Avocado
The avocado, alligator pear or avocado pear is an evergreen tree in the laurel family. It is native to the Americas, with archaeological evidence of early human avocado use dating back thousands of years across various regions of Central and South America. It was prized for its large and unusually oily fruit. The native range of avocado extends from Mexico to Peru, encompassing much of Central America and parts of northern and western South America.
Its fruit, sometimes also referred to as an alligator pear or avocado pear, is botanically a large berry containing a single large seed. Sequencing of its genome showed that the evolution of avocados was shaped by polyploidy events and that commercial varieties have a hybrid origin. Avocado trees are partly self-pollinating, and are often propagated through grafting to maintain consistent fruit output. Avocados are presently cultivated in the tropical and Mediterranean climates of many countries., Mexico is the world's leading producer of avocados, supplying 29% of the global harvest of 10.5 million tonnes.
The fruit of domestic varieties have smooth, buttery, golden-green flesh when ripe. Depending on the cultivar, avocados have green, brown, purplish, or black skin, and may be pear-shaped, egg-shaped, or spherical. For commercial purposes, the fruits are picked while unripe and ripened after harvesting. The nutrient density and high fat content of avocado flesh are advantages for various cuisines, including vegetarian diets.
In major production regions like Chile, Mexico and California, the water demands of avocado farms place strain on local resources. Avocado production is implicated in other externalities, including deforestation and human rights concerns associated with the partial control of their production in Mexico by organized crime. Global warming is expected to result in significant changes to the suitable growing zones for avocados, and place additional pressures on the locales in which they are produced due to heat waves and drought.
Description
Persea americana is a tree that grows to with a trunk diameter between. The leaves are long and alternately arranged.Flower
Panicles of flowers with deciduous bracts arise from new growth or the axils of leaves. The tree flowers thousands of blossoms every year. Avocado blossoms sprout from racemes near the leaf axils; they are small and inconspicuous wide. They have no petals but instead two whorls of three pale-green or greenish-yellow downy perianth lobes, each blossom has 9 stamens with 2 basal orange nectar glands.Fruit
The avocado fruit is a climacteric, single-seeded berry, due to the imperceptible endocarp covering the seed, rather than a drupe. The pear-shaped fruit is usually long, weighs between, and has a large central seed, long. Early wild avocados prior to domestication had much smaller seeds around in diameter, likely corresponding to smaller fruit size.The species produces various cultivars with larger, fleshier fruits with a thinner exocarp because of selective breeding by humans.
Taxonomy and evolution
The species was scientifically named by the British botanist Philip Miller in 1768. The genus Persea to which the avocado belongs is considered to have a North American origin, with Persea suggested to have diversified in Central America during the Pleistocene epoch. The modern avocado is thought to have speciated from other Persea during the Pleistocene, estimated at around either 1.3 million or 430,000 years ago. A number of authors, including Connie Barlow in her 2001 book The Ghosts of Evolution, have speculated that the avocado is an "evolutionary anachronism" with megafaunal dispersal syndrome, arguing that the avocado likely coevolved dispersal of its large seed by now-extinct megafauna. Barlow proposed that the dispersers included the gomphothere Cuvieronius, as well as ground sloths, toxodontids, and glyptodonts. The concept of evolutionary anachronisms/megafaunal dispersal syndrome has been criticised by some authors, who note that many large fruit are readily dispersed by non-megafaunal animals, with it being noted that living agoutis disperse avocado seeds, with spectacled bears also having been observed eating domestic avocados.History
The earliest known written account of the avocado in Europe is that of Martín Fernández de Enciso in 1519 in his book, Suma De Geographia Que Trata De Todas Las Partidas Y Provincias Del Mundo, while describing the native settlement of Yaharo. The first detailed account that unequivocally describes the avocado was given by Gonzalo Fernández de Oviedo y Valdés in his work Sumario de la natural historia de las Indias in 1526, while holding administrative Spanish colonial duties in Santo Domingo and visiting Castilla de Oro. The first written record in English of the use of the word 'avocado' was by Hans Sloane, who coined the term, in a 1696 index of Jamaican plants.Etymology
The word avocado comes from the Spanish aguacate, which derives from the Nahuatl word āhuacatl, which goes back to the proto-Aztecan *pa:wa. In Molina's Nahuatl dictionary "auacatl" is given also as the translation for compañón "testicle", and this has been taken up in popular culture where a frequent claim is that testicle was the word's original meaning. This is not the case, as the original meaning can be reconstructed as "avocado" – rather the word seems to have been used in Nahuatl as a euphemism for "testicle".The modern English name comes from a rendering of the Spanish aguacate as avogato. The earliest known written use in English is attested from 1697 as avogato pear, later avocado pear, a term sometimes corrupted to alligator pear.
Regional names
In Central American, Caribbean Spanish-speaking countries, and Spain it is known by the Mexican Spanish name aguacate, while South American Spanish-speaking countries Argentina, Chile, Perú and Uruguay use a Quechua-derived word, palta. In Portuguese, it is abacate. The Nahuatl āhuacatl can be compounded with other words, as in ahuacamolli, meaning avocado soup or sauce, from which the Spanish word guacamole derives.In Trinidad and Tobago, it is known as 'Zaboca', which is derived from the French Creole, 'l'avocat'.
In the United Kingdom the term avocado pear, applied when avocados first became commonly available in the 1960s, is sometimes used.
Originating as a diminutive in Australian English, a clipped form, avo, has since become a common colloquialism in South Africa and the United Kingdom.
It is known as "butter fruit" in parts of India and Hong Kong.
Cultivation
Domestication and cultivation history
Domestication, leading to genetically distinct cultivars, is traditionally believed to have originated in the Tehuacan Valley in the state of Puebla, Mexico. However, archaeological findings suggest a much earlier human interaction with the fruit. The oldest known avocado remains were discovered at Huaca Prieta, a preceramic site on the northern coast of Peru, where humans were consuming avocados as early as 10,500 years ago. This predates other known evidence, such as avocado pits found in Coxcatlan Cave, dating from around 9,000 to 10,000 years ago, which was previously thought to be the oldest discovery of an avocado pit. Other caves in the Tehuacan Valley from around the same time period also show early evidence for the presence and consumption of avocado.In addition to early archaeological evidence from Peru, genetic and linguistic research has identified three major domesticated avocado landraces—Guatemalan, Mexican, and West Indian —which developed in distinct ecological regions of Mesoamerica and Central America. The Guatemalan and Mexican landraces originated in the highlands of those countries, while the West Indian landrace is a lowland variety that ranges from Guatemala, Costa Rica, Colombia, Ecuador to Peru, achieving a wide range through human agency before the arrival of the Europeans. The three separate landraces were most likely to have already intermingled in pre-Columbian America and were described in the Florentine Codex. As a result of artificial selection, the fruit and correspondingly the seeds of cultivated avocados became considerably larger relative to their earlier wild forebears millennia before the Columbian exchange.
The earliest residents of northern coastal Peru were living in temporary camps in an ancient wetland and eating avocados, along with chilies, mollusks, sharks, birds, and sea lions. There is additional evidence for avocado use at Norte Chico civilization sites in Peru at Caballo Muerto in Peru from around 3,800 to 4,500 years ago.
The avocado tree has a long history of cultivation in Central and South America, now known to be much earlier than previously thought. A water jar shaped like an avocado, dating to AD 900, was discovered in the pre-Inca city of Chan Chan.
The plant was introduced to Spain in 1601, Indonesia around 1750, Mauritius in 1780, Brazil in 1809, the United States mainland in 1825, South Africa and Australia in the late 19th century, and the Ottoman Empire in 1908. In the United States, the avocado was introduced to Florida and Hawaii in 1833 and in California in 1856.
The name avocado has been used in English since at least 1764, with minor spelling variants such as avogato attested even earlier. The avocado was commonly referred to in California as ahuacate and in Florida as alligator pear until 1915, when the California Avocado Association popularized the term ''avocado.''
Requirements
As a subtropical species, avocados need a climate without frost and with little wind. High winds reduce the humidity, dehydrate the flowers, and affect pollination. When even a mild frost occurs, premature fruit drop may occur; although the 'Hass' cultivar can tolerate temperatures down to −1 °C. Several cold-hardy varieties are planted in the region of Gainesville, Florida, which survive temperatures as low as with only minor leaf damage. The trees also need well-aerated soils, ideally more than 1 m deep. However, Guatemalan varieties such as "MacArthur", "Rincon", or "Nabal" can withstand temperatures down to.According to information published by the Water Footprint Network, it takes an average of approximately of applied fresh ground or surface water, not including rainfall or natural moisture in the soil, to grow one avocado. However, the amount of water needed depends on where it is grown; for example, in the main avocado-growing region of Chile, about of applied water are needed to grow one avocado.
Increasing demand and production of avocados may cause water shortages in some avocado production areas, such as the Mexican state of Michoacán. Avocados may also cause environmental and socioeconomic impacts in major production areas, illegal deforestation, and water disputes. Water requirements for growing avocados are three times higher than for apples, and 18 times higher than for tomatoes.