Luffa (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Luffa P. Miller

Protologue: Gard. dict. abr. ed. 4. ord. alph. (1754).

Family: Cucurbitaceae

Chromosome number: x= 13; 2n= 26 (L. acutangula, L. aegyptiaca)

Major species and synonyms

• Luffa acutangula (L.) Roxburgh, Hort. Beng.: 70 (1814), synonym: Cucumis acutangulus L. (1753).

• Luffa aegyptiaca P. Miller, Gard. dict. ed. 8. ord. alph. (1768), synonyms: Momordica luffa L. (1753), M. cylindrica L. (1753), Luffa cylindrica (L.) M.J. Roemer sensu auct.

Vernacular names

L. acutangula:

• Angled loofah, ridged gourd, Chinese okra (En).
• Papangay (Fr)
• Indonesia: oyong, gambas (Javanese), petola
• Malaysia: ketola, petola sagi
• Philippines: patola (Tagalog), kabatiti (Ilocano), buyo-buyo (Bisaya)
• Cambodia: ronôông chrung
• Laos: looy
• Thailand: buap, buap-liam (central), manoi-liam (northern)
• Vietnam: mướp khía, mướp tâù.

L. aegyptiaca:

• Smooth loofah, sponge gourd, dish-cloth gourd (En)
• Eponge végétale, courge-torchon (Fr)
• Indonesia: blustru, emes (Sundanese), petulo panjang (Halmaheru)
• Malaysia: ketola manis, petola buntal
• Philippines: patola (Tagalog), kabatiti (Ilocano), kabawang (Tagbanua)
• Cambodia: ronôông muul
• Laos: bwàp khôm
• Thailand: buap-hom (central), buap-klom (northern)
• Vietnam: mướp hương.

Origin and geographic distribution

At present the genus Luffa is considered to comprise 7 species: 4 native to the Old World tropics and 3 to the New World tropics. The two major species described here are of Old World origin but it is not known from where exactly. L. acutangula is believed to originate from India where wild forms still occur. It is now cultivated in South and South-East Asia and occasionally in other tropical and subtropical areas. It sometimes grows wild as an escape from cultivation.

Wild forms of L. aegyptiaca occur from Burma to the Philippines and southwards to north-eastern Australia and Tahiti. It is not known where it was first domesticated. Now it is cultivated pantropically and it easily grows wild as an escape from cultivation.

Uses

The immature fruits, young leaves and flower buds of both species are used as vegetables. The fruits are usually cooked or fried and used in soups or sliced and dried for later use. Young fruits of sweet cultivars may be eaten raw like cucumbers and small fruits are sometimes pickled. Mature fruits are inedible, becoming fibrous and very bitter due to the development of purgative substances. The mature fruits of L. aegyptiaca, which develop an internal fibrous skeleton in the form of a spongy network, are more important than the young fruits. These loofah sponges are easily extracted from ripe fruits by removing the rind and the seeds: most of the initially soft internal tissue (used as a vegetable) has disappeared by maturity. Loofah sponges became important commercially very before and during the Second World War as filters in several kinds of engines, for which no acceptable substitutes existed when Japan, the main producer, stopped exports because of the war. Because of their shock- and sound-absorbing properties they were also used in steel helmets and armoured vehicles. At present they are used as insulating material (sound, shock and temperature), bath sponges, scourers and in the manufacture of potholders, table mats, door and bath mats, insoles, sandals and gloves. The sponges of L. acutangula are little used because they are difficult to extract from the mature fruits.

The fibres, charred fruits, fresh fruits, seeds, leaves and the sap of the stem of the smooth loofah are used for medicinal and cosmetic purposes, especially in China and Japan. The seeds yield an edible oil.

Production and international trade

Angled loofah is mainly produced as a home garden crop, whereas smooth loofah is an important field vegetable. Some export from Thailand occurs to Western Europe to provide the Asiatic community, mainly Chinese, with young fruits.

There are no clear statistics on the production of loofah. Japan is the main exporter of loofah sponges, followed by Brazil. Efforts to set up large commercial plantations in the tropics have failed. The United States is the main importer, with several million sponges per year.

Properties

The edible portion of immature fruits is 70-80%. Per 100 g edible portion they contain: water 93 g, protein 0.6-1.2 g, fat 0.2 g, carbohydrates 4-4.9 g, Ca 16-20 mg, Fe 0.4-0.6 mg, P 24-32 mg, vitamin A 45-410 IU, vitamin B₁ 0.04-0.05 mg, vitamin B₂ 0.02-0.06 mg, niacin 0.3-0.4 mg, vitamin C 7-12 mg. The energy value is approximately 85 kJ/100 g.

Young leaves contain per 100 g edible portion: water 89 g, protein 5.1 g, carbohydrates 4 g, fibre 1.5 g, Ca 56 mg, Fe 11.5 mg, P 140 mg, β-carotene 9.2 mg, vitamin C 95 mg.

The amount of oil in L. acutangula seeds is 26% and the fatty acid composition is: linoleic acid 34%, oleic acid 24%, palmitic acid 23% and stearic acid 10%.

In L. aegyptiaca the seed kernels comprise 51% of the weight of the seeds and contain about 46% oil and 40% protein. The pure oil is colourless, odourless and tasteless and its fatty acid composition is: linoleic acid 42%, oleic acid 41%, palmitic acid 10% and stearic acid 7%.

The presence of glucosides and saponins in the fruits and of colocynthin in the seeds may explain their medicinal activity.

The 1000-seed weight is about 90 g.

Description

• Climbing annual monoecious (seldom dioecious) herbs with simple, palmately lobed leaves.
• Tendrils 2-6-fid.
• Male flowers racemose with 3 or 5 stamens that are often variously united.
• Female flowers solitary, with 3 bilobed stigmas.
• Fruit a dry and fibrous capsule, dehiscent by an apical operculum, with a fibrous skeleton inside that is a spongy network.
• Seeds numerous, flattened.

L. acutangula:

• Stem acutely 5-angled; tendrils hairy, 3-fid or more.
• Leaves 5-7-angled or shallowly lobed, 10-25 cm × 10-25 cm, scabrous, pale green.
• Peduncle of male flowers 15-35 cm long, female flowers borne in same leaf-axils as male flowers; flowers 4-5 cm in diameter, 5-merous, fragrant, pale yellow, opening in the evening; stamens appearing as 3, 2 double 2-thecous, 1 single 1-thecous.
• Fruit club-shaped, angled, 10-ribbed, 15-50 cm × 5-10 cm, crowned by enlarged calyx and style.
• Seed ellipsoid, 41-1.3 cm × 0.7-0.9 cm, pitted, black, without wing-like margin.

L. aegyptiaca:

• Stem 5-angled, up to 15 m long; tendrils 2-6-fid.
• Leaves broadly ovate to reniform, deeply 5-7-lobed, 6-25 cm × 8-27 cm, scabrous, cordate at base, dentate, apex acute, dark green; petiole 5-10 cm long, hairy.
• Male flowers 4-20 in 12-35 cm long racemes, female flowers borne in same leaf-axils as male flowers; flowers 5-10 cm in diameter, 5-merous, deep yellow, opening during the day; stamens 3 or 5.
• Fruit subcylindrical, smooth or not prominently ribbed, 30-60 cm long, crowned by enlarged calyx and style.
• Seed broadly ellipsoid, 1-1.5 cm long, smooth, black, with a narrow wing-like margin.

Growth and development

Germination is epigeal and seedlings emerge 4-7 days after sowing. Depending on cultivar, ecological circumstances and cultural practices, flowering may start 6-10 weeks after sowing. Initially mainly male flowers are produced. The ratio of male to female flowers is high. It is possible to induce pistillate flowers by phytohormone sprayings, e.g. indole-acetic acid. In L. acutangula the flowers open in the evening and in L. aegyptiaca during the day. The stigmas remain receptive for 36-60 hours after anthesis. Normally, loofahs are cross-pollinated by a large number of insects.

Harvesting of fruits for vegetable use may start 9-13 weeks after sowing. Fruits take 4-5 months to attain full maturity. Fruits for vegetable use can be picked regularly during 4-5 months, but yield declines after 2-3 months of harvesting.

Other botanical information

In L. acutangula 3 groups are distinguished:

• cv. group Angled Loofah (synonym: var. acutangula ), the large-fruited cultivated forms. In India cultivar "Satputia" is hermaphrodite.

• var. amara (Roxb.) C.B. Clarke, a wild or feral form, confined to India with small, extremely bitter fruits.

• var. forskalii (Harms) Heiser & Schilling, a wild form confined to Yemen, but possibly developed from escapes of the cultivated forms.

In L. aegyptiaca 2 groups are distinguished:

• cv. group Smooth Loofah (synonym: var. aegyptiaca ), the large-fruited, less bitter, cultivated forms, with different cultivars for the production of the best vegetable or the best sponge.

• var. leiocarpa (Naudin) Heiser & Schilling, the wild forms occurring from Burma to the Philippines, to north-eastern Australia and Tahiti.

There is still controversy about the correct botanical name of the smooth loofah. Here, L. aegyptiaca P. Miller is adopted, following the most cautious interpretation of available information. In the literature, L. cylindrica (L.) M.J. Roemer is mostly used.

Ecology

Loofahs grow best in the low humid tropics, up to 500 m altitude. Although L. aegyptiaca is tropical in origin, excellent loofahs of adapted cultivars are grown during the summer season in Japan.

Both species are frost-sensitive. Too heavy rainfall during flowering and fruiting is harmful. In seasonal climates dry-season planting is more successful than wet-season planting. Daylength sensitivity differs per cultivar; there are day-neutral, short-day and long-day cultivars.

Loofahs prefer rich soils with high organic matter content, good drainage and pH values of 6.5-7.5. Sandy loams may be used if sufficient essential nutrients are supplied.

Propagation and planting

Loofahs are propagated by seed. Sometimes seeds are soaked for 24 hours. For angled loofah, seeds are sown on mounds or ridges 75-100 cm apart, 45 cm between plants or 60-90 cm × 60-90 cm, 2-3 cm deep. For smooth loofah, distances of ridges or mounds are 75-90 cm apart, 45-60 cm between the plants or 90-120 cm × 90-120 cm. Seed rate for angled loofah is 3.5-5 kg/ha, for smooth loofah 2.5-3.5 kg/ha. Transplanting is sometimes practised.

Husbandry

Smooth loofah is mostly grown as a sole crop by commercial growers, while angled loofah is especially important in home gardens and intercropped with other vegetables. Smooth loofah is always grown on strong supports, but angled loofah is sometimes allowed to trail on the ground. During dry conditions, irrigation at regular intervals is required. In some areas, hand pollination is recommended. Laterals are often pruned to stimulate early production of female flowers. Top pruning and partial leaf pruning also promotes flower and fruit development, resulting in higher fruit yield. NPK should be incorporated in the soil before planting, followed by an N fertilizer up to the period of fruit formation. High N under high temperatures promotes maleness in flowering. Normally, in smooth loofah the number of fruits is limited to 20-25 per plant.

Diseases and pests

Loofah is not very sensitive to diseases and pests. Powdery mildew (Erysiphe cichoracearum), downy mildew (Pseudoperonospora cubensis) and fruit flies (Dacus spp.) may cause problems but are rarely serious.

Harvesting

For use as a vegetable, young immature fruits are picked starting 12-15 days after fruit set. Maximum yield is obtained by harvesting the fruits as late as possible, i.e. when they are about half the size of a mature fruit. Older fruits become bitter and fibrous and are inedible.

For use as a sponge, fruits of the smooth loofah are harvested when they are fully mature, which is indicated by yellowing of the base and apex, about 4-5 months after planting. When cut, part of the stalk is usually left on the fruit for convenience in handling.

Yield

Each plant of L. acutangula may produce 15-20 fruits. Fruits for vegetable production may weigh 0.2-0.8 kg. L. aegyptiaca produces 20-25 fruits per plant, with a comparable weight. For vegetable production 8-12 t/ha of immature fruits is reasonable. With top pruning, the yield can be as high as 37 t/ha. In Japan yields of 60 000 matured fruits/ha of the smooth loofah (for sponge use) are reported, equivalent to 50 t/ha. Individual mature fruits weigh 0.5-2.5 kg. Crossings of the improved hermaphrodite cultivar "Satputia" with a traditional cultivar gave five times more yield than both parents.

Handling after harvest

Immature fruits of loofah are easily damaged. Careful wrapping and packaging is needed to enable long distance transport. Storage life of young fruits is 2-3 weeks at 12-16°C.

The best sponges are from mature but still green fruits of smooth loofah. They are processed by immersing in running water until the rind disintegrates. When the rind has disappeared, the pulp and seeds are washed out. The sponges are then bleached with hydrogen peroxide and dried in the sun.

Genetic resources

Germplasm collections of loofah for vegetable use are kept in India (Vivekananda Parvatiyakrishi Anusandhan Shala, Almora, Uttar Pradesh), Nigeria (NACGRAB, Ibadan), the Philippines (NPGRL-IPB, Los Baños), Taiwan (Taiwan Agricultural Research Institute, Wufeng, Taichung), and the United States (SRPIS-USDA, Georgia). Germplasm collections of sponge loofah are kept in Japan.

Breeding

Crossing experiments are easy to perform, because in most loofah cultivars and landraces the flowers are unisexual. Local cultivars and landraces are open-pollinated and hence populations are very variable. Such local populations are being collected in Malaysia, India and the Philippines for use in breeding programmes. High-yielding cultivars are available from seed companies in Thailand and Indonesia. In Japan and Taiwan, F₁hybrids between angled and smooth loofah have been developed. These are very bitter and inedible but suitable for sponge production. Hybrids with other wild species are highly sterile.

Prospects

Loofah is expected to assume more importance as a vegetable than it does now. Moreover, in the mature state it yields sponges, which are a useful renewable resource. Sponge production, combined with harvest of seeds as a source of protein and oil, might offer attractive prospects for South-East Asian countries.

Literature

• Dutt, B. & Roy, R.P., 1990. Cytogenetics of the Old World species of Luffa. In: Bates, D.M., Robinson, R.W. & Jeffrey, C. (Editors): Biology and utilization of the Cucurbitaceae. Comstock, Cornell University Press, Syracuse, New York, United States. pp. 134-140.
• Hamid, S., Salma, Sabir, A.W. & Khan, S.A., 1985. Cultivation conditions and physico-chemical properties of Luffa acutangula var. acutangula seed oil. Pakistan Journal of Scientific and Industrial Research 28(2): 119-122.
• Heiser, C.B. & Schilling, E.E., 1990. The genus Luffa: a problem in phytogeography. In: Bates, D.M., Robinson, R.W. & Jeffrey, C. (Editors): Biology and utilization of the Cucurbitaceae. Comstock, Cornell University Press, Syracuse, New York, United States. pp. 120-133.
• Martin, F.W., 1979. Vegetables for the hot, humid tropics. Part 4. Sponge and bottle gourds, Luffa and Lagenaria. Science and Education Administration, United States Department of Agriculture, New Orleans, United States. 21 pp.
• Porterfield, W.M., 1955. Loofah: the sponge gourd. Economic Botany 9: 211-223.
• Purseglove, J.W., 1968. Tropical Crops. Dicotyledons 2. Longman, London, United Kingdom. pp. 128-132.
• Sahni, G.P., Singh, R.K. & Saha, B.C., 1987. Genotypic and phenotypic variability in ridge gourd. Indian Journal of Agricultural Sciences 57(9): 666-668.
• Seshadri, V.S., 1985. Cucurbits. In: Bose, T.K. & Som, M.G. (Editors): Vegetable crops in India. Naya Prokash Press, Calcutta, India. pp. 91-164.

Authors

• G.J. Jansen, B.H. Gildemacher & L. Phuphathanaphong