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Overview

Brief Summary

Citrus species are small evergreen trees or shrubs growing to between 5 and 15 meters (15-45 feet) in height. Apparently native to northeast India, Myanmar and the Yunnan area of China, they have been introduced into cultivation around the world, primarily in subtropical and tropical regions. They are generally not frost hardy.

Citrus species hybridize readily and most species recognized are probably of hybrid origin, and only known from cultivation. Plants of the genus (oranges and pummelo) have been cultivated for at least 4400 years in China. This long history of cultivation and their easy hybridization confuses the issue of their native origin.

Also because of their easy hybridization, all commercially available varieties are reproduced through grafting.

Citrus fruits are known for their fragrance, and their high citric acid content which gives them a tangy flavor. They are eaten by humans either directly or used in preparing many dishes.

The plants require at least 25 cm/yr (10 in/yr) rainfall to be planted without irrigation. They have a fairly shallow but wide root system to collect water from their surroundings.

In addition to fruit consumption, all species are used in traditional medicine and their wood is used in crafts and for fuel.

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Comprehensive Description

Description

Small trees or shrubs, sometimes armed. Leaves alternate, 1-foliolate, sometimes with a winged rhachis. Flowers solitary or in clusters, bisexual, (4-)5-merous. Stamens numerous, arranged in bundles. Ovary (4-)5-many-locular; loculi 4-8-ovulate. Fruit large, spherical, ovoid or obovoid, many-seeded.
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Source: Flora of Zimbabwe

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Ecology

Associations

Foodplant / sap sucker
hypophyllous Coccus hesperidum sucks sap of live leaf (near veins) of Citrus
Remarks: season: 1-12

Foodplant / feeds on
Heliothrips haemorrhoidalis feeds on Citrus

Foodplant / sap sucker
Icerya purchasi sucks sap of live Citrus
Other: major host/prey

In Great Britain and/or Ireland:
Foodplant / sap sucker
hypophyllous Pulvinaria floccifera sucks sap of live leaf of Citrus

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Evolution and Systematics

Evolution

Caffeine

The plants cultivated for our popular caffeinated products- including Coffee, Tea, Cacao, Maté, Kola and Guarana- tend to produce fairly high levels of caffeine, but many others that you might not expect also produce it. It can be found in flowers of lemon and other citrus, for instance (Duke, 1992). Why do so many plants produce caffeine, especially in important tissues like flowers and fruit?

Some plants offer attractive chemicals in flowers or fruit as a reward to animals that, for instance, disperse their seeds. Researchers in Zurich have found this is not likely to be the primary use a plant has for caffeine, at least for Guarana. The outer part of the guarana fruit, which is eaten by large birds such as toucans, contains lots of sugar but no measurable caffeine. Experiments simulating the acid conditions of a bird’s digestive tract suggest very little caffeine is leeched from the seed before it leaves the bird’s body (Baumann et al, 1995; Goncalves, 1971).

Caffeine is widely listed as a secondary compound in plant chemical profiles, meaning a harmful or unpalatable chemical that discourages grazers. That could account for the caffeine in citrus flowers, too. If they’re not chemically defended, flowers could be eaten by herbivores before they have a chance to get pollinated and produce seeds. On the other hand, flowers also need to attract the attention of pollinators. Citrus pollen and nectar, both of which are harvested and consumed by pollinators, contain significant amounts of caffeine (Kretschmar and Baumann, 1999). The caffeine in the flowers may benefit the plant by discouraging herbivores, but it is equally plausible that it attracts pollinators- assuming they like the buzz.

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage

Barcode of Life Data Systems (BOLD) Stats
Specimen Records:431
Specimens with Sequences:463
Specimens with Barcodes:304
Species:92
Species With Barcodes:88
Public Records:309
Public Species:81
Public BINs:0
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Barcode data

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Wikipedia

Citrus

For other uses, see Citrus (disambiguation).

Citrus is a common term and genus (Citrus) of flowering plants in the rue family, Rutaceae. The most recent research indicates an origin in Australia, New Caledonia and New Guinea.[1] Some researchers believe that the origin is in the part of Southeast Asia bordered by Northeast India, Burma (Myanmar) and the Yunnan province of China,[2][3][4] and it is in this region that some commercial species such as oranges, mandarins, and lemons originated. Citrus fruit has been cultivated in an ever-widening area since ancient times; the best-known examples are the oranges, lemons, grapefruit, and limes.

Name[edit]

The generic name originated in Latin, where it referred to either the plant now known as Citron (C. medica) or a conifer tree (Thuja). It is somehow related to the ancient Greek word for cedar, κέδρος (kédros). This may be due to perceived similarities in the smell of citrus leaves and fruit with that of cedar.[5] Collectively, Citrus fruits and plants are also known by the Romance loanword agrumes (literally "sour fruits").

Taxonomy[edit]

Main article: Citrus taxonomy
Citrus fruits clustered by genetic similarity (PCA of SNP diversity). Citrus micrantha (top right) is a papeda.
-
Hybrids are expected to plot between their parents. ML: ‘Mexican’ lime; A: ‘Alemow’; V: ‘Volkamer’ lemon; M: ‘Meyer’ lemon; L: Regular and ‘Sweet’ lemons; B: Bergamot orange; H: Haploid clementine; C: Clementines; S: Sour oranges; O: Sweet oranges; G: Grapefruits.

The taxonomy and systematics of the genus are complex and the precise number of natural species is unclear, as many of the named species are hybrids clonally propagated through seeds (by apomixis), and there is genetic evidence that even some wild, true-breeding species are of hybrid origin.[6]

Cultivated Citrus may be derived from as few as four ancestral species.[7] Recent studies show that only four domesticated citrus fruit — the citron, pummelo, mandarine, and papeda — are actually original, and all the rest of citrus types developed through natural or artificial hybridization (see image).[8] Natural and cultivated origin hybrids include commercially important fruit such as the oranges, grapefruit, lemons, limes, and some tangerines.

Description[edit]

Slices of various citrus fruits

Tree[edit]

These plants are large shrubs or small to moderate-sized trees, reaching 5–15 m (16–49 ft) tall, with spiny shoots and alternately arranged evergreen leaves with an entire margin.[citation needed] The flowers are solitary or in small corymbs, each flower 2–4 cm (0.79–1.57 in) diameter, with five (rarely four) white petals and numerous stamens; they are often very strongly scented.

Fruit[edit]

The fruit is a hesperidium, a specialised berry, globose to elongated, 4–30 cm (1.6–11.8 in) long and 4–20 cm (1.6–7.9 in) diameter, with a leathery rind or "peel" called a pericarp. The outermost layer of the pericarp is an "exocarp" called the flavedo, commonly referred to as the zest. The middle layer of the pericarp is the mesocarp, which in citrus fruits consists of the white, spongy "albedo", or "pith". The innermost layer of the pericarp is the endocarp. The segments are also called "liths", and the space inside each lith is a locule filled with juice vesicles, or "pulp". From the endocarp, string-like "hairs" extend into the locules, which provide nourishment to the fruit as it develops.[9][10]

Citrus fruits are notable for their fragrance, partly due to flavonoids and limonoids (which in turn are terpenes) contained in the rind, and most are juice-laden. The juice contains a high quantity of citric acid giving them their characteristic sharp flavour. The genus is commercially important as many species are cultivated for their fruit, which is eaten fresh, pressed for juice, or preserved in marmalades and pickles.

They are also good sources of vitamin C and flavonoids. The flavonoids include various flavanones and flavones.[11]

Cultivation[edit]

Further information: Citrus production
Persian Limes in a grocery store.

Citrus trees hybridise very readily – depending on the pollen source, plants grown from a Persian lime's seeds can produce fruit similar to grapefruit. Thus all commercial citrus cultivation uses trees produced by grafting the desired fruiting cultivars onto rootstocks selected for disease resistance and hardiness.

The colour of citrus fruits only develops in climates with a (diurnal) cool winter.[citation needed] In tropical regions with no winter at all, citrus fruits remain green until maturity, hence the tropical "green oranges".[citation needed] The Persian lime in particular is extremely sensitive to cool conditions, thus it is not usually exposed to cool enough conditions to develop a mature colour.[citation needed] If they are left in a cool place over winter, the fruits will change colour to yellow.

The terms "ripe" and "mature" are usually used synonymously, but they mean different things. A mature fruit is one that has completed its growth phase. Ripening is the changes that occur within the fruit after it is mature to the beginning of decay. These changes usually involve starches converting to sugars, a decrease in acids and a softening and change in the fruit's colour.[12]

Citrus fruits are non-climacteric and respiration slowly declines and the production and release of ethylene is gradual.[13] The fruits do not go through a ripening process in the sense that they become "tree ripe." Some fruits, for example cherries, physically mature and then continue to ripen on the tree. Other fruits, like pears, are picked when mature but before they ripen, then continue to ripen off the tree. Citrus fruits pass from immaturity to maturity to over-maturity while still on the tree. Once they are separated from the tree, they will not increase in sweetness or continue to ripen. The only way change may happen after being picked is that they will eventually start to decay.

With oranges, colour cannot be used as an indicator of ripeness because sometimes the rinds turn orange long before the oranges are ready to eat. Tasting them is the only way to know whether or not they are ready to eat.

Citrus trees are not generally frost hardy. Mandarin oranges (C. reticulata) tend to be the hardiest of the common Citrus species and can withstand short periods down to as cold as −10 °C (14 °F), but realistically temperatures not falling below −2 °C (28 °F) are required for successful cultivation. Tangerines, tangors and yuzu can be grown outside even in regions with more marked sub-freezing temperatures in winter, although this may affect fruit quality. A few hardy hybrids can withstand temperatures well below freezing, but do not produce quality fruit. Lemons can be commercially grown in cooler-summer/moderate-winter coastal Southern California, because sweetness is neither attained nor expected in retail lemon fruit. The related trifoliate orange (Citrus trifoliata) can survive below −20 °C (−4 °F); its fruit are astringent and inedible unless cooked but a few better-tasting cultivars and hybrids have been developed (see citranges).

Leaf of Citrus tree

The trees thrive in a consistently sunny, humid environment with fertile soil and adequate rainfall or irrigation. Abandoned trees in valleys may suffer, yet survive, the dry summer of Central California's Inner Coast Ranges. At any age citrus grows well enough with infrequent irrigation in partial shade, but the fruit crop is smaller. Though broadleaved, they are evergreen and do not drop leaves except when stressed. The stems of many varieties have large sharp thorns. The trees flower in the spring, and fruit is set shortly afterward. Fruit begins to ripen in fall or early winter months, depending on cultivar, and develops increasing sweetness afterward. Some cultivars of tangerines ripen by winter. Some, such as the grapefruit, may take up to eighteen months to ripen.

Major commercial citrus growing areas include southern China, the Mediterranean Basin (including southern Spain), South Africa, Australia, the southernmost United States, Mexico and parts of South America. In the United States, Florida, California, Arizona, and Texas are major producers, while smaller plantings are present in other Sun Belt states and in Hawaii.

As ornamental plants[edit]

Citrus trees grown in tubs and wintered under cover were a feature of Renaissance gardens, once glass-making technology enabled sufficient expanses of clear glass to be produced. An orangery was a feature of royal and aristocratic residences through the 17th and 18th centuries. The Orangerie at the Palace of the Louvre, 1617, inspired imitations that were not eclipsed until the development of the modern greenhouse in the 1840s. In the United States the earliest surviving orangery is at the Tayloe House, Mount Airy, Virginia. George Washington had an orangery at Mount Vernon.

Some modern hobbyists still grow dwarf citrus in containers or greenhouses in areas where it is too cold to grow it outdoors. Consistent climate, sufficient sunlight, and proper watering are crucial if the trees are to thrive and produce fruit. Compared to many of the usual "green shrubs", citrus trees better tolerate poor container care. For cooler winter areas, limes and lemons should not be grown, since they are more sensitive to winter cold than other citrus fruits. Hybrids with kumquatsCitrofortunella) have good cold resistance.

Pests and diseases[edit]

Major producer regions
Citrus canker is caused by the gammaproteobacterium Xanthomonas axonopodis

Citrus plants are very liable to infestation by aphids, whitefly and scale insects (e.g. California red scale). Also rather important are the viral infections to which some of these ectoparasites serve as vectors such as the aphid-transmitted Citrus tristeza virus which when unchecked by proper methods of control is devastating to citrine plantations. The newest threat to citrus groves in the United States is the Asian citrus psyllid.

The Asian citrus psyllid is an aphid-like insect that feeds on the leaves and stems of citrus trees and other citrus-like plants – but the real danger lies in that it can carry a deadly, bacterial tree disease called Huanglongbing (HLB), also known as citrus greening disease.[14]

In June 2008, the psyllid was spotted dangerously close to California – right across the international border in Tijuana, Mexico. Only a few months later, it was detected in San Diego and Imperial counties, and has since spread to Riverside, San Bernardino, Orange, Los Angeles and Ventura counties sparking quarantines in those areas. The Asian citrus psyllid has also been intercepted coming into California in packages of fruit and plants, including citrus, ornamentals, herbs and bouquets of cut flowers, shipped from other states and countries.[14]

The foliage is also used as a food plant by the larvae of Lepidoptera (butterfly and moth) species such as the Geometridae Common Emerald (Hemithea aestivaria) and Double-striped Pug (Gymnoscelis rufifasciata), the Arctiidae Giant Leopard Moth (Hypercompe scribonia), H. eridanus, H. icasia and H. indecisa, many species in the family Papilionidae (swallowtail butterflies), and the Black-lyre Leafroller Moth ("Cnephasia" jactatana), a tortrix moth.

Since 2000, the citrus leafminer (Phyllocnistis citrella) has been a pest in California,[15] boring meandering patterns through leaves.

In eastern Australia, the bronze-orange bug (Musgraveia sulciventris) can be a major pest of citrus trees, particularly grapefruit. In heavy infestations it can cause flower and fruit drop and general tree stress.

European brown snails (Helix aspersa) can be a problem in California, though laying female Khaki Campbell and other mallard-related ducks can be used for control.

Deficiency diseases[edit]

Citrus plants can also develop a deficiency condition called chlorosis, characterized by yellowing leaves highlighted by contrasting leaf veins. The shriveling leaves eventually fall, and if the plant loses too many, it will slowly die. This condition is often caused by an excessively high pH (alkaline soil), which prevents the plant from absorbing iron, magnesium, zinc, or other nutrients it needs to produce chlorophyll. This condition can be cured by adding an appropriate acidic fertilizer formulated for citrus, which can sometimes revive a plant to produce new leaves and even flower buds within a few weeks under optimum conditions. A soil which is too acidic can also cause problems; citrus prefers neutral soil (pH between 6 and 8). Citrus plants are also sensitive to excessive salt in the soil. Soil testing may be necessary to properly diagnose nutrient deficiency diseases.[16]

Production[edit]

According to UN 2007 data, Brazil, China, the United States, Mexico, India, and Spain are the world's largest citrus-producing countries.

Uses[edit]

Culinary[edit]

Wedges of pink grapefruit, lime, and lemon, and a half orange (clockwise from top)

Many citrus fruits, such as oranges, tangerines, grapefruits, and clementines, are generally eaten fresh. They are typically peeled and can be easily split into segments. Grapefruit is more commonly halved and eaten out of the skin with a spoon.[17] There are special spoons (grapefruit spoons) with serrated tips designed for this purpose. Orange and grapefruit juices are also very popular breakfast beverages. More acidic citrus, such as lemons and limes, are generally not eaten on their own. Meyer Lemons can be eaten 'out of hand' with the fragant skin; they are both sweet and sour. Lemonade or limeade are popular beverages prepared by diluting the juices of these fruits and adding sugar. Lemons and limes are also used as garnishes or in cooked dishes. Their juice is used as an ingredient in a variety of dishes; it can commonly be found in salad dressings and squeezed over cooked meat or vegetables.

A variety of flavours can be derived from different parts and treatments of citrus fruits. The rind and oil of the fruit is generally very bitter, especially when cooked, and so is often combined with sugar. The fruit pulp can vary from sweet and tart to extremely sour. Marmalade, a condiment derived from cooked orange and lemon, can be especially bitter, but is usually sweetened to cut the bitterness and produce a jam-like result. Lemon or lime is commonly used as a garnish for water, soft drinks, or cocktails. Citrus juices, rinds, or slices are used in a variety of mixed drinks. The colourful outer skin of some citrus fruits, known as zest, is used as a flavouring in cooking; the white inner portion of the peel, the pith, is usually avoided due to its bitterness. The zest of a citrus fruit, typically lemon or an orange, can also be soaked in water in a coffee filter, and drunk.

Medical[edit]

Oranges were historically used for their high content of vitamin C, which prevents scurvy. Scurvy is caused by vitamin C deficiency, and can be prevented by having 10 milligrams of vitamin C a day. An early sign of scurvy is fatigue. If ignored, later symptoms are bleeding and bruising easily. British sailors were given a ration of citrus fruits on long voyages to prevent the onset of scurvy, hence the British nickname of Limey.

Pectin is a structural heteropolysaccharide contained in the primary cell walls of plants. Limes and lemons as well as oranges and grapefruits are among the highest in this level.[18]

After consumption, the peel is sometimes used as a facial cleanser.

Before the development of fermentation-based processes, lemons were the primary commercial source of citric acid.

Citrus fruit intake is associated with a reduced risk of stomach cancer.[19] Also, citrus fruit juices, such as orange, lime and lemon, may be useful for lowering the risk of specific types of kidney stones. Grapefruit is another fruit juice that can be used to lower blood pressure because it interferes with the metabolism of calcium channel blockers.[20] Lemons have the highest concentration of citrate of any citrus fruit, and daily consumption of lemonade has been shown to decrease the rate of kidney stone formation.[21]

List of citrus fruits[edit]

Main article: List of citrus fruits
Citrons (Citrus medica) for sale in Germany
Red Finger Lime (Citrus australasica), a rare delicacy from Australia

The genus Citrus has been suggested to originate in Southeast Asia. Prior to human cultivation, it consisted of just a few species, namely:

Hybrids and cultivars[edit]

See also: Citrus hybrids
Sweetie or Oroblanco is a pomelo-grapefruit hybrid.
The Etrog, or Citron, is central to the ritual of the Jewish Sukkot festival. Many varieties are used for this purpose (including the Yemenite variety pictured).
Clementines (Citrus ×clementina) have thinner skins than oranges.
Mikan (Citrus ×unshiu), also known as satsumas
Sweet oranges (Citrus ×sinensis) are used in many foods. Their ancestors were probably pomelos and mandarin oranges.

Sorted by parentage. As each hybrid is the product of (at least) two parent species, they are listed multiple times.

Citrus maxima-based

  • Amanatsu, natsumikan – Citrus ×natsudaidai (C. maxima × unknown)
  • Cam sành – (C. reticulata × C. ×sinensis)
  • GrapefruitCitrus ×paradisi (C. maxima × C. ×sinensis)
  • Imperial lemon – (C. ×limon × C. ×paradisi)
  • Kinnow – (C. ×nobilis × C. ×deliciosa)
  • Kiyomi – (C. ×sinensis × C. ×unshiu)
  • Lemon – (probably C. maxima × C. medica)
  • Minneola tangelo – (C. reticulata × C. ×paradisi)
  • Orangelo, Chironja – (C. ×paradisi × C. ×sinensis)
  • Oroblanco, Sweetie – (C. maxima × C. ×paradisi)
  • Sweet orangeCitrus ×sinensis (probably C. maxima × C. reticulata)
  • TangeloCitrus ×tangelo (C. reticulata × C. maxima or C. ×paradisi)
  • TangorCitrus ×nobilis (C. reticulata × C. ×sinensis)
  • Ugli – (C. reticulata × C. maxima or C. ×paradisi)

Citrus medica-based

Citrus reticulata-based

Cross section of Odichukuthi lime.

Other/Unresolved

Odichukuthi fruit
A pompia fruit.

For hybrids with kumquats, see ×Citrofortunella. For hybrids with the Trifoliate Orange, see citrange.

See also[edit]

Footnotes[edit]

  1. ^ Liu, Y.; Heying, E.; Tanumihardjo, S. (2012). "History, Global Distribution, and Nutritional Importance of Citrus Fruits". Comprehensive Reviews in Food Science and Food Safety 11: 6. 
  2. ^ Gmitter, Frederick; Hu, Xulan (1990). "The possible role of Yunnan, China, in the origin of contemporary Citrus species (Rutaceae)". Economic Botany 44 (2): 267–277. doi:10.1007/bf02860491. 
  3. ^ United Nations Conference on Trade and Development. Market Information in the Commodities Area: Citrus fruits [1]
  4. ^ Scora, Rainer W. (1975). "On the history and origin of citrus". Bulletin of the Torrey Botanical Club 102 (6): 369–375. JSTOR 2484763. 
  5. ^ Spiegel-Roy, Pinchas; Eliezer E. Goldschmidt (1996). Biology of Citrus. Cambridge University Press. p. 4. ISBN 978-0-521-33321-4. 
  6. ^ Nicolosi et al. (2000)
  7. ^ "International Citrus Genomics Consortium". ucr.edu. 
  8. ^ "Citron Cultivation, Production and Uses in the Mediterranean Region". springer.com. 
  9. ^ "Citrus fruit diagram". ucla.edu. 
  10. ^ "Lith". TheFreeDictionary.com. 
  11. ^ "Flavonoid Composition of Fruit Tissues of Citrus Species". 
  12. ^ Helgi Öpik; Stephen A. Rolfe; Arthur John Willis; Herbert Edward Street (2005). The physiology of flowering plants. Cambridge University Press. pp. 309–. ISBN 978-0-521-66251-2. Retrieved 31 July 2010. 
  13. ^ Pinchas Spiegel-Roy; Eliezer E. Goldschmidt (1996). Biology of citrus. Cambridge University Press. pp. 101–. ISBN 978-0-521-33321-4. Retrieved 31 July 2010. 
  14. ^ a b "About the Asian Citrus Psyllid and Huanglongbing". californiacitrusthreat.org. 
  15. ^ "Citrus Leafminer – UC Pest Management". 
  16. ^ Mauk, Peggy A.; Tom Shea. "Questions and Answers to Citrus Management (3rd ed.)". University of California Cooperative Extension. Retrieved 2014-05-24. 
  17. ^ "American Indian Health – Health". Aihd.ku.edu. Retrieved 2011-12-17. 
  18. ^ Morgan, Laura (March 15, 2011). "What Fruits & Vegetables Contain Pectin?". Demand Media. Retrieved 2011-07-22. 
  19. ^ González CA, Sala N, Rokkas T (2013). "Gastric cancer: epidemiologic aspects". Helicobacter 18 (Supplement 1): 34–38. doi:10.1111/hel.12082. PMID 24011243. 
  20. ^ "Grapefruit and Medication". Total Health 27 (2): 39–39. 2005. 
  21. ^ Carr, Jackie (April 22, 2010). "Five Ways to Prevent Kidney Stones". UC San Diego. Retrieved 2010-12-03. 
  22. ^ a b c GRIN. "Species list in GRIN for genus Citrus". Taxonomy for Plants. National Germplasm Resources Laboratory, Beltsville, Maryland: USDA, ARS, National Genetic Resources Program. Retrieved Jan 6, 2011. 

References[edit]

  • Andrews, A.C. (1961). "Acclimatization of citrus fruits in the Mediterranean region". Agricultural History 35 (1): 35–46. 
  • Araújo, De; Freitas, E.; de Queiroz, L. Paganucci; Machado, M.A. (2003). "What is Citrus? Taxonomic implications from a study of cp-DNA evolution in the tribe Citreae (Rutaceae subfamily Aurantioideae)". Organisms Diversity & Evolution 3 (1): 55–62. doi:10.1078/1439-6092-00058. 
  • Nicolosi, E.; Deng, Z.N.; Gentile, A.; La Malfa, S.; Continella, G.; Tribulato, E. (2000). "Citrus phylogeny and genetic origin of important species as investigated by molecular markers". Theoretical and Applied Genetics 100 (8): 1155–1166. doi:10.1007/s001220051419. 

Further reading[edit]

  • Calabrese, Francesco (2002): Origin and history. In: Dugo, Giovanni & Di Giacomo, Angelo (eds.) (2002): Citrus. Taylor & Francis. ISBN 0-415-28491-0
  • Ellis, R.H.; Hong, T.D. & Roberts, E.H. (1985): Chapter 64. Rutaceae. In: Handbook of Seed Technology for Genebanks (Volume II: Compendium of Specific Germination Information and Test Recommendations). International Board for Plant Genetic Resources, Rome, Italy. HTML fulltext
  • Frison, E.A. & Taher, M.M. (eds.) (1991): FAO/IBPGR Technical Guidelines for the Safe Movement of Citrus Germplasm. FAO, IOCV, IPGRI. PDF fulltext
  • International Plant Genetic Resources Institute (IPGRI) (1999): Descriptors for Citrus (Citrus spp.). PDF fulltext
  • Janick, Jules (2005): Purdue University Tropical Horticulture Lecture 32: Citrus
  • Luro, F.; Laigret, F.; Bové, J.M. & Ollitrault, P. (1995): RFLP analysis of cytoplasmic and nuclear genomes used for citrus taxonomy. In: Mandarines – développements scientifiques récents, résumés oraux et posters: 12–13. CIRAD-FLHOR, San Nicolao, France. HTML abstract
  • Molina, A.B.; Roa, V.N.; Bay-Petersen, J.; Carpio, A.T. & Joven, J.E.A. (eds.) (2000): Citrus, Proceedings of a regional workshop on disease management of banana and citrus through the use of disease-free planting materials held in Davao City, Philippines, 14–16 October 1998. INIBAP. PDF fulltext
  • Sackman. Douglas Cazaux (2005): Orange Empire: California and the Fruits of Eden.
  • University of California Division of Agricultural Sciences (UC-DAS) (1967–1989): The Citrus Industry. HTML fulltext of Vol. 1, 2, & Vol. 5, Chapter 5
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Kinnow

Kinnows.jpg

Kinnow (or kinoo) is a variety of mandarin (citrus fruit) often grown in the Punjab province of Pakistan, and to a lesser extent in northern Indian states, mainly Punjab and Rajasthan. The kinnow was developed by H. B. Frost at the University of California, Riverside in 1935, by cross-pollinating the King tangor and the Willow Leaf or Mediterranean Mandarin.[1] Courtesy of the parent stock, another name for this hybrid citrus is Wilking.

Contents

Description

The small orange fruits have more seeds per wedge in comparison to other citrus fruits. The seeds of kinnow are naturally diploid or tetraploid. Seedless triploid varieties have been developed, but these are still undergoing testing whether the fruit is healthy for consumption.

Kinnow season in the Northern Hemisphere starts in November and ends in March, a longer picking season than any other citrus variety.

Production and consumption

The kinnow is a hybrid of two citrus cultivars—"King" and "Willow Leaf"—and is classified as Kinnow mandarin. It was introduced from California to the Punjab Agricultural College and Research Institute, Lyallpur (now University of Agriculture, Faisalabad) in the subcontinent in 1943-44. This "easy peel" citrus has assumed special economic importance and export demand, being acknowledged for its high juice content, special flavour, and as a rich source of vitamin C. In per capita terms, the annual availability of citrus is nearly 12.5 kg, of which kinnow makes up about 8 kg. A consumption of 8 kg per capita implies the availability of 1206 milligrams of vitamin C, 1520 milligrams of calcium, 684 milligrams of phosphorus and nearly 16 milligrams of iron per head during the citrus production season. In the citrus production season, kinnow consumption can make a significant contribution to improve human diet in terms of total micronutrient intake.

Most of the target export markets of Pakistani kinnow are those of developing countries. Only 2.6 per cent of kinnow exports target markets of developed countries, which is due to the emerging demand for seedless kinnow by the developed countries. About 61 percent of total world exports of oranges and mandarins are of seedless varieties. Unfortunately, Pakistan is not producing seedless kinnow, due to which its target markets are limited and mostly confined to Middle East countries. Some important export markets for kinnow are: Bahrain, Dubai, Kuwait, Oman, Qatar, Saudi Arabia, Indonesia, Malaysia, Afghanistan, Netherlands, Philippines, Singapore, the United Kingdom and Vietnam.[2]

Fruit processing

Food processing includes the selection of good-quality mandarins. The ideal kinnow is firm to slightly soft, smooth-skinned with no deep grooves, and deep orange to almost red. Human hands can better judge and avoid product with soft spots, dull and faded coloring or rough and bumpy skin.

Juice processing

There are some juice extracting units in Pakistan, producing kinnow juice concentrate intended for export to the United States and the European Union. In India, the kinnow juice processing industry is developing rapidly. In 2008, two new juice processing plants began operating, each with a processing capacity of about 400 tons per day. Tropicana and Jain Irrigation have hired these plants from PunjabAgro to produce kinnow juice concentrate. The Thapar Institute of Engineering and Technology in Patiala recently developed a patented method of debittering its juice.

References

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Lime (fruit)

Unripened Key limes
Lime, raw (edible parts)
Nutritional value per 100 g (3.5 oz)
Energy126 kJ (30 kcal)
Carbohydrates11 g
Sugars1.7 g
Dietary fiber3 g
Fat0.2 g
Protein0.7 g
Water88 g
Vitamin C29 mg (48%)
Percentages are relative to US recommendations for adults.
Source: USDA Nutrient database

Lime is a term referring to a number of different fruits, both species and hybrids, citruses, which have their origin in the Himalayan region of India and which are typically round, green to yellow in color, 3–6 cm in diameter, and containing sour and acidic pulp. Limes are often used to accent the flavours of foods and beverages. They are usually smaller than lemons, and a source of vitamin C. Limes are grown all year round and are usually sweeter than lemons.

Limes are a small citrus fruit, Citrus aurantifolia, whose skin and flesh are green in color and which have an oval or round shape with a diameter between one to two inches. Limes can either be sour or sweet, with the latter not readily available in the United States. Sour limes possess a greater sugar and citric acid content than lemons and feature an acidic and tart taste, while sweet limes lack citric acid content and are sweet in flavor.

Contents

Uses

Cooking

Zesting a lime

In cooking, lime is valued both for the acidity of its juice and the floral aroma of its zest. It is a very common ingredient in authentic Mexican, Southwestern United States, Vietnamese and Thai dishes. It is also used for its pickling properties in ceviche. Additionally, the leaves of lime are used in southeast Asian cuisine. The use of dried limes (called black lime or loomi) as a flavouring is typical of Persian cuisine and Iraqi cuisine, as well as in Gulf-style baharat (a spice mixture that is also called kabsa or kebsa). Lime is an essential ingredient of any cuisine from India and many varieties of pickles are made e.g. Sweetened lime pickle, salted pickle, Lemon Chutney [1] [2]. Limes are also an essential element in Tamil cuisine.

Lime leaves are also a herb in South, East, and particularly Southeast Asia. In Vietnam, people have boiled chicken with lime leaves and a mixture of salt, black pepper and lime juice.

Other uses

In order to prevent scurvy during the 19th century, British sailors were issued a daily allowance of citrus such as lemon, and later switched to lime[3], which was not as effective at preventing scurvy but led over time to the nickname "limey" for all Britons. It was later discovered that this beneficial effect derived from the 4-fold higher quantities of Vitamin C lemon juice contains compared to the West Indian limes used by the British.

Lime extracts and essential oils are frequently used in perfumes, cleaning products, and aromatherapy. Lime is also used occasionally to enhance vision by many Asian martial artists.[who?] It is done by squeezing a drop or two on the inside corner of the eye.[citation needed]

In India, the lime is used in Tantra for removing evil spirits. It is also combined with Indian chilis to make a protective charm to repel the evil eye[4] . Furthermore, it was believed that hanging limes over sick peoples cured them of the illness by repelling evil spirits lurking inside the body.

Production trends

Lemon and lime output in 2005

India, with about 16% of the world's overall lemon and lime output, tops the production list, followed by Mexico (~14.5%), Argentina (~10%), Brazil (~8%) and Spain (~7%).

Promotional photo for California limes, 1948
Top ten lemon and limes producers — 2007
CountryProduction (Tonnes)Footnote
 India2060000F
 Mexico1880000F
 Argentina1260000F
 Brazil1060000F
 Spain880000F
 People's Republic of China745100F
 United States722000
 Turkey706652
 Iran615000F
 Italy546584
 World13032388A
No symbol = official figure, P = official figure, F = FAO estimate, * = Unofficial/Semi-official/mirror data, C = Calculated figure A = Aggregate (may include official, semi-official or estimates);

Source: Food And Agricultural Organization of United Nations: Economic And Social Department: The Statistical Division


Plants known as "lime"

Gallery

References

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