Cucurbita ficifolia (PROSEA)
Cucurbita ficifolia Bouché
- Protologue: Verh. Ver. Beförd. Gartenb., Berlin 12: 205 (1837).
- Family: Cucurbitaceae
- Chromosome number: 2n= 40
- Cucurbita melanosperma A. Braun (1824),
- Pepo ficifolia Britton (1925).
General: all names like pumpkin and squash mentioned in the article on Cucurbita L. may also refer to this species. More specific names are:
- fig-leaf gourd, Malabar gourd, black-seeded squash (En)
- Courge de Siam, melon de Malabar (Fr).
Origin and geographic distribution
C. ficifolia is a cultigen which probably originated in Central Mexico and mainly spread to South America with an ecological preference for highland areas (high plateaus of Central America and along the Andes to central Chile). 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. In South-East Asia it is only grown in the highlands of Luzon, the Philippines, at an elevation of 1700 m above sea-level.
Fig-leaf gourd is mainly grown for its large fruits. The tender immature fruits are used like summer squash or cucumber. The flesh of the mature fruits is often impregnated with sugar, and the resulting product used as candy or "dulce". It may also be fermented to make an alcoholic beverage. The young leaves and vine tips may be prepared as a green vegetable. The male flowers and buds are used in soups, stews and salads. In some areas, the raw or roasted seeds are eaten as a snack food. Fig-leaf gourd is also cultivated for its ornamental watermelon-like fruits and abundant foliage. It became popular in western countries as a rootstock for winter production of greenhouse cucumber due to its cold tolerance and good resistance to soilborne pathogens.
Production and international trade
The main production area of C. ficifolia is Central and South America. It is only of local importance in South-East Asia, i.e. in the Philippines. No production statistics are available.
The composition of C. ficifolia is comparable to mature fruits of other Cucurbita species, and lies in the following range (per 100 g edible portion): water 85-91 g, protein 0.8-2.0 g, fat 0.1-0.5 g, carbohydrates 3.3-11.0 g, vitamin A 340-7800 IU, vitamin B1 0.07-0.14 mg, vitamin B2 0.01-0.04 mg, niacin 0.5-1.2 mg, vitamin C 6-21 mg, Ca 14-48 mg, Fe 7.0 mg, Mg 16-34 mg, P 21-38 mg. The energy value is 85-170 kJ/100 g. The fruit pulp contains a proteolytic enzyme that has potential value in the food industry. The seeds are the most nutritious part of the fruit; they are rich in protein and oil. The weight of 1000 seeds is 180-250 g.
- A monoecious, short-lived perennial vine, herbaceous but becoming somewhat woody.
- Taproot up to 2 m long, lateral roots forming a network slightly below the soil surface.
- Stem with numerous runners, up to 10 m long, prickly or spiny, hard, smoothly 5-angled to rounded, often rooting at the nodes; tendrils long, branched.
- Leaves simple, alternate; leaf-blade circular-ovate to nearly reniform in outline, 18-25 cm in diameter, sinuate to lobed and with obtuse sinuses, margins apiculate-serrate to entire.
- Flowers solitary, yellow to light orange, up to 7.5 cm in diameter; calyx and corolla campanulate with short tube; staminate flowers with short, thick and columnar androecium, filaments with trichomes more than 1 mm long; pistillate flowers on short, ridged pedicels with small, smooth, pale yellow gynoecium.
- Fruit a pepo, globular to cylindrical, 15-50 cm long, white to green with white stripes and blotches, rind smooth, hard; flesh white, coarse, tough, fibrous and rather dry; fruit stalk hard, round to 5-angled, without cork development, not or only slightly enlarged at point of fruit attachment.
- Seed flattened, oblong-ellipsoidal, 1.5-2.5 cm long, length to width ratio of 3 : 2, hard, without a spongy epidermis, black or sometimes light buff-coloured.
Growth and development
Most forms of fig-leaf gourd require a short photoperiod for flowering and are normally very late in flowering compared to other species. Bees are the main pollinating agents and in South America, squash and gourd bees are specialized in pollinating Cucurbita species, including C. ficifolia. There are even indications that a certain bee species (Peponapis atrata) is restricted to the pollen of C. ficifolia. It takes approximately 16 weeks from anthesis to seed maturity. Under suitable growing conditions, fig-leaf gourd behaves like the other Cucurbita species and will continue to grow indefinitely when the stems are permitted to root at the nodes. However, it is usually grown as an annual.
Other botanical information
In the taxonomic literature, 3 characteristics are often mentioned to distinguish C. 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 C. 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 cucurbitas). Some well-known cultivars are "Fig-leaf Gourd", "Malabar Gourd", "Lacayote" and "Silacayote".
Among the cultivated Cucurbita species, C. ficifolia has the most restricted habitat. In the high-altitude tropics where it is grown, it will often maintain vigour through cool humid periods while the other species perish because of limited cold tolerance. In South and Central America it is usually grown between 1000-2800 m above sea-level. It requires a short photoperiod for flower initiation, but day-neutral cultivars have also been reported. C. ficifolia is moderately tolerant to acid conditions and grows successfully in fertile, well-drained soils with a pH range of 6.5-7.5.
Propagation and planting
Propagation is by seed. For seed germination, soil temperatures should be above 15 °C; the germination percentage is highest at 35 °C. Seed can be sown in flats, flat ridges or on mounds or hills. The seed rate is 2-4 kg/ha depending on the desired plant density. It is normal practice to sow 3 seeds per hill and thin to one seedling after emergence. Seeds are planted 2-5 cm deep, depending on the soil texture. Plant densities vary from 1000-6000 plants/ha. Fig-leaf gourd is usually grown on small acreages or in home gardens, and occasionally as an intercrop in maize.
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. Trickle or furrow irrigation is preferable above sprinkler irrigation as any moisture on the leaves increases the incidence of leaf diseases.
Diseases and pests
Diseases observed include leaf and stem rot ( Alternaria spp.), watery soft rot (Sclerotinia sclerotiorum), leaf and stem spot (Stemphyllium spp.), bacterial leaf-spot (Xanthomonas cucurbitae), powdery mildew (Erysiphe chicoracearum) and virus diseases (cucumber, melon, squash, watermelon mosaic viruses), but C. ficifolia is a hardy crop. 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 include squash yellow beetle (Aulocophora similis), whitefly (Bemisia tabaci) and aphids (Aphis sp.), all of which are important vectors of viruses. Sanitation practices and the use of chemicals will help to control the pests.
Fruits are allowed to mature on the vine. In temperate climates, if the fruits are mature, the rind is hard and the vines senesce; the fruits should be harvested before the occurrence of frost. In the tropics, the plants continue their growth and harvestable fruits must be selected. A sharp knife is used to cut the fruit stalk 2-5 cm from the fruit. Fruits are selected for uniform size, shape and colour.
A yield of over 50 t/ha mature fruit can be realized under optimal conditions.
Handling after harvest
Cuts and bruises of mature fruits can be healed by suberization. This is accomplished at 27-30 °C and 80% relative humidity for a period of 10 days. Mature fruits can be stored for up to 6 months at 10-15 °C and 60% relative humidity without much loss of quality.
C. ficifolia is the least variable of the cultivated Cucurbita species. It is represented by varying numbers of accessions 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), in the United States (Southern Regional Plant Introduction Station, Georgia) and in Russia (Vavilov Institute of Plant Industry, Petersburg). The one sizable collection in South-East Asia is at the Institute of Plant Breeding, the Philippines.
There have been no breeding programmes for the improvement of C. ficifolia. Although the cultivated Cucurbita species have developed a sequence of sterility barriers that prevents gene flow, C. ficifolia is potentially valuable for squash breeding. It is resistant to several viruses, shows some tolerance to powdery mildew, has the ability to grow under cool, moist conditions, and the mature fruits have long storage life without refrigeration. C. ficifolia can be hybridized with the other squash species by the use of embryo culture.
Fig-leaf gourd has good potential as a fresh vegetable in the tropics, in particular at higher elevations. So far, it has a very limited distribution in South-East Asia. A detailed study of this crop will provide a better understanding of its cultivation and potential. In addition, it has valuable characteristics (disease resistance, cold tolerance, long storage life of the fruits) for squash breeding in general.
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- V.P. Roxas