prog/docs4four

About coconut tree

COCONUT TREE

The coconut tree (Cocos nucifera) is a member of the palm tree family (Arecaceae) and the only living species of the genus Cocos.[1] The term "coconut" (or the archaic "cocoanut")[2] can refer to the whole coconut palm, the seed, or the fruit, which botanically is a drupe, not a nut. The name comes from the old Portuguese word coco, meaning "head" or "skull", after the three indentations on the coconut shell that resemble facial features. They are ubiquitous in coastal tropical regions and are a cultural icon of the tropics. The coconut tree provides food, fuel, cosmetics, folk medicine and building materials, among many other uses. The inner flesh of the mature seed, as well as the coconut milk extracted from it, form a regular part of the diets of many people in the tropics and subtropics. Coconuts are distinct from other fruits because their endosperm contains a large quantity of clear liquid, called "coconut water" or "coconut juice". Mature, ripe coconuts can be used as edible seeds, or processed for oil and plant milk from the flesh, charcoal from the hard shell, and coir from the fibrous husk. Dried coconut flesh is called copra, and the oil and milk derived from it are commonly used in cooking – frying in particular – as well as in soaps and cosmetics. Sweet coconut sap can be made into drinks or fermented into palm wine or coconut vinegar. The hard shells, fibrous husks and long pinnate leaves can be used as material to make a variety of products for furnishing and decoration. The coconut has cultural and religious significance in certain societies, particularly in the Austronesian cultures of the Western Pacific where it features in their mythologies, songs, and oral traditions. The fall of its mature fruit has led to a preoccupation with death by coconut.[3][4] It also had ceremonial importance in pre-colonial animistic religions.[3][5] It has also acquired religious significance in South Asian cultures, where it is used in rituals of Hinduism. It forms the basis of wedding and worship rituals in Hinduism. It also plays a central role in the Coconut Religion founded in 1963 in Vietnam. Coconuts were first domesticated by the Austronesian peoples in Island Southeast Asia and were spread during the Neolithic via their seaborne migrations as far east as the Pacific Islands, and as far west as Madagascar and the Comoros. They played a critical role in the long sea voyages of Austronesians by providing a portable source of food and water, as well as providing building materials for Austronesian outrigger boats. Coconuts were also later spread in historic times along the coasts of the Indian and Atlantic Oceans by South Asian, Arab, and European sailors. Based on these separate introductions, coconut populations can still be divided into Pacific coconuts and Indo-Atlantic coconuts, respectively. Coconuts were introduced by Europeans to the Americas during the colonial era in the Columbian exchange, but there is evidence of a possible pre-Columbian introduction of Pacific coconuts to Panama by Austronesian sailors. The evolutionary origin of the coconut is under dispute, with theories stating that it may have evolved in Asia, South America, or Pacific islands. Trees grow up to 30 metres (100 feet) tall and can yield up to 75 fruits per year, though fewer than 30 is more typical. Plants are intolerant to cold and prefer copious precipitation and full sunlight. Many insect pests and diseases affect the species and are a nuisance for commercial production. About 75% of the world's supply of coconuts is produced by Indonesia, the Philippines and India. Cocos nucifera is a large palm, growing up to 30 metres (100 feet) tall, with pinnate leaves 4–6 m (13–20 ft) long, and pinnae 60–90 centimetres (2–3 ft) long; old leaves break away cleanly, leaving the trunk smooth.[6] On fertile soil, a tall coconut palm tree can yield up to 75 fruits per year, but more often yields less than 30.[7][8][9] Given proper care and growing conditions, coconut palms produce their first fruit in six to ten years, taking 15 to 20 years to reach peak production.[10] True-to-type dwarf varieties of Pacific coconuts have been cultivated by the Austronesian peoples since ancient times. These varieties were selected for slower growth, sweeter coconut water, and often brightly colored fruits.[11] Many modern varieties are also grown, including the Maypan, King, and Macapuno. These vary by the taste of the coconut water and color of the fruit, as well as other genetic factors.[12] "Botanically, the coconut fruit is a drupe, not a true nut.[13] Like other fruits, it has three layers: the exocarp, mesocarp, and endocarp. The exocarp is the glossy outer skin, usually yellow-green to yellow-brown in color. The mesocarp is composed of a fiber, called coir, which has many traditional and commercial uses. Both the exocarp and the mesocarp make up the "husk" of the coconut, while the endocarp makes up the hard coconut "shell". The endocarp is around 4 millimetres (1⁄8 inch) thick and has three distinctive germination pores (micropyles) on the distal end. Two of the pores are plugged (the "eyes"), while one is functional.[14][15] Palm heavy with fruit The interior of the endocarp is hollow and is lined with a thin brown seed coat around 0.2 mm (1⁄64 in) thick. The endocarp is initially filled with a multinucleate liquid endosperm (the coconut water). As development continues, cellular layers of endosperm deposit along the walls of the endocarp up to 11 mm (3⁄8 in) thick, starting at the distal end. They eventually form the edible solid endosperm (the "coconut meat" or "coconut flesh") which hardens over time. The small cylindrical embryo is embedded in the solid endosperm directly below the functional pore of the endosperm. During germination, the embryo pushes out of the functional pore and forms a haustorium (the coconut sprout) inside the central cavity. The haustorium absorbs the solid endosperm to nourish the seedling.[14][16][17] Coconut fruits have two distinctive forms depending on § domestication. Wild coconuts feature an elongated triangular fruit with a thicker husk and a smaller amount of endosperm. These allow the fruits to be more buoyant and make it easier for them to lodge into sandy shorelines, making their shape ideal for ocean dispersal.[18][19][20] Domesticated Pacific coconuts, on the other hand, are rounded in shape with a thinner husk and a larger amount of endosperm. Domesticated coconuts also have more amounts of coconut water.[18][19][20] These two forms are referred to by the Samoan terms niu kafa for the elongated wild coconuts, and niu vai for the rounded domesticated Pacific coconuts.[18][19][20] A full-sized coconut fruit weighs about 1.4 kilograms (3 pounds 1 ounce). Coconuts sold domestically in coconut-producing countries are typically not de-husked. Especially immature coconuts (6 to 8 months from flowering) are sold for coconut water and softer jelly-like coconut meat (known as "green coconuts", "young coconuts", or "water coconuts"), where the original coloration of the fruit is more aesthetically pleasing.[21][22] Whole mature coconuts (11 to 13 months from flowering) sold for export, however, typically have the husk removed to reduce weight and volume for transport. This results in the naked coconut "shell" with three pores more familiar in countries where coconuts are not grown locally. De-husked coconuts typically weigh around 750 to 850 grams (1 lb 10 oz to 1 lb 14 oz). De-husked coconuts are also easier for consumers to open, but have a shorter postharvest storage life of around two to three weeks at temperatures of 12 to 15 °C (54 to 59 °F) or up to 2 months at 0 to 1.5 °C (32.0 to 34.7 °F). In comparison, mature coconuts with the husk intact can be stored for three to five months at normal room temperature .[21][22]"> "Unlike some other plants, the palm tree has neither a taproot nor root hairs, but has a fibrous root system.[23] The root system consists of an abundance of thin roots that grow outward from the plant near the surface. Only a few of the roots penetrate deep into the soil for stability. This type of root system is known as fibrous or adventitious, and is a characteristic of grass species. Other types of large trees produce a single downward-growing tap root with a number of feeder roots growing from it. 2,000–4,000 adventitious roots may grow, each about 1 cm (1⁄2 in) large. Decayed roots are replaced regularly as the tree grows new ones.[24]"> The evolutionary history and fossil distribution of Cocos nucifera and other members of the tribe Cocoseae is more ambiguous than modern-day dispersal and distribution, with its ultimate origin and pre-human dispersal still unclear. There are currently two major viewpoints on the origins of the genus Cocos, one in the Indo-Pacific, and another in South America.[26][27] The vast majority of Cocos-like fossils have been recovered generally from only two regions in the world: New Zealand and west-central India. However, like most palm fossils, Cocos-like fossils are still putative, as they are usually difficult to identify.[27] The earliest Cocos-like fossil to be found was Cocos zeylandica, a fossil species described as small fruits, around 3.5 cm (1+1⁄2 in) × 1.3 to 2.5 cm (1⁄2 to 1 in) in size, recovered from the Miocene (~23 to 5.3 million years ago) of New Zealand in 1926. Since then, numerous other fossils of similar fruits were recovered throughout New Zealand from the Eocene, Oligocene, and possibly the Holocene. But research on them is still ongoing to determine their phylogenetic affinities.[27][28] Endt & Hayward (1997) have noted their resemblance to members of the South American genus Parajubaea, rather than Cocos, and propose a South American origin.[27][29][30] Conran et al. (2015), however, suggests that their diversity in New Zealand indicate that they evolved endemically, rather than being introduced to the islands by long-distance dispersal.[28] In west-central India, numerous fossils of Cocos-like fruits, leaves, and stems have been recovered from the Deccan Traps. They include morphotaxa like Palmoxylon sundaran, Palmoxylon insignae, and Palmocarpon cocoides. Cocos-like fossils of fruits include Cocos intertrappeansis, Cocos pantii, and Cocos sahnii. They also include fossil fruits that have been tentatively identified as modern Cocos nucifera. These include two specimens named Cocos palaeonucifera and Cocos binoriensis, both dated by their authors to the Maastrichtian–Danian of the early Tertiary (70 to 62 million years ago). C. binoriensis has been claimed by their authors to be the earliest known fossil of Cocos nucifera.[26][27][31] Outside of New Zealand and India, only two other regions have reported Cocos-like fossils, namely Australia and Colombia. In Australia, a Cocos-like fossil fruit, measuring 10 cm × 9.5 cm (3+7⁄8 in × 3+3⁄4 in), were recovered from the Chinchilla Sand Formation dated to the latest Pliocene or basal Pleistocene. Rigby (1995) assigned them to modern Cocos nucifera based on its size.[26][27] In Colombia, a single Cocos-like fruit was recovered from the middle to late Paleocene Cerrejón Formation. The fruit, however, was compacted in the fossilization process and it was not possible to determine if it had the diagnostic three pores that characterize members of the tribe Cocoseae. Nevertheless, Gomez-Navarro et al. (2009), assigned it to Cocos based on the size and the ridged shape of the fruit.[32] Further complicating measures to determine the evolutionary history of Cocos is the genetic diversity present within C. nucifera as well as its relatedness to other palms. Phylogenetic evidence supports the closest relatives of Cocos being either Syagrus or Attalea, both of which are found in South America. However, Cocos is not thought to be indigenous to South America, and the highest genetic diversity is present in Asian Cocos, indicating that at least the modern species Cocos nucifera is native to there. In addition, fossils of potential Cocos ancestors have been recovered from both Colombia and India. In order to resolve this enigma, a 2014 study proposed that the ancestors of Cocos had likely originated on the Caribbean coast of what is now Colombia, and during the Eocene the ancestral Cocos performed a long-distance dispersal across the Atlantic Ocean to North Africa. From here, island-hopping via coral atolls lining the Tethys Sea, potentially boosted by ocean currents at the time, would have proved crucial to dispersal, eventually allowing ancestral coconuts to reach India. The study contended that an adaptation to coral atolls would explain the prehistoric and modern distributions of Cocos, would have provided the necessary evolutionary pressures, and would account for morphological factors such as a thick husk to protect against ocean degradation and provide a moist medium in which to germinate on sparse atolls.[33] Wild coconuts are naturally restricted to coastal areas in sandy, saline soils. The fruit is adapted for ocean dispersal. Coconuts could not reach inland locations without human intervention (to carry seednuts, plant seedlings, etc.) and early germination on the palm (vivipary) was important.[59] Coconuts today can be grouped into two highly genetically distinct subpopulations: the Indo-Atlantic group originating from southern India and nearby regions (including Sri Lanka, the Laccadives, and the Maldives); and the Pacific group originating from the region between maritime Southeast Asia and Melanesia. Linguistic, archaeological, and genetic evidence all point to the early domestication of Pacific coconuts by the Austronesian peoples in maritime Southeast Asia during the Austronesian expansion (c. 3000 to 1500 BCE). Although archaeological remains dating to 1000 to 500 BCE also suggest that the Indo-Atlantic coconuts were also later independently cultivated by the Dravidian peoples, only Pacific coconuts show clear signs of domestication traits like dwarf habits, self-pollination, and rounded fruits. Indo-Atlantic coconuts, in contrast, all have the ancestral traits of tall habits and elongated triangular fruits.[49][5][48][60] Indo-Atlantic coconut from eastern India with the elongated triangular niu kafa-type fruits Domesticated Pacific coconut from the Philippines with bright yellow rounded niu vai-type fruits and a slow-growing dwarf habit The coconut played a critical role in the migrations of the Austronesian peoples. They provided a portable source of both food and water, allowing Austronesians to survive long sea voyages to colonize new islands as well as establish long-range trade routes. Based on linguistic evidence, the absence of words for coconut in the Taiwanese Austronesian languages makes it likely that the Austronesian coconut culture developed only after Austronesians started colonizing the Philippines. The importance of the coconut in Austronesian cultures is evidenced by shared terminology of even very specific parts and uses of coconuts, which were carried outwards from the Philippines during the Austronesian migrations.[49][5] Indo-Atlantic type coconuts were also later spread by Arab and South Asian traders along the Indian Ocean basin, resulting in limited admixture with Pacific coconuts introduced earlier to Madagascar and the Comoros via the ancient Austronesian maritime trade network.[49] Coconuts can be broadly divided into two fruit types – the ancestral niu kafa form with a thick-husked, angular fruit, and the niu vai form with a thin-husked, spherical fruit with a higher proportion of endosperm. The terms are derived from the Samoan language and was adopted into scientific usage by Harries (1978).[49][18][61] The niu kafa form is the wild ancestral type, with thick husks to protect the seed, an angular, highly ridged shape to promote buoyancy during ocean dispersal, and a pointed base that allowed fruits to dig into the sand, preventing them from being washed away during germination on a new island. It is the dominant form in the Indo-Atlantic coconuts.[18][49] However, they may have also been partially selected for thicker husks for coir production, which was also important in Austronesian material culture as a source for cordage in building houses and boats.[5] A coconut plantation in Efate, Vanuatu The niu vai form is the domesticated form dominant in Pacific coconuts. They were selected for by the Austronesian peoples for their larger endosperm-to-husk ratio as well as higher coconut water content, making them more useful as food and water reserves for sea voyages. The decreased buoyancy and increased fragility of this spherical, thin-husked fruit would not matter for a species that had started to be dispersed by humans and grown in plantations.[18][19] Niu vai endocarp fragments have been recovered in archaeological sites in the St. Matthias Islands of the Bismarck Archipelago. The fragments are dated to approximately 1000 BCE, suggesting that cultivation and artificial selection of coconuts were already practiced by the Austronesian Lapita people.[5] Coconuts can also be broadly divided into two general types based on habit: the "Tall" (var. typica) and "Dwarf" (var. nana) varieties.[62] The two groups are genetically distinct, with the dwarf variety showing a greater degree of artificial selection for ornamental traits and for early germination and fruiting.[61][63] The tall variety is outcrossing while dwarf palms are self-pollinating, which has led to a much greater degree of genetic diversity within the tall group.[64] The dwarf coconut cultivars are fully domesticated, in contrast to tall cultivars which display greater diversity in terms of domestication (and lack thereof).[65][64] The fact that all dwarf coconuts share three genetic markers out of thirteen (which are only present at low frequencies in tall cultivars) makes it likely that they all originate from a single domesticated population. Philippine and Malayan dwarf coconuts diverged early into two distinct types. They usually remain genetically isolated when introduced to new regions, making it possible to trace their origins. Numerous other dwarf cultivars also developed as the initial dwarf cultivar was introduced to other regions and hybridized with various tall cultivars. The origin of dwarf varieties is Southeast Asia, which contain the tall cultivars that are genetically closest to dwarf coconuts.[49][11][65][64] Sequencing of the genome of the tall and dwarf varieties revealed that they diverged 2 to 8 million years ago and that the dwarf variety arose through alterations in genes involved in the metabolism of the plant hormone gibberellin.[66] Another ancestral variety is the niu leka of Polynesia (sometimes called the "Compact Dwarfs"). Although it shares similar characteristics to dwarf coconuts (including slow growth), it is genetically distinct and is thus believed to be independently domesticated, likely in Tonga. Other cultivars of niu leka may also exist in other islands of the Pacific, and some are probably descendants of advanced crosses between Compact Dwarfs and Southeast Asian Dwarf types.[11][65] The nuts we had in baskets on deck remained edible and capable of germinating the whole way to Polynesia. But we had laid about half among the special provisions below deck, with the waves washing around them. Every single one of these was ruined by the sea water. And no coconut can float over the sea faster than a balsa raft moves with the wind behind it. He also notes that several of the nuts began to germinate by the time they had been ten weeks at sea, precluding an unassisted journey of 100 days or more.[57] Drift models based on wind and ocean currents have shown that coconuts could not have drifted across the Pacific unaided.[57] If they were naturally distributed and had been in the Pacific for a thousand years or so, then we would expect the eastern shore of Australia, with its own islands sheltered by the Great Barrier Reef, to have been thick with coconut palms: the currents were directly into, and down along this coast. However, both James Cook and William Bligh[70] (put adrift after the Bounty mutiny) found no sign of the nuts along this 2,000 km (1,200 mi) stretch when he needed water for his crew. Nor were there coconuts on the east side of the African coast until Vasco da Gama, nor in the Caribbean when first visited by Christopher Columbus. They were commonly carried by Spanish ships as a source of fresh water. Sapling on a black sand beach Coconut germinating on Punaluʻu Beach on the island of Hawaiʻi These provide substantial circumstantial evidence that deliberate Austronesian voyagers were involved in carrying coconuts across the Pacific Ocean and that they could not have dispersed worldwide without human agency. More recently, genomic analysis of cultivated coconut (C. nucifera L.) has shed light on the movement. However, admixture, the transfer of genetic material, evidently occurred between the two populations.[71] Given that coconuts are ideally suited for inter-island group ocean dispersal, obviously some natural distribution did take place. However, the locations of the admixture events are limited to Madagascar and coastal east Africa, and exclude the Seychelles. This pattern coincides with the known trade routes of Austronesian sailors. Additionally, a genetically distinct subpopulation of coconut on the Pacific coast of Latin America has undergone a genetic bottleneck resulting from a founder effect; however, its ancestral population is the Pacific coconut from the Philippines. This, together with their use of the South American sweet potato, suggests that Austronesian peoples may have sailed as far east as the Americas.[71] In the Hawaiian Islands, the coconut is regarded as a Polynesian introduction, first brought to the islands by early Polynesian voyagers (also Austronesians) from their homelands in the southern islands of Polynesia.[39] Specimens have been collected from the sea as far north as Norway (but it is not known where they entered the water).[72] They have been found in the Caribbean and the Atlantic coasts of Africa and South America for less than 500 years (the Caribbean native inhabitants do not have a dialect term for them, but use the Portuguese name), but evidence of their presence on the Pacific coast of South America antedates Columbus's arrival in the Americas.[45] They are now almost ubiquitous between 26° N and 26° S except for the interiors of Africa and South America. The 2014 coral atoll origin hypothesis proposed that the coconut had dispersed in an island hopping fashion using the small, sometimes transient, coral atolls. It noted that by using these small atolls, the species could easily island-hop. Over the course of evolutionary time-scales the shifting atolls would have shortened the paths of colonization, meaning that any one coconut would not have to travel very far to find new land.[33] Coconuts are susceptible to the phytoplasma disease, lethal yellowing. One recently selected cultivar, the 'Maypan', has been bred for resistance to this disease.[73] Yellowing diseases affect plantations in Africa, India, Mexico, the Caribbean and the Pacific Region.[74] Konan et al., 2007 explains much resistance with a few alleles at a few microsatellites.[75] They find that 'Vanuatu Tall' and 'Sri-Lanka Green Dwarf' are the most resistant while 'West African Tall' breeds are especially susceptible.[75] The coconut palm is damaged by the larvae of many Lepidoptera (butterfly and moth) species which feed on it, including the African armyworm (Spodoptera exempta) and Batrachedra spp.: B. arenosella, B. atriloqua (feeds exclusively on C. nucifera), B. mathesoni (feeds exclusively on C. nucifera), and B. nuciferae.[76] Brontispa longissima (coconut leaf beetle) feeds on young leaves, and damages both seedlings and mature coconut palms. In 2007, the Philippines imposed a quarantine in Metro Manila and 26 provinces to stop the spread of the pest and protect the Philippine coconut industry managed by some 3.5 million farmers.[77] The fruit may also be damaged by eriophyid coconut mites (Eriophyes guerreronis). This mite infests coconut plantations, and is devastating; it can destroy up to 90% of coconut production. The immature seeds are infested and desapped by larvae staying in the portion covered by the perianth of the immature seed; the seeds then drop off or survive deformed. Spraying with wettable sulfur 0.4% or with Neem-based pesticides can give some relief, but is cumbersome and labor-intensive. In Kerala, India, the main coconut pests are the coconut mite, the rhinoceros beetle, the red palm weevil, and the coconut leaf caterpillar. Research into countermeasures to these pests has as of 2009 yielded no results; researchers from the Kerala Agricultural University and the Central Plantation Crop Research Institute, Kasaragode, continue to work on countermeasures. The Krishi Vigyan Kendra, Kannur under Kerala Agricultural University has developed an innovative extension approach called the compact area group approach to combat coconut mites.