Piper betle (PROSEA)
Piper betle L.
- Protologue: Sp. pl.: 28 (1753).
- Family: Piperaceae
- Chromosome number: 2n= 26, 32, 42, 52, 58, 64, 68, 78
Chavica betle (L.) Miquel (1844), Piper pinguispicum C. DC. & Koord. (1909).
- Betel pepper, betelvine (En). Bétel (Fr)
- Indonesia: sirih (Indonesian), suruh (Javanese), seureuh (Sundanese)
- Malaysia: sirih (Malay)
- Papua New Guinea: daka
- Philippines: ikmo (Tagalog), buyo (Bikol), mamon (Bisaya)
- Cambodia: mlu:
- Laos: ph'u
- Thailand: phlu (general)
- Vietnam: trầu, trầu không.
Origin and geographic distribution
Betel pepper is native to central and eastern Malesia and was taken into cultivation more than 2500 years ago throughout Malesia and tropical Asia. It reached Madagascar and East Africa much later, and was also introduced into the West Indies. Written Chinese sources from the period of the Tang dynasty (A.D. 618-907) described South-East Asia as a region of betel users. Betel chewing was widespread in South India and South China when the first Europeans arrived in the 15th Century.
A mixture of betel leaves and other ingredients is used as a masticatory, which acts as a gentle stimulant and is taken after meals to sweeten the breath. The ingredients of the betel mixture (quid) can vary widely per country or region. The three basic ingredients are often the betel leaf, the seed ("nut") from the areca palm ( Areca catechu L.) and lime, produced by burning seashells or slabs of limestone. In the Moluccas and certain regions of Papua New Guinea, the betel leaf is replaced by the inflorescence of P. siriboa L. Other possible ingredients include gambier ( Uncaria gambir (Hunter) Roxb.), tobacco, palm sugar and various spices, such as cardamom ( Elettaria cardamomum (L.) Maton) and clove ( Syzygium aromaticum (L.) Merrill & Perry). The various mixtures provide a wide range of different tastes. Chewing the quid discolours teeth and stains saliva, mouth and lips red. It results in copious salivation, so users have to spit frequently.
Not just the chewing of betel mixtures, but also their preparation occupied a central position in the ritual and social life of people throughout Malesia. In the old days, betel chewing was central to the spiritual rituals of birth and death as well as the rituals of courtship and marriage. It was also widely associated with health and healing. In time, betel mixtures came to be associated with contracts, agreements, weddings or other celebrations. After contracts were signed, betel was chewed to signify the final "sealing" of the agreement. In Thailand, a prospective bridegroom would ask for the hand of his beloved by presenting a special bowl full of betel leaves and areca nuts to his future in-laws.
The gradual demise of betel as a universal social grace can be traced to the advent of tobacco. Although initially more expensive and rarer than betel, South-East Asian men took to the new stimulant and by early 19th Century betel use had become increasingly associated with female usage, though even here tobacco was making inroads. Today the chewing of betel in South-East Asia is limited, by and large, to the older generation, although in Thailand it is still popular among young people. At the Chatuchak weekend market in Bangkok a popular betel quid includes a segment of the lime fruit, peanuts, shallots and palm sugar wrapped in betel leaves.
The leaves, roots and seeds are all used for medicinal purposes in Asia. The leaves are credited with, among others, carminative, stimulant, stomachic, expectorant, tonic, astringent, sialagogue, laxative, anthelminthic and aphrodisiac properties. Leaf preparations and leaf sap are used as an antiseptic and applied on wounds, ulcers, boils and bruises. Heated leaves are applied on the chest against cough and asthma, on the breasts to stop milk secretion, and on the abdomen to relieve constipation. Leaves are also used to treat nosebleed, ulcerated noses, gums and mucous membranes while the extract from the leaves is applied for wounds in the ears and as an infusion for the eye. A decoction of the leaves is used to bathe a woman after childbirth, or is drunk to lessen an unpleasant body odour. The essential oil has been used to treat affections of the mucous membrane of nose, throat and respiratory organs.
Production and international trade
India is probably the largest grower of betel pepper with an estimated cultivated area of about 50 000 ha in 1986/1987. At that time, Bangladesh was reported to have a production area of about 12 700 ha, yielding 60 100 t of leaves. Thailand exported about 4 500 t in 1991, with a value of 3.7 million US$. No other production figures are available. In South-East Asia betel pepper is a typical smallholder product.
Per 100 g chewable portion, fresh leaves of betel pepper contain approximately: water 80-85 g, protein 3 g, fat 0.8 g, reducing sugars (including glucose) 1.4-3.2 g, non-reducing sugars (including sucrose) 0.6-2.5 g, starch 1 g, fibre 2 g, ash 2 g (Ca 230 mg, P 40 mg, Fe 7 mg, ionizable iron 3.5 mg), vitamin A 9600 IU, thiamine 70μg, riboflavin 30μg, nicotinic acid 0.7 mg, vitamin C 5 mg, potassium nitrate 0.2-0.4 g, essential oil 0.1-1.8 g and tannin 1-1.3 g. The essential oil is yellowish brown, with an aromatic odour resembling that of creosote and tea, and a burning sharp flavour. Important constituents are the phenols eugenol, chavicol, methyl chavicol (estragol) and chavibetol (betelphenol; an isomer of eugenol). However, the composition of the essential oil varies strongly per cultivar. The essential oil and the sugars are responsible for the characteristic flavour which reflects the quality of the leaf of a particular cultivar. Leaves for chewing should preferably contain little starch and reducing sugars but a high proportion of sucrose. Leaves from the upper parts of the plant are said to contain more essential oil than those from the lower parts.
The betel leaf is reputed to have tumour-inhibiting properties. Some other ingredients used in the quid, however, are carcinogenic and there are indications of interactions with allopathic medicines.
Leaf extracts and the essential oil have antibacterial and antifungal activity. The essential oil also has shown anthelminthic activity against tapeworms and hookworms. The antifungal activity of betel pepper has been related to the presence of eugenol.
Adulterations and substitutes
The leaves of several Piper species are used as a substitute for those of betel pepper, e.g. P. caninum Blume in Malaysia. In the Philippines, the leaves of Premna nauseosa Blanco are sometimes used as a substitute, in Java those of Acmena acuminatissima (Blume) Merrill & Perry and Gaultheria leucocarpa Blume, and in northern Thailand those of Rubus blepharoneurus Cardot.
Dioecious, perennial, woody, glabrous climber, 5-20 m long. Stem swollen at the nodes; orthotropic branches vegetative, bearing adventitious roots for adhering in climbing; plagiotropic branches generative, without roots. Leaves alternate, coriaceous, rather variable; petiole 1-2.5 cm long; blade ovate to ovate oblong, 5-20 cm × 2-11 cm, base cordate, rounded or oblique, margin entire, apex acuminate, with 2-3 pairs of arcuate veins from the base and one pair from the midrib 1-3 cm above the base, shiny bright green. Inflorescence a cylindrical, pendulous spike, opposite a leaf; peduncle 1-6 cm long; male spike up to 12 cm long, crowded with small flowers with 2 stamens; female spike up to 5 cm × 5 mm, crowded with female flowers with 3-5 stigmas. Fruit a fleshy drupe, only apex of fruit free, at base immersed in the rachis of the spike forming a green cylindrical fleshy body, up to 5 cm × 1.5 cm. Seed suborbicular, 3-5 mm in diameter.
Growth and development
Under favourable conditions and appropriate management, stem cuttings of betel pepper grow fast and produce leaves of consumable size quite early (1.5 year after planting). Betel pepper grown under favourable conditions usually has larger and less pungent leaves. When a vine becomes 2 m long, it produces smaller and poorer quality leaves, so must be rejuvenated. The life of betel pepper plantations may vary considerably: from 3-4 years in temporary gardens to 30-50 years in permanent ones.
Other botanical information
Although P. betle is only known from cultivation, it is a very variable species. Part of the variability can be explained by its dioecious nature. Moreover, it is a polyploid species ( x = 13) with different ploidy levels within the species. Numerous cultivars exist with leaves differing in size, shape and colour, and in softness, pungency, aroma and bleaching response. Some cultivars have red veins and petioles. In Indonesia and Malaysia some cultivars have a clove-like flavour. In India 5 cultivars are known, differing in morphology and essential-oil composition: "Bangla", "Desawari", "Kapoori", "Meetha" and "Sanchi". Closely related species and also only known from cultivation are P. siriboa L. ( P. betle L. var. siriboa (L.) C. DC.) and P. chuvya (Miquel) C. DC.
Betel pepper thrives under per-humid forest conditions with high relative humidity and ample supply of soil moisture. It flourishes in areas with 2250-4750 mm annual rainfall and is cultivated at altitudes up to 900 m. It prefers shade and needs protection from wind. Betel pepper prefers deep, well-drained, friable loamy and clayey soils, rich in organic matter and with a pH of about 7-7.5.
Propagation and planting
Betel pepper is propagated by 30-45 cm long cuttings taken from the tips of orthotropic shoots. Cuttings usually have 3-5 nodes and are planted with the lowest 2 nodes buried in the soil. The cuttings are planted in nurseries or, more commonly, directly in the field, where they are planted close together in pits or long mounds. When the cuttings begin to sprout and creep along, they are tied to the support.
In vitro micropropagation of betel pepper is possible with explants from shoot and leaf tissue, which form multiple shoots and regenerate into plantlets, either directly or through callus formation. In India, betel pepper is mainly cultivated in small plots, in a very labour-intensive manner. It is also often intercropped with coconut palm and areca palm. In South-East Asia, betel pepper is mainly grown on a very small scale near the homestead.
Betel pepper needs support for its growth, which may be provided by trees, bamboo, wooden poles or concrete pillars. Where the vines are trained on live supports, the latter are thinned and pruned as required, to ensure optimal shade. Weeding is carried out when needed. Betel pepper is often irrigated, and in Indonesia ditches are dug for irrigation and drainage. It is usually heavily manured. A crop of 10 t of leaves will remove approximately 80 kg N, 14 kg P and 100 kg K. Betel pepper vines are seldom allowed to grow higher than 2-3 m in a plantation. Regular rejuvenation is achieved by taking the vines off their supports and burying the lower part in the soil. New roots form and the vigorous new sprouts are trained along supports. In Malaysia, the plants may be allowed to grow for 10-12 years without rejuvenation. In northern India, betel pepper gardens are usually hedged and covered over with thatch or roofed with jute matting to create a favourable microclimate.
Diseases and pests
The occurrence of diseases is an important constraint in betel pepper cultivation. The most important diseases are foot and leaf rot, anthracnose, stem or collar rot and bacterial leaf spot. The causal agents of foot and leaf rot are one of several Phytophthora spp. Phytophthora palmivora MF4 which also causes foot rot in black pepper ( Piper nigrum L.) has been isolated from Indonesian betel pepper. Symptoms of foot rot are leaf yellowing, wilting, with the vines finally drying up, and the main stem darkening at ground level. Leaf rot symptoms (circular dark brown spots, turning black and increasing in size) are mainly found during rainy periods when both temperature and humidity are high. If not controlled, foot and leaf rot may cause widespread damage and even total destruction of betel pepper plantations. Anthracnose caused by Colletotrichum capsici is an important foliage disease. It is characterized by brownish, circular leaf spots with a yellowish halo, which may coalesce into large lesions. On the stem, black specks appear under the bark; under humid conditions these grow in size and form streaks. When streaks combine and encircle the stem, the plant may wilt rapidly. Stem or collar rot is caused by Sclerotium rolfsii . Here the stem turns dark, the leaves droop and finally the plant withers and dies. Bacterial leaf spot is caused by Xanthomonas campestris p.v. beticola . Symptoms are minute lesions spread over the leaf blade, which coalesce to form brownish spots, surrounded by a yellow halo. Leaves may fall prematurely. Betel pepper is infested by a range of pests, including betelvine bugs ( Disphinctus politus ), mealy bugs ( Ferrisia virgata ), scales ( Lepidosaphes cornutus ) and whiteflies ( Dialeurodes pallida ).
Leaf harvesting of betel pepper may begin 1.5-3 years after planting. Only leaves from plagiotropic branches are picked for chewing. Each vine is picked 3-4(-5) times a year. The pickings are so arranged that not all vines are harvested at the same time. Leaves are traditionally plucked early in the morning by cutting the petiole with a sharpened steel thumbnail. They should be kept out of the sun to preserve their aroma. Other factors determining chewing quality are cultivar, leaf position and plant age. The best leaves are large, yellow and grow on the upper lateral branches. In Malaysia leaves on the lower lateral branches are regarded as medicinal and are used in preparations applied on ulcers and wounds.
Annual yields of betel pepper leaf are estimated on 6-10 t/ha. Each vine yields 40-50 leaves per year.
Handling after harvest
Leaves of betel pepper are consumed or marketed as soon as possible after harvest. When grown for commercial purposes in India, harvested leaves are washed, cleaned, graded according to size, colour, texture and maturity, and packed. Betel leaves remain fresh for 10-20 days, depending on maturity, age, quality, season and method of packing. Whereas fresh leaves are generally used for chewing, in some areas leaves are bleached before use. Bleached betel leaves normally fetch a higher price, as they are believed to possess some improved qualities (i.e. flavour). The bleaching process consists of moistening the leaves and allowing them to stand in a warm, ventilated place in the absence of sunlight. Leaves may also be bleached by packing them tightly in baskets lined with banana leaves and keeping them in the dark for several days. Leaves for bleaching should not be very tender and are taken from older vines with well-developed leaves. These have a dark green colour with a prominent midrib and a rather rough petiole and surface. In India, the whole process normally takes 10-15 days during the hot season and 15-20 days under cooler circumstances. Finally, bleached leaves are dried and packed for the market. Under optimal bleaching conditions, nitrate and tannin contents will remain the same, but starch and some sugars will disappear.
In India the National Botanic Research Institute has a betel pepper germplasm collection of 85 accessions, maintained at various research centres under the All India Coordinated Research Project on Betelvine.
Growers have selected cultivars that give high yields of palatable leaves suited to local taste and environment, but little scientific breeding work has been done. Before the discovery of male and female flowering plants in India in 1989, it was thought that only male plants were cultivated there. This belief was due to the usual absence of flowers. The discovery of male and female plants has opened the possibility of developing breeding programmes for betel pepper in India.
Because of the association of betel quid use with oral cancer, stimulation of betel quid chewing should not be encouraged from a public health point of view. However, betel pepper leaves alone may have tumour-inhibiting and other medicinal properties, and increased pharmacological use may improve the prospects for growing betel pepper.
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- Tsao, P.H., Kasim, R. & Mustika, I., 1985. Morphology and identity of black pepper Phytophtora isolates in Indonesia. FAO Plant Protection Bulletin 33(2): 61-66.
Stephen P. Teo & R.A. Banka