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Latest revision as of 12:09, 23 March 2015

Plant Resources of Tropical Africa Introduction

List of species

Sechium edule (Jacq.) Sw.

Protologue: Fl. Ind. occid. 2(2): 1150 (1800).

Family: Cucurbitaceae

Chromosome number: 2n = 26, 28

Synonyms

Vernacular names

Chayote, choyote (En). Chayote, chouchou, chouchoutte, christophine, mirliton (Fr). Chuchú, chahiota, caiota, pepinela, chocho (Po).

Origin and geographic distribution

The centre of origin and domestication of Sechium edule is southern Mexico and Guatemala, where wild types are still found. The Aztecs and Mayas already cultivated chayote in pre-Columbian times, but fossil records are lacking. It has now spread throughout the tropics and subtropics. In tropical Africa it occurs in many areas as a minor fruit and leaf vegetable, e.g. in East Africa, Madagascar and the Mascarene Islands. In Réunion and Mauritius it is locally naturalized.

Uses

Chayote is mainly grown for its immature or almost mature fruits, harvested before enlargement of the seed, and eaten as a cooked vegetable. In tropical America and Asia also young, small fruits and young leaves and shoots are used as vegetables, whereas the tuberous roots are consumed especially in Central America. In Jamaica the seeds are eaten fried or roasted. In the Mascarene Islands chayote shoots (‘brède chouchou’) are an important component of local dishes, besides the fruits. The fruits vary in flavour from bland or starchy to sweetish, depending on the cultivar. Fruits of bland cultivars are used industrially as food filler for pastes and sauces. Because of its low energy value, chayote is gaining importance as a dietary food in hospitals and nursing homes. Chayote fruits are also considered good baby food. The seed is nutlike in flavour and a source of protein. Fruits, shoots and tubers are used as fodder for pigs, poultry and cattle. In the past, fibres from the stem have been used to make baskets and hats and – as reported from Ghana – as binding material in the construction of mud houses. During the 19^th and early 20^th centuries, Réunion had an important home industry of hats and other artefacts for export made from these attractive fibres, called ‘paille de chouchou’. The leaves of chayote are said to possess cardiovascular modifying as well as blood pressure lowering properties and to dissolve kidney stones. The tubers are a potent diuretic and are also applied for pulmonary ailments and relief of intestinal inflammation. Medicinal uses of chayote have not been reported from Africa.

Production and international trade

In quantity chayote is one of the leading market vegetables in Central and South America and in South-East Asia, but its commercial value is low. There is considerable international trade, e.g. for export to Europe and the United States. In tropical Africa, it is locally of some importance, e.g. in Sierra Leone, Ghana, Malawi, Réunion and Mauritius, but no statistical data on production or trade are available.

Properties

The edible portion of chayote fruits is about 86%. The average nutritional composition of fruits per 100 g edible portion is: water 94 g, energy 80 kJ (19 kcal), protein 0.8 g, fat 0.1 g, carbohydrate 4.5 g, dietary fibre 1.7 g, Ca 17 mg, Mg 12 mg, P 18 mg, Fe 0.3 mg, Zn 0.7 mg, vitamin A 56 IU, thiamin 0.03 mg, riboflavin 0.03 mg, niacin 0.47 mg, folate 93 μg, ascorbic acid 7.7 mg (USDA, 2002). The young leaves and shoots contain per 100 g: water 90 g, energy 251 kJ (60 kcal), protein 4.0 g, fat 0.4 g, carbohydrate 4.7 g, fibre 1.2 g, Ca 58 mg, P 108 mg, Fe 2.5 mg, vitamin A 615 μg, thiamin 0.08 mg, riboflavin 0.18 mg, niacin 1.1 mg, ascorbic acid 16 mg. The tuberous roots contain per 100 g edible portion (73% of total): water 80 g, energy 331 kJ (79 kcal), protein 2.0 g, fat 0.2 g, carbohydrate 17.8 g, fibre 0.4 g, Ca 7 mg, P 34 mg, Fe 0.8 mg, thiamin 0.05 mg, riboflavin 0.03 mg, niacin 0.9 mg, ascorbic acid 19 mg (Engels, J.M.M., 1983).

Extracts of Sechium edule showed antimutagenic activity in a Salmonella typhimurium assay. The ribosome-inactivating protein sechiumin was purified from the seeds. It has been suggested that this compound could be used for the preparation of immunotoxin as a potential cancer chemotherapeutic agent. Fruit extracts exhibited hypotensive effect in tests with rats. Chayote may cause hypokalaemia in pregnancy.

Description

Monoecious, perennial herb, sprawling or climbing with large, 2–5-branched tendrils; root large, tuberous; stem up to 15 m long, longitudinally grooved. Leaves arranged spirally, simple; stipules absent; petiole 3–25 cm long; blade broadly ovate-circular in outline, 7–25 cm in diameter, 3–7-angular or lobed, base deeply cordate, margins obtusely toothed, scabrid hairy, 5–7-veined from the base. Flowers unisexual, regular, 5-merous; male flowers in an axillary raceme, small, greenish or cream, stamens 3, with filaments united; female flowers usually solitary on short pedicel, corolla c. 0.5 cm in diameter, ovary inferior, 1-celled, style short, stigma headlike. Fruit a fleshy berry, variable in shape but commonly pear-shaped, 4–27 cm long, somewhat ribbed, smooth or shortly spiny, dark green to almost white, pulp white or greenish-white, 1-seeded. Seed ovoid to ellipsoid, compressed, 2.5–5 cm long, white.

Other botanical information

Sechium comprises about 10 species. Only Sechium edule and Sechium tacaco (Pittier) C.Jeffrey are cultivated, the latter only in Costa Rica. Wild types of Sechium edule differ from cultivated types by their more robust growth and larger leaves, flowers and male inflorescences; the pulp of their fruits is bitter and usually more fibrous. Sechium compositum (J.D.Sm.) C.Jeffrey, occurring in southern Mexico and Guatemala, is considered the closest wild relative of Sechium edule. Its fruit is bitter and both spiny and spineless types have been found. Chayote cultivars do not breed true, although it has been observed that cultivars do not segregate significantly from one generation to the next because of the relative isolation of chayote plants from one another when planted in home gardens. Many types with different fruit characters are known. Commercially grown chayote consists of two types: one with a medium-sized, pale green, smooth, pear-shaped fruit and one with a small, white, smooth, globular fruit.

Growth and development

Chayote is a long-lived perennial, but in cultivation it is recommended to renew it at least every 3 years because of disease problems. The tubers do not develop until the second year, and do not develop well in climates without a dry season. In regions with a season of arrested growth, they can reach 10 kg in weight and resemble yam tubers. Flowering starts 1–2 months after germination. Flowers are pollinated by insects. Chayote is self-compatible; single plants show good fruit set and there are no clear inbreeding symptoms. In addition, parthenocarpy has been reported. Chayote is a renowned honey-producing plant, loved by beekeepers because it flowers abundantly throughout the year. Fruit development takes 1–2 months after pollination. In good conditions, chayote plants grow profusely and can form a dense foliage cover on trellis, producing hundreds of hanging fruits. The seed germinates in the ripe fruit while still on the mother plant. The stem of the seedling grows out from the fruit apex and curves upwards. It produces roots which abort when they do not make contact with soil.

Ecology

The natural habitat of wild chayote is montane rainforest on steep hillsides. Chayote requires high relative humidity (80–85%) and well-distributed annual rainfall of at least 1500–2000 mm (or irrigation). Growth and fruit set are strongly influenced by day and night temperatures. Chayote succeeds at average day temperatures of 15–28°C (optimum 25ºC) and at average night temperatures below 23ºC. Temperatures below 13°C cause damage to small unripe fruits, and temperatures above 28°C lead to excessive vegetative growth and the falling of flowers and unripe fruits. In West Africa chayote does not set fruit at sea-level, but produces well at 350–2500 m altitude. At higher latitudes, it grows and produces well in lowlands, but the production stops during the hottest months. In the Antilles, chayote produces fruit at sea-level only during the cool season, at medium elevations the whole year round, and at 1600 m altitude only during the warmest months. Some observers consider chayote as day-neutral, others as a slightly short-day plant. The photoperiodism and the relation between temperature and fruit set need further clarification. Chayote is susceptible to drought and wind, and is killed by night frost. It grows best in a rich well-drained, rather loose sandy loam soil.

Propagation and planting

Chayote is propagated by placing a whole fruit on its side in a hollow scooped out at the foot of a trellis support and covering the fruit slightly with soil and farmyard manure. Sometimes up to 4 fruits already bearing sprouts of 10–12 cm long are planted in the same pit. Immersion of the fruit for several minutes in a fungicide and insecticide solution provides protection against diseases and pests. The plants are usually spaced 1.5 m apart along a fence or trellis, but when they are allowed to sprawl they need much more space.

Management

A trellis support must be provided for optimum growth, but in the Mascarene Islands chayote is grown without any support. In gardens, plants can be trained over a fence, porch or tree. In trees they may grow to a height of more than 10 m. They are best planted where there is some shelter from strong winds. Chayote requires large quantities of water (about 50 mm per week) and should be abundantly irrigated in periods of drought. Incorporation of manure or compost is recommended, as well as application of NPK before planting followed by regular topdressing with nitrogen fertilizer or liquid manure until fruit formation. In the Antilles incorporation of farmyard manure every 3 months is recommended. In India ammonium sulphate and superphosphate at the rate of 1 kg and 0.5 kg respectively per pit are applied in two doses before flowering. In some parts of the world, the plants are pruned at the end of the season, leaving only a small portion of about 1.5 m of the stem.

Diseases and pests

Chayote is in general not very susceptible to pests and diseases, but it is often heavily attacked by root-knot nematodes. Application of large amounts of organic manure to the planting holes reduces damage. Chayote plants sometimes suffer from mosaic virus. Powdery mildew (Erysiphe cichoracearum), downy mildew (Pseudoperonospora cubensis) and leaf spot (Mycosphaerella sp.) occur but are rarely serious. In Trinidad a disease called web blight and caused by the fungus Thanatephorus cucumeris has been reported. Spider mites and insects such as leaf beetles may cause some damage. The use of pesticides may lead to reduction in yield by killing pollinating insects. Because of nematodes and other disease problems, chayote crops are usually removed at the end of a 3-year cultivation period.

Harvesting

Chayote plants start production of fruits 3–5 months after planting and a fruit needs 4–6 weeks from pollination to market size (usually about 0.5 kg). The fruits are hand-picked at an immature stage, when they have reached full size but before the enlargement of the seed. Harvesting late gives fibrous fruits, harvesting early watery ones that do not keep well. Traditionally, maturity is tested by lightly pressing the fruit skin with a finger nail; the right stage is reached if this does not dent the skin. To harvest tubers, it is not necessary to kill the plant; individual tubers can be carefully dug up, while the plant continues to produce fruits and new tubers.

Yield

Production can be seasonal or almost continuous, depending on the climate, and annual yields may range from 75–300 or more fruits per plant. In commercial plantations, yields of 20–30 t/ha have been reported.

Handling after harvest

. When fruits are stored in a cool and dark place, sprouting will start after approximately 2 weeks. In cold storage, at 9–11ºC and high relative humidity and wrapped in plastic, the fruits keep well for several weeks.

Genetic resources

Chayote seed cannot be stored for much longer than one month since it is viviparous and has no dormancy. Long-term maintenance of germplasm collections must therefore be in the form of living plants in field genebanks, or as tissue cultures under slow growth conditions. Promising results have been obtained in Costa Rica with cryopreservation of shoot tissue. Germplasm collections are at present held by CATIE (Turrialba, Costa Rica), Centro Regional Universitario Oriente (CRUO) of the Autonomous University of Chapingo (Huatusco, Vera Cruz, Mexico), INIA (Celaya, Guanajuato, Mexico), EMBRAPA (Brasilia, Brazil) and Tribhuvan University (Kathmandu, Nepal). Genetic erosion of chayote in its centre of diversity is accelerating as a result of replacement of landraces by a few improved cultivars. Collection and evaluation of landraces is required, as well as the evaluation of wild relatives of chayote, especially for finding disease resistances.

Breeding

Efforts made at CATIE (Costa Rica) to describe cultivars on the basis of fruit characteristics proved to be of limited relevance because of the extraordinary variability, with continuous variation in almost all characters, including size (4–27 cm long), weight (60–1200 g), colour (continuous range from white to dark green), shape (pear-shaped, ovoid, flattened globular), fruit-wall features (spines, lenticels, grooves and ridges), flavour and texture. Micro-cuttings are being used in Costa Rica to propagate selected genotypes for commercial production on large acreages. Commercial production is limited by disease problems as well as by the demand for quality fruits; consequently, a breeding programme with these two objectives is needed. However, private seed companies are not interested in chayote because it is viviparous. In Ghana a type called ‘Ivory White’ is grown. Bland cultivars are required for the industrial market and tasty ones for the table-vegetable market.

Prospects

Chayote is a multipurpose, high-yielding and easy-to-produce vegetable, suitable for home gardens and market production, meriting promotion in tropical Africa.

Major references

• Abbiw, D.K., 1990. Useful plants of Ghana: West African uses of wild and cultivated plants. Intermediate Technology Publications, London and Royal Botanic Gardens, Kew, Richmond, United Kingdom. 337 pp.

• Aung, L.H., Ball, A. & Kushad, M., 1990. Developmental and nutritional aspects of chayote (Sechium edule, Cucurbitaceae). Economic Botany 44: 157–164.

• Engels, J.M.M., 1983. Variation in Sechium edule in Central America. Journal of the American Society for Horticultural Science 108: 706–710.

• Engels, J.M.M., 1984. Chayote: a little known Central American crop. Plant Genetic Resources Newsletter 63: 2–5.

• Engels, J.M.M. & Jeffrey, C., 1993. Sechium edule (Jacq.) Swartz. In: Siemonsma, J.S. & Kasem Piluek (Editors). Plant Resources of South-East Asia No 8. Vegetables. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 246–248.

• Lira Saade, R., 1996. Chayote: Sechium edule (Jacq.) Sw. Promoting the conservation and use of underutilized and neglected crops 8. International Plant Genetic Resources Institute, Rome, Italy. 58 pp.

• Newstrom, L.E., 1989. Reproductive biology and evolution of the cultivated chayote (Sechium edule, Cucurbitaceae). In: Bock, J.H. & Linhart, Y.B. (Editors). The evolutionary ecology of plants. Westview Press, Boulder CO, United States. pp. 491–509.

• Newstrom, L.E., 1991. Evidence for the origin of chayote Sechium edule (Cucurbitaceae). Economic Botany 45(3): 410–428.

• Newstrom, L.E., 1985. Collection of chayote and its wild relatives. Plant Genetic Resources Newsletter 64: 14–20.

• USDA, 2002. USDA nutrient database for standard reference, release 15. [Internet] U.S. Department of Agriculture, Beltsville Human Nutrition Research Center, Beltsville Md, United States. http://www.nal.usda.gov/fnic/foodcomp. June 2003.

Other references

• Abdelnour, A., Ramirez, C. & Engelmann, F., 2002. Micropropagacion de chayote (Sechium edule (Jacq.) Sw.) a partir de brotes vegetativos. Agronomia Mesoamericana 13: 147–151.

• Hernández Bermejo, J.E. & León, J. (Editors), 1994. Neglected crops: 1492 from a different perspective. FAO Plant Production and Protection Series No 26. Rome, Italy. 341 pp.

• Holland, B., Unwin, I.D. & Buss, D.H., 1991. Vegetables, herbs and spices. The fifth supplement to McCance & Widdowson’s The Composition of Foods. 4th Edition. Royal Society of Chemistry, Cambridge, United Kingdom. 163 pp.

• Jensen, L.P. & Lai, A.R., 1986. Chayote (Sechium edule) causing hypokalemia in pregnancy. American Journal of Obstetrics and Gynecology 155(5): 1048–1049.

• Lira, R., Caballero, J. & Davila, P., 1997. A contribution to the generic delimination of Sechium (Cucurbitaceae, Sicynae). Taxon 46: 269–282.

• Messiaen, C.-M., 1989. Le potager tropical. 2nd Edition. Presses Universitaires de France, Paris, France. 580 pp.

• Monnerville, K., Boc, Y., Jean-Charles, O., Dornier, M. & Reynes, M., 2001. Principales charactéristiques de Sechium edule Sw. Fruits 56: 155–167.

• Newstrom, L.E., 1986. Studies in the origin and evolution of chayote, Sechium edule (Jacq.) Sw. (Cucurbitaceae). PhD thesis, University of California, Berkeley, United States. 149 pp.

• Norman, J.C., 1992. Tropical vegetable crops. Arthur Stockwell, Elms Court, United Kingdom. 252 pp.

• Wu, T.H., Chow, L.P. & Lin, J.Y., 1998. Sechiumin, a ribosome-inactivating protein from the edible gourd, Sechium edule Swartz: purification, characterization, molecular cloning and expression. European Journal of Biochemistry 255(2): 400–408.

Sources of illustration

• Engels, J.M.M. & Jeffrey, C., 1993. Sechium edule (Jacq.) Swartz. In: Siemonsma, J.S. & Kasem Piluek (Editors). Plant Resources of South-East Asia No 8. Vegetables. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 246–248.

Author(s)

• J.M.M. Engels

IPGRI, Via Delle Sette Chiese 142, 00145 Rome, Italy

Correct citation of this article

Engels, J.M.M., 2004. Sechium edule (Jacq.) Sw. [Internet] Record from PROTA4U. Grubben, G.J.H. & Denton, O.A. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. <http://www.prota4u.org/search.asp>.

Accessed 23 December 2024.

• See the Prota4U database.