Tropical Fruits and NutsCoconutsBananasMangoesPineapplesPapayasDuriansGuavaBreadfruitLichis & RambutanMacadamia nutsBrazil nutsCashew nuts

Tropical Fruit and Nut Crops

Coconuts

Coconut, Cocos nucifera, belongs to the Arecaceae, the same family that includes date palms. A monocot family.

Coconut plants are monoecious, with male and female flowers in the same inflorescence.

The seeds of coconuts are important for food, but the coconut plant is also grown for fiber.

The exact region of origin of coconuts is not known, the plant was already present in SE Asia, Poynesian islands, and Pacific coast of S America when European explorers arrived.

Region of origin is thought to be Indo-Pacific, with natural spread around the Pacific by ocean currents and also aided by Polynesian people. Coconuts were probably first domesticated in Malaysia.

Coconuts

The edible part of the coconut is really part of the seed. When immature, the endosperm is liquid and has nuclei but no cell walls. [What is the ploidy of endosperm nuclei?]

Coconut water is liquid endosperm.

As the endosperm matures, cell walls form around the nuclei and endosperm becomes the oil-rich, solid white “meat” of the coconut.

The coconut seed is encased in a fruit (a drupe) with a fibrous mesocarp and a thick, hard endocarp.

Coconuts

endocarp

endosperm

Coconut flowers have three carpels (only onedevelops to produce the seed), which leave three “eyes” or germination pores. The embryo is located at this end of the seed and the cotyledon emerges through one of the pores.

Most coconut meat is processed into coconut oil, which is >90% saturated fat. Often coconut oil is further hydrogenated in processing,increasing the degree of saturation.

Coconut oil is used for cooking, as the main ingredient in margarine, and as an ingredient in soaps and cosmetics.

Most coconuts are produced in the Phillipines, Indonesia, India and Brazil.In the US coconuts are produced only in Hawaii and Florida.

Bananas and PlantainsBananas and plantains are members of the genus Musa in the family Musaceae, a monocot.

Bananas probably originated in the Indo-Malaysian region, which is a center of diversity for Musaspecies. Many wild species of Musa are known from Malaysia, Indonesia, and Papua New Guinea. Cultivation of bananas in the highlands of New Guinea date to about 8,000 BP, and likely other species of banana were domesticated in other parts of SE Asia at about the same time.

Bananas have also been cultivated in Africa for at least 1500 years, possibly as much as 2500 years, and were spread throughout N Africa and theMediterranean region between 700 and 1500 AD by Islamic Arabs.

Bananas were introduced to the West Indies in the 1600s

Bananas and PlantainsDomestication of banana involved hybridization and polyploidy in two diploid species, Musa acuminata and M. balbisiana.

M. acuminata was domesticated in Malaysia and SE Asia. As cultivation of this species gradually spread to the north, it hybridized with M. balbisiana.Hybrids between these two species are all lumped together under the name Musa x paradisiaca. Contemporary banana cultivars have different ploidy and different contributions of the two parent species genomes.

Most contemporary cultivated bananas are triploids.

The contribution of the two banana species is designated by A for the genome of M. acuminata and B for M. balbisiana. Pure diploid M. acuminata is AA. The most common banana cultivar ‘Cavendish’ is a triploid M. acuminata, so is designated AAA. Sweet “dessert” bananas are all AAA types.

The AB hybrids are more starchy. Horn Plantain is AAB triploid.

Cavendish bananas are triploids derived from one species Musa acuminataThe original triploid Cavendish resulted from combination of normal haploid gametes with nonreduced diploid gametes.

Triploids are almost invariably sterile, incapable of producing viable seed, because during meiosis chromosomes pair up with their homologues. Diploids and tetraploids can produce viable gametes because there is an equal number of chromosome pairs. But triploids have 1 1/2 pairs of chromosomes. When chromosomes don’t pair properly, nonfunctional nuclei result from the cell division.

Because Cavendish bananas are triploids, they are all vegetatively propagated clones, and identical to the original Cavendish plant. The lack of genetic diversity makes the Cavendish vulnerable to pathogens.

A root disease, Panama disease, caused by a fungal pathogen devastated the Gros Michel (AAA) banana cultivar in the 1950s. Now a fungal leaf disease called Black Sigatoka is threatening to exterminate Cavendish bananas.

Bananas and Plantains

Bananas and PlantainsAll banana varieties cultivated for their fruit are parthenocarpic, seedless.The large, hard, flinty seeds in wild diploid bananas make them inedible.

In a parallel with the story of domestication of figs, parthenocarpy must have been recognized and selected by early agriculturalists. Parthenocarpic plants necessarily would have been vegetatively propagated.

M. acuminata was probably the first banana species domesticated in Malaysia. As its cultivation spread north into SE Asia, hybrids with M. balbisiana occurred spontaneously. A variety of diploid, triploid, and tetraploid hybrids throughout SE Asia, Indonesia, and Africa.

Wild diploid bananas have large, hard seeds

In export value worldwide, bananas rank fourth among all agricultural commodities (only rice, wheat and milk are more valuable) and are the most valuable of all fruits, with world trade totaling $2.5 billion annually.

Yet, only about 10% of the annual global output of 86 million tons enters international commerce. So actual world production of bananas is much greater than the export value suggests.

Much of the remaining harvest is consumed by poor subsistence farmers in tropical Africa, America and Asia. For most of the latter producers, banana and plantain are staple foods that represent major dietary sources of carbohydrates, fiber, vitamins, potassium, phosphorus and calcium.

Starchy bananas are grown as a primary source of dietary carbohydrate, in parts of Asia, Africa, and the Caribbean.

Bananas and Plantains

Although commonly called trees, banana plants are actuallyvery large herbaceous plants.

Bananas and Plantains

Bananas and PlantainsCavendish banana cultivars, which are grown in large monocultureplantations in tropical areas worldwide, are extremely susceptible to the fungal disease “Black Sigatoka”, usually requiring expensive aerially applied fungicide sprays for control.

Fungicides are not an economically viable option for subsistence farmers

Bananas and Plantains

Bananas are propagated vegetatively by planting corms or sucker shoots

Corms are a type of underground stem tissue, often mistaken for a bulb.Corms are often a starchy storage organ, taro for example is a starchy corm. Large banana corms can be broken into pieces and used forpropagation.

A banana corm

Pineapples

Pineapples, Ananas comosus, are native to S america, and were being cultivated by native people in the West Indies at the time of Columbus (1493) who introduced the fruit to Europe. In Europe, pineapples were cultivated in glasshouses or “pineapple pits”

From there, pineapple cultivaton was spread by Spanish, Dutch and Portugues traders to the Phillipines, Hawaiian Islands, Guam, Africa.

Pineapple is a major crop in Hawai’i, where it has been produced commercially since the early 1900s.

Pineapples are multiple fruits, formed by the fusion of flower tissues (receptacle, bracts, corolla, pericarp). The edible part is bract and corolla (petals and sepals) that become fleshy.

Like bananas, modern pineapple cultivars are parthenocarpic and are propagated vegetatively.

Pineapples

leafy bracts

stem tissue

fruitlet

fruitlet

bract

fleshy carpel tissue

sepal

MangoesMangoes, Mangifera indica, are members of the plant family Anacardiaceae. Fruits are drupes.

North American members of this family are in the genus Rhus, which includes the common species poison oak and poison ivy, which produce a skin irritating oil.

Another important food plant that belongs to the Anacardiaceae is the cashew.

Mangoes are native to India and SE Asia. They appeared in Africa ca 1000 years ago, were brought to S America by the Portuguese in the early 1700s and from there to the West Indies in 1742. Mangoes now are an important seasonal food source for the poor populations of Jamaica and Haiti.

Mangoes

Mangoes are a major world fruit crop. Production in 2007 was about 33,500,000 metric tonnes, making mangoes the 4th most important world food crop based on production, after bananas, apples, and oranges

Major producers of mangoes (2007 metric tonnes) are:

Mexico 2,050,000Pakistan 2,250,000India 13,501,000China 3,752,000Brazil 1,546,000Thailand 1,800,000Indonesia 1,620,000

Papaya

Papaya, Carica papaya (Caricaceae), is native to Central America and have been cultivated in Mexico since before the Mayan period.

The papaya fruit is a multiseeded berry, like a tomato. The fruits are attached directly to the stem of the tree.

Papayas are grown as food in several tropical countries. The fruit flesh is edible but production of the enzyme papain is more commercially important.

The fruit and latex from the stems is also the source of a proteolytic enzyme, papain.

PapayaPapain is a very effective proteolytic enzyme derived from the skin of green papaya fruits and from the latex of the tree.

The effectiveness of the latex in papaya fruits in breaking down the fibers of tough meats has been known by native South America people for at least several centuries.

Papain is the major ingredient in commercial meat tenderizer products.

It is also used medicinally as a treatment for venomous bites and stings.

Litchi and Rambutan

Litchi, or lychee, Litchi chinensis (Sapindaeae) is a tropical fruit native to China

The trees are cultivated primarily in southern China, but a limited amount is produced in Florida and Hawai’i. A related fruit, the rambutan (Nephelium lappaceum) is native to Malaysia.

The fruit is a drupe, and the edible portionis the succulent, smooth-textured inner partthat surrounds the seed.

Rambutan

Litchi and Rambutan

Rambutans are grown in Malaysia, Thailand, The Philippines, and more recently in Australia and Central America.

A number of varieties have been selected on the basis of fruit characteristics, i.e. storage, size, color, loose vs. adhering seed.

The fruits tend to degenerate very soon after they are picked, they do not have a shelf life of only a few days, which has hindered the commercialization of the fruit.

BreadfruitBreadfruit, Artocarpus altilis (Moraceae) belongs to the same plant family as figs, but the flowers and fruits are very different. Breadfruits are multiple fruits, like figs, but are not produced in a syconium.

Breadfruit is an important staple food of many of the tropical Pacificislands. It is thought to be native to Malaysia and its spread througout the tropical Pacific was assisted by Polynesian migrations. The average breadfruit is about 20% carbohydrate, and when cooked is similar in taste and consistency to potatoes.

Breadfruit has an immortal history as part of the famous story of the mutiny on the H.M.S. Bounty in 1787. The mission of the Bounty, commanded by Capt. Bligh, was to collect breadfruit trees from Tahiti for introduction to the islands of theWest Indies.

DuriansDurians, Durio zibethinus, epitomize exotic fruits. Durians are considered the “king of fruits” in parts of SE Asia. However they have aodor that is rather repulsive, causing them to be forbidden in some public areas. The distinctive odor of durians is said to combine rotting onions, strong cheese, turpentine and sewage. The flesh has a custard-like consistency and the taste is saidto be indescribably wonderful.

The durian center of diversity is Indonesia (Borneo) and the fruit has been cultivated in SE Asia since prehistoric times.

Commercial production in SE Asia is very recent, butdemand for the fruit has been increasing.

Durian pulp and paste are used in a variety of traditional SE Asian foods

CashewsCashew, Anacardium occidentale, is native to NE South America, and belongs to the same family (Anacardiaceae) as mangoes, poison oak and poison ivy.

Cashews have a toxic latex in the hard pericarp coat, but the seed is edible. Botanically, cashew fruits are a bit strange.

The cashew nut is the embryo, surrounded by a hard exocarp. While the true fruit is developing, the receptacle tissue begins to enlarge, eventually becoming large, fleshy, and red.

The fleshy receptacle tissue is called a cashew apple, and this, rather than the fruit, has been consumed by South American natives. It is a false fruit or accessory fruit. fruit

apple (modified receptacle)

Cashews

World production of cashews in 2007 was 3,186,039 MT, with the major producing countries being Vietnam, Nigeria, and India.

Macadamia Nuts

Macadamia nuts, Macadamia integrifolia, are members of the Proteaceae, a plant family that has a primarily southern hemisphere distribution and includes Protea, and Banksia, flowers used for floral arrangements.

Macadamia Nuts

Other species of Macadamia contain high levels of cyanogenic glycosides, similar to amygdalin that occurs in the unrelated almond. Nuts of these wild species are collected, leached to detoxify them and consumed by indigenous Australian people.

Macadamia nuts are native to Australia, but the major production ofmacadamia nuts comes from Hawai’i. Commercial production of macadamia nuts in Hawai’i began in the 1920s.

Macadamia nut oil is also used as an ingredient in some cosmetics.

Brazil NutsBrazil nut, Bertholletia excelsa, is a rainforest tree native tonortheast South America (Guiana, Venezuela, Brazil). The trees are large and long-lived.

The fruits of the brazil nut tree are large, woody spheres, called capsules, similar in size to a coconut, that can weigh more than 2 kg and contain the seeds. The seeds are arranged like the segments of an orange inside the brazil nut fruit. The edible part of the brazil nut is a seed.

Brazil nuts are an unusual crop because almost all production comes from wild collected nuts. Brazil nut plantations have not been very cost effective. One reason for this is that the large flowers require specific pollinator insects, bees large enough to be able to pry open a hood that covers the nectar bearing part of the flower. These bees only occur in mature forests and are solitary, not social, so are not amenable tohuman apiculture.

Brazil Nuts

The reproductive cycle of the pollinator bees also requires a specific orchid. Male orchid bees visit the orchid flowers to obtain a scent that is attractive to female orchid bees. For some reason, female orchid bees do not visit these flowers but are attracted to male bees that have the orchid scent. This allows them to make more orchid bees.

Only female orchid bees pollinate brazil nuts. So, no orchids, no bee sex, no brazil nuts.

The brazil nut capsules are collected after they fall to the ground during the rainy season by migrant “castanhieros”. The capsules must be collected promptly to prevent the attack of the nuts by fungi.

Brazil nuts are eaten and cached by a small rodent, called an Agouti. Agoutis are necessary for the dispersal and propagation of the trees.

Unfortunately, brazil nuts are very susceptible to attack by certain fungi that produce aflatoxin, a potent mycotoxin associated with a variety of cancers in humans. The nuts are collected during the rainy season when moisture is high an the conditions are most favorable for producing aflatoxins.

The European Union instituted very strict standards for aflatoxin levels inbrazil nuts in 1998.

Bolivia and Brazil are the major producers of brazil nuts, each with about 30,000 metric tonnes.

Brazil Nuts