|
Introduction
Narrow-leaved African nightshades, also called mnavu,
can be found throughout East Africa. There are several species
with black berries, but the most popular are those with orange
berries belonging to Solanum villosum. This group of species
is often erroneously referred to as Solanum nigrum, a
poisonous plant from Europe that is not usually grown in Africa.
African nightshades can grow on a wide range of soil types but
require regular rains or frequent irrigation. It does not tolerate
drought.
Seeds and Sowing
The soil in the nursery should be loosened and enriched with
decomposed manure. Seeds should be mixed with sand and/or ash
for uniform sowing. Sow the mixture thinly, either by broadcasting
or in rows, 15–20 cm apart and cover with a fine layer of
soil. After sowing, the bed should be mulched with tall grass
or a similar material to retain moisture. This mulch can be removed
once the plants are 3 cm. Transplant when seedlings have six
true leaves and are 10–15 cm tall. The spacing should be
20 cm in the row by 40 cm between the rows.
Crop Management
Nightshades require large amounts of nutrients, and therefore
do well in soils that are rich in organic matter. They also grow
well on land covered with ash from recently burned vegetation.
Farmers generally use 20-10-10 NPK, urea, or sulphate of ammonia
when there is no manure available. Sidedressing is practiced
after every second harvest. However, excessive applications of
nitrogen can lead to foliar diseases as well as a build-up of
nitrites, which could become a human health risk.
Frequent irrigation is needed
for good yields. Aphids are a major pest, causing leaves to curl
and become unattractive to customers. Diseases are similar to
those of potatoes and tomatoes, thus rotating with other crops
like amaranth is essential. In areas with a high humidity, wider
plant spacing should be used.
Harvesting
and Postharvest
The first harvest will be five weeks after transplanting. The
stems can be cut about 10 cm from the ground, so that new side
shoots develop. Pickings at roughly 7–14 day intervals will
allow three to four harvests per plant (more if plants are sidedressed).
If once-over harvesting is practiced, spacing can be as close
as 10 x 10 cm and plants are uprooted. This method is mainly
used when there is less than two months before the main staple
food crop will be planted. Roots of these crops can be kept in
water to keep the plants fresh.
Picking should be done very early
in the morning and the produce sold the same day. Alternatively,
the crop can be harvested late in the afternoon and placed on
plastic sheets or banana leaves. These should be tied in small
bundles. The flowers should be removed before the crop is taken
to market. Water these bundles sparingly to retain freshness. |
