Common Name: Niger Seed

General Information

Guizotia abyssinica is a stout, erect annual herb growing up to 2 metres tall[, , ]. The root system is well developed, with a taproot and many lateral roots, particularly in the upper 5cm[].
Niger seed is often harvested as a source of a good quality oil; it also provides an edible seed, and has local medicinal uses. It has a history of cultivaion dating back to around 3,000 BC and is still often grown, especially in Africa and India, as an oil seed crop[, , , ], it has also been cultivated in Germany[]. Plants grown in Africa produce a better drying oil than plants from India, though it is still considered to be inferior to linseed oil (Linum usitatissimum) and is often used as an extender to that oil[].
Several factors lend credence to fears that niger seed might become a pest if introduced into warm temperate areas:- grazing animals do not relish it; the plant tolerates poor soil and drought; it has few serious pests or diseases especially outside its native range; the seeds store for a year or more without deterioration; and the seeds mature 3 - 4.5 months after planting[]. Arguing against its weed potential are the facts that it is a short day plant and therefore does not flower or set seed until daylight hours average 13 hours or less; it is self-sterile; and requires bees for pollination[].

Known Hazards

None known

Botanical References

,

Range

Northeastern tropical Africa - Eritrea, Ethiopia

Habitat

Open waste places in montane situations in west Africa[]. Casual on tips and waste ground near oil mills, and as a bird-seed alien, in Britain[].

Properties

Weed Potential	Yes
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Annual
Height	1.80 m
Pollinators	Bees, Insects
Self-fertile	No
Cultivation Status	Cultivated, Wild

Cultivation Details

Niger seed is a short-day plant adapted to the cool tropical environment of the middle elevations as well as the highland regions of eastern Africa, but it has also adapted to the tropical and subtropical lowlandsin India and to temperate conditions in Europe[]. It is reported to tolerate an annual precipitation of 660 - 1790mm, and an annual temperature range of 13.6 - 27.5°c[]. At temperatures above 30°c, the rates of growing and flowering are adversely affected and maturity is hastened. Night temperatures should not fall below 2°c[].
An easily grown plant, it succeeds in any rich soil[]. The plant is adapted to a wide range of soils, from sandy to heavy, growth being poor on light sandy or gravelly soils[]. Niger is often cultivated on very poor acid soils, on hilly slopes, where fertility is low due to leaching and washing away of the plant nutrients by erosion[]. Succeeds in soils with a pH in the range of 5.5 - 7.5[].
The first side-shoots are formed when plants have 6 - 8 leaves and are about 30cm tall[].
Most types of niger seed are short-day plants with only few day-length-insensitive individual plants. The critical day length is about 12 hours[].
Under short days, flowering starts about 60 days after germination. Photoperiod sensitivity is stronger in Ethiopian than in Indian cultivars, while in Indian plants induction of flowering probably takes place at an earlier stage of evelopment[]..
Short days 1 month after sowing gave full induction in Indian material but no induction in Ethiopian plants. In the latter, induction took place 55 - 75 days after sowing[].
Because the heads of niger seed mature over a period of time and shattering can reduce the yield by as much as 25%, the time of harvesting has to be established carefully. The best time for harvesting is just before the crop matures, about 3 weeks after 50% floret drop. At this stage, when the top leaves start turning from green to yellow, the fruits are yellow-brown and their moisture content is about 45%[].
Average seed yields in India range from 100 - 200 kg/ha when grown with ragi, and 300 - 400 kg/ha when grown in pure stands[]. In Kenya, monocultural yields average 600 kg/ha[]. Seed yields of 1,000 to 1,200 kg/ha have been obtained on fertile Himalayan soils[].
Oil content of the seed varies from 30 - 50%, reaching a maximum at 45 days after flower-opening[]. Oil yields range about 235 kg/ha[].
The flowers are very attractive to bees[].

Edible Uses

The seed is eaten fried, used as a condiment or dried then ground into a powder and mixed with flour etc to make sweet cakes[, , , ]. The black seed has an adherent thick seed coat, and can be stored for a year or so without deterioration[].
In Ethiopia the slightly roasted seeds are ground with salt and mixed with roasted cereals to prepare snacks, locally called 'litlit' and 'chibito', which are presented during coffee ceremonies[].

The seeds contains around 45% of a clear, excellent, slow-drying edible oil, with some selected cultivars containing up to 60%[]. It is used as a substitute for olive oil, can be mixed with linseed oil, and is used as an adulterant for rape oil, sesame oil etc[]. The oil is used in cooking as a ghee substitute and can be used in salad dressings etc[, ]. A pleasant nutty taste[, ]. Once extracted, the oil has the disability of rather rapid deterioration[].
The major fatty acids in the oil are palmitic acid 7.6 - 8.7%; stearic acid 5.6 - 7.5%; oleic acid 4.8 - 8.3% ;and linoleic acid 74.8 - 79.1%[]. Palmitoleic acid, linolenic acid, arachidic acid, eicosenoic acid, behenic acid, erucic acid and lignoceric acid make up the remaining 2 - 3% of the oil[]. The oil has a solidification point between -9°c and -15°c[].
While Ethiopian niger seed oil contains over 70% linoleic acid, Indian oil contains only 45 - 70% linoleic acid and 15 - 40% oleic acid[].

Medicinal

The oil from the seeds is used in the treatment of rheumatism[, , ]. The oil is also used in birth control and to treat syphilis[].
The oil is applied topically to treat burns[].
A paste of the seeds is applied as a poultice in the treatment of scabies[].
Niger seed sprouts, mixed with garlic and honey, are taken to treat cough[].

A medical test for the identification of the fungus Cryptococcus neoformans, which causes a serious brain disease, is carried out on a niger seed-based agar medium[].

Agroforestry Uses:

The plant can be used as a green manure[]. It is usually dug in when the plants are about to come into flower[].
The residual seed-cake after oil extraction has a high manurial value[].
Cattle in India will not browse the plant and it is often planted around other crops to discourage trespass by cattle[].
Niger seed is grown both as an intercrop (commonly with sorghum, maize, millet, cowpea, soya bean and sweet potato) and in pure stands[].
Niger seed is a good precursor for many crops because crops following niger seed have less weed infestation and profit from the large amount of organic matter left in the ground[].

Other Uses

A drying oil is obtained from the seed[, , , , ]. It is used medicinally, for burning, in making soap, paints etc[, , , ]. The oil readily absorbs smells and appears to offer some scope in cosmetics[].

In Ethiopia the straw is used as fuel for cooking[].

Propagation

Seed - sow spring in situ and only just cover the seed. Make sure the soil does not dry out because this would delay germination. In warm weather, germination should take place within 3 - 4 days of sowing the seed. When sowing larger areas, the seed may be broadcast at rate of 10 kg/ha or sown in rows 40 to 50 cm apart at rate of 5 kg/ha[].