Momordica (PROSEA Vegetables)

Plant Resources of South-East Asia
Introduction

List of species

Momordica L.

Protologue: Sp. pl.: 1009 (1753); Gen. pl. ed. 5: 440 (1754).

Family: Cucurbitaceae

Chromosome number: x= 7, 11, 14; 2n= 14 (M. cochinchinensis); 2n= 22 (M. charantia)

Major species and synonyms

Momordica charantia L., Sp. pl.: 1009 (1753), synonyms: M. indica L. (1754), M. elegans Salisb. (1796), M. chinensis Sprengel (1893).

Momordica cochinchinensis (Loureiro) Sprengel, Syst. veg. 3: 14 (1826), synonyms: Muricia cochinchinensis Loureiro (1790), Momordica mixta Roxburgh (1832).

Momordica subangulata Blume, Bijdr.: 928 (1826), synonym: M. eberhardtii Gagnepain (1918).

Vernacular names

M. charantia:

Bitter gourd, bitter cucumber, balsam pear (En)
Paroka (Fr)
Indonesia: paria, pare (Javanese)
Malaysia: peria, peria laut, periok
Philippines: ampalaya (Tagalog), paria (Ilocano), palia (Bisaya)
Cambodia: mreah
Laos: haix, s'aix
Thailand: mara (general), phakha (north-eastern), maha (northern)
Vietnam: mướp dắng (north), khổ qua (south).

M. cochinchinensis:

Sweet gourd, spiny bitter cucumber, giant spine gourd (En)
Indonesia: pupia, torobuk, toropu (Moluccas)
Malaysia: teruah
Philippines: buyok-buyok (Tagalog), paruk-paruk (Ilocano), taboguak (Bicol)
Cambodia: makkao
Laos: khaawz
Thailand: fak-khao (central), phak-khao (northern), khika-khrua (southern)
Vietnam: dây gấc.

M. subangulata:

Indonesia, Malaysia: kamas
Thailand: phakmae (southern).

Origin and geographic distribution

The genus Momordica belongs entirely to the Old World. It comprises about 45 species, mainly occurring in Africa and 5-7 species in Asia; a few species have been introduced into the New World tropics.

M. charantia was possibly domesticated first in eastern India and southern China. It now has a pantropical distribution, with wild and cultivated populations. It is thought that it came from Africa to Brazil with the slave trade and that bird dispersal of the seeds accounts for its spread within continents. It is the most important cultivated Momordica species. M. cochinchinensis occurs wild and cultivated from India to Japan and throughout Malesia. It has not been reported from Java. M. subangulata is only known from the wild and is distributed in Thailand, Indo-China, Peninsular Malaysia and Java.

Uses

The immature fruits of M. charantia are the main vegetable product; they are prepared in many ways. Fruits, young shoots and flowers are used as flavouring, the leaves as a leafy vegetable (popular in the Philippines) and the pulpy arils as a sweet. Bitter gourd may be canned, pickled or dehydrated. To reduce the bitter taste, the fruits can be blanched or soaked in salt water before cooking. Bitter gourd has numerous medicinal uses. In folk medicine it is used to treat diabetes; ripening fruits contain inhibitory compounds which affect glucose metabolism. Juice from various plant parts is used externally to treat skin disorders and is ingested to cure arthritis, rheumatism and asthma. Most plant parts act as a purgative when ingested. There are reports about abortifacient properties of seed extracts. Occasionally, M. charantia is planted as an ornamental.

Immature fruits, young leaves and flowers of M. cochinchinensis are similarly used as a vegetable. The seeds contain an oil which is used as an illuminant in Indo-China. Its roots froth in water and may be used as soap. The seeds are used in folk medicine for several diseases, e.g. a paste is applied to treat warts, abscesses and ulcers.

Young shoots and immature fruits of M. subangulata can be eaten as a vegetable, but they are not very popular.

Production and international trade

Bitter gourd is mainly cultivated in South-East Asia and India. In the Philippines it ranks second to squash in total hectarage (4600 ha) among the traditional cucurbits; average annual production is estimated at 17 000 t. On a worldwide basis, exact statistics are lacking. The other Momordica species are only important for the local market.

Properties

The edible portion of bitter gourd fruits is about 95%. Per 100 g edible portion it contains: water 83-92 g, protein 1.5-2 g, fat 0.2-1 g, carbohydrates 4-10.5 g, fibre 0.8-1.7 g. The energy value is 105-250 kJ/100 g. Compared with other Cucurbitaceae it is high in minerals and vitamins: Ca 20-23 mg, Fe 1.8-2 mg, P 38-70 mg, vitamin C 88-96 mg. Per 100 g edible portion the leaves contain: water 82-86 g, protein 2.3 g, fat 0.1 g, carbohydrates 17 g, fibre 0.8 g. They are an excellent source of iron and calcium and a good source of phosphorus and vitamin B.

Per 100 g edible portion sweet gourd fruits contain approximately: water 90 g, protein 0.6 g, fat 0.1 g, carbohydrates 6.4 g, fibre 1.6 g, minerals 0.9 g. The energy value is 120 kJ/100 g. It is low in vitamins.

Bitterness in M. charantia is attributed to the non-toxic alkaloid momordicine. The fruit contains the hypoglycemic principle charantin. The ripe fruit and the leaves have been found to contain a guanylate cyclase inhibitor which has the ability to impair chemical carcinogen-induced increases in guanylate cyclase activity.

Eleostearic acid is the dominant fatty acid in the oil of the seeds of M. charantia and M. cochinchinensis (50-65%).

The 1000-seed weight of bitter gourd (M. charantia) is about 60 g.

Description

Monoecious or dioecious, annual or perennial herbs, with climbing or trailing stems.
Tendrils simple or bifid, one at each node, positioned as a stipule.
Leaves alternate, simple or 3-15-foliolate, petiolate.
Male flowers solitary, umbellate or in short racemes or fascicled, often subtended by a conspicuous bract; calyx tubular with 5 lobes; petals 5, free; stamens 3, 2 double 2-thecous, 1 single 1-thecous.
Female flowers solitary; perianth usually similar as in male flowers; stigma 3-lobed.
Fruit a berry (pepo), ovoid-ellipsoid to elongate-fusiform, fleshy, ornamented with tubercles, spines, wings or ridges, indehiscent or often dehiscent by 3 valves and exposing the seeds enveloped in scarlet pulp.
Seeds usually compressed, with sculptured testa and grooved margins.

M. charantia.

Monoecious, annual, up to 5 m long. Stem 5-ridged.
Tendrils simple.
Leaves simple, pellucidly dotted, palmately veined; petiole 1-7 cm long; leaf-blade broadly ovate-reniform or suborbicular in outline, 2.5-10 cm × 3-12.5 cm, cordate at base, deeply palmately (3-)5(-9)-lobed, lobes obovate and sinuate-lobulate or sinuate-toothed.
Flowers axillary, solitary, about 3 cm in diameter, yellow; peduncle 0.5-3 cm (male), 0.2-5 cm (female) long, bearing an apical bract up to 2 cm (male), 1 cm (female) in diameter; pedicel 2-5.5 cm (male), 1-10 cm (female) long.
Fruit 3-11(-45) cm × 2-4(-8) cm, irregularly warty, orange, dehiscing from apex downwards to the base into 3 valves.
Seed 8-16 mm × 4-10 mm × 2.5-3.5 mm, brown.

M. cochinchinensis.

Dioecious, perennial, starting from a tuberous root, often climbing high in trees. Stem robust, angular.
Tendrils simple, robust.
Leaves simple, palmately veined; petiole 5-10 cm long, with 2-5 glands near the middle; leaf-blade suborbicular in outline, 12-20 cm in diameter, cordate and with some glands at base, deeply 3(-5)-lobed, lobes subovate with entire or subdentate margins.
Flowers axillary, solitary, about 8 cm in diameter, yellow, but blackish at base inside.
Male flowers with peduncle 5-30 cm long, bearing an apical, suborbicular, sessile bract, 3-4 cm × 4-5 cm; pedicel 3-10 mm long.
Female flowers with much smaller bract situated near the middle of the peduncle; pedicel 3-10 mm long.
Fruit 10-20 cm × 6-10 cm, yellow, turning red at maturity, densely covered with small tubercles.
Seed 2.5 cm × 2 cm × 0.5 cm, brown.

M. subangulata.

Dioecious, perennial, with annual vines. Stem angular.
Tendrils simple, rather short.
Leaves simple, thin, palmately 3-5-veined; petiole 2-5 cm long; leaf-blade ovate-reniform, 6-13 cm × 4-9 cm, sometimes 3-5-lobed, cordate at base, margins denticulate.
Flowers axillary, solitary, up to 5 cm in diameter, yellow.
Male flowers with peduncle up to 10 cm long, bearing an apical, reniform bract, 1-2 cm long; pedicel 1-3 mm long; calyx lobes ovate, emarginate at apex.
Female flowers with peduncle 6-7 cm long, bearing a small bract at the base.
Fruit ovoid, 6-7 cm × 3-4 cm, densely covered with longitudinal wings.
Seed 1 cm × 1 cm × 0.5 cm, grey.

Growth and development

Emergence of bitter gourd takes 5-7 days after sowing. Wild types may exhibit some kind of seed dormancy and germinate after 15-20 days. Within two weeks rapid vine elongation takes place, followed by growth of lateral stems. Apical dominance is not common. Under optimal conditions, flowering starts 45-55 days from sowing. Flowering continues throughout the cropping season, which usually lasts up to 6 months. Flower opening starts early in the morning; however, low temperature may delay flower opening and shedding by about one hour. Anthers dehisce about two hours before anthesis and optimum viability of pollen and receptivity of the stigma are attained at anthesis. Flowers are cross-pollinated by insects, especially bees. For vegetable use the green fruits can be harvested about 2 weeks after anthesis. Fruits left on the vine turn orange or yellow and dehisce some 25-30 days after anthesis. Removal of fruits before ripening permits continued fruiting and prolongs crop duration.

Seeds of M. cochinchinensis germinate very unevenly. Flowering starts 2 months after planting and continues for 6-8 months. At higher latitudes plants remain dormant in winter and start growing again from the tuberous root in spring.

Other botanical information

The wild and cultivated forms of M. charantia have been variously classified (cultivated: ssp. charantia or var. charantia; wild: ssp. abbreviata (Ser.) Grebensc. or var. abbreviata Ser.). The cultivated forms can better be classified in cultivar groups and cultivars, but there is no good classification system. A provisional solution has been proposed for India and South-East Asia, in which cultivated M. charantia is divided into 2 groups: fruits with diameter less than 5 cm (var. minima Williams & Ng) and fruits with diameter larger than 5 cm (var. maxima Williams & Ng). In var. minima all fruits are green and the seed is 13-14.5 mm × 6.8-8.5 mm; cultivars fall into 3 groups: short fruited (6-7.5 cm), medium fruited (8-12 cm) and long fruited (12-22 cm). In var. maxima the fruits are white or green and the seed is 14.8 mm × 8.5 mm; cultivars fall into 2 groups: medium fruited (12-17 cm) with white fruits, and long fruited (about 20 cm) with green fruits. The system is rather artificial; cv. group names and cultivar names, as well as voucher specimens, are lacking.

Popular cultivars of bitter gourd in the Philippines are the OP's "Sta Rita" and "Makiling" and their F₁ hybrids "Jade Star A" and "Jade Star B".

M. charantia seems to be closely related to M. balsamina L., a pantropical species of dry areas, whose leaves and fruits are also edible. Its occurrence and position in South-East Asia are not clear. M. dioica Roxb. ex Willd., a species with edible fruits, occurring from India to Burma, closely resembles M. subangulata, which is often confused with it. M. dioica has echinulate fruits, in M. subangulata the fruits are longitudinally alate.

Ecology

M. charantia grows well in tropical and subtropical climates. It is adapted to a wide range of environments and can be grown year-round. The plant is sensitive to waterlogging. It tolerates a wide range of soils but it thrives in a well-drained sandy loam, rich in organic matter. It grows wild in lowland rain forest and riverine forest, up to 1000 m altitude.

M. cochinchinensis prefers a warm humid climate with temperatures ranging from 20-35 °C and an average rainfall of 1500-2500 mm. It fruits mainly in the rainy season. The plants stay dormant during the dry, cool season. Sweet gourd grows well in fertile, well-drained sandy loam soils with pH near neutral. In the wild it can often be found in open places on lowland riverbanks.

M. subangulata prefers disturbed areas, but its ecological requirements are unknown.

Propagation and planting

M. charantia is propagated by seed. Direct seeding is most common, but transplanting may be done if seeds are scarce. The use of pre-germinated seed results in an even establishment. Seeds are sown in the field at a spacing of 30-50 cm between hills and 2-3 m between rows. Optimum plant density differs per cultivar, but ranges from 6500-11 000 plants per ha. In some areas closer spacings are used, 50 cm × 50 cm, resulting in 40 000 plants/ha.

M. cochinchinensis is mainly propagated by its tuberous roots. Since it is dioecious, tubers from male and female plants should be planted together. A male population of 8-10% should be maintained to ensure proper pollination. About 50 000 sprouted tubers per ha are required. When started from seed, about 3-5 kg/ha of seed is needed.

To control weeds, soil preparation should be started 4-6 weeks before planting.

Husbandry

Not much research has been done on cultural practices, but in general these are comparable with those of cucumber (Cucumis sativus L.). The use of compost (10 t/ha) together with chemical fertilizer is recommended, e.g. 40 kg N, 30 kg P and 30 kg K. Half the nitrogen is usually applied as a side dressing during flowering. Supplementary irrigation, preferably furrow irrigation, is necessary to maintain a good crop in the dry season. Bitter gourd is almost always trellised, especially in the wet season. Overhead trellises are also needed. Trellising should be done before the vines are 1 m long.

Diseases and pests

Diseases of bitter gourd, especially Cercospora leaf spot and downy mildew (Pseudoperonospora cubensis), may have a drastic effect on yield if not controlled. Bacterial wilt (Pseudomonas solanacearum) also attacks the crop, as do root knot nematodes (Meloidogyne incognita).

Fruit fly (Dacus cucurbitae) is the most destructive insect pest of bitter gourd. Chemical sprays are not effective, because adult female fruit flies only lay eggs on growing fruits and do not feed on them. Sanitation practices like burying and burning of infested fruits are recommended to prevent build-up of the pest population. Epilachna beetles, caterpillars (Spodoptera litura, Heliothis armigera), aphids and mites also attack the crop.

Chemical control of these diseases and pests should be done as a last resort. The most toxic pesticides should be avoided, because of possible harm to pollinators. Light traps and poison baits are sometimes used against fruit fly, using a sex attractant like hydrolysate 0.5 kg + 1.25 kg of 50% malathion wp + 200 g of molasses. Many growers protect young fruits with paper bags against fruit fly.

In M. cochinchinensis no serious diseases have been recorded, but Epilachna beetle and fruit fly may be serious pests.

Harvesting

Bitter gourd requires much attention at harvest time. It usually takes 15-20 days after fruit set to reach a marketable stage. Delaying harvesting for 3-4 days leads to loss of fruit lustre and acceptability. Fruits are best harvested by cutting the fruit stalk with scissors or a sharp knife. Fruits of M. cochinchinensis are harvested when they are almost mature.

Yield

A yield of 20-30 t/ha is considered satisfactory for M. charantia. The number of fruits per plant may reach 20-25 during the cropping period. Some F₁ hybrids yield up to 40 t/ha. M. cochinchinensis may yield 30-60 fruits per plant, each weighing 1-3 kg.

Handling after harvest

Fruits of bitter gourd do not keep well and should be sent immediately to the market. Damaged and deformed fruits are removed. Fruits are arranged in bamboo baskets layered with newspapers or banana leaves, and can then be kept for 2-3 days. If stored at 4 °C, fruits can be kept for 3 weeks.

Genetic resources

The world collection of Momordica germplasm is held at NBPGR, New Delhi, India. In South-East Asia, collections are available in the Philippines (NPGRL-IPB, Los Baños) and in Thailand (Department of Horticulture, Kasetsart University, Bangkok). Elsewhere, collections are held in several institutes in India, South Africa, Taiwan and the United States.

Breeding

Breeding work on bitter gourd is geared towards developing cultivars with superior quality (i.e. less bitter fruits), a high female to male ratio, high yield, and resistance to diseases and pests. Resistance to foliar diseases and fruit fly is important. The wild forms of bitter gourd are potential sources for resistance. The exploitation of hybrid vigour in this crop is well documented. In many South-East Asian countries, commercial F₁ hybrids often twice as productive as the traditional open-pollinated cultivars, have been released.

Prospects

In South-East Asia bitter gourd will remain an important vegetable crop although production is expected to remain small-scale. Breeding for less bitterness will increase the crop's popularity. The potential and limitations of M. cochinchinensis, M. subangulata and other wild Momordica species need further investigation.

Literature

Keraudren-Aymonin, M., 1975. Cucurbitacées. Momordica. In: Flore du Cambodge, du Laos et du Vietnam [Flora of Cambodia, Laos and Vietnam]. Vol. 15. Muséum National d'Histoire Naturelle, Laboratoire de Phanérogamie, Paris, France. pp. 36-44.
Ochse, J.J. & Bakhuizen van den Brink, R.C., 1980. Vegetables of the Dutch East Indies. 3rd English edition (translation of "Indische groenten", 1931). Asher & Co., Amsterdam, the Netherlands. pp. 205-208.
Seshadri, V.S., 1986. Cucurbits. In: Bose, T.K. & Som, M.G. (Editors): Vegetable crops in India. Naya Prokash Press, Calcutta, India. pp. 91-164.
Shadeque, A. & Baruah, G.K.S., 1984. Sweet gourd: a popular vegetable of Assam. Indian Farming 34(8): 25-35.
Tindall, H.D., 1983. Vegetables in the tropics. MacMillan, London, United Kingdom. pp. 179-181.
Walters, T.W. & Decker-Walters, D.S., 1988. Balsam-pear (Momordica charantia, Cucurbitaceae). Notes on economic plants. Economic Botany 42: 286-288.
Williams, J.T. & Ng, N.O., 1976. Variation within Momordica charantia L., the bitter gourd (Cucurbitaceae). Annales Bogorienses 6(2): 111-123.

Authors

M.E.C. Reyes, B.H. Gildemacher & G.J. Jansen