Benincasa hispida (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Benincasa hispida (Thunberg ex Murray) Cogniaux

Protologue: In: A. DC, Monogr. phan. 3: 513 (1881).

Family: Cucurbitaceae

Chromosome number: 2n= 24

Synonyms

• Cucurbita hispida Thunberg ex Murray (1784),
• Benincasa cerifera Savi (1818).

Vernacular names

• Wax gourd, white gourd, Chinese preserving melon (En)
• Courge à la cire, courge cireuse (Fr)
• Indonesia: kundur, bligo, kundo (Aceh)
• Malaysia: kundor
• Philippines: kondol (Tagalog), tibiayon (Bisaya), rodal (Bicol)
• Cambodia: trâllaach
• Laos: tônx
• Thailand: fak, faeng (central), mafaeng (northern)
• Vietnam: bí dao, bí xanh.

Origin and geographic distribution

The genus Benincasa Savi is usually considered monotypic. There is no general agreement on the origin of the wax gourd. Indo-China and India are the centres of greatest diversity, but wax gourd is not known from the wild and no related wild species are known. There is some evidence that B. hispida has been cultivated in China since 500 AD. The wax gourd is now widely cultivated throughout tropical Asia, and has been introduced to other tropical, subtropical and warm temperate parts of the world as well (e.g. the Caribbean).

Uses

Wax gourd is cultivated for its immature as well as mature fruits. People in Indonesia normally scrape the skin off the gourd, discard the seeds and pith, and chop the greenish-white flesh into small blocks to be cooked in various kinds of soups. The Chinese cook wax gourd in various ways, including stuffing the entire gourd with chopped meats, shrimps, lotus seeds, mushrooms and bamboo shoots, and then steaming it in a pot. The firm flesh is often cut into pieces and candied with sugar, yielding the well-known "tangkwè". The flesh can also be dried for later use. In India the young fruits are extensively used in curries. Young shoots, leaves and flowers are also used as a vegetable. The seeds are often consumed after frying as a snack food; they are considered vermifugal as well. The Madurese (Indonesia) are known to use young wax gourd leaves as wrappers in preparing broiled salted fish to influence the flavour and the appearance of the dish. The waxy coat of the fruits is sometimes used to make candles. The fruits are valued for their medicinal (diuretic, laxative, tonic) and cooling properties and for their beneficial effect in treating nervous disorders.

Production and international trade

Wax gourd is grown throughout South-East Asia for local consumption, but seldom on a large scale. In local markets, however, it is a rather highly commercialized vegetable due to the long storage life of the mature fruits.

Properties

Like most other cucurbitaceous vegetables, wax gourd is not very high in food value. It contains little vitamin A because the flesh is white. The edible portion of mature fruits is about 75%. Per 100 g edible portion, it contains: water 96 g, protein 0.2 g, fat 0.1 g, carbohydrates 3.5 g, traces of vitamin A, vitamin B₁ 0.02 mg, vitamin B₂ 0.03 mg, niacin 0.5 mg, vitamin C 14 mg, Ca 14 mg, Fe 0.4 mg, Mg 16 mg, P 7 mg. The energy value is 63 kJ/100 g. The seeds yield a pale yellow oil. The 1000-seed weight is approximately 70 g.

Description

• Robust, annual, usually monoecious, hispid, climbing herb up to several m long.
• Stem thick, terete, longitudinally furrowed, whitish-green with scattered rough hairs; tendrils inserted beside the leaves, 2-3-fid, 10-35 cm long, spirally coiled at the top, the two lateral arms much shorter than the central one.
• Leaves simple, distichous; petiole 5-20 cm long; leaf-blade broadly ovate in outline, 10-25 cm × 10-20 cm, deeply cordate at base, apex acuminate, margin more or less deeply and irregularly 5-11-angular or -lobed and irregularly undulate-crenate or dentate-serrate, densely patently hispid on both sides, shiny-green.
• Flowers solitary in leaf axils, large, 6-12 cm in diameter, yellow, unisexual, 5-merous; pedicel densely hispid, 5-15 cm long in male flowers, 2-4 cm in female ones; calyx campanulate, densely silky; petals almost free; male flowers with 5 stamens, 4 of these in connate pairs; female flowers with densely villose ovoid or cylindrical ovary and a short style with 3 curved stigmas.
• Fruit a large, stalked berry (pepo), ovoid-oblong, ellipsoid or globose, 20-60(-200) cm × 10-25 cm, dark green to speckled light green or glaucous, thinly hispid or subglabrous, covered with a chalk-white, easily removable layer of wax; flesh 2-4 cm thick, white, succulent, slightly fragrant, spongy in the middle.
• Seeds numerous, flat, ovate-elliptic, 10-15 mm × 5-7 mm × 1-2 mm, yellow-brown, sometimes prominently ridged.

Growth and development

Germination is usually completed within 1-2 weeks. Wax gourd is a vigorous grower but needs a long growing season of 4-5 months. Flowering starts about 50-80 days after planting. Flowers are insect-pollinated. The fruits need 1-2 months from anthesis until full maturity. Harvest of young fruits prolongs crop duration.

Other botanical information

Numerous local forms are distinguished, mainly differing from each other in fruit shape. Four groups have been proposed based on vegetative and fruit characters, but the differences seem rather small for the status of cv. groups:

• Unridged Winter Melon: seed with unridged margins; fruit cylindrical, up to 2 m long, maturing 3 months after pollination; rind dark green, almost waxless;
• Ridged Winter Melon: seed with ridged margins; otherwise very similar to the first group;
• Fuzzy Gourd: seed with ridged margins; fruit cylindrical, 20-25 cm long maturing within 2 months after pollination; rind green, almost waxless, covered with white soft hairs;
• Wax Gourd: seed with ridged margins; fruit globose to oblongoid, 10-60 cm long or in diameter, maturing within 2 months after pollination; rind light green, covered with a white waxy bloom, glabrous or finely hairy.

Cultivars are offered by seed companies in India, Thailand, Taiwan, China, Japan and the United States.

Ecology

Wax gourd is best suited to the moderately dry areas of the lowland tropics. It is relatively drought-tolerant. It is grown in South-East Asia from sea-level up to 1000 m altitude. High soil temperatures are required for optimum seed germination. The optimum temperature for growth is 23-28°C. The ratio of female to male flowers is increased by relatively cool weather and short days.

Propagation and planting

Wax gourd is propagated by seed. Direct-seeding in well-prepared trenches or planting holes filled with manure or compost is usually practised. When supported, plants should be spaced 60-80 cm in the row, with the rows spaced 1-1.5 m apart. For trailing over the ground, spacing must be wider (2-3 m between plants).

Husbandry

Wax gourd is commonly found in home gardens where it is grown on trellises or trained over the roof, fence or onto a tree. It is also cultivated as a cash crop in the field without support. It is adapted to a wide range of soils, but prefers well-drained light soils. A high organic matter content is necessary. NPK fertilizer should be applied before sowing, and a nitrogenous fertilizer side-dressed at regular intervals until flowering.

Techniques to regulate the growth and fruiting behaviour of cucurbits are the removal of growing points, fruit thinning, and assisted pollination, but there is little detailed information on the needs of wax gourd. However, it is known that removing the growing point on young plants after the appearance of about 4 leaves, allowing 4 laterals to develop, has proved successful in greenhouse production in temperate areas. Fruits on trailing plants are often protected from soil moisture by putting them on a little straw.

Diseases and pests

Wax gourd is a hardy crop and is rather tolerant to diseases such as downy mildew ( Pseudoperonospora cubensis ) during the dry season, and powdery mildew (Erysiphe cichoracearum and Sphaerotheca fuliginea) during the wet season. However, considerable damage may be incurred under high disease pressure, especially if the crop is left unmanaged.

Among the insect pests are squash beetle (Aulacophora foveicollis), aphids Aphis gossypii) and fruit flies (Dacus spp.); usually these are controlled by chemical sprays.

Harvesting

Immature fruits can be harvested about a week after anthesis or later, depending on the required size. Mature fruits are harvested from 100-160 days after sowing.

Yield

Individual fruits can weigh between 1-45 kg. Yields up to 20 t/ha have been reported from northern India.

Handling after harvest

Young fruits must be used as soon as possible because they do not store well. Mature fruits can be stored for a long period due to the waxy layer which protects them from attack by micro-organisms. Ideal storage conditions are at temperatures of 13-15 °C in a fairly dry atmosphere.

Genetic resources

Small germplasm collections of wax gourd are available at horticultural institutes in South-East Asia (Institute of Plant Breeding, the Philippines), India (Kerala Agricultural University), Russia (Vavilov Institute of Plant Industry, Petersburg) and the United States (Southern Regional Plant Introduction Station, Georgia; Cornell University, New York). There seems to be no danger of large-scale genetic erosion.

Breeding

Some selection work on local forms has been done in India, Thailand, Taiwan, China, Japan and the United States, where wax gourd is offered in seed catalogues.

Prospects

Wax gourd is still a small-scale vegetable crop in South-East Asia. Attractive characteristics are the long shelf life of the mature fruits and its resistance to diseases and pests. A disadvantage is the relatively bland taste. Some research seems justified to extend its use; dissemination of information and commercial seed sources could be improved. The potential of wax gourd as a rootstock for grafting other high-priced cucurbits deserves consideration.

Literature

• Engel, J., 1975. Underexploited tropical plants with promising economic value. National Academy of Sciences, Washington, D.C., United States. pp. 53-55.
• Esquinas-Alcazar, J.T. & Gulick, P.J., 1983. Genetic resources of Cucurbitaceae. International Board for Plant Genetic Resources (IBPGR), Rome, Italy. 101 pp.
• Keraudren-Aymonin, M., 1975. Benincasa Savi. In: Flore du Cambodge, du Laos et du Vietnam [Flora of Cambodia, Laos and Vietnam]. Vol. 15. Cucurbitacées. Muséum National d'Histoire Naturelle, Laboratoire de Phanérogamie, Paris, France. pp. 44-46, 95.
• Larkcom, J., 1991. Oriental vegetables. The complete guide for garden and kitchen. John Murray, London, United Kingdom. pp. 83-85.
• Morton, J.F., 1971. The wax gourd, a year-round Florida vegetable with unusual keeping quality. Proceedings of the Florida State Horticultural Society 84: 104-109.
• Walters, T.W. & Decker-Walters, D.S., 1989. Systematic re-evaluation of Benincasa hispida (Cucurbitaceae). Notes on economic plants. Economic Botany 43(2): 274-278.

Authors

• M.A. Rifai & M.E.C. Reyes