seeds are generally sown broadcast and thinned and some of the thinned plants used for transplanting. The crop is rarely attacked by diseases and occasional pests may be controlled by spraying, although the value of  the crop rarely justifies this. The removal of flower heads before they mature promotes the development
of leaves and lateral branches which also develop after the first harvest, giving a second crop.

Vegetable jute, long-fruited jute, bush okra (Cultural and environmental requirements)
In some areas, this vegetable is also known as African sorrel and is widely grown in most parts of West Africa. It is closely related to the jute (Corchorus capsularis) which is used in the  production of fibres for produce bags. A lowland crop, yields may be reduced if grown at elevations of more than 800 m. Soils with a good moisture retaining capacity and high organic content give early production of the leaves and young shoots which are used as a spinach.

Fertilisers also promote vigorous growth, particular nitrogenous fertilisers used as a dressing every 14-21 days until flowering. The seeds are sown on raised beds or ridges at the beginning or the end of the wet season, usually broadcast and thinned to one per stand, the thinning are often used as transplants.

Late sown crops may require irrigation in the early stages. Weeds should be controlled until the plants are well established. Nematode damage can be reduced by regular rotation.

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Lettuce (Cultural and environmental requirements)
This exotic vegetable is gaining in popularity in West Africa and is generally grown by market gardeners for sale. Many cultivars have been found to be well adapted to low elevations and high temperatures, but larger plants are produced in hilly areas or at elevations over 500 m where plants have less tendency to run to seed. There are two main groups: the 'cabbage" and the 'cos' lettuce, the latter have long crisp leaves
which are sometimes tied to encourage blanching.

Fertile soils with good reserves of organic material are essential for rapid and vigorous growth which is also
promoted by fertiliser applications, particularly nitrogen.

Seeds may be sown direct but are generally sown in containers in a nursery and transplanted to raised beds or on flat land. Young transplanted seedlings require protection from excessive rain and sun until well established; weeds should be controlled until the plants are mature. Irrigation will be necessary for dry
season crops. Pests and diseases may be controlled by spraying and crop rotation will reduce nematode infestation.

Cabbage (Cultural and environmental requirements)
This crop is normally grown for market and large heads may be obtained if cultivars suitable to the locality are grown. At low elevations, heads are slow to develop, but at elevations over 500 m, growth is more rapid and higher yields are obtained. Soils should be moisture retaining and have a good reserve of organic material. Fertilisers applied before and after transplanting will promote growth and nitrogenous fertilisers are particularly required by this crop.

Seeds are raised in containers in nursery conditions and transplanted to raised beds, ridges or flat land when 10-15 cm high; protection from wind, sun and heavy rainfall should be provided until they are well established. Diseases and pests may become serious if not controlled early, the use of sprays is normally justified due to the market value of the crop. Irrigation is required for crops grown in the dry season.

Cauliflower (Cultural and environmental requirements)
This is also an exotic crop which can be grown in West Africa if cultivars adapted to the local environment are selected. The edible part is the enlarged flower head which may grow to 15 cm in diameter, particularly if grown at elevations over 800m.

Lowland cultivation is rarely successful. As for cabbage, the soil requirements are fairly demanding, soils of high fertility and good moisture retaining capacity producing the higher yields. Fertilisers, particularly nitrogen, are required for most soils and irrigation during the dry season should be regular.

Seeds are sown in containers and transplanted to beds, ridges or on flat land; they should be shaded and watered carefully until established. Weeds should be removed until the crop is mature and irrigation will be required until the heads are formed. Excessive sun may scorch the developing heads and leaves are often
bent over the flowers or curds, as a protection against heavy rain or sun scorch. Spraying will protect the plants from diseases and pests, and rotation will reduce nematode infestation.

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