Roselle (plant)

Roselle
	Roselle plant
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Rosids
Order:	Malvales
Family:	Malvaceae
Genus:	Hibiscus
Species:	H. sabdariffa
Binomial name
	Hibiscus sabdariffa; L.

The Roselle (Hibiscus sabdariffa) is a species of hibiscus native to the Old World tropics. It is an annual or perennial herb or woody-based subshrub, growing to 2–2.5 m tall. The leaves are deeply three- to five-lobed, 8–15 cm long, arranged alternately on the stems.

The flowers are 8–10 cm in diameter, white to pale yellow with a dark red spot at the base of each petal, and have a stout fleshy calyx at the base, 1.5–2 cm wide, enlarging to 3–3.5 cm, fleshy and bright red as the fruit matures. It is an annual plant, and takes about six months to mature.

Names

The roselle is known as the rosella or rosella fruit in Australia. It is also known as meśta/meshta on the Indian subcontinent, Gongura in Telugu,chin baung in Myanmar, krajeab in Thailand, bissap in Senegal, Mali, and Niger, the Congo and France, dah or dah bleni in other parts of Mali, wonjo in the Gambia, zobo in Nigeria (the Yorubas in Nigeria call the white variety Isapa (pronounced Ishapa)), karkade (كركديه; IPA: ['karkade]) in Egypt, Saudi Arabia, and Sudan, omutete in Namibia, sorrel in the Caribbean and in Latin America, Saril in Panama, rosela in Indonesia, asam paya or asam susur in Malaysia. In Chinese it is 洛神花 (Luo Shen Hua) .

Uses

The plant is considered to have antihypertensive properties. Primarily, the plant is cultivated for the production for bast fibre from the stem of the plant. The fibre may be used as a substitute for jute in making burlap ^[1]. Hibiscus, specifically Roselle, has been used in folk medicine as a diuretic, mild laxative, and treatment for cardiac and nerve diseases and cancer. ^[2]

The red calyces of the plant are increasingly exported to America and Europe, where they are used as food colourings. Germany is the main importer. It can also be found in markets (as flowers or syrup) in some places such as France, where there are Senegalese immigrant communities. The green leaves are used like a spicy version of spinach. They give flavour to the Senegalese fish and rice dish thiéboudieune. Proper records are not kept, but the Senegalese government estimates national production and consumption at 700 metric tons per year. Also in Myanmar their green leaves are the main ingredient in making chin baung kyaw curry.

In East Africa, the calyx infusion, called "Sudan tea", is taken to relieve coughs. Roselle juice, with salt, pepper, asafetida and molasses, is taken as a remedy for biliousness.

The heated leaves are applied to cracks in the feet and on boils and ulcers to speed maturation. A lotion made from leaves is used on sores and wounds. The seeds are said to be diuretic and tonic in action and the brownish-yellow seed oil is claimed to heal sores on camels. In India, a decoction of the seeds is given to relieve dysuria, strangury and mild cases of dyspepsia. Brazilians attribute stomachic, emollient and resolutive properties to the bitter roots.^[3]

Tea

In Africa, especially the Sahel, roselle is commonly used to make a sugary herbal tea that is commonly sold on the street. The dried flowers can be found in every market. In the Caribbean the drink is made from the fresh fruit, and it is considered an integral part of Christmas celebrations. The Carib Brewery Trinidad Limited, a Trinidad and Tobago brewery, produces a Shandy Sorrel in which the tea is combined with beer.

In Thailand, Roselle is drunk as a tea, believed to also reduce cholesterol. It can also be made into a delicious wine - especially if combined with Chinese tea leaves - in the ratio of 1:4 by weight (1/5 Chinese tea).

Beverage

See also Hibiscus tea

In the Caribean sorrel drink is made from calyces of the roselle. In Malaysia, roselle calyces are harvested fresh to produce pro-health drink due to high contents of vitamin C and anthocyanins. In Mexico, 'agua de Jamaica' (water of roselle) is most often homemade. It is prepared by boiling the dried flowers of the Jamaica plant in water for 8 to 10 minutes (or until the water turns red), then adding sugar. It is often served chilled. The drink is one of several inexpensive beverages (aguas frescas) commonly consumed in Mexico and Central America, and they are typically made from fresh fruits, juices or extracts. In Mali and Senegal, calyces are used to prepare cold, sweet drinks popular in social events, often mixed with mint leaves, dissolved menthol candy, and/or various fruit flavors.

With the advent in the U.S. of interest in south-of-the-border cuisine, the calyces are sold in bags usually labeled "Flor de Jamaica" and have long been available in health food stores in the U.S. for making a tea that is high in vitamin C. This drink is particularly good for people who have a tendency, temporary or otherwise, toward water retention: it is a mild diuretic.

In addition to being a popular homemade drink, Jarritos, a popular brand of Mexican soft drinks, makes a Jamaica flavored carbonated beverage. Imported Jarritos can be readily found in the U.S.

Medicinal uses

Many parts of the plant are also claimed to have various medicinal values. They have been used for such purposes ranging from Mexico through Africa and India to Thailand. Roselle is associated with traditional medicine and is reported to be used as treatment for several diseases such as hypertension and urinary tract infections.

Phytochemicals

The plants are rich in anthocyanins, as well as protocatechuic acid. The dried calyces contain the flavonoids gossypetin, hibiscetine and sabdaretine. The major pigment, formerly reported as hibiscin, has been identified as daphniphylline. Small amounts of delphinidin 3-monoglucoside, cyanidin 3-monoglucoside (chrysanthenin), and delphinidin are also present.

Production

Harvesting roselle planted on bris (sandy) soils in Terengganu

China and Thailand are the largest producers and control much of the world supply. Thailand invested heavily in roselle production and their product is of superior quality, whereas China's product, with less stringent quality control practices, is less reliable and reputable. The world's best roselle comes from the Sudan, but the quantity is low and poor processing hampers quality. Mexico, Egypt, Senegal, Tanzania, Mali and Jamaica are also important suppliers but production is mostly used domestically.^[4]

In the Indian subcontinent (especially in the Ganges Delta region), roselle is cultivated for vegetable fibres. Roselle is called meśta (or meshta, the ś indicating an sh sound) in the region. Most of its fibres are locally consumed. However, the fibre (as well as cuttings or butts) from the roselle plant has great demand in various natural fibre utilizing industries.

Roselle, a tetraploid species, is a relatively new crop and industry in Malaysia. It was introduced in early 1990s and its commercial planting was first promoted in 1993. It is gradually becoming an important pro-health drink in the country. To a small extent, the calyces are also processed into sweet pickle, jelly and jam. The planted area is still small, around 150 ha annually, planted with mainly two varieties. In Peninsula Malaysia, Terengganu state used to be the largest producer, but now the production has spread to other states.

Genetic variation is important for plant breeders to increase its productivity. Being an introduced crop species in Malaysia, there is a limited number of germplasm accessions available for breeding. Furthermore, conventional hybridization is difficult to carry out in roselle due to its cleistogamous nature of reproduction. Because of this, a mutation breeding programme was iniated to generate new genetic variability. The use of induced mutations for its improvement was initiated in 1999, and has produced some promising breeding lines.

Crop research

In the initial years, limited research work were conducted by UM and MARDI. Research work at UKM was initiated in 1993. To date, the amount of research work is still considered small.

Crop genetic resources & improvement

Genetic variation is important for plant breeders to increase the crop productivity. Being an introduced species in Malaysia, there is a very limited number of germplasm accessions available for breeding. At present, UKM maintains a working germplasm collection, and also conducts agronomic research and crop improvement.

Mutation Breeding

Conventional hybridisation is difficult to carry out in roselle due to its cleistogamous nature of reproduction. Because of this, a mutation breeding programme was initiated to generate new genetic variability. The use of induced mutations for its improvement was initiated in 1999 in cooperation with MINT (now called Malaysian Nuclear Agency), and has produced some promising breeding lines. *Workshop on Mutation Breeding [FNCA 2005]

Natural outcrossing under local conditions

A study was conducted to estimate the amount of outcrossing under local conditions in Malaysia. It was found that outcrossing occurred at a very low rate of about 0.02%. However, this rate is much lower in comparison to estimates of natural cross-pollination of between 0.20% and 0.68% as reported in Jamaica.

Gallery

A roselle variety planted in Malaysia. Roselle fruits are harvested fresh, and their calyces are made into a drink rich in vitamin C and anthocyanins.
Two varieties are planted in Malaysia (Left - variety Terengganu; right - variety Arab)
Dried roselle calyces
Roselle calyces can also be processed into sweet pickle
Some flowers of roselle
Calyx - collective term for sepals of a flower; Epicalyx - calyx-like structure outside, but close to, the true calyx, also called false calyx.
Decorring - removal of a seed capsule from the fruit using a simple hand-held gadget to obtain its calyx (plural calyces)
Some lines developed from the breeding programme at UKM