Brassica rapa (PROTA)

Plant Resources of Tropical Africa Introduction

List of species

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

distribution in Africa (planted)

1, plant habit of turnip; 2, plant habit of caisin; 3, plant habit of Chinese cabbage; 4, head of Chinese cabbage; 5, plant habit of pakchoi. Redrawn and adapted by Iskak Syamsudin

caisin, product

Chinese cabbage, plant habit in the field

cv. groups Pakchoi (left) and Chinese cabbage (right), market

cv. group Vegetable Turnip, harvested plants

Brassica rapa L.

Protologue: Sp. pl. 2: 666 (1753).

Family: Brassicaceae (Cruciferae)

Chromosome number: 2n = 20

Synonyms

• Brassica campestris L. (1753).

Vernacular names

• Neep crops (En).

• Chinese cabbage, petsai, pe-tsai (En).
• Pétsaï, chou chinois, pétsaï (Fr).
• Couve petsai (Po).

• Pakchoi, pak-choi, celery cabbage, bok choi (En).
• Pakchoï, pakchoy, chou de Shanghaï, chou chinois (Fr).
• Couve chinesa, couve da China (Po).

• Caisin, caisim, cai xin, choisum, choi-sum (En).
• Choy sum, brocoli chinois (Fr).
• Couve d’inflorescência (Po).

• Turnip (En).
• Navet, rave (Fr).
• Nabo (Po).

Origin and geographic distribution

The origin of Brassica rapa is not known; the area extending from the eastern Mediterranean to Pakistan and eastern China has been suggested. Turnip is the oldest Brassica rapa vegetable. It was described at the times of Alexander the Great (356–323 BC), whose empire included the Middle East and Persia. From there it is supposed to have spread to South-East Asia and Africa via trade routes. The wide variation in Brassica rapa, together called neep crops, evolved in different parts of the Eurasian continent. Chinese cabbage and pakchoi developed in temperate regions of eastern Asia and caisin probably in subtropical regions of China. Vegetable turnip is highly regarded in Japan, and rather popular in Europe. Oil-seed types, including turnip rape and the southern Asian crops sarson and toria, are grown for rape-oil, with production centres in India, China, Canada and Australia.

In tropical Africa Brassica rapa is occasionally reported as a cultivated vegetable in many countries, and is likely to occur in all countries. Chinese cabbage is most common, recorded as locally rather popular e.g. in Cameroon and DR Congo, followed by turnip, whereas pakchoi and caisin are found in areas with people of Asian origin. Caisin has been reported from Sierra Leone and is quite popular in Congo, where it is called ‘loundif’ in the Lengvele language, and mistakenly ‘endive’ in French.

Brassica rapa has also been recorded as a weed, e.g. in Eritrea, Ethiopia, Kenya, Uganda, Tanzania, Zimbabwe and Mozambique, probably as an escape from cultivation.

Uses

Brassica rapa comprises many crops with a variety of uses. Most important are the vegetables. The foliage of Chinese cabbage, pakchoi and caisin and the thickened taproot of vegetable turnip are used as vegetables. They are consumed boiled, in soups, fresh in salads, or stir-fried in special dishes. Caisin plants are often consumed in the flowering stage. When stir-fried, the smooth and tender petioles and peduncle retain a pleasing crispness. Chinese cabbage and pakchoi leaves are also eaten pickled. In Europe, special cultivars of turnip are important as fodder crop. Brassica rapa oil crops are of no importance in tropical Africa, but may be important elsewhere, e.g. in India, Canada and France, together with cultivars of Brassica juncea (L.) Czern. and Brassica napus L.

Production and international trade

Chinese cabbage, pakchoi and caisin are leading market vegetables in China, Japan and South-East Asia, grown on more than 500,000 ha. Vegetable turnip is rather important in Japan and Europe. In tropical Africa Chinese cabbage and turnip are rather common in city markets, but pakchoi and caisin are of minor importance. All Brassica rapa types are grown occasionally for specialized markets in major cities for consumers of Asian and – to a lesser degree – European origin. No statistical data on yield and trade are known, but international trade is probably limited to some occasional export from East Africa to Europe and Arab countries.

Properties

The nutritional composition of Chinese cabbage is per 100 g edible portion (93%): water 94.4 g, energy 67 kJ (16 kcal), protein 1.2 g, fat 0.2 g, carbohydrate 3.2 g, dietary fibre 1.2 g, Ca 77 mg, Mg 13 mg, P 29 mg, Fe 0.31 mg, Zn 0.23 mg, vitamin A 318 IU, thiamin 0.04 mg, riboflavin 0.05 mg, niacin 0.4 mg, folate 79 μg, ascorbic acid 27 mg. Raw pakchoi contains per 100 g edible portion (88%): water 95.3 g, energy 54 kJ (13 kcal), protein 1.5 g, fat 0.2 g, carbohydrate 2.2 g, dietary fibre 1.0 g, Ca 105 mg, Mg 19 mg, P 37 mg, Fe 0.8 mg, Zn 0.2 mg, vitamin A 4468 IU, thiamin 0.04 mg, riboflavin 0.07 mg, niacin 0.5 mg, folate 66 μg, ascorbic acid 45 mg. The nutritional composition of turnip roots is per 100 g edible portion (81%): water 92 g, energy 117 kJ (28 kcal), protein 0.9 g, fat 0.1 g, carbohydrate 6.4 g, dietary fibre 1.8 g, Ca 30 mg, Mg 11 mg, P 27 mg, Fe 0.3 mg, Zn 0.3 mg, vitamin A absent, thiamin 0.04 mg, riboflavin 0.03 mg, niacin 0.4 mg, folate 15 μg, ascorbic acid 21 mg (USDA, 2002).

Leaf and root extracts of Brassica rapa showed antibacterial and antifungal activities.

Description

• Erect, annual to biennial herb up to 1.5 m tall, with stout taproot, sometimes partly swollen (turnip); stem branched.
• Leaves arranged spirally but in a rosette during the vegetative stage; stipules absent; lower leaves more or less petiolate, pinnately parted with 1–5 pairs of small lateral lobes and large terminal lobe up to 90 cm × 35 cm, crenate, toothed, sinuate or entire, usually hairy; stem leaves pinnately parted to simple, clasping at base, glabrous, glaucous.
• Inflorescence a terminal umbel-like raceme up to 60 cm long, with open flowers overtopping the buds, elongating in fruit.
• Flowers bisexual, regular, 4-merous; pedicel up to 3 cm long, ascending; sepals 5–8 mm long, spreading, yellow-green; petals obovate, 0.5–1 cm long, clawed, bright yellow; stamens 6; ovary superior, cylindrical, 2-celled, stigma globose.
• Fruit a linear silique 4–10 cm × 2–4 mm, with a tapering beak 0.5–3 cm long, dehiscent, up to 30-seeded.
• Seeds globose, 1–1.5 mm in diameter, finely reticulate, dark brown.
• Seedling with epigeal germination, with a taproot and lateral roots; hypocotyl c. 5 cm long, epicotyl 2–4 mm long; cotyledons with petiole c. 2 cm long, blade cordate, 1–1.5 cm long, cuneate at base, notched at apex.

Other botanical information

The taxonomy of Brassica rapa is confused. Several infraspecific classifications have been proposed, each trying to capture the wide variation of the cultivated taxa in one taxonomical system, the result always being unsatisfactory. A classification in cultivar-groups has been made and of the approximately 12 distinguished, the following are of at least some importance for tropical Africa:

• Chinese Cabbage Group (synonym: Brassica pekinensis (Lour.) Rupr.): producing short barrel-shaped to long torpedo-shaped heads, more or less tight but never as tight as in Brassica oleracea L. (headed cabbage).

• Pak Choi Group (synonym: Brassica chinensis L.): producing a loose rosette of leaves, petioles enlarged, flattened, fleshy.

• Caisin Group (synonym: Brassica parachinensis L.H.Bailey): producing a loose rosette with orbicular basal leaves, hardly winged petioles and non-clasping stem leaves, plants harvested before flowering or when the first flowers appear.

• Vegetable Turnip Group: producing a swollen root (hypocotyl), varying in shape from flattened globose to ellipsoid and cylindrical, blunt or sharply pointed, and in colour from white to pink or yellow, apex white, green, red, pink or bronze, leaves sometimes also used as a vegetable.

Several other groups of oriental vegetables are part of Brassica rapa but are practically unknown in Africa. These include the leafy vegetables Mizuna Group, Neep Greens Group and Taatsai Group.

Growth and development

Brassica rapa seed has no dormancy, but it is advisable to wait for at least one week after seed drying before sowing. The seeds require 3–5 days to germinate under optimum soil moisture and temperature (20–25ºC). Germination is not influenced by light. Brassica rapa plants can be vernalized by low temperatures at a young stage.

Chinese cabbage seedlings normally develop 5 leafs in two whorls (early type) or 8 leaves in three whorls (late type). At this stage, when the leaves are still horizontal, the plants are transplanted to the field. New inner leaves then start to grow more upright. Heading can start at the 12^th leaf stage for early cultivars and at the 25^th leaf stage for late ones. The heads can be harvested 40–80 days after sowing. In comparison with early cultivars, late ones have both more and larger non-heading leaves and more leaves forming the head (up to 100 leaves for late types). Bolting starts with elongation of the thick short stem while flower buds develop. Biennial types bolt after a period of relatively low temperature.

Pakchoi is non-headed. The first two true leaves are opposite, later leaves are arranged spirally. At the harvest stage (after 40–45 days) a plant will have about 30 leaves: 10 juvenile, 14 fully expanded and 6 small inner leaves.

Caisin has a small number of large elliptical leaves on a relatively thin stem. It bolts 30–80 days after sowing and bolting is less temperature-dependent than in Chinese cabbage.

Turnip can be frost tolerant and is able to germinate far below the optimum temperature (starting 5 ºC). In 3 weeks the plant develops a strong taproot, 5–7 leaves and becomes 10–15 cm tall. Part of the root but mainly the hypocotyl will thicken as storage organ. In plants less than 10 weeks old, bolting can be induced by a few nights under 3ºC. Older plants require several weeks of low temperatures.

Like all Brassica species Brassica rapa has a strong taproot and an extensive finely branched root system, primarily rooting in the top 40 cm of soil. In the generative stage the root system becomes much more extensive. The plants are cross-pollinated by insects such as honeybees. After fertilization, the slender fruits develop rapidly and reach full length some 3 weeks later and are ready for harvest after another 2 weeks.

Ecology

Caisin, pakchoi and a limited number of cultivars of Chinese cabbage are normally grown at low elevations in the tropics. Turnip and most cultivars of Chinese cabbage perform better in tropical highlands, above 800 m altitude. High temperatures can cause ‘tip burn’ and prevent head formation. High day and low night temperatures promote heading. Some turnip and caisin cultivars can tolerate light frost. Most cultivars of vegetable turnip are biennial in temperate areas, requiring a cold induction for bolting of about 6 weeks below 10°C. This condition can be met in East Africa above 2000 m, but in most cases the seed is imported. Caisin can be grown year round for its leaves and tender young inflorescences in subtropical and tropical regions, indicating that flower induction is not influenced by temperature, but there is a tendency towards faster bolting during long days. Brassica rapa plants have a high water requirement, but do not tolerate flooding. They prefer a well-drained fertile clay-loam soil with a pH of 5.5–6.5. A high level of organic matter will benefit the plants and balance the availability of essential elements. Plants are sensitive to salinity.

In East and southern Africa Brassica rapa occurs locally as a weed on waste places and along roads at 1500–3000 m altitude.

Propagation and planting

Seed production of Brassica rapa is normally done outside the lowland humid tropics. Vernalization is easier and plants tend to bolt faster under cooler and longer days. Early bolting reduces the duration and cost of a seed crop. Also, many diseases occurring in the (humid) tropics cause fewer problems in cooler seed production areas. Dry seeds (less than 7% moisture content) can be stored at 20°C for at least 5 years without loss of viability. For open-pollinated cultivars of Chinese cabbage, caisin and pakchoi, seed yields of 1500 kg/ha can be achieved, and hybrids can yield 600–700 kg/ha. Decapitation of newly bolted plants stimulates the development of axillary buds and increases seed yield. For hybrid seed production, a male sterile or self-incompatible female parent is used. Commercial seed is graded for good and uniform germination. On average larger seeds give faster germination and more vigorous seedlings.

Before sowing seed may be treated with hot water or a chemical such as thiram or hypochlorite to prevent seedborne diseases. Plants can be direct seeded (sowing depth 6 mm), raised in densely sown seedbeds or raised in pots or trays for transplanting to the field. For plants raised in seedbeds or trays, water soluble fertilizer (75 ppm, NPK 20–20–20) can best be added to the irrigation water given in the early morning. In the early stage seedlings may require light shading. Hybrids (mainly of Chinese cabbage) are transplanted due to the much higher seed cost. For Chinese cabbage the 1000-seed weight is 2–4.5 g and seed requirement 300–600 g/ha if transplanted and up to 5 times as much if directly sown. Plant density depends strongly on the cultivar grown and planting method used, but is usually 60,000–80,000 plants/ha. Seedlings are transplanted 20–30 days after sowing, in the late afternoon, and in rows 30–50 cm apart and 50 cm between rows. Planting holes may be treated with fungicides before transplanting to prevent damping off.

Caisin and pakchoi are normally direct sown into the field in rows 20 cm apart or broadcast on raised beds. The 1000-seed weight is 2 g and the seed requirement 6–10 kg/ha. Seeds are covered with a thin layer of soil, rice straw or husk, and kept moist. Plants are thinned to 1 plant per 10 cm after about two weeks. In the first 2–3 weeks regular weeding is needed. If raised in seedbeds or trays, plants can be transplanted about 15–20 days after sowing.

Turnip is thinly sown in drills 30 cm apart; the seedlings are thinned to 15 cm apart in the row.

Management

The plants are grown on ridges or raised beds. Beds can be mulched with straw or plastic to reduce weed growth and retain moisture in the soil. The soil should be fine and well manured (20–50 t/ha). Good drainage especially during the rainy season is essential. The first 3–4 weeks the crop needs regular weeding. The mineral uptake is rather high. A Brassica rapa crop yielding 25 t/ha requires per ha 150–200 kg N, 15–20 kg P and 100–150 kg K. For a correct fertilizer use, soil analyses are essential, combined with crop and cultivar requirements. Fertilizer is normally given in a few steps. It is advised to give 3.5 kg/ha of boron (Borax) before planting. Asian growers give fast-growing crops foliar fertilizer including calcium and boron once a week. Crops in the tropics often suffer from lack of micronutrients resulting in yield loss and increased disease incidence. Watering should be done as required to keep the rooting zone at 65–85% field capacity. Gradual dosage of water and nutrients as in modern cultivation (drip-tape, drippers, sprinklers) will increase yield and can reduce the spread of diseases with the irrigation water. In seed production it is important to supply sufficient boron (up to 10 kg/ha).

Diseases and pests

Many diseases attack Brassica rapa in tropical areas. Grey leaf mould (Alternaria brassicae, Alternaria circinans) and downy mildew (Peronospora parasitica) can be controlled by fungicides and growing tolerant cultivars. Anthracnose (Colletotrichum higgingsianum) is a serious leaf disease of Brassica species, e.g. in Côte d’Ivoire. Bacterial soft rot (Erwinia carotovora) occurs under hot humid conditions; its incidence can be reduced by increasing soil pH (liming). Storage rots caused by Erwinia can be controlled by alum powder. Black rot (Xanthomonas campestris pv. campestris) can be controlled by the use of disease-free seeds and seedlings, by planting cultivars with a high level of tolerance and by avoiding overhead irrigation. Clubroot (Plasmodiophora brassicae) has been spreading fast during recent decades and has become a detrimental disease in African highland areas. It is often introduced with soil on roots of transplants from other infested areas and can spread rapidly with irrigation water. Once it is established it can only be eradicated by growing non-host (non-Brassica) crops for at least five years. Damage can be reduced by wide crop rotation, eradication of cruciferous weeds (alternative hosts), by liming and avoiding cultivation on soils with pH < 6.5; a new control method is adding antagonistic soil fungi (Trichoderma, Mortierella spp.). A few cultivars of Chinese cabbage appear to have some resistance to some races of the pathogen, but high levels of durable resistance are not yet available. Other noxious fungal diseases are ringspot (Mycosphaerella brassicicola) and cabbage yellows (Fusarium oxysporum), which can be controlled by crop rotation and resistant cultivars. Cauliflower mosaic virus (CaMV) and turnip mosaic virus (TuMV) can be prevented by control of the aphid vectors and by eradicating hosts like weedy Brassica species.

The most important pest of Brassica rapa is diamondback moth (Plutella xylostella) of which chemical control is increasingly ineffective because of the quick build-up of resistance to all except neem-based insecticides, whereas biological control with sex pheromones and parasitoids (Diadegma semiclausum, Apanteles plutellae, Diadromus collaris and Oomyzus sokolowski) is promising. Other insect pests are leaf webber (Crocidolomia binotalis), web worm (Hellula undalis) particularly in southern Africa, cut worm (Spodoptera littoralis), flea beetle (Phyllotreta spp.) and cabbage butterfly (Pieris canidia). The cabbage aphid (Brevicoryne brassicae) is vector of mosaic viruses; spraying is advised if more than two percent of plants are infested with aphids.

Harvesting

Leafy vegetables are best harvested early in the morning. Chinese cabbage heads are harvested when compact and firm, 40–75 days after sowing (tropical cultivars after 40–55 days). The plant is cut at the base, keeping the head intact. A few outer leaves are sometimes kept for protection during transport. Hybrids can be harvested once over, but heads of open-pollinated cultivars are checked for maturity and harvested in a few rounds. Pakchoi may be harvested as early as 3 weeks after sowing, but is usually harvested 30–45 days after sowing. Plants left in the field too long lose quality fast due to soft rot or bolting. Caisin is harvested just before the flowers open or at the maximum size of the plant just before bolting starts, generally 30–80 days after sowing. In the lowland cultivars are normally harvested several times during a period of 30–45 days after sowing. Late-bolting caisin hybrids are suitable for once-over harvesting. Plants are uprooted or cut at the base and packed in small bundles.

Turnip can be harvested after 35 days for the earliest hybrids, after up to 80 days for later types. Depending on the cultivar, the swollen taproot is 5–10 cm in diameter when ready. It is separated from the leaves (topped) or packed and sold in bundles. In older plants, quality and taste of the turnip deteriorates fast.

In seed production, plants are severed at the base when a noticeable proportion (about 80%) of the fruits have turned orange-brown; the fruits should not yet split when rubbed between the hands. Plants are bundled and hung on a pole for after-ripening and drying for one week. Then the fruits are threshed and sieved with 1.3–3.0 mm sieves, and the seed is dried in the sun. Healthy fully sun-dried seed (12% moisture content) should sink in water.

Yield

The yield of Chinese cabbage varies widely according to crop and maturity period, 30–50 t/ha of fresh product being the range for well-grown crops. Caisin can yield 20–45 t/ha in intensive cultivation. Highest yields can be achieved in very dense fields with large nitrogen applications. Pakchoi yields 10–30 t/ha depending on cultivar and time of harvest. Turnip yields 12–25 t/ha in the United States. Normally the swollen taproot is no more than 30% of the total weight of the plant.

Handling after harvest

Under ambient conditions harvested Chinese cabbage, caisin and pakchoi plants have a very limited shelf life. The produce should reach the markets on the second day after harvesting at the latest. In some cases the outer leaves of the head can be peeled off and the head still be sold after 2–3 days. Storage on ice may cause chilling injury. Chinese cabbage heads can be stored for 3–6 months at 0°C without freezing and 98–100% relative humidity. The heads of some cultivars are chilling sensitive and should be stored at slightly higher temperatures. Storage in perforated polyethylene bags can extend shelf life, as can storing the heads upside down. In general, plants grown during cooler weather and plants with firmer heads store better. Harvested caisin plants can best be stored at 0–5°C at 95% relative humidity. Because of its general tenderness, it is not suited to pickling or other post-harvest processing. Turnip is not sensitive to chilling injury and can be stored for 4–5 months at 0°C at 90–95% relative humidity. During cooling, the temperature should be reduced gradually to prevent cracking. Turnip is also pickled and slices are deep frozen or dried.

Genetic resources

The largest variation in Chinese cabbage, pakchoi and caisin is found in China. The tendency is for the many landraces to be replaced by a few improved cultivars. The collection of African landraces of Chinese cabbage, e.g. farm-saved seed of old introductions in Cameroon and Congo, might be of interest for future breeding. Many cultivars of turnip can be found in Europe and Japan. The Chinese Academy of Agricultural Sciences (CAAS) at Beijing, the Asian Vegetable Research and Development Center (AVRDC) in Taiwan, the Institute of Horticultural Research at Wellesbourne, United Kingdom, the United States Department of Agriculture (USDA) and the National Institute of Agrobiological Research at Tsukuba, Japan hold large Brassica rapa collections.

Breeding

Breeding of Chinese cabbage has received much attention from AVRDC (Taiwan) and from Asian seed companies. In the tropics, breeding is limited by difficult vernalization at ambient temperatures. If flowering can be induced in the field, plants are bagged for controlled pollination. If flowering has to be induced artificially, plants are dug out and vernalized in cold rooms. Part of the head may be cut to make bolting easier. Brassica rapa plants show inbreeding depression and clear heterosis in hybrids. F₁ hybrid breeding using self-incompatibility started in the 1950s. Both genetic and cytoplasmatic male sterility occur naturally in Brassica species. Cytoplasmatic male sterility is now widely used to produce hybrids, systems based on genetic male sterility being impractical and costly. Anther microspore culture is used for the fast creation of completely homozygous lines. The breeding efforts resulted in early producing F₁ hybrid cultivars for tropical lowland conditions, that combine medium firm heads with heat tolerance and resistance to major diseases (soft rot, anthracnose, downy mildew, leaf spot, viruses).

In caisin, hybrids are still of lesser importance, the advantages over open-pollinated cultivars being minor. Many improved cultivars are sold in large quantities in South-East Asia and southern China. Several breeding companies (Japan, China, Taiwan, Thailand) have small breeding programmes offering a wide variety of plant types. Some seed traders in Hong Kong offer good open-pollinated selections especially in the early bolting types. East-West Seed Company is the leading supplier of the late bolting type (‘Tosakan’) used in South-East Asia.

Pakchoi breeding is concentrated in Japan and China, and improved open-pollinated and hybrid cultivars are offered. Mushashino Seed is a leading supplier of tropical hybrids. Turnip breeding is mainly done by European and Japanese seed companies and many cultivars are available, but none are especially adapted to tropical conditions. Brassica rapa breeding programmes especially for tropical Africa have not yet been reported, the activities being limited to cultivar testing of Asian and European introductions.

Prospects

In tropical Africa the only important Brassica rapa crop is Chinese cabbage and interest in it is increasing. Research on its breeding and agronomy for African conditions merits attention. Pakchoi and caisin are productive tropical leafy vegetables with an excellent nutritional value; they are relatively easy to grow and worth promotion. Turnip is less adapted to the tropics and not easy to grow, and is likely to remain a minor vegetable in Africa.

Major references

• Déclert, C., 1990. Manuel de phytopathologie maraîchère tropicale: cultures de Côte d’Ivoire. Editions de l'ORSTOM, Paris, France. 333 pp.

• Jonsell, B., 1982. Cruciferae. In: Polhill, R.M. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. pp. 15–17.

• Kuo, C.G. & Toxopeus, H., 1993. Brassica rapa L. cv. group Chinese Cabbage. In: Siemonsma, J.S. & Kasem Piluek (Editors). Plant Resources of South-East Asia No 8. Vegetables. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 127–130.

• Mansfeld, R., 1986. Verzeichnis landwirtschaftlicher und gärtnerischer Kulturpflanzen (ohne Zierpflanzen). 2nd edition, revised by J. Schultze-Motel. 4 volumes. Springer Verlag, Berlin, Germany. 1998 pp.

• Opeña, R.T., Kuo, C.G. & Yoon, J.Y., 1988. Breeding and seed production of Chinese cabbage in the tropics and subtropics. AVRDC, Shanhua, Tainan, Taiwan. 92 pp.

• Opeña, R.T. & Tay, D.C.S., 1993. Brassica rapa L. cv. group Caisin. In: Siemonsma, J.S. & Kasem Piluek (Editors). Plant Resources of South-East Asia No 8. Vegetables. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 123–126.

• Shinohara, S. (Editor), 1984. Vegetable seed production technology of Japan. Volume 1. Shinohara's Authorized Agricultural Consulting Engineer Office, Tokyo, Japan. 432 pp.

• Tay, D.C.S. & Toxopeus, H., 1993. Brassica rapa L. cv. group Pak Choi. In: Siemonsma, J.S. & Kasem Piluek (Editors). Plant Resources of South-East Asia No 8. Vegetables. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 130–134.

• Toxopeus, H., 1993. Brassica rapa L. In: Siemonsma, J.S. & Kasem Piluek (Editors). Plant Resources of South-East Asia No 8. Vegetables. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 121–123.

• Toxopeus, H., Oost, E.H., Yamagishi, H. & Prescott-Allen, R., 1988. Cultivar group classification of Brassica rapa L.: update 1988. Cruciferae Newsletter 13: 9–11.

Other references

• Burkill, H.M., 1985. The useful plants of West Tropical Africa. 2nd Edition. Volume 1, Families A–D. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 960 pp.

• Holland, B., Unwin, I.D. & Buss, D.H., 1991. Vegetables, herbs and spices. The fifth supplement to McCance & Widdowson’s The Composition of Foods. 4th Edition. Royal Society of Chemistry, Cambridge, United Kingdom. 163 pp.

• Oost, E.H., Brandenburg, W.A., Reuling, G.T.M. & Jarvis, C.E., 1987. Lectotypification of Brassica rapa L., B. campestris L. and neotypification of B. chinensis L. (Cruciferae). Taxon 36(3): 625–634.

• Queensland Government, 2003. Horticulture and fresh produce. [Internet] The State of Queensland, Department of Primary Industries, Brisbane, Australia. http://www.dpi.qld.gov.au/horticulture/. January 2004.

• Toxopeus, H., Yamagishi, H. & Oost, E.H., 1987. A cultivar group classification of Brassica rapa L., update 1987. Cruciferae Newsletter 12: 5–6.

• USDA, 2002. USDA nutrient database for standard reference, release 15. [Internet] U.S. Department of Agriculture, Beltsville Human Nutrition Research Center, Beltsville Md, United States. http://www.nal.usda.gov/fnic/foodcomp. June 2003.

Sources of illustration

• Kuo, C.G. & Toxopeus, H., 1993. Brassica rapa L. cv. group Chinese Cabbage. In: Siemonsma, J.S. & Kasem Piluek (Editors). Plant Resources of South-East Asia No 8. Vegetables. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 127–130.

• Opeña, R.T. & Tay, D.C.S., 1993. Brassica rapa L. cv. group Caisin. In: Siemonsma, J.S. & Kasem Piluek (Editors). Plant Resources of South-East Asia No 8. Vegetables. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 123–126.

• Tay, D.C.S. & Toxopeus, H., 1993. Brassica rapa L. cv. group Pak Choi. In: Siemonsma, J.S. & Kasem Piluek (Editors). Plant Resources of South-East Asia No 8. Vegetables. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 130–134.

• Toxopeus, H., 1993. Brassica rapa L. In: Siemonsma, J.S. & Kasem Piluek (Editors). Plant Resources of South-East Asia No 8. Vegetables. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 121–123.

Author(s)

• H. Toxopeus, Wageningen, Netherlands

• J. Baas, East West Seed International Ltd., P.O. Box 3, Bang Bua Thong, Nonthaburi 11110, Thailand

Correct citation of this article

Toxopeus, H. & Baas, J., 2004. Brassica rapa L. [Internet] Record from PROTA4U. Grubben, G.J.H. & Denton, O.A. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands.

Accessed 18 December 2024.