Indigenous crop production: The versatile African eggplant

The current buzz around diversity is not just trendy scientific talk. It really is important in agriculture to diversify your farming operation. If all your eggs are in one basket and you drop the basket… well, you know the deal. If all your lands are planted to maize and the fall armyworm invades… again, you know the deal.

Indigenous food crops are highly nutritious; they have a natural resilience and are able to fight pests and diseases; they are adapted to the areas from which they originate and can survive droughts and marginal conditions.

The vigour of indigenous plant species is said to be better than that of non-native plants. To make this relative, imagine going to live among the Eskimos in Greenland. The chances are good that the cold would hammer your immune system because you are not used to those conditions and you would get sick. Bring the Eskimos here, to Africa, and one bout of malaria would probably kill them.

Description and range

The African eggplant (garden egg, bitter tomato) is a solanaceous plant (Solanum aethiopicus), a member of the same group of plants as tomatoes and potatoes.

The plant which grows up to 200 cm high, has alternate, simple leaves that get smaller towards the top. The calyx (the green ‘cup’ holding the flower) is bell-shaped and the flowers are white or, less commonly, mauve. Fruits are generally oval but can be shaped like the chilli, only bigger.

It grows in a range of ecosystems from the humid West African bush to the non-humid Savannah and is harvested for its leaves, fruit and (sometimes) roots. The nutritious leaves are high in beta-carotene, alkaloids and calcium, while the berries are high in carotene.

The leaves and fruit of the African eggplant are very popular as fresh produce on African markets. Most of the demand is met by small-scale commercial farmers. Herbalists use the roots to treat chest problems.

Because of its popularity, there is potential for production on a greater commercial scale – or, from another angle, there is a gap for more small-scale farmers to take it into their crop rotation.

The three groups of African eggplant – Gilo, Kumba and Shum – have a common wild ancestor Solanum anguivi.

Gilo grows in woodland Savannah and can take daytime temperatures of up to 35°C; Kumba grows in hotter areas and can handle temperatures of up to 49°C during the day and Shum grows in warm, humid areas. Kumba group cultivars are short cycle plants.

Soil, sun, seed fertiliser and water

All Solanaceae are heavy feeders and need fertiliser. The African eggplant can take full sun and prefers a loamy, well-drained soil.

Gilo cultivars do well in full sun on deep soils. The Kumba cultivars can tolerate pretty dry conditions and high temperatures while the Sham cultivars do better in moist environments. No cultivar of Solanum aethiopicum will tolerate cold or waterlogged conditions.

Home processed seed

There is no point in planting bad seed; it wastes your money and your time. So, make sure you get quality seed to get a decent yield. If you can’t find a reputable source of seed, grow your own and process the seed.

Home processed seed is perfectly acceptable as long as it has been properly dried and stored in a cool place.

Store ripe harvested fruit in shade for a week and then cut the fruit into quarters with a sharp, clean knife. Put the quartered fruit into a mortar and grind lightly with a pestle. Don’t grind too hard or you will crush the seed and kill the embryo.

Put the crushed fruit and seed material into a bowl of water and stir. Bits of material like the skin, partly dried fleshy parts and bad seed will float to the surface. Scoop this off, then wash the seed a few times until you have got rid of all the muck.

Hang the seed in a cloth bag (muslin or cotton) in light shade for about 24 hours by which time most of the moisture should be out. Unfurl the cloth and lay the partly dry seed on a piece of canvas, or a tarpaulin, off the ground and out of direct sunlight. Use anything handy like bricks, stone or logs to get the canvas off the ground. You do this to avoid damp rising and stopping the seed from drying out properly.

Loosen clumped seed 2 to 3 times a day to make sure that it all dries at the same time. Put the dried seed into containers and store it in a cool but airy shed, barn or room.

I have read literature on the successful use of earthenware containers with clay stoppers. If it’s really dry I don’t see the harm in using plastic containers with lids – but this would obviously be a problem if there was any moisture left in the seed.

Huge volumes of grain are stored in enormous metal silos and I’ve personally bagged Eragrostis (teff) seed to use in the following season. As usual common sense is king, and the key is to make sure the seed is dry.

(Next – Preparation, planting and feeding)

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