Tropical and Subtropical

Tropical and subtropical fruits, in contrast with temperate fruits, can be broadly defined as those meeting all of the following criteria: crops that have their origin and commercial growing areas (when such exist) in the tropics or subtropics, plants that are evergreen and perennial, crops with a limited degree of frost resistance, and plants whose growth is practically nonexistent below 50°F (10°C) (with some exceptions according to species and individual age). A distinction between tropical and subtropical is possible if one considers that tropical species are not only sensitive to temperatures below 68°F (20°C) but indeed require a climate with average mean temperatures higher than 50°F (10°C) for the coldest month (Watson and Moncur, 1985, p. 3). Additionally most tropicals require humid environmental conditions. Examples of truly tropical crops are traditional fruits native to Southeast Asia, like mangosteen, durian, and rambutan. A good example of a typical subtropical fruit crop is the cherimoya, which when cultivated in cold subtropical areas may suffer some foliage loss during the winter with regrowth in spring. However, some fruit crops can be cultivated equally well in either the tropics or the subtropics, of which the banana and the avocado are the most outstanding examples.

Strictly speaking, the tropics extend between the Tropics of Cancer and Capricorn, at 23° north and south of the equator. But, agronomically speaking, these boundaries are too rigid. Not only do they contain areas, especially at higher altitudes, that do not conform to the climatic characteristics generally assigned to the tropics, but regions outside this belt have coastal areas or insular climates that may exhibit climatic conditions fitting properly in the tropics. This is the reason why some climatologists have extended the region to the thirtieth parallels (Nakasone and Paull, 1998, p.1). In any event the main feature associated with the tropics is not so much that of heat but rather steady warm temperatures throughout the year. J. A. Samson (1986, p. 1) gave a good working definition of the tropical climate: temperature averages around 80.6°F (27°C), with the warmest month being only a few degrees higher than the coldest and temperature differences between night and day, at any given time, being greater than those between winter and summer, and, finally, little variation in day length, with the longest day being less than thirteen hours long. In comparison, the subtropics have hotter summers and cooler winters. Humidity is also generally lower. Day length differences become greater with increased latitude. The limit for the subtropics is the isotherm of 50°F (10°C) average for the coldest month (Nakasone and Paull, 1998, p. 12).

Hundreds of tropical and subtropical fruits exist, but only some fifty are well known throughout most of the world (Martin et al., 1987, p.1). These are important production crops (see Box 1), although a considerable gap exists between world per capita consumption (54.9 kilograms per year) and estimated consumption saturation (about 100 to 120 kilograms per year) (Jansen and Subramanian, 2000). Production and trade figures allow the division of tropicals and subtropicals into three main categories (Galán Saúco, 1996) with some overlapping.

1. Major fruits, such as banana and plantain, citrus, coconut, mango, and pineapple.
2. Minor fruits, such as abiu, atemoya, avocado, breadfruit, carambola, cashew nut, cherimoya, durian, guava, jaboticaba, jackfruit, langsat, litchi, longan, macadamia, mangosteen, papaya, passion fruit, pulusan, rambutan, sapodilla, soursop, and white sapote.
3. Wild fruits belonging to diverse botanical families. These are not cultivated commercially in any country and are much in need of characterization, conservation (both in situ, including on farm, and ex situ), selection, and breeding.

Major-category fruits are cultivated in most tropical (and subtropical) countries and are well known in both local and export-import markets. Minor fruits are not so extensively cultivated, and consumption and trade tend to be more limited, both geographically and quantitatively. However, many are of considerable economic importance in their respective regional markets, as is the case with carambola, durian, and mangosteen, which are major fruits throughout Southeast Asia (Anang and Chan, 1999).

Botanical Aspects

Tropical and subtropical fruits include not only woody plants, such as the mango or the orange, but also herbaceous crops like the banana and vines like the passion fruit. Most botanical families can lay claim to at least one species of tropical or subtropical fruit. Franklin Martin and colleagues (1987) list some 137 families, and the best known are in Box 2.

From the botanical point of view, a fruit is the structure developed from flowers or inflorescences. In most cases the fruit consists only of the developed ovary, but it may include other parts of the flower, such as the pedicel, sepal, or receptacle, or even a portion of the seed stalk. As with temperate crops, many different fruit types appear among the tropicals and subtropicals, from single fruits, including berries, such as the avocado or orange; drupes, such as the mango; pomes, such as the loquat; capsules, such as the durian; nutlets, such as the litchi and the longan; to compound fruits, as in the typical syncarpium of the pineapple; or even a bunch of individual berries, as in the banana. To differentiate fruit crops from perennial vegetables whose fruits are also eaten, it is necessary to keep in mind that in a horticultural sense a fruit is something that is normally eaten fresh and out of hand. A number of exceptions exist, like the breadfruit and the plantain, considered fruits by all but only palatable when cooked, as if they were vegetables. Nuts, obviously not eaten out of hand, and some tree crops whose seeds are the only part eaten, are also included among tropicals and subtropicals in most horticultural books and as such are included in this entry.

Areas of Origin and Spread

Although most of the continents, including the islands throughout the Pacific, have contributed tropical and subtropical fruits (see Box 3), most of the best-known ones came from the tropical and subtropical regions of America (for example, papaya, avocado, pineapple, guava) and Asia (for example, orange and most citrus fruits, mango, banana, litchi). Only two commercially important fruits originated in Oceania, the macadamia in Australia (specifically Queensland) and the coconut in the Pacific, the latter to the extent that its origin is considered pantropical (Martin et al., 1987, p. 47). The only important fruit native to the African continent is the date. Europe, with no tropical and limited subtropical areas, has none.

Spread to the regions surrounding their areas of origin probably began early, as soon as humans realized their value in terms of nutrition and the variety they could add to the primitive diets of the time. The potential of some species to provide not only food but also shelter or clothing (some types of banana), wood, and medicine hastened distribution.

An outstanding example is the mango. Native to the Indo-Burman region, by the end of the fourth century C.E. it had spread to all the tropical countries of Southeast Asia (Galán Saúco, 1999, p. 36). The Arabs were apparently responsible for its spread to the east coast of Africa around 700 C.E. as an adjunct to their slaving ventures. Just as Malaysians introduced the banana to Madagascar some two centuries earlier, Islamic domination brought the orange to the Mediterranean and southern Europe. Crops from the Americas are not as well documented, but archaeological findings have shown connections between the cultures of Mexico and Peru dating as far back as 1000 b.c.e. (Purseglove, 1968, p.12), giving a solid opportunity for some tropical and subtropical fruits to spread around the warmer American lands.

Soon after the European discovery of America, the Old and New Worlds rapidly exchanged crops. The sixteenth-century monk Bartolomé de las Casas mentioned that orange seeds were carried from the island of La Gomera (Canary Islands, Spain) to Haiti on Christopher Columbus's second voyage in 1493 (Amador de los Ríos, 1851–1855, vol. 1, p. 3). It is similarly well documented that the banana was carried to Santo Domingo from the Canary Islands in 1516 (the Canaries were a routine last port of call for European ships facing an Atlantic crossing). After Columbus's voyages, a veritable avalanche of expeditions explored all corners of the world, and where the ships went, food went also, to say nothing of tasty fruits and easily propagated species. Between 1500 and 1650 Portuguese sailors connected Brazil and the Cape of Good Hope, touching Goa, Malacca, the Moluccas, Canton, and Macao, trading from there with Japan and Formosa. The Spanish Manila galleon route dominated shipping from 1565 to 1815, plying the seas between the Philippines and Mexico. Dutch, British, and French voyagers were also important in spreading tropical fruits around the world.

No hard and fast rule explains why some fruits spread quickly throughout the world while others remain limited in scope even in the twenty-first century. Several factors may be involved, among them crop adaptability, shelf life, ease of propagation (including the capacity to survive long voyages), size of the plant, multiplicity of uses (that is, other than as fresh fruit), and taste acceptance.

The excellent taste of the pineapple, the long-lasting viability of the plant's suckers as planting material, and the rapidity with which it produces fruit all account for its prompt appearance in Europe—albeit in glasshouses—and India as early as 1548 (Nagy and Shaw, 1980, p.16; Galán Saúco, 2001). Similar considerations apply to the banana and the papaya and even to woody perennial trees like the mango or the guava, which soon spread throughout the tropics and subtropics, even though their size precluded cultivation in greenhouses outside these areas. On the other hand true tropical trees are usually demanding in climate and in some cases are difficult to propagate. The mangosteen, rambutan, and durian (this last deemed by many people to have a peculiar taste) have remained confined almost exclusively to their area of origin in Southeast Asia. The mangosteen is notable among tropical fruits in that it has proven particularly intractable to most attempts to establish it outside of its area of origin via the usual method, which is selection or breeding of cultivars capable of adapting to environments different in climate or edaphic conditions. The species consists of a single genotype, which in essence means no genetic variation exists with which to breed or improve stock, and it is entirely possible that its evolution has ceased (Yaacob and Tindall, 1995, p. 25).

Nutritional and Medicinal Value

Despite the relatively low caloric values of tropical and subtropical fruits (banana and plantain and avocado are the notable exceptions), they play an important role in human diet mainly because of their high and diverse vitamin and mineral content. This has been of capital importance in the tropics, where people have been consuming them since ancient times, either by collecting fruit from the wild or by cultivating plants in kitchen gardens. They have become an important part of the diet of people in the developed countries of the world, especially among the health and fitness conscious. In a properly balanced diet, tropical and subtropical fruits may be an excellent component for the sports-oriented person. This is not to say that one can live by tropical fruits alone or that they can be considered staple fruits within the diet (again the banana and especially its relative the plantain are the exception in some tropical areas). But nutritionists have long recommended a minimum of one hundred grams of fruit per day and that it be as varied as possible. Toward the end of the twentieth century market campaigns commonly recommended consumption of five fruits per day, which, while it may have more to do with commerce than with science, does reinforce the value of fruit as a part of the human diet.

Tropical and subtropical fruits also have some medicinal properties. Many tropical fruits, notably the mango and the papaya, are a good source of carotene (provitamin A). An indication of the high content of this vitamin is the orange-yellow color of the flesh. Others, like all citrus fruits and the guava, are well known as good sources of ascorbic acid (vitamin C). In general they are not a good source of the B group of vitamins (thiamine, riboflavin, and niacin) except for nuts, which are also a good source of vitamin E, proteins, and fats (Martin et al., 1987, p. 7). Tropical and subtropical fruits are also rich in pectin, fiber, and cellulase, which promote intestinal motility. In common with other fruits, they are good sources of antioxidants, and some are also good sources of organic acids, which stimulate appetite and aid digestion.

Values for the chemical composition of tropical and subtropical fruits are widely available in many texts, some of which are included in the bibliography cited here, but the salient points related to general nutritional value follow. Banana is a good source of vitamins A, B, and C and riboflavin. Together with the tropical and subtropical nut fruits, the banana has the highest calorie content. It is low in protein and fat and rich in potassium. Easy to digest, it constitutes an excellent food for young and old alike and is recommended for athletes. Avocado has a good oil content (of the different avocado races, the West Indian types have the lowest) composed of highly digestible unsaturated fatty acids, and it is rich in folic acid. Some cultivars contain good quantities of proteins, vitamin A, riboflavin, and phosphorus.

All citrus fruits have fairly high amounts of vitamin C, as does the guava, which in turn contains fair amounts of niacin and iron. The papaya has high quantities of vitamins C and A as well as potassium and calcium, and it is low in carbohydrates. However, its outstanding feature, which distinguishes the papaya from all other fruits, is the fact that it contains papain, an enzyme that promotes digestion (although papain content does decrease as the fruit ripens). It is highly recommended for people with certain digestive disorders. The mango is rich in provitamin A and carbohydrates and is an acceptable source of vitamin C. The same is true of the passion fruit, which additionally has acceptable quantities of niacin. The pineapple is also rich in vitamin C and carbohydrates and is a good source of calcium, phosphorus, iron, potassium, and thiamine.

The litchi and the longan, most of the Annonaceae, and the durian are all good sources of carbohydrates and vitamin C. The durian also has fair amounts of iron and niacin. The mangosteen is considered by many to be one of the finest tasting fruits of all, according it the title of "queen of fruits" (Yaacob and Tindall, 1995, p. v). It is one of the lowest in nutritive value, but even so it can boast moderate quantities of calcium, phosphorus, ascorbic acid, and carbohydrates. The carambola is low in calories and rich in vitamin C, and it is an adequate source of vitamin A. It is prohibited for people with kidney problems (specifically stone formation) due to its high oxalic acid content, but new cultivars have been selected for lower oxalic content while maintaining sugar and vitamin levels (Galán Saúco et al., 1993, p. 5).

The macadamia nut is rich in protein, oil, iron, calcium, thiamine, riboflavin, and niacin. The subtropical date also has a high nutritive value. Rich in carbohydrates, it is a good source of vitamin A, potassium, and iron but is low in oils and sodium. The coconut is high in phosphorus, iron, proteins, and oils—in this case all saturated fatty acids, the consumption of which should be limited according to health recommendations. Coconut milk aids in balancing pH in the body due to its alkaline reaction.

The medicinal value of tropicals and subtropicals, both the fruits themselves and their actual plant parts (bark, roots, and even pollen), has long been acknowledged by the diverse peoples in and around their areas of origin. These regions are rich in recipes for preparing infusions, decoctions, syrups, pastes, jellies, juices, and so forth for myriad purposes. All the citrus fruits and several others rich in vitamin C are obviously useful to prevent colds and similar infections, while fruits rich in vitamin A prevent dietary deficiencies, such as those leading to blindness. An excellent compilation of popular medicinal uses is in the book Fruits of Warm Climates (1987), written by Julia F. Morton, but a few examples follow.

The date has a high tannin content that is reportedly useful as an astringent in intestinal complaints and is good for sore throats, colds, and bronchial catarrh. Breadfruit is reported to reduce high blood pressure. Carambola fruit and pineapple juice are reportedly useful diuretics, while the flesh of the very young fruit of the pineapple is reputedly an abortifacient. The skin of the avocado and extracts of ripe and unripe fruits and seeds of the papaya reportedly have antibiotic properties. In traditional medicine a decoction of young mango leaves is recommended as a remedy for asthma, blenorraghia, and bronchitis. The roots, bark, leaves, and immature fruits of many tropical fruit crops are widely used in the tropics as astringents to stop gastroenteritis, diarrhea, and dysentery. A decoction of the boiled fruit of the sapodilla has also been reported useful in treating diarrhea. The flesh of the longan has been recommended for its febrifuge and vermifuge properties and as an antidote against some types of poisons. The infusion of passion fruit leaves, rich in the glycosid passiflorine, is reported to have sedative properties.

Consumption and Other Uses

The main method of consumption of most tropical and subtropical fruits is as fresh fruit. The breadfruit is the most important exception, as it is only eaten cooked. Nuts can be eaten directly or processed (roasted, candied, and so forth). Salads, both savory and sweet types, are prepared with many fruits. Indeed consumption is virtually as unlimited as the chef's imagination. Jams, jellies, juices (made with fresh fruits, concentrates, or frozen pulp), sauces, ice cream and sherbets, and other desserts and diverse confectionaries are typical of the uses to which tropical and subtropical fruits are put, both industrially and domestically. Infusions as social beverages, not as medicinal remedies, are made from many different fruits.

A specific product is baby food, especially made with "healthy" fruits like the banana or the papaya, based on different kinds of puree (industrially known as aseptic, chilled aseptic, or simply chilled purees). Flour is also made from the durian and the banana. Pickles and chutneys are made from many fruits, the most famous of which is mango chutney, a staple in Indian cuisine and highly esteemed by gourmets. Dips are also popular in many countries, of which perhaps the best known is avocado-based guacamole. Guava paste or spread is consumed, usually with bread and cheese, in many countries, particularly Cuba, Brazil, and the Canary Islands.

Besides their edible and pleasant fruits, the actual plants of several tropical and subtropical fruit crops are also put to good use. Descriptions of the many properties of parts other than fruits—wood, leaves, flowers, roots, seeds—are frequently dealt with in older texts (including, among others not yet mentioned, Popenoe, 1974 [1920]; Chandler, 1958; Singh, 1960; Purseglove, 1968; Ochse et al., 1972; Coronel, 1983), but a clear dearth of in-depth studies on many of these aspects is apparent. The potential of leaves or flower extracts as biological products for use against pests and diseases is in much the same situation and is an issue relevant to organic produce, of increasing importance to concerned consumers. Some outstanding examples of alternative uses follow.

Religious uses. Some orchards of date palms in the Mediterranean are maintained solely to supply young leaves used on Palm Sunday during the Christian Easter week.

Oils, perfumes, and the like. An essential oil is extracted from some citrus species, particularly from certain oranges and their flowers. Avocado oil, occasionally used for cooking, is a commercial product in some countries. Soaps, bath gels, and shampoos include extracts from different tropical and subtropical fruits. Loquat seed oil is used in soaps and paints.

Animal feed. Banana leaves, pseudostems, and fruits are fed to goats in several countries, particularly in the Canary Islands (Galán Saúco, 2001). Dried dates and their pits, breadfruit leaves, and mango seed kernels are used as feed in several countries. In India, Gandhi recommended using peanuts and mango seed kernels rather than expensive cereals and imported fodders (Galán Saúco, 1999, p. 44).

Textiles and paper. Fibers from pineapple and banana leaves are used in several places for papermaking and cloth, notably in the Philippines to make the typical loose-fitting shirts called guayaberas.

Handicrafts. Mature date palm leaves and avocado wood are excellent for decorative carvings.

Construction and furniture. The wood of breadfruit, citrus in general, guava, longan, mango, and mangosteen are regularly used for interior paneling or for furniture. The wood of the caki is highly prized. Banana and date palm leaves are a traditional roofing material in many regions.

Firewood. Orange wood is long lasting, while avocado wood is highly combustible. Mango wood is held in high esteem in Bangladesh, to the extent that the locals consider the best trees those that faithfully provide both wood and fruit (Galán Saúco, 1999, p. 44).

Other uses. For many years chewing gum (chicle) was made from sapodilla latex. Although the industry subsequently began to use artificial substances, the trend in favor of organic products may signify a return to traditional chicle. Garden brooms are made out of the stripped fruit clusters of the date palm. Fishermen in the Pacific have used the coconut as a fishing aid, chewing the coconut meat and spitting the resulting mass onto the water to produce a glossy calm spot, smooth enough to allow a brief glimpse of the fish below the surface (Hawaii).

The potential for development of tropical fruits does not rely only on consumption. Planting tropical fruits for agroforestry and for urban horticulture are important endeavors. In fact tropical countries like Malaysia encourage and promote intercropping of suitable perennial fruits with compatible forest species (Anang and Chan, 1999). Many tropical fruit trees make beautiful ornamental plants not only capable of improving air quality but also capable of contributing to ecological stability. They are easy to handle in gardens or in industrial or community buildings and are adequate for planting along country roads. These considerations may involve new lines of research, particularly searching for cultivars that can be oriented toward wood (or flower) production. As indicated at the World Conference on Horticultural Research (WCHR) held in Rome in June 1998, international agencies and local authorities should work together with university and government scientists to promote the utilization of horticultural plants in large metropolitan areas (Gosselin et al., 1999).

Commercialization and Trade

In addition to citrus and the banana, four other tropical and subtropical fruits, pineapple, mango, avocado, and papaya, dominate the fresh fruit export trade (see Box 4). Pineapple clearly leads the ranking in processed fruits with a wide range of products, although juice and rings in syrup are the best known.

Many other tropical and subtropical fruits are no longer exotic products in world markets, having become firmly established with guaranteed supply and reasonable prices. Carambola, guava, litchi, mangosteen, passion fruit, and rambutan have experienced notable development. The main importers of most of these tropical and subtropical fruits are the European Union, the United States, Japan, Canada, and China.

Exports of fresh fruits are mainly by ship or surface transport. Postharvest techniques for extending the shelf life of most tropical and subtropical fruits have been mastered, and refrigerated boats (some even providing controlled atmosphere installations) move these commodities from production countries to their ultimate markets with ease. A small proportion of the major fruits, particularly pineapple, mango, and papaya, are transported by air, either destined specially for gourmet or niche markets or for celebrations at certain times of the year, such as Christmas and New Year's, when they command higher prices. Some of the minor crops, still considered exotics, like the mangosteen and the rambutan, have a more difficult postharvest life and therefore are exported by air.

Many countries from virtually all the continents have designated specific areas for production of fruits destined purely for export. Those countries include India, Malaysia, Thailand, and China in Asia; the Philippines and Australia in Oceania; South Africa and Ivory Coast in Africa; Mexico, Brazil, the United States, Peru, Costa Rica, and Chile in North and South America; Spain in Europe; and Israel.

While banana, pineapple, and citrus have a long history of international trade, the avocado trade burst upon the scene in the 1970s. The mango did not become a well-known fruit (from a consumption point of view) until the 1990s, with Mexico as the leading exporter. The papaya and the litchi may still revolutionize trade.

Of particular relevance for the development of tropical and subtropical fruit trade is the World Trade Organization (WTO) agreement in Marrakech on 15 April 1994 following the conclusion of the Uruguayan round of General Agreement on Tariffs and Trade (GATT) talks. Basically these agreements established the principle of free trade not exposed to arbitrary market entrance taxes, and obligate signatory countries (in practice most of the world) to use only sanitary and phytosanitary quarantine measures based on solid scientific information, thus effectively halting the use of these measures as a loophole to arbitrarily restrict imports.

As in other commodities, an interesting market is developing for organically produced tropical and subtropical fruits, and organic pineapples and bananas are available in Western markets.

International Forum on Tropical and Subtropical Fruits

Many organizations and horticultural societies at national and international levels are dedicated to particular tropical or subtropical fruits (or a closely related group). Their members include amateurs, growers, researchers and academics, handlers, traders, and consumers. By reason of both magnitude and global concern, some of these merit special mention.

The International Society of Horticultural Science (ISHS), headquartered in Louvain, Belgium, has established a Commission of Tropical and Subtropical Horticulture with working groups in specific tropical and subtropical fruits. The ISHS meets regularly in different countries to discuss aspects of production, research, and trade of these fruits, and it holds an international congress every four years, which congregates a minimum of four thousand people.

The Interamerican Society of Tropical Horticulture was formerly known as the Tropical Region of the American Society of Horticultural Science. It holds annual meetings in different American countries with tropical crops to discuss the same issues mentioned above but including vegetables and ornamental plants.

The Intergovernmental Group on Bananas and on Tropical Fruits, under the auspices of the Food and Agriculture Organization of the United Nations (FAO), meets every two years to discuss issues related to marketing and trade.

See also Banana and Plantain; Durian; Nuts; Vegetables .

BIBLIOGRAPHY

Amador de Los Ríos, José. Historia General y Natural de las Indias, Islas y Tierra-Firme del Mar Océano, por el Capitán Gonzalo Fernández de Oviedo y Valdés (General and natural history of the Indies, islands, and Terra Firme of the Ocean Sea). Critical edition. 4 vols. Madrid: Impr. de Real Academia de la Historia, 1851–1855.

Anang, S., and Y. K. Chan. "Recent Developments of the Fruit Industry in Malaysia." Paper presented at the FAO–IGG on Bananas and on Tropical Fruits. Gold Coast, Australia, 4–8 May 1999.

Chandler, William Henry. Evergreen Orchards. Philadelphia: Lea and Febiger, 1958.

Coronel, Robert E. Promising Fruits of the Philippines. College, Laguna, Philippines: College of Agriculture, University of the Philippines at Los Baòos, 1983.

Galán Saúco, Víctor. 1999. El Cultivo del Mango (The cultivation of the mango). Madrid: Ediciones Mundi-Prensa, 1999.

Galán Saúco, Víctor. "Current Situation, Trends, and Future of Agronomic Research on Tropical Fruits." In Proceedings of the International Conference on Tropical Fruits, Kuala Lumpur, Malaysia, 23–26 July 1996.

Galán Saúco, Víctor. "Greenhouse Cultivation of Tropical Fruits." International Symposium on Tropical and Subtropical Fruits. Cairns, Australia, 26 November–1 December 2001; Acta Horticulturae 575 (2002): 727–735.

Galán Saúco, Victor, Umberto G. Menini, and H. Don Tindall. Carambola Cultivation. FAO Plant Production and Protection Paper 108. Rome: Food and Agriculture Organization of the United Nations, 1993.

Gosselin, A., S. Yelle, and B. Dansereau. 1999. "Policy Issues in University Horticultural Research." Acta Horticulturae 495 (1999): 511–515.

Hawaii. "Canoe Plants of Ancient Hawaii." Available at http://hawaii-nation.org.

Jansen, M. J. J., and B. Subramaniam. "Long-term Perspectives of Fruit and Other Tree Crops in the New Century." Acta Horticulturae 531 (2000): 23–27.

Martin, Franklin W., Carl W. Campbell, and Ruth M. Ruberté. Perennial Edible Fruits of the Tropics: An Inventory. Washington, D.C.: U.S. Department of Agriculture, Agricultural Research Service, 1987.

Morton, Julia F. Fruits of Warm Climates. Miami, Fla.: Morton, 1987.

Munier, Pierre. Le Palmier-Dattier [The Date palm]. Paris: Maisonneuve and Larose, 1973.

Nagy, Steven, and Philip E. Shaw. Tropical and Subtropical Fruits: Composition, Properties, and Uses. Westport, Conn.: Avi, 1980.

Nakasone, Henry Y., and Robert E. Paull. Tropical Fruits. New York: Cab International, 1998.

Ochse, J. J., M. J. Soule, M. J. Dickman, and C. Wehlburg. Cultivo y Mejoramiento de Plantas Tropicales y Subtropicales [Cultivation and improvement of tropical and subtropical plants]. 2 vols. México: Limusa-Wiley, 1972.

Popenoe, Paul B. Date Growing in the Old and New Worlds. Altadena, Calif.: West India Gardens, 1913.

Popenoe, Wilson. Manual of Tropical and Subtropical Fruits. New York: Hafner Press, 1974. Facsimile of the original 1920 edition.

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Víctor Galán Saúco

Dates

The date palm (Phoenix dactylifera ) has been cultivated in the Middle East since ancient times, where it has assumed a role as more than simply a source of food and become culturally associated with Islamic culture. In the words of the Prophet Muhammad, "There is among trees one tree which is blessed . . . it is the palm."

The date palm is adapted to areas with long, very hot summers with little rain, low humidity, and abundant underground water. This is expressed by the saying that the date palm "must have its feet in running water and its head in the fire of the sky." These conditions are found in oases and river valleys in the arid subtropical deserts of the Middle East, the area of origin of the date palm. This is the "Fertile Crescent," where agriculture in the Old World is thought to have arisen. The date palm has been cultivated in this area since about 7000 b.c.e., and was possibly one of the first crops domesticated. By 2000 b.c.e., date palm culture had spread to Palestine, Arabia, Egypt, North Africa, and western India.

Date palms or their wild progenitors were undoubtedly used by man even before actual cultivation began. A date palm oasis must have been a welcome sight to those crossing the desert. Here were water, shade, and fresh and dried fruits high in carbohydrates. The dried fruits were easily stored and transported after leaving the oasis. The date palm also supplied building material, fiber, fuel, animal feed, honey (syrup), and wine.

The date palm had great spiritual and cultural significance to peoples of the region. It is depicted on many ancient tablets, bas-reliefs, and so forth. The date palm is mentioned a number of times in Jewish and Christian writings, but achieved its greatest esteem in Islamic culture. The date palm was consecrated by Muhammad in both his public and private life, and is prominently mentioned in the Koran and in other Islamic writings. Date consumption spread from Arabia along with Islam, and dates are now eaten by Muslims in areas unsuitable for their production, such as Indonesia and Thailand. Date culture eventually spread to non-Islamic countries with suitable growing conditions, but its culture and consumption in these areas is minor compared to that in the Islamic world.

In the early twenty-first century, the Middle East is still the center of date production and consumption. The largest producers of dates are Egypt, Iran, Iraq, and Saudi Arabia. Most dates are consumed locally, but there is some export, mostly to other Islamic countries that do not have suitable growing conditions. Production of dates is highly specialized and labor-intensive. There are great variations in date growing practices: from traditional oasis culture to modern industrial plantings. The United States has led the way in mechanization of date production, but this practice is spreading to other countries as they modernize.

There are thousands of local varieties of dates grown in the Middle East. Other countries have a more limited number of varieties derived from a few importations. Recently, barhee and medjool have become increasingly prominent due to their use as foundation materials for tissue-cultured plants. The use of tissue-cultured plants has become common in some countries as the increase in land area devoted to date culture has expanded beyond that which can be planted with offshoots, the traditional method of propagation.

Dates are consumed fresh or in processed form. Fresh market dates are divided into dry, semidry, and soft varieties. In Middle Eastern countries, they are also eaten in the early khalal stage. Dates are nutritious, being high in carbohydrate and fiber. In most varieties, the sugar content is mostly invert sugar (glucose and fructose), with only low levels of sucrose. Processed products are more common in the Middle East, where large amounts of dates are produced, than they are elsewhere. Processed products include sugars, pastes, flours, preserves, syrups, and fermentation products.

Robert R. Krueger