Brassica carinata (PROTA)

Plant Resources of Tropical Africa Introduction

List of species

General importance
Geographic coverage Africa
Geographic coverage World
Vegetable
Vegetable oil
Medicinal
Forage / feed
Food security

distribution in Africa (planted and naturalized)

1, habit of young plant; 2, flowering and fruiting branch; 3, fruit. Redrawn and adapted by Iskak Syamsudin

plant habit

the distinctly broad siliques

Ethiopian kale in homegarden

Brassica carinata A.Br.

Protologue: Flora 24: 267 (1841).

Family: Brassicaceae (Cruciferae)

Chromosome number: 2n = 34

Synonyms

• Brassica integrifolia (H.West) Rupr. var. carinata (A.Braun) O.E.Schulz (1919).

Vernacular names

• Ethiopian kale, Ethiopian mustard, Ethiopian rape, Abyssinian mustard (En).
• Chou éthiopien, moutarde d’Abyssinie (Fr).
• Figiri (Sw).

Origin and geographic distribution

Brassica carinata is an amphidiploid with one genome from Brassica nigra (L.) Koch and the other from Brassica oleracea L. Ethiopia is the centre of genetic diversity of Brassica carinata, and its cultivation is thought to have started there about 4000 years BC. Truly wild types are not known, but Brassica carinata often escapes from cultivation. In the literature it has been much confused with Brassica juncea (L.) Czern., and therefore its exact distribution in Africa is difficult to indicate. The cultivation of Brassica carinata as an oil crop is restricted to Ethiopia, but as a leafy vegetable it is often grown in East and southern Africa, less so in West and Central Africa.

Uses

In most parts of Africa, the primary use of Brassica carinata is as a cooked leafy vegetable, whereas in Ethiopia, where it is called ‘gomen zer’ in Amarainya, the seed oil is of major importance too. Outside Africa, especially in western and southern Asia, it is occasionally grown as an oilseed crop or for mustard. The seeds are crushed and the oil is used for cooking and in the mustard industry. The oil has limitations for cooking because of high contents of glucosinolates and erucic acid. In Ethiopia it is used for oiling the baking plates of earthenware ‘injera’ stoves. It is also used for illumination. The seed is used in folk medicine to treat stomach-ache. People in Ethiopia use the sharp-tasting seeds as a spice to flavour raw meat. The crop is occasionally used as fodder for livestock and the seeds to feed birds. The seed cake is used as high protein food for animals, although the presence of glucosinolates is a limiting factor. Of late, there has been an interest in utilizing the oil, like other Brassica seed oils, as a biodiesel and for the preparation of special erucic acid derivatives.

Production and international trade

Production of Brassica carinata for its seed is important only in Ethiopia; production in Canada and the Mediterranean region is still mainly experimental. As a leafy vegetable it is mostly grown as a kitchen garden crop, although in Tanzania, Malawi, Zambia and to a lesser extent in Zimbabwe it is also grown as a market crop. Its use as a leaf crop appears to be declining because of higher yielding leaf cabbage (Brassica oleracea) and leaf mustard (Brassica juncea). No statistical data on its production are known.

Properties

There is no information on the nutritional composition of Brassica carinata leaves, but it is probably comparable to Brassica juncea. The seeds are rich in oil, containing 25–47% depending on cultivar and growing conditions; the protein content is also high, 25–45% and comparable to that of pulses. The oil consists of: erucic acid 35–44%, linoleic acid 15–22%, linolenic acid 16–20%, oleic acid 10–12%, eicosenoic acid 7–9% and palmitic acid 2–4%. Lines containing oil without erucic acid have been developed through cross-breeding with Brassica juncea and Brassica napus L. and through mutagenesis. The seeds have a high content of glucosinolates (100–200 μmoles/g), almost exclusively sinigrin, which has antioxidant but also goitrogenic properties. The phytoalexin brassilexin and several of its precursors are synthesized by Brassica carinata in response to attack by the blackleg pathogen Leptosphaeria maculans, which may explain its resistance to it.

Adulterations and substitutes

The Brassica carinata leaf crop can be replaced by the various types of leaf cabbage (Brassica oleracea) or leaf mustard (Brassica juncea), the seed crop by Brassica juncea, Brassica napus or Brassica nigra.

Description

• Erect, annual or occasionally biennial or perennial herb up to 150(–200) cm tall, usually branched, glabrous to slightly hairy at stem and petiole bases, slightly glaucous; taproot strong.
• Leaves alternate, usually simple, lower ones sometimes with 1 pair of small side lobes at base; stipules absent; all leaves with short petiole; blade obovate, up to 20 cm × 10 cm, double-crenulate but upper ones often more or less entire.
• Inflorescence initially a rather loose umbel-like raceme but soon elongating, up to 50 cm long.
• Flowers bisexual, regular, 4-merous; pedicel ascending, 5–12 mm long; sepals oblong, 4–6(–7) mm long, green; petals obovate, 6–10 mm long, clawed, pale to bright yellow; stamens 6; ovary superior, cylindrical, 2-celled, stigma globose.
• Fruit a linear silique 2.5–6 cm × 2–3.5 mm, often somewhat constricted between the seeds, with a conical beak 2–6(–7) mm long, dehiscent, up to 20-seeded.
• Seeds globose, 1–1.5 mm in diameter, finely reticulated, pale to dark brown.
• Seedling with epigeal germination, with a strong main root and fibrous lateral roots; hypocotyl 2–3 cm long, epicotyl very short; cotyledons broadly obovate, c. 2.5 cm long, dark green.

Other botanical information

Three wild Brassica species are found in the Mediterranean region: Brassica nigra (L.) Koch (black mustard) with the basic chromosome number n = 8 (B genome), Brassica oleracea L. (cabbage) with n = 9 (C genome) and Brassica rapa L. (turnip) with n = 10 (A genome). Brassica carinata is considered an amphidiploid hybrid between Brassica nigra and Brassica oleracea, with genomes BBCC, 2n = 34. The hybridization may have occurred on several occasions; genetic evidence indicates that in all cases Brassica nigra has been the female parent. Brassica juncea is an amphidiploid hybrid between Brassica nigra and Brassica rapa with 2n = 36. It is often confused with Brassica carinata and information can not always be attributed to either of these species with certainty. The lower leaves of Brassica juncea usually have more lobes and its fruit beak is longer (usually > 6 mm).

Growth and development

The time from sowing to emergence of the seedling is about 5 days, depending on temperature and soil moisture. Plants develop an extensive root system, larger than in other Brassica species. In general, large-leaved cultivars have fewer branches than small-leaved ones. There is a difference in first flowering date between oil types and vegetable types; oil types start flowering about 10 weeks after germination, vegetable cultivars after about 12 weeks, depending on cultivar and growing conditions. Flowering of vegetable cultivars is delayed by regular harvesting of leaves or young shoots. Plants grown in dry regions flower earlier and produce ripe seeds within 4 months from sowing. Vegetable crops grown with adequate moisture produce seeds in 5–6 months. Some tall cultivars, when grown with adequate moisture, may develop new shoots after removal of the infructescences and become perennial, normally for one further season, but plants of up to 4 years old have been recorded. Most Brassica species are cross-pollinating, which contributes to the great diversity within species. Brassica carinata is an exception as it sets seed very efficiently through self-pollination without insects acting as pollinators. It does not need low temperatures for flower initiation, and seed production is therefore much easier in Africa than for most Brassica oleracea leaf cabbages except for Portuguese kale.

Ecology

Ethiopian kale is rather versatile and can be found in highland regions up to 2600 m with a cool climate, but also in lowlands with relatively warm and dry conditions. It grows best in the dry season under irrigation when there are few pests and diseases. The crop is suited to a wide range of soils and especially the oil crop is often grown in marginal areas; the vegetable crop is mostly grown on more fertile soils. Ethiopian kale can grow from the equator to Canada and appears to be daylength neutral. It is sensitive to salt and seeds may not germinate in soils with an above average salinity level. Waterlogging is not tolerated.

Propagation and planting

Propagation is normally by seed and rarely through cuttings. The weight of 1000 seeds is 3–5 g. When grown for the leaves, sowing in a nursery and transplanting are widely practised. Seedbeds are normally raised above the soil to reduce the incidence of damping off. The top layer is dug and some well-fermented manure is worked in to produce a friable soil. Seeds are drilled in the nursery in lines 15–20 cm apart. Watering in the nursery should be done with a fine rose. Farmers may cover the seedbeds with long grass or similar material to keep the surface moist and dark. When the cotyledons have spread after germination, this mulch is removed or placed next to the plantlets. Seedlings can be transplanted at the 4-leaf stage, about 5 weeks after germination. When seedlings become too tall, they may become spindly and unlikely to develop into strong plants. The field spacing is about 35–40 cm within and 50–60 cm between rows, depending on the plant size. Near Nairobi (Kenya) the space between rows is interplanted with shallot, parsley and the leafy vegetable Crotalaria sp. When grown as an oil crop, seeds are sown directly in lines or broadcast when a short-duration leaf crop is aimed for.

Management

Ethiopian kale responds well to organic manure of up to 20 t/ha. Most farmers find it easier to incorporate chemical fertilizers in the plant beds at the rate of about 100 kg N and 30 kg P. Higher levels of nitrogen will increase proteins and enhance leaf production, whereas more phosphorous will enhance the seed production potential. Some vegetable farmers will therefore increase the initial amount to 300 kg N, whereas others give a fortnightly side dressing of 50 kg N at a time. For oilseed production, all fertilizers are incorporated at planting and no topdressing is given. For leaf production regular irrigation is necessary when it is not raining since water stress induces early flowering. When the crop is sown at the onset of the rains, attack by pests and diseases will be severe. To avoid such attacks, it is recommended that the crop be sown 5–6 weeks before rains are expected so that the crop can be transplanted at the onset of the rains.

Diseases and pests

Ethiopian kale is sensitive to turnip mosaic virus (TuMV) and especially the leaf crop is vulnerable. TuMV is transmitted by a range of aphids, of which the cabbage aphid Brevicoryne brassicae and the green peach aphid Myzus persicae are the most important. Oilseed types with bluish leaves have a thicker layer of leaf wax than green-leaved vegetable types and it has been noticed that leaf wax keeps aphids at bay to some extent. Leaf wax is also associated with the level of tolerance to Alternaria leaf spot (Alternaria brassicae). Ethiopian kale is susceptible to black rot (Xanthomonas campestris), black spot (Alternaria brassicicola), and to damping off and seedling root rot (Rhizoctonia solani). Cultivar ‘Nanga’ from Zambia has shown tolerance to black rot. Ethiopian kale is tolerant to black leg disease Leptosphaeria maculans (asexual form: Phoma lingam). White rust (Albugo candida) is mainly found on vegetable cultivars, but not in the oil crop. Xanthomonas, Alternaria, Phoma and Rhizoctonia are seedborne diseases, so a reliable seed source is most important, but these diseases are also retained in the soil so appropriate crop rotation is also essential. To avoid black rot, production during the rainy season is not recommended. The best disease control is proper management rather than a spraying regime with agro-chemicals.

Diamondback moth (Plutella xylostella) is less problematic on Ethiopian kale than on cabbages and cauliflower. Other pests include caterpillars of the cabbage butterfly (Pieris brassicae) and the grubs of mustard sawfly (Athalia proxima), a pest that is particularly important at the seedling stage. Other pests are the cabbage and mustard aphid (Hyadaphis pseudobrassicae, synonym: Lipaphis erysimi), cabbage weevil (Lixus sp.), flea beetles (Phyllotreta spp.), and hurricane bug (Bagrada cruciferarum).

Harvesting

There are several ways to harvest this vegetable. Plants from seeds that were broadcast at high density can be harvested by uprooting the whole plant 6 weeks after sowing. This method is normally used when the land is needed for another crop. For a conventional crop, the first harvest takes place about 5 weeks after transplanting. Leaf harvesting is best done once in 2 weeks with 50% defoliation. Small-leaved cultivars are often collected in the form of shoots rather than as individual leaves.

Seed crops are harvested when the fruits turn brown. Infructescences are cut and placed on a tarpaulin or similar sheet, where they are allowed to dry without risk of seed shattering. The crop is then threshed and winnowed.

Yield

The farmer can expect an average leaf and shoot yield of 35 t/ha, but at research stations leaf yields of 50–55 t/ha have been reported, depending on production season and cultivar. In India and Canada farmers may get seed yields of 1200–1800 kg/ha in a good year.

Handling after harvest

The leaves are rather perishable and wilt or become yellow when left on the shelf for more than a day. Farmers therefore harvest small quantities at a time. To retain freshness, the leaves are kept moist inside a bag that is left in the shade or in a cool place. When the product is offered as whole plants with roots, traders place the roots in water and plants can thus be kept for a few days.

Genetic resources

The genetic diversity in Brassica carinata based on molecular DNA markers is much less than in Brassica juncea. In spite of the comparatively small variation in Brassica carinata, there are many landraces for both the oilseed and the leafy vegetable types, differing in earliness, plant structure, leaf size, shape and structure, seed yield, and glucosinolate and erucic acid levels in the seed. There is a need for further collection, conservation and evaluation of this diversity before farmers start using new cultivars at the expense of their traditional landraces. A collection is maintained at the Centre for Genetic Resources (CGN), Wageningen, Netherlands. Working collections are available at research institutes in Ethiopia, Tanzania, Zambia and Zimbabwe.

Breeding

In Africa some breeding work has been done and several selections have been made in Tanzania, Zambia and Zimbabwe. Selection criteria are leaf size, late bolting, reduced susceptibility to major diseases and pests, and high yield. Well-known cultivars are ‘White Figiri’, ‘Purple Figiri’, ‘Lushoo’, ‘Mbeya Green’ and the large-leaved ‘Lambo’ from Tanzania, ‘RRS-V’ from Zimbabwe, ‘Chibanga’ and ‘NIRS-2’ from Zambia. ‘TAMU Tex Sel’ is a vegetable cultivar released in Texas (United States). In Zambia, Ethiopian kale has been crossed with Portuguese cabbage and with Brassica nigra. More breeding work has taken place on cultivars used for oilseed, mainly in Canada, India and Italy. Low erucic acid and glucosinolate content and high seed yield are major selection criteria.

Prospects

Ethiopian kale is a leafy vegetable and oil crop that is fully adapted to African conditions and has a high potential. There are many different landraces, allowing the breeder ample scope for advancement. Seed production by farmers themselves is easy, but the availability of reliable and healthy commercial seed would also benefit farmers. If no action is taken soon, this species will gradually disappear, and be replaced by new cultivars of especially Brassica juncea and loose-leaved types of Brassica oleracea, for which more research has been done and which receive more attention from breeders.

Major references

• Alemayehu, N. & Becker, H., 2002. Genotypic diversity and patterns of variation in a germplasm material of Ethiopian mustard (Brassica carinata A. Braun). Genetic Resources and Crop Evolution 49: 573–582.

• Getinet, A., Rakow, G. & Downey, R.K., 1996. Agronomic performance and seed quality of Ethiopian mustard in Saskatchewan. Canadian Journal of Plant Science 76: 387–392.

• Getinet, A., Rakow, G., Raney, J.P. & Downey, R.K., 1997. Glucosinolate content in interspecific crosses of Brassica carinata with B. juncea and B. napus. Plant Breeding 116: 39–46.

• Getinet, A., Rakow, G., Raney, J.P. & Downey, R.K., 1997. The inheritance of erucic acid content in Ethiopian mustard. Canadian Journal of Plant Science 77: 33–41.

• Maundu, P.M., Ngugi, G.W. & Kabuye, C.H.S., 1999. Traditional food plants of Kenya. Kenya Resource Centre for Indigenous Knowledge (KENRIK), Nairobi, Kenya. 270 pp.

• Mingochi, D.S. & Jensen, A., 1988. Reaction of rape and Ethiopian mustard selections to blackrot and turnip mosaic virus (TuMV) in Zambia. Acta Horticulturae 218: 289–294.

• Mnzava, N.A. & Msikita, W.W., 1988. Leaf yield response of Ethiopian mustard (Brassica carinata A. Br.) selections to defoliation regimes. Acta Horticulturae 218: 77–81.

• Mnzava, N.A. & Olsson, K., 1990. Studies in tropical vegetables: Part 1. Seed amino, fatty acid and glucosinolates profile of Ethiopian mustards (Brassica carinata Braun). IBPGR 1990. Food Chemistry 35: 229–235.

• Msikita, W.W. & Mnzava, N.A., 1988. Comparitive field performance of mustard, tronchuda and kale during mild winters in Zambia. Acta Horticulturae 218: 59–61.

• Schippers, R.R., 2002. African indigenous vegetables, an overview of the cultivated species 2002. Revised edition on CD-ROM. National Resources International Limited, Aylesford, United Kingdom.

Other references

• Cardone, M., Mazzoncini, M., Menini, S., Rocco, V., Senatore, A., Seggiani, M. & Vitolo, A., 2003. Brassica carinata as an alternative oil crop for the production of biodiesel in Italy: agronomic evaluation, fuel production by transesterification and characterization. Biomass and Bioenergy 25: 623–636.

• Cowley, W.R., 1970. Quality of Brassica carinata as a green leaf vegetable. Journal of the American Society for Horticultural Science 95(1): 3–5.

• del Río, M., de Haro, A. & Fernández-Martínez, J.M., 2003. Transgressive segregation of erucic acid content in Brassica carinata A. Braun. Theoretical and Applied Genetics 107: 643–651.

• Edwards, S.B., 1991. Crops with wild relatives found in Ethiopia. In: Engels, J.M.M., Hawkes, J.G. & Melaku-Worede (Editors). Plant Genetic Resources of Ethiopia. Cambridge University Press, Cambridge, United Kingdom. pp. 42–74.

• FAO, 1988. Traditional food plants: a resource book for promoting the exploitation and consumption of food plants in arid, semi-arid and sub-humid lands of Eastern Africa. FAO food and nutrition paper 42. FAO, Rome, Italy. 593 pp.

• Gildemacher, P., 1997. Ethiopian mustard (Brassica carinata A. Br.) as a leafy vegetable in Tanzania: farmers practices and possible improvements. Student report Wageningen University/AVRDC-Tengeru. Wageningen University, Wageningen, Netherlands.

• Gómez-Campo, C. (Editor), 1999. Biology of Brassica coenospecies. Elsevier, Amsterdam, Netherlands. 489 pp.

• Jonsell, B., 2000. Brassicaceae (Cruciferae). In: Edwards, S., Mesfin Tadesse, Demissew Sebsebe & Hedberg, I. (Editors). Flora of Ethiopia and Eritrea. Volume 2, part 1. Magnoliaceae to Flacourtiaceae. The National Herbarium, Addis Ababa University, Addis Ababa, Ethiopia and Department of Systematic Botany, Uppsala University, Uppsala, Sweden. pp. 121–154.

• Mathai, P.J., 1984. Vegetable growing in Zambia. Zambia Seed Co., Lusaka, Zambia. 344 pp.

• Mnzava, N.A., 1986. Compensatory leaf and seed yield increase in vegetable mustard (Brassica carinata A. Braun) in response to defoliation intensity. HortScience 21(3): 723.

• Pearson, M.N. & Bock, K.R., 1976. Notes on East African plant virus diseases. 10. Turnip mosaic virus. East African Agricultural and Forestry Journal 41: 344–348.

• Pedras, M.S.C., Loukaci, A. & Okanga, F.I., 1998. The cruciferous phytoalexins brassinin and cyclobrassinin are intermediates in the biosynthesis of brassilexin. Bioorganic & Medicinal Chemistry Letters 8: 3037–3038.

• Seegeler, C.J.P., 1983. Oil plants in Ethiopia, their taxonomy and agricultural significance. Agricultural Research Reports 921. Pudoc, Wageningen, Netherlands. 368 pp.

• SEPASAL, 2003. Acanthosicyos naudinianus. [Internet] Survey of Economic Plants for Arid and Semi-Arid Lands (SEPASAL) database. Royal Botanic Gardens, Kew, Richmond, United Kingdom. http://www.rbgkew.org.uk/ ceb/sepasal/acantho.htm. 24 February 2003.

• Stephens, J.M., 1994. Mustard collard - Brassica carinata L. [Internet] Fact Sheet HS–629, Horticultural Sciences Department, Florida Cooperative Extension Service, University of Florida, Gainesvile FL, United States. http://edis.ifas.ufl.edu/MV096. March 2004.

• Stephens, T.S., Saldana & Lime, B., 1975. Quality of tex-sal greens (Brassica carinata A. Br.) during maturation. Journal of the Rio Grande Valley Horticultural Society 29: 91–97.

• Westphal, A. & Marguard, R., 1981. Yield and quality of Brassica spp. in Ethiopia. Plant Research and Development 13: 114–127.

Sources of illustration

• Jonsell, B., 2000. Brassicaceae (Cruciferae). In: Edwards, S., Mesfin Tadesse, Demissew Sebsebe & Hedberg, I. (Editors). Flora of Ethiopia and Eritrea. Volume 2, part 1. Magnoliaceae to Flacourtiaceae. The National Herbarium, Addis Ababa University, Addis Ababa, Ethiopia and Department of Systematic Botany, Uppsala University, Uppsala, Sweden. pp. 121–154.

• Jonsell, B., 1982. Cruciferae. Flore de Madagascar et des Comores, familles 84–87. Muséum National d’Histoire Naturelle, Paris, France. pp. 3–32.

Author(s)

• N.A. Mnzava, Oleris Consultancy, P.O. Box 1371, Arusha, Tanzania

• R.R. Schippers, De Boeier 7, 3742 GD Baarn, Netherlands

Correct citation of this article

Mnzava, N.A. & Schippers, R.R., 2007. Brassica carinata A.Braun. [Internet] Record from PROTA4U. van der Vossen, H.A.M. & Mkamilo, G.S. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands.

Accessed 18 December 2024.