Prota 2: Vegetables/Légumes
Verh. Vereins Beförd. Gartenbaues Königl. Preuss. Staaten 12: 205 (1837).
2n = 40
Cucurbita melanosperma A.Braun ex Gasp. (1847), Pepo ficifolia Britton (1925).
Fig-leaf gourd, Malabar gourd, black-seeded gourd (En). Courge de Siam, melon de Malabar (Fr). Abóbora chila, abóbora gila (Po). Mboga ya kimasai (Sw).
Origin and geographic distribution
Cucurbita ficifolia is a cultigen originating from highland regions of Latin America (from Mexico to Chile) where it is still widely cultivated. The first fruits to reach Europe apparently took a circuitous route from South America to the Malabar Coast of India along the much travelled trade routes in the 16th and 17th centuries, hence the vernacular names in English and French. Fig-leaf gourd occurs in tropical Africa in the highlands of Ethiopia, Kenya and Tanzania and is occasionally grown in Angola. In Asia it is grown in India, Japan, Korea and China and in the highlands of the Philippines.
Fig-leaf gourd is grown as a vegetable for the leaves and the immature fruits. In East Africa mainly the leaves are eaten. In Kenya, where it is known as ‘kahurura’ (Kikuyu), and in Tanzania, where the vegetable is known as ‘boga la kimasai’ (Swahili), the leaves are prepared in a mixture with maize, pulses, green bananas or Irish potato. Young fruits are occasionally eaten as a cooked vegetable like pumpkin, but in most places in Kenya and Tanzania the fruits are considered not edible. However, they are used to prepare an alcoholic drink. In Latin America and the Philippines tender young fruits are used like summer squash (Cucurbita pepo L.). The flesh of mature fruits is impregnated with sugar for preparation of a candy or jam, mature fruits are fermented for an alcoholic beverage, male flowers and buds are used in soups, stews and salads, and the raw or roasted seeds are eaten as a snack food. Also in Spain, the fruits are used for jam preparation. In Europe, fig-leaf gourd is also cultivated as an ornamental because of its decorative white-spotted dark green fruits. Fig-leaf gourd is used in temperate countries as a rootstock for greenhouse cucumber (western Europe, Korea, China, Japan) and for melon and watermelon (Korea, China, Japan). It gives the grafted crop increased cold tolerance and high resistance to soilborne pathogens and increases the resistance to Pythium and powdery mildew. Like several other cucurbits, fig-leaf gourd consumption by diabetic patients has a hypoglycaemic effect, making it an appropriate medicine against diabetes mellitus. The seed complete with the husk is ground into a flour that is made into an emulsion with water and taken as a vermifuge. A purgative should be taken afterwards to expel tapeworms or other parasites.
Production and international trade
Fig-leaf gourd is of local importance in East Africa, but no production statistics are available.
No data on the composition of Cucurbita ficifolia are reported, but it is probably similar to that of other cucurbits. The composition of pumpkin (Cucurbita spp.) leaves per 100 g edible portion is: water 89 g, energy 105 kJ (25 kcal), protein 4.0 g, fat 0.2 g, carbohydrate 2 g, fibre 2.4 g, Ca 475 mg, P 135 mg, Fe 0.8 mg, β-carotene 1.0 mg, thiamin 0.08 mg, riboflavin 0.06 mg, niacin 0.3 mg, ascorbic acid 80 mg. The composition of immature fruits is comparable to that of Cucurbita pepo (summer squash). The fruit pulp contains a proteolytic enzyme that has potential value in the food industry. The seeds are rich in protein and oil; the oil is made up mainly of oleic acid.
Hypoglycaemic activity of fruit extracts of Cucurbita ficifolia has been demonstrated in animal models (mice, rabbits) as well as in clinical tests with diabetic patients. The mechanism of the hypoglycaemic effect is still unknown.
Adulterations and substitutes
Leaves and fruits of fig-leaf gourd can be replaced by musk pumpkin (Cucurbita moschata Duchesne), fruits also by summer squash (Cucurbita pepo) and roasted seed by those of any other Cucurbita species.
Short-lived perennial vine climbing by long, branched tendrils, herbaceous but becoming somewhat woody; taproot up to 2 m long, lateral roots forming a network slightly below the soil surface; stem with numerous long runners, smoothly 5-angled to rounded, prickly or spiny, often rooting at nodes. Leaves alternate, simple, without stipules; blade circular-ovate to nearly reniform in outline, sinuate to lobed with obtuse sinuses, 18–25 cm in diameter, margins toothed to entire. Flowers solitary, unisexual, regular, 5-merous, up to 7.5 cm in diameter, yellow to pale orange; calyx and corolla campanulate with short tube; male flowers with short, thick and columnar androecium, filaments with trichomes more than 1 mm long; female flowers on short, ridged pedicels with inferior ovary. Fruit a large, globose to cylindrical berry 15–50 cm long, green with white stripes and blotches; rind smooth, hard; flesh of mature fruits white, coarse, tough, fibrous and rather dry, many-seeded; fruit stalk not or only slightly enlarged at apex. Seeds oblong-ellipsoid, flattened, 1.5–2.5 cm long, without a spongy epidermis, usually black, sometimes pale buff-coloured. Seedling with epigeal germination.
Other botanical information
In the taxonomic literature, 3 characteristics are often mentioned to distinguish Cucurbita ficifolia from the other cultivated Cucurbita species: perennial growth habit, leaf shaped like a leaf of the fig (Ficus carica L.) and black seeds. Those characteristics can be misleading because Cucurbita ficifolia does not differ in longevity from the other squash species, the fig-leaf form also occurs in other species, and the seeds are not always black. Most diagnostic are the following characteristics: the presence of trichomes on the filaments in the male flowers, and the shape of the seeds (length-to-width ratio of 3:2, which is broader than in other cultivated Cucurbita species).
Local cultivars of fig-leaf gourd occur in East Africa. The main variation is in fruit size and the white and green spotting.
Growth and development
Seeds germinate 5–7 days after sowing. The plants are extremely vigorous and form an extensive fibrous root system. The stems may reach a length of over 30 m. Under suitable conditions, the branching and trailing stems will grow indefinitely when they are permitted to root at the nodes touching the soil. However, fig-leaf gourd is usually grown as an annual. Flowering under short-day conditions starts 30–60 days after emergence of the seedling and is continuous. The ratio of male to female flowers is about 20:1, but is influenced by growing conditions; long days and high temperatures favour the male sex expression. Production of sticky pollen is abundant. Anthesis and pollination take place early in the morning. Insects, mainly bees, effect pollination. Solitary plants also set a fair number of fruits; 1–2 fruits per stem develop. The fruit matures 30–40 days after pollination. The harvest period of young leaves extends from 2–6 months after sowing.
In the tropics it is grown at altitudes above 1000 m, in the mountains of Latin America from 1000–3000 m. It is more cold resistant than any other Cucurbita species, but night frost kills the plant. Fig-leaf gourd requires a short or shortening photoperiod for flowering. In temperate areas it is grown in the summer, starting flowering with decreasing daylength. Daylength-neutral cultivars have been reported. Fig-leaf gourd prefers fertile, well-drained soils with a pH range of 6.5–7.5.
Fig-leaf gourd responds well to applications of up to 30 t/ha of organic manure during site preparation; additional application of inorganic fertilizers (110 kg/ha N, 40 kg/ha P, 90 kg/ha K) is beneficial. Under dry conditions irrigation should be applied, e.g. weekly 50 mm.
Propagation and planting
Propagation is by seed, although fig-leaf gourd may be easily vegetatively propagated because of the root development from the nodes. The weight of 1000 seeds is 180–250 g. For seed germination, soil temperatures should be above 15°C; the germination percentage is highest at 35°C. Stored seeds are hard-coated, and scouring or soaking in water for some hours is recommended. Seed are sown in flats, flat ridges or on mounds or hills. Seeds are planted 2–5 cm deep, depending on the soil texture. A practical planting distance is 2 m × 2 m giving a plant population of 2500 plants/ha; the seed requirement is 2–3 kg/ha. Because of the creeping plant habit, the optimal planting density is flexible, varying from 1000–6000 plants/ha. With a dense planting, the soil is covered sooner and weeds are suppressed. Fig-leaf gourd is usually grown on small acreages, even as a single plant in home gardens, against trellises and walls or trees. It is occasionally grown as an intercrop in maize or sorghum.
Diseases and pests
Fig-leaf gourd is strongly resistant to pests and diseases, more so than other Cucurbita species. Diseases observed in India and the Philippines are leaf and stem rot (Alternaria spp.), watery soft rot (Sclerotinia sclerotiorum), leaf and stem spot (Stemphylium spp.), bacterial leaf spot (Xanthomonas cucurbitae), powdery mildew (Erysiphe cichoracearum) and virus diseases (cucumber, melon, squash, watermelon mosaic viruses). Usually no control measures are taken. For virus diseases, it is important to use virus-free seed, to remove infected plants early, and to control the vectors. The major insect pests reported are yellow beetle (Aulocophora similis), whitefly (Bemisia tabaci) and aphids (Aphis spp.), all of which are potential vectors of viruses.
Continuous weekly picking of young leaves may take place from 6 weeks after emergence of the seedling to the end of the vegetative growth period. The harvest of immature fruits by cutting the fruit stalk occurs in many rounds, from 2 months to the end of the crop. For home consumption, young leaves and shoots are picked when needed. Seeds are extracted from mature fruits for future planting.
The fruit yield largely depends on cultivar and growing conditions. Up to 10 mature fruits may be harvested per plant. The weight of young fruits is about 1 kg, mature fruits weigh 3–8 kg. Per ha, an estimated quantity of 20 t of leaves or 40 t of young fruits might be harvested. Regular picking of leaves will decrease the fruit yield. Seed yield is about 500 kg/ha.
Handling after harvest
Leaves have to be consumed within two days after harvesting, young fruits can be kept for some weeks. Cuts and bruises of mature fruits heal by suberization within a week. Mature fruits can be kept for a long period in a dry place at room temperature, in temperate areas for even longer than a year. They become sweeter with storage.
Cucurbita ficifolia is the least variable of the cultivated Cucurbita species. It is represented in the Cucurbita collections of many institutions, in particular in Central and South America (CATIE, Turrialba, Costa Rica; San Carlos University, Guatemala; INIFAP, Celaya, Mexico). It is also found in germplasm collections in the United States (National Seed Storage Laboratory, Fort Collins, Colorado; Southern Regional Plant Introduction Station, Georgia), Russia (Vavilov Institute of Plant Industry, St Petersburg) and the Philippines (Institute of Plant Breeding, Los Baños). These collections, however, are not representative of its full geographic distribution.
Cucurbita ficifolia is naturally cross-pollinated but self-compatible, inbreeding causing little loss of vigour. No breeding programme has been reported, although distinct local cultivars are known, and international seed companies trade cultivars for rootstock. Fig-leaf gourd has been tried frequently as genitor for disease- and cold-resistance to pumpkins (Cucurbita maxima Duchesne ex Lam., Cucurbita moschata) and squashes (Cucurbita pepo), but it shows considerable isoenzymatic and chromosomal differences compared with all other taxa of the genus. F1 plants have only been obtained by embryo rescue and no further progress has been reported.
Fig-leaf gourd has potential as a fresh leaf and fruit vegetable in East Africa and southern Africa in highland regions. The fruit quality should be improved by breeding. It may become a rootstock for cucumber, melon and other cucurbits.
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Sources of illustration
• Siemonsma, J.S. & Kasem Piluek (Editors), 1993. Plant Resources of South-East Asia No 8. Vegetables. Pudoc Scientific Publishers, Wageningen, Netherlands. 412 pp.
Correct citation of this article:
Grubben, G.J.H., 2004. Cucurbita ficifolia Bouché In: Grubben, G.J.H. & Denton, O.A. (Editors). PROTA 2: Vegetables/Légumes. [CD-Rom]. PROTA, Wageningen, Netherlands.
1, part of stem with leaf and female flower; 2, female flower in longitudinal section; 3, male flower in longitudinal section; 4, fruit.
female (left) and male flower (front tepals removed)