TAXONOMYCitrus: Lemon, Lime, Orange, Tangerine, Grapefruit – Citrus spp.The genus Citrus belongs to the Rutaceae or Rue family, sub-family Aurantoideae. While Citrus is by far the most economically important genus, two other genera contain species important in citriculture:1. Fortunella spp. (Kumquat trees). Originally classified with citrus, kumquat trees were then moved to their own genus, named after Robert Fortune, who introduced kumquats to Europe. They are evergreen shrubs or small trees (8-15 ft), native to southern China, but can be grown around the world into subtropical areas. Unlike citrus fruits, the peel of the fruit is edible, and usually sweeter than the pulp. Four major cultivars were given species status by Swingle, a noted citrus taxonomist: ‘Nagami’ – F. margarita Swing. Also called Oval or Long Kumquat. Fruits are longer than wide, 1-1 ½” long, with thin, yellow-orange peel.‘Meiwa’, or Large Round Kumquat – F. crassifolia Swing. Possibly a hybrid between ‘Nagami’ and ‘Marumi’. Round fruit, thick orange-yellow peel.‘Hong Kong’, or ‘Hong Kong Wild’ – F. hindsii Swing. Fruit is orange/scarlet when ripe, many seeds.‘Marumi’ – F. japonica Swing. (syn. Citrus madurensis Lour.). Also called round kumquat. Thin, golden-yellow peel surrounds aromatic and spicy pulp. 2. Poncirus trifoliata L. Raf. – trifoliate orange trees. Important as a rootstock for citrus, especially in Japan, although the fruit is scarcely edible. It is used as a male parent in production of citrange (sweet orange* trifoliate orange) rootstocks, and as an ornamental. It has a deciduous habit in cooler areas, and can tolerate more freezing than any other citrus relative. It is native to northern China, and grown as far north as Philadelphia in the eastern USA.The 5 commercially important fruit crops (sweet orange, tangerine, grapefruit, lemon, and lime) are recognized as single species within Citrus:C. sinensis (L.) Osb. – Sweet orange trees. This is a widely accepted name for this crop, containing 4 groups of cultivars: common oranges, blood oranges, navel oranges, and acidless oranges (see below). The term “orange” is used rather loosely, sometimes for fruits that look like oranges but are not C. sinensis. Examples include: ‘Temple’ and ‘Page’ oranges ( tangerine hybrids), Satsuma orange (a cold hardy variant of tangerine), and Trifoliate orange (Poncirus trifoliata).C. reticulata Blanco – Tangerine, mandarin, or satsuma. Due to the success of breeding with these types, many cultivars and hybrids have been produced or formed naturally, some erroneously given species status. I prefer to use C. reticulata for all tangerines, but other species names sometimes given in the literature include: C. unshiu (Satsuma), C. deliciosa (Willowleaf), C. reshni (Cleopatra), C. nobilis (King), and C. temple (Temple).C. paradisi Macf. – Grapefruit. This is clearly not a true species, but its economic importance today has granted species status that even a lumper could not deny. Grapefruit is thought to be a hybrid of pummelo and sweet orange that occurred naturally somewhere in the Caribbean between the time of Columbus’ voyages and its introduction to Florida in 1809.C. limon Burm. f. – Lemons. I would lump the rough lemon (C. jambhiri), sweet lemon (C. limetta), and Volkamer lemon (C. volkameriana) as variants within this species.C. aurantifolia L. – Limes. The literature distinguishes the two main cultivars – ‘Key’ and ‘Tahiti’ – as separate species, with the latter labeled C. latifolia Tanaka or Citrus X tahiti Campbell. I would lump these two, along with the ‘Rangpur’ lime (C. limonia) and sweet limes (C. limettioides), all under C. aurantifolia. Three other citrus fruits given species status and worthy of mention include:C. grandis (L.) Osb. or C. maxima (Burm.) Merr. – Pummelo or shaddock. This species originates from southeast Asia where it is as common as grapefruit is in the USA. It is much larger and thicker-peeled than grapefruit, but said to have milder flavor.C. aurantium L. – Sour orange. This is allied with limes by some, but is a very important rootstock and ornamental. Cultivars and variants include: Bittersweet, Oklawaha, Vermillion Globe, Paraguay, Trabut, var. myrtifolia (Myrtle), Bergamot, daidai (Japanese), Leaf of Chinnoto, and C. taiwanica Tanaka.C. medica L. – Citron. This lemon-like fruit may be the progenitor species of modern lemons and limes. The peel is very thick, and the white, spongy portion of the peel is edible.
pummelo (or shaddock)
citron
Hybrids
Several hybrids among Citrus species, and between Citrus and Poncirus or Fortunella, have been produced either naturally or through controlled breeding. A series of prefixes and suffixes is used to denote the parents of such hybrids:
Citrange (trifoliate orange x sweet orange)
Citrumelo (trifoliate orange x grapefruit)
Tangor (sweet orange x tangerine)
Tangelo (tangerine x grapefruit)
Cultivars
Sweet Orange. Cultivars are subdivided into 4 groups based on fruit characteristics:
Common or round oranges
Blood oranges
Navel oranges
Acidless oranges
Tangerine. Like sweet oranges, tangerine cultivars fall into 4 main groups:
Common
Satsuma
Mediterranean or ‘Willowleaf‘
Hybrids. Crosses of tangerine with orange (tangors) or grapefruit (tangelos) have produced many cultivars of importance in the USA.
Grapefruit. The major white-fleshed cultivars are ‘Duncan‘ and ‘Marsh‘; the former is seedy and the latter seedless. ‘Thompson‘ (syn. ‘Pink Marsh‘) was a mutation of ‘Marsh‘ with pink flesh, and is also seedless. Other deep red cultivars include ‘Star Ruby‘, ‘Ruby Red‘, ‘Rio Red‘, and ‘Flame‘, grown largely in Texas.
Limes. ‘Key‘ (syn. ‘Mexican‘, ‘West Indian‘) and ‘Tahiti‘ (syn. Persian) are the major cultivars. ‘Key‘ limes are small, round, and seedy, and turn yellow under Mediterranean conditions. ‘Tahiti‘ limes are larger, green, and shaped like lemons.
Lemons. The main cultivars are ‘Lisbon‘ (oval to round, more pronounced stylar end furrow and point) and ‘Eureka‘ (oval, less pronounced stylar end). ‘Meyer‘ is a cold hardy, larger fruited cultivar used as an ornamental or containerized plant, and is probably a lemon hybrid. ‘Femminello‘ and ‘Verna‘ are the major cultivars in Italy and Spain, respectively.
The two major lime cultivars are ‘Tahiti’ (on left – large, oval and seedless) and ‘Key’ (on right – small, round, and seedy).
The ‘Lisbon’ lemon is the most common lemon in the USA.
ORIGIN OF CITRUS SPP, HISTORY OF CULTIVATION
The center of diversity for Citrus ranges from northeastern India eastward through the Malay archipelago and south to Australia. Sweet oranges probably arose in India, the trifoliate orange and mandarin in China, and acid citrus types in Malaysia. Oranges and pummelos were mentioned in Chinese literature in 2400 BC, and later in Sanskrit writings (800 BC) lemons were mentioned. Theophrastus, the Father of Botany, gave a taxonomic description of the citron in 310 BC, classifying it with apple as Malus medica or Malus persicum. At the time of Christ and shortly thereafter, the term “citrus” arose as a mispronunciation of either the Greek word for cedar cones, “Kedros”, or “Callistris”, the name for the sandalwood tree.
At this time, citrus fruits were spread throughout Asia, North Africa, and Europe along trade routes. The dissemination was carried out by many cultures, indicating widespread appeal of the fruits at this time. From the first centuries BC to medieval times, orangeries and citrus “groves” were established in Europe, and cultivation became more sophisticated. Christopher Columbus, Ponce de Leon, and Juan de Grijavla carried various citrus fruits to the new world in the late 1400′s early 1500′s. Citrus culture proliferated in Florida in the late 1700′s, when the first commercial shipments were made. Right about this time, citrus was introduced to California, although it was much later that commercial production began in the west. With the advent of large-scale irrigation projects in the 1940′s, citrus culture increased greatly in western states. Today, citrus fruits are grown commercially in Florida, California, Arizona, and Texas.
WORLD AND UNITED STATES CITRUS PRODUCTION
Sweet Orange trees
World (2002 FAO) – 64,128,523 MT or 141 billion pounds. Oranges are produced commercially in 114 countries worldwide, on about 9 million acres. Worldwide average yields are just over 15,000 lbs/acre.
Top 10 Countries
(% of world production)
1. Brazil (29%) 6. Spain (4%)
2. USA (18%) 7. Italy (3%)
3. Mexico (6%) 8. Iran (3%)
4. China (6%) 9. Egypt (3%)
5. India (5%) 10. Pakistan (2%)
United States (2002 USDA) – 11,403,136 MT or 25 billion pounds. Production has increased 1.5% per year in last decade. The industry value is $1.8 billion. Leading states:
1. Florida (82%) 587,000 acres
2. California (16%) 194,000 acres
3. Arizona (<1%) 6,200 acres
4. Texas (<1%) 9,100 acres
Prices received by growers are among the lowest of any fruit crop in the USA: 5-15 ¢/lb, with fresh fruit receiving 10-15 ¢/lb, and processed about 5-6 ¢/lb.
Grapefruit
World (2002 FAO) – 4,979,781 MT or 10.9 billion pounds. FAO statistics include pummelo with grapefruit, so a small fraction of this amount is actually not grapefruit. Produced commercially in 74 countries worldwide, on about 653,000 acres. Yields average 16,700 lbs/acre.
Top 10 Countries
(% of world production)
1. USA (44%) 6. Israel (5%)
2. China (7%) 7. Argentina (3%)
3. South Africa (6%) 8. Turkey (3%)
4. Cuba (6%) 9. India (3%)
5. Mexico (5%) 10. Tunisia (1%)
United States (2002 USDA) – 2,206,464 MT or 4.8 billion pounds. The industry value is $285 million. Yields range from about 8000 lbs/acre in Arizona to 38,000 lbs/acre in Florida. Prices received by growers are extremely low, about 5 ¢/lb. Leading states:
1. Florida (83%) 101,000 acres
2. Texas (10%) 20,000 acres
3. Ca
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