Vegetables Crops Explanation And It Examples

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

Onion (Cultural and environmental requirements)

A popular crop in West Africa and, although the bulb or globe types are more difficult to grow than shallots, the area under cultivation is rapidly increasing. Many local cultivars, e.g. Gindin Tassa, are in cultivation and form seeds at higher elevations. Onions require a fertile, deep soil, with a good water-retaining capacity.

Alluvial soils are suitable if liberally treated with organic material.

Onion seeds are sown in boxes and transplanted during the early rains, when about 12-15 cm in height, to well-firmed beds. Mature bulbs are also sometimes used, the tops being cut back before planting. NPK fertiliser should be applied to the soil before planting, and later dressings with phosphate and potassium at intervals of 14-21 days are usually beneficial to

growth. Hoeing, weeding and mulching are required and irrigation may be needed in hot weather. Bulbs require a dry period for ripening, the leaves turn brown and wither when the bulbs are ripe. Pests and diseases may be checked by spraying and crop rotation.

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Legumes Crops, Explanation And It Examples

Shallot (Cultural and environmental requirements)

Soil preparation and general cultural operations are similar to those required by onions. Bulbs are planted during the early rains or at any time of the year if the soil can be kept moist. There are many local selections e.g. 'Bawku',  varying in size, colour of skin. Mature bulbs which are required for replanting should be well dried in the sun and stored for 6-8 weeks before being planted, up to 3 crops per year may be obtained.

Water melon or egusi (Cultural and environmental requirements)

Excessive rainfall may affect flowering and the spread of leaf diseases, but this crop is tolerant to a wide range of environmental conditions. Seeds are sown on mounds, ridges or raised beds or they may be raised in a nursery and transplanted. Soils with a good organic content and moisture retaining capacity are preferable, and a general dressing of NPK should be given before planting. Sulphate of ammonia may be applied at intervals of 14-21 days until flowering begins. Plants should be kept free of weeds until well developed, watering may be required in the dry season. Spraying with insecticides and fungicides gives reasonable crop protection.

Pumpkin, squash gourd (Cultural and environmental requirements)

High temperatures are required for rapid growth but excessively high humidity may be harmful and crops are usually sown to mature in the dry season. Soils with a high organic content are preferable and holes

60x 60x 60 cm, filled with compost or fym, are usually prepared in advance of planting. Seeds are sown in boxes or containers, or direct into the prepared holes.

The planting distances will vary, bush types requiring less space to develop than the trailing types. Young seedlings may require protection from strong winds or rain. NPK fertiliser may be applied before planting, followed by dressings of a nitrogenous fertiliser until flowering, at intervals of 14-21 days. Pests and diseases may be controlled by spraying.

Mature fruits may be stored for a considerable period after harvesting.

Tomato (Cultural and environmental requirements)

This is an increasingly important crop in West Africa and a great deal of experimentation and research has been done in selecting suitable cultivars for various areas and exploring the most efficient methods of growing the crop for both local consumption and processing. The control of various pests and diseases is important since this crop is liable to many fungal, bacterial and viral diseases, in addition to several pests, particularly when grown in high rainfall areas.

The best yields are obtained from plants grown to maturity during the dry season although very high temperatures may result in poor yields due to pollen becoming sterile. Well drained, fertile soils, with a good organic content are most suitable, the application of an fertiliser before sowing or planting is generally recommended.

Seeds may be sown direct or in containers and transplanted when about 10-15 cm in height, some protection from wind, rain or hot sun may be required and frequent watering will be needed until the plants are established. NPK fertiliser, possibly with additional potassium, may be applied at intervals of 14-21 days but the nitrogen content should be reduced after the first flowers have been produced. Regular weeding and watering, also mulching and staking are required, although some cultivars are short-stemmed and do not require the 2 m long stakes which are needed for supporting the taller growing cultivars.

Side shoots are usually removed to increase the size of fruits and a regular spraying programme should be followed to prevent serious outbreaks of pests and diseases. The most serious disease is bacterial with which may be partly controlled by sowing seeds direct into beds, growing them in containers to maturity, or treating the soil with a formalin solution. Nematodes may also be serious and regular crop rotation is

essential. Tomatoes and other plants of the same family (Solanaceae) should not be grown in the same area within a period of 4-5 years.

Fruits of the tomato vary widely in size and shape, depending on the cultivar grown.