Brassica rapa subsp. chinensis

Brassica rapa is an annual to biennial plant species native to Eurasia that is from the Brassicaceae family. It has been widely cultivated into many forms, including the turnip (a root vegetable), komatsuna, Chinese cabbage, bomdong, pak choi / bok choy, and rapini. Its domesticated forms include turnips and leafy greens, such as bok choy and napa cabbage. The oilseed types are grown for food and industrial uses. Genetic studies indicate that B. rapa was one of the earliest domesticated brassicas, with turnip-like forms arising first and additional morphotypes developing independently across Eurasia. Wild, feral, and cultivated populations are found worldwide, making the species important agriculturally, economically, and ecologically. Brassica rapa subspecies oleifera is an oilseed commonly known as turnip rape, field mustard, bird's rape, and keblock. Rapeseed oil is a general term for oil from some Brassica species. Food grade oil made from the seed of low-erucic acid Canadian-developed strains is also called canola oil, while non-food oil is called colza oil. Canola oil can be sourced from Brassica rapa and Brassica napus, which are commonly grown in Canada, and Brassica juncea, which is less common.

Description

A leafy cabbage grown as an annual. It grows 40-60 cm high. The taproot is not fleshy. The stem is short. The leaves are arranged in spirals. They are simple and broadly oval. They can be 30 cm long by 10 cm wide. The leaves form a rosette. They do not form a head. The leaf stalk is thickened. It forms a half cylinder in cross section and does not have wings. The leaf blade is entire and can have a wavy edge. Flowers are small and yellow with 4 petals. The fruit is a pod 3.5 cm long. The seeds are black and 2 mm long. Several different kinds occur.

Edible Uses

The leaves are cooked and eaten, and the stems are cooked and served with oyster sauce. Flowers are also edible.

Traditional Uses

The leaves are cooked and eaten. The stems are cooked and served with oyster sauce.

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Medicinal Uses

Cultivated varieties of B. rapa are consumed commonly as vegetables, such as turnip roots, napa cabbage, komatsuna, pak choi, and other leafy greens, particularly in East Asian, South Asian, and Mediterranean cuisines. The young leaves are a leaf vegetable eaten raw, while older leaves are typically cooked. The taproot and seeds can also be eaten raw, although the seeds contain an oil that can cause irritation for some people. Rapeseed oil from the plant is also used to make canola and colza oils. B. rapa is also commonly used as a rotational cover crop for vegetables due to its ability to prevent erosion and deter disease. Because of their fast life-cycle and genetic diversity, the B. rapa cultivar Wisconsin Fast Plants is widely used in genetics and plant biology education.

Distribution

A tropical plant. More common in lowland areas but will grow in the highlands. It suits cool seasons but will not tolerate frost. In PNG it grows between sea level and 2,300 m above sea level.

Where It Grows

Africa, Asia, Australia, Bougainville, Canada, China, Congo DR, Cook Islands, Cuba, East Africa, Fiji, FSM, Guam, Hawaii, Indochina, Indonesia, Japan, Kiribati, Madagascar, Malawi, Mozambique, Nauru, Nigeria, North America, Pacific, Papua New Guinea, PNG, Philippines, Pohnpei, Rotuma, Samoa, SE Asia, Singapore, Solomon Islands, Sri Lanka, St. Vincent and Grenadines, Tasmania, Thailand, Tonga, Tuvalu, USA, Vanuatu, Vietnam, West Africa, West Indies, West Timor,

Cultivation

Plants are grown from seed and often transplanted. A spacing of 40 cm x 40 cm is suitable. Seeds are sown direct. They are sown 1 cm deep. They germinate in about 7 days with soil temperature of 21°C. Plants are thinned to about 20 cm between plants.

Production

The whole plant is harvested after 2-3 months.

Other Information

It is a commercially cultivated vegetable. They are common and popular in lowland areas of Papua New Guinea.

Notes

There are about 30 Brassica species and many cultivated varieties.

Synonyms

Also Known As

Broad-beak mustard, Caisin, Celery mustard, Chinese cabbage, Chinese mustard, Chinese savoy, Chinese white cabbage, Choi sum, False pak-choi, Flat cabbage, Flowering white cabbage, Kisaragina, Mock pak-choi, Mustard cabbage, Pak choy, Ramirebaka, Ramiriba, Taatsai, Tah Tsai, Te kabiti n Tiaina, Tsoi sum, Yow choy

References (55)

• Brouk, B., 1975, Plants Consumed by Man. Academic Press, London. p 92
• Chin, H. F., 1999, Malaysian Vegetables in Colour. Tropical Press. p 14 (As Brassica chinensis var. parachinensis and Brassica campestris var. chinensis)
• Cundall, P., (ed.), 2004, Gardening Australia: flora: the gardener's bible. ABC Books. p 256
• Epenhuijsen C.W. van., 1974, Growing Native vegetables in Nigeria. FAO Rome, p 40
• Facciola, S., 1998, Cornucopia 2: a Source Book of Edible Plants. Kampong Publications, p 55

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