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  • Strawberry

    The garden strawberry (or simply strawberryFragaria × ananassa)[1] is a widely grown hybrid cultivated worldwide for its fruit. The genus Fragaria, the strawberries, is in the rose family, Rosaceae. The fruit is appreciated for its aroma, bright red colour, juicy texture, and sweetness. It is eaten either fresh or in prepared foods such as jamice cream, and chocolates. Artificial strawberry flavourings and aromas are widely used in commercial products. Botanically, the strawberry is not a berry, but an aggregate accessory fruit. Each apparent ‘seed’ on the outside of the strawberry is actually an achene, a botanical fruit with a seed inside it.

    The garden strawberry was first bred in Brittany, France, in the 1750s via a cross of F. virginiana from eastern North America and F. chiloensis, which was brought from Chile by Amédée-François Frézier in 1714. Cultivars of F. × ananassa have replaced the woodland strawberry F. vesca in commercial production. In 2022, world production of strawberries exceeded nine million tons, led by China with 35% of the total.

    Strawberries have appeared in literature and art from Roman times; Virgil wrote about the snake lurking beneath the strawberry, an image reinterpreted by later writers including Shakespeare. Strawberries appear in Italian, Flemish, and German paintings, including Hieronymus Bosch‘s The Garden of Earthly Delights. It has been understood to symbolise the ephemerality of earthly joys or the benefit that blessed souls get from religion, or to allegorise death and resurrection. By the late 20th century, its meaning had shifted: it symbolised female sexuality.

    Evolution

    History and taxonomy

    In Europe, until the 17th century cultivated plants were obtained by transplanting strawberries from the forests; the plants were propagated asexually by pegging down the runners, allowing them to root, and then separating the new plants.[2] F. virginiana, the Virginia strawberry, was brought to Europe from eastern North America; F. chiloensis, the Chilean strawberry, was brought from Chile by Amédée-François Frézier in 1714. At first introduction to Europe, the Chilean strawberry plants grew vigorously, but produced no fruit. French gardeners in Brittany in the 1750s noticed that the Chilean plants bore only female flowers. They planted the wild woodland strawberry F. vesca among the Chilean plants to provide pollen; the Chilean strawberry plants then bore abundant fruits.[3]

    In 1759, Philip Miller recorded the ‘pine strawberry’ (F. ananassa) in Chelsea, England.[3] In the gardens of the Palace of Versailles, France, Antoine Nicolas Duchesne found in 1766 that F. ananassa was a hybrid of the recently arrived F. chiloensis and F. virginiana.[1] In 1806, Michael Keens of Isleworth, England selected the Keens Imperial cultivar from many hybrids,[4] winning the Royal Horticultural Society‘s Silver Cup.[3] Both the names ‘pine’ and ‘ananassa’ meant “pineapple”, for the fruit’s flavour.[4] Modern strawberries and both parent species are octoploid (8N, meaning they have 8 sets of 7 chromosomes).[5] The genome sequence of the garden strawberry was published in 2019.[6]

    Hybridisation and polyploidy in strawberries. Garden strawberries are octoploid (8N), like both parents, the Virginia and Chilean strawberries.

    Further breeding in the following centuries produced varieties with a longer cropping season and more fruit.[3] During the Green Revolution of the 1950s, agronomists used selective breeding to expand phenotypic diversity of the garden strawberry. Adoption of perpetual flowering hybrids not sensitive to changes in photoperiod gave higher yields and enabled production in California to expand.[1]

    Phylogeny

    The phylogeny of the cultivated strawberry within the genus Fragaria of the Rosaceae family was determined by chloroplast genomics in 2021. The polyploidy (number of sets of chromosomes) is shown as “2N” etc. by each species.[7]

    RosaceaeRosa and other genera Potentilla (cinquefoils) Fragariaat least 11 other speciesF. viridis 2N (green strawberry) F. orientalis 4N (eastern strawberry) F. moschata 6N (musk strawberry) F. mandshuricaF. vesca ssp. vesca 2N (wild strawberry) F. vesca ssp. bracteata 2NF. virginiana 8N (Virginia strawberry, parent species) F. chiloensis 8N (Chilean strawberry, parent species) F. x ananassa 8N (the hybrid garden strawberry) 

    Description

    See also: Fragaria

    Botanical structure of a strawberry, compared to a peapod. The strawberry is a swollen receptacle, covered with many small achenes, the botanical fruits.[8]

    In culinary terms, a strawberry is an edible fruit. From a botanical point of view, it is not a berry but an aggregate accessory fruit, because the fleshy part is derived from the receptacle. Each apparent seed on the outside of the strawberry is actually an achene, a botanical fruit with a seed inside it.[8]

    • Leaves
    • Flower
    • Achenes (botanical fruits)
    • Growth (video)

    Composition

    Nutrition

    Nutritional value per 100 g (3.5 oz)
    Energy136 kJ (33 kcal)
    Carbohydrates7.68 g
    Sugars4.89 g
    Dietary fiber2 g
    Fat0.3 g
    Protein0.67 g
    showVitamins and minerals
    Other constituentsQuantity
    Water90.95 g
    Link to USDA Database entry
    Percentages estimated using US recommendations for adults,[9] except for potassium, which is estimated based on expert recommendation from the National Academies.[10]

    Raw strawberries are 91% water, 8% carbohydrates, 1% protein, and contain negligible fat (table). A reference amount of 100 grams (3.5 oz) supplies 33 kilocalories, is a rich source of vitamin C (65% of the Daily Value, DV), and a good source of manganese (17% DV), with no other micronutrients in significant content (table). Strawberries contain a modest amount of essential unsaturated fatty acids in the achene (seed) oil.[11]

    Phytochemicals

    Garden strawberries contain diverse phytochemicals, including the dimeric ellagitannin agrimoniin, which is an isomer of sanguiin H-6.[12][13] Other polyphenols present include flavonoids, such as anthocyaninsflavanolsflavonols and phenolic acids, such as hydroxybenzoic acid and hydroxycinnamic acid.[11] Although achenes comprise only about 1% of the total fresh weight of a strawberry, they contribute 11% of all polyphenols in the whole fruit; achene phytochemicals include ellagic acid, ellagic acid glycosides, and ellagitannins.[14]

    Pelargonidin-3-glucoside is the major anthocyanin pigment in strawberries, giving them their red colour, with cyanidin-3-glucoside in smaller amounts. Strawberries also contain purple minor pigments, such as dimeric anthocyanins.[15]

    Flavour and fragrance

    Furaneol contributes to the fragrance of strawberries.

    Sweetness, fragrance and complex flavour are important attributes of strawberries.[16] In plant breeding and farming, emphasis is placed on sugars, acids, and volatile compounds, which improve the taste and fragrance of the ripe fruit.[17] Estersterpenes, and furans are the chemical compounds having the strongest relationships to strawberry flavour, sweetness and fragrance, with a total of 31 out of some 360 volatile compounds significantly correlated to desirable flavour and fragrance.[17][18][19] In breeding strawberries for the commercial market in the United States, the volatile compounds methyl anthranilate and gamma-decalactone, prominent in aromatic wild strawberries, are especially desired for their “sweet and fruity” aroma characteristics.[18][19] As strawberry flavour and fragrance appeal to consumers,[18][19][20] they are used widely in manufacturing, including foods, beverages, perfumes and cosmetics.[21][22]

    Allergy

    Some people experience an anaphylactoid reaction to eating strawberries.[23] The most common form of this reaction is oral allergy syndrome, but symptoms may also mimic hay fever or include dermatitis or hives, and, in severe cases, may cause breathing problems.[24] Proteomic studies indicate that the allergen may be tied to a protein for the red anthocyanin biosynthesis expressed in strawberry ripening, named Fra a1 (Fragaria allergen1). White-fruited strawberry cultivars, lacking Fra a1, may be an option for people allergic to strawberries.[25] They ripen but remain pale, appearing like immature berries. A virtually allergen-free cultivar named ‘Sofar’ is available.[26][27]

    Varieties

    Further information: Breeding of strawberries

    For a more comprehensive list, see List of strawberry cultivars.

    Strawberries are often grouped according to their flowering habit.[28][29] Traditionally in the Northern Hemisphere, this has consisted of a division between “June-bearing” strawberries, which bear their fruit in the early summer and “everbearing” strawberries, which often bear several crops of fruit throughout the season.[29] One plant throughout a season may produce 50 to 60 times or roughly once every three days.[30] Strawberries occur in three basic flowering habits: short-day, long-day, and day-neutral. These describe the day-length sensitivity of the plant and the type of photoperiod that induces flower formation. Day-neutral cultivars produce flowers regardless of the photoperiod.[31] Strawberry cultivars vary widely in size, colour, flavour, shape, degree of fertility, season of ripening, liability to disease and constitution of plant.[28]

    Cultivation

    Production

    Top strawberry producers
    in 2022
    Numbers in million tonnes
    1.  China3.35 (35.01%)
    2.  United States1.26 (13.17%)
    3.  Turkey0.73 (7.63%)
    4.  Egypt0.64 (6.69%)
    5.  Mexico0.57 (5.96%)
    6.  Spain0.33 (3.45%)
    World total9.57
    Source: FAOSTAT[32]

    In 2022, world production of strawberries was 9.6 million tonnes, led by China with 35 percent of the total and the United States and Turkey as other significant producers.[32] Due to the relatively fragile nature of the strawberry, approximately 35 percent of the $2.2 billion United States crop was spoiled in 2020. An Idaho company announced plans to launch more durable gene-edited strawberries. In the U.S., as of 2021, it cost growers around $35,000 per acre to plant and $35,000 per acre to harvest strawberries.[33]

    For commercial production, plants can be propagated from bare root plants or plugs. One method of cultivation uses annual plasticulture;[34] another is a perennial system of matted rows or mounds which has been used in cold growing regions for many years.[35] In some areas, greenhouses are used; in principle they could provide strawberries during the off season for field crops.[36]

    In the plasticulture system, raised beds are covered with plastic to prevent weed growth and erosion. Plants are planted through holes punched in this covering. Irrigation tubing can be run underneath if necessary.[34][37]

    Another method uses a compost sock. Plants grown in compost socks have been shown to produce significantly more flavonoidsanthocyaninsfructoseglucosesucrosemalic acid, and citric acid than fruit produced in the black plastic mulch or matted row systems.[38] Similar results in an earlier study conducted by United States Department of Agriculture confirms how compost plays a role in the bioactive qualities of two strawberry cultivars.[39]

    Strawberries may be propagated by seed.[40] Strawberries can be grown indoors in pots.[41] Strawberries will not grow indoors in winter though an experiment using a combination of blue and red LED lamps shows that this could be achieved in principle.[42] In Florida, winter is the natural growing season and harvesting begins in mid-November.[30]

    • Strawberry field in North Rhine-Westphalia, Germany
    • A field using the plasticulture method

    Manuring and harvesting

    A man carries a flat of strawberries in a field
    Strawberries are usually picked and placed in shallow boxes in the field.

    Nitrogen fertiliser is often needed at the beginning of every planting year. There are normally adequate levels of phosphorus and potash when fields have been fertilised for other crops in preceding years. To provide more organic matter, a cover crop of wheat or rye can be planted in the year before planting the strawberries. Strawberries prefer a somewhat acidic pH from 5.5 to 6.5, so lime is usually not required.[43]

    To achieve top quality, berries are harvested at least every other day. The berries are picked with the caps and half the stem still attached. Strawberries need to remain on the plant until fully ripe, because they do not continue to ripen after being picked.[44] The harvesting and cleaning process has not changed substantially over time. As they are delicate, strawberries are still often harvested by hand and packed in the field.[45]

    Domestic cultivation

    Strawberries are popular in home gardens, and numerous cultivars have been selected for consumption and for exhibition purposes.[46] The following cultivars have gained the Royal Horticultural Society‘s Award of Garden Merit:

    Pests and diseases

    Over 200 species of pest arthropods attack strawberries.[53] These include mothsfruit flies, chafers, strawberry root weevils, strawberry thrips, strawberry sap beetles, strawberry crown moth, mites, and aphids. Non-arthropod pests include slugs.[53][54] Some are vectors of plant diseases; for instance, the strawberry aphid, Chaetosiphon fragaefolii,[55] can carry the strawberry mild yellow-edge virus.[56]

    Strawberry plants are subject to many diseases, especially when subjected to stress. The leaves may be infected by powdery mildewleaf spot (caused by the fungus Sphaerella fragariae), leaf blight (caused by the fungus Phomopsis obscurans), and by a variety of slime molds. The crown and roots may fall victim to red stele, verticillium wilt, black root rot, and nematodes. The fruits are subject to damage from gray mold (Botrytis cinerea), rhizopus rot, and leather rot.[57][58]

    Disease resistance and protection

    The NPR1 gene from Arabidopsis thalianaAtNPR1, confers A. thaliana‘s broad-spectrum resistance when transexpressed in F. ananassa. This includes resistance to anthracnose, powdery mildew, and angular leaf spot.[59]

    A 1997 study found that many wound volatiles were effective against gray mold (B. cinerea). Both Tribute and Chandler varieties benefited from the treatments, although the effects vary widely with substance and variety. Strawberry plants metabolise these volatiles, more rapidly than do either blackberry or grape.[60]

    Culinary use

    See also: List of strawberry dishes

    Strawberries were eaten fresh with cream in the time of Thomas Wolsey in the court of King Henry VIII.[61] Strawberries can be frozen or made into jam or preserves,[62] as well as dried and used in prepared foods, such as cereal bars.[63] In the United Kingdom, strawberries and cream is a popular dessert at the Wimbledon tennis tournament.[61] Desserts using strawberries include pavlova,[64] fraisier,[65][66] and strawberry shortcake.[67]

    In art, literature and culture

    The Roman poet Ovid wrote that in the past Golden Age, people had lived on wild fruits such as mountain strawberries.[68] Virgil wrote in his Eclogues that “Ye who cull flowers and low-growing strawberries, / Away from here lads; a chill snake lurks in the grass”, and his imagery was taken up by medieval and early modern writers, the snake beneath the strawberry standing for dangerous literature, or beautiful but unfaithful women, or eventually any risky pleasure. In this vein, Shakespeare‘s King Richard III asks for a dish of strawberries while feigning friendship to his enemy; while in OthelloIago shows Desdemona‘s handkerchief “spotted with strawberries”, implying she has been unfaithful and hinting at Iago’s own devious plans.[69]

    The strawberry is found in Italian, Flemish, and German art, and in English miniatures.[69] In medieval depictions, the strawberry often appears in the Virgin Mary‘s garden, while in the Madonna of the Strawberries, she is seated on a strawberry bed and garlanded with strawberry leaves.[69]

    In the work of the late medieval painter Hieronymus Bosch, strawberries feature in The Garden of Earthly Delights amongst “frolicking nude figures”.[68] Fray Jose de Siguenza described the painting as embodying the strawberry as a symbol of the ephemerality of earthly joys.[68] More recently, scholars have seen the symbolism entirely differently: Clément Wertheim-Aymes believed it meant the blessed souls’ benefit from religion; Pater Gerlach supposed it meant spiritual love; and Laurinda Dixon asserted it was part of an allegory of death and resurrection.[68] By the late 20th century, the strawberry (and the raspberry) had become “traditional symbols of the mouth and female sexuality”.[70]

  • Orange

    The orange, also called sweet orange to distinguish it from the bitter orange (Citrus × aurantium), is the fruit of a tree in the family Rutaceae. Botanically, this is the hybrid Citrus × sinensis, between the pomelo (Citrus maxima) and the mandarin orange (Citrus reticulata). The chloroplast genome, and therefore the maternal line, is that of pomelo. There are many related hybrids including of mandarins and sweet orange. The sweet orange has had its full genome sequenced.

    The orange originated in a region encompassing Southern ChinaNortheast India, and Myanmar; the earliest mention of the sweet orange was in Chinese literature in 314 BC. Orange trees are widely grown in tropical and subtropical areas for their sweet fruit. The fruit of the orange tree can be eaten fresh or processed for its juice or fragrant peel. In 2022, 76 million tonnes of oranges were grown worldwide, with Brazil producing 22% of the total, followed by India and China.

    Oranges, variously understood, have featured in human culture since ancient times. They first appear in Western art in the Arnolfini Portrait by Jan van Eyck, but they had been depicted in Chinese art centuries earlier, as in Zhao Lingrang’s Song dynasty fan painting Yellow Oranges and Green Tangerines. By the 17th century, an orangery had become an item of prestige in Europe, as seen at the Versailles Orangerie. More recently, artists such as Vincent van GoghJohn Sloan, and Henri Matisse included oranges in their paintings.

    Description

    The orange tree is a relatively small evergreenflowering tree, with an average height of 9 to 10 m (30 to 33 ft), although some very old specimens can reach 15 m (49 ft).[1] Its oval leaves, which are alternately arranged, are 4 to 10 cm (1.6 to 3.9 in) long and have crenulate margins.[2] Sweet oranges grow in a range of different sizes, and shapes varying from spherical to oblong. Inside and attached to the rind is a porous white tissue, the white, bitter mesocarp or albedo (pith).[3] The orange contains a number of distinct carpels (segments or pigs, botanically the fruits) inside, typically about ten, each delimited by a membrane and containing many juice-filled vesicles and usually a few pips. When unripe, the fruit is green. The grainy irregular rind of the ripe fruit can range from bright orange to yellow-orange, but frequently retains green patches or, under warm climate conditions, remains entirely green. Like all other citrus fruits, the sweet orange is non-climacteric, not ripening off the tree. The Citrus sinensis group is subdivided into four classes with distinct characteristics: common oranges, blood or pigmented oranges, navel oranges, and acidless oranges.[4][5][6] The fruit is a hesperidium, a modified berry; it is covered by a rind formed by a rugged thickening of the ovary wall.[7][8]

    • Flowers
    • Fruit starting to develop
    • Flowers and fruit simultaneously
    • Mature tree in Galicia, Spain, fruiting in November
    • Structure of the botanical hesperidium

    History

    Hybrid origins

    Citrus trees are angiosperms, and most species are almost entirely interfertile. This includes grapefruitslemonslimes, oranges, and many citrus hybrids. As the interfertility of oranges and other citrus has produced numerous hybrids and cultivars, and bud mutations have also been selected, citrus taxonomy has proven difficult.[9]

    The sweet orange, Citrus x sinensis,[10] is not a wild fruit, but arose in domestication in East Asia. It originated in a region encompassing Southern ChinaNortheast India,[11] and Myanmar.[12] The fruit was created as a cross between a non-pure mandarin orange and a hybrid pomelo that had a substantial mandarin component.[13][14] Since its chloroplast DNA is that of pomelo, it was likely the hybrid pomelo, perhaps a pomelo BC1 backcross, that was the maternal parent of the first orange.[15][16] Based on genomic analysis, the relative proportions of the ancestral species in the sweet orange are approximately 42% pomelo and 58% mandarin.[17] All varieties of the sweet orange descend from this prototype cross, differing only by mutations selected for during agricultural propagation.[16] Sweet oranges have a distinct origin from the bitter orange, which arose independently, perhaps in the wild, from a cross between pure mandarin and pomelo parents.[16]

    Sweet oranges have in turn given rise to many further hybrids including the grapefruit, which arose from a sweet orange x pomelo backcross. Spontaneous and engineered backcrosses between the sweet orange and mandarin oranges or tangerines have produced the clementine and murcott. The ambersweet is a complex sweet orange x (Orlando tangelo x clementine) hybrid.[17][18] The citranges are a group of sweet orange x trifoliate orange (Citrus trifoliata) hybrids.[19]

    The orange is a hybrid of mandarin and pomelo.[17]

    Arab Agricultural Revolution

    Further information: Arab Agricultural Revolution

    The Arab Agricultural Revolution spread citrus fruits as far as the Iberian Peninsula. Page from the Hadith Bayad wa Riyad, 13th century

    In Europe, the Moors introduced citrus fruits including the bitter orange, lemon, and lime to Al-Andalus in the Iberian Peninsula during the Arab Agricultural Revolution.[20] Large-scale cultivation started in the 10th century, as evidenced by complex irrigation techniques specifically adapted to support orange orchards.[21][20] Citrus fruits—among them the bitter orange—were introduced to Sicily in the 9th century during the period of the Emirate of Sicily, but the sweet orange was unknown there until the late 15th century or the beginnings of the 16th century, when Italian and Portuguese merchants brought orange trees into the Mediterranean area.[11]

    Spread across Europe

    Shortly afterward, the sweet orange quickly was adopted as an edible fruit. It was considered a luxury food grown by wealthy people in private conservatories, called orangeries. By 1646, the sweet orange was well known throughout Europe; it went on to become the most often cultivated of all fruit trees.[11] Louis XIV of France had a great love of orange trees and built the grandest of all royal Orangeries at the Palace of Versailles.[22] At Versailles, potted orange trees in solid silver tubs were placed throughout the rooms of the palace, while the Orangerie allowed year-round cultivation of the fruit to supply the court. When Louis condemned his finance minister, Nicolas Fouquet, in 1664, part of the treasures that he confiscated were over 1,000 orange trees from Fouquet’s estate at Vaux-le-Vicomte.[23]

    To the Americas

    Further information: Columbian exchange

    Spanish travelers introduced the sweet orange to the American continent. On his second voyage in 1493, Christopher Columbus may have planted the fruit on Hispaniola.[6] Subsequent expeditions in the mid-1500s brought sweet oranges to South America and Mexico, and to Florida in 1565, when Pedro Menéndez de Avilés founded St AugustineSpanish missionaries brought orange trees to Arizona between 1707 and 1710, while the Franciscans did the same in San Diego, California, in 1769.[11] Archibald Menzies, the botanist on the Vancouver Expedition, collected orange seeds in South Africa, raised the seedlings on board, and gave them to several Hawaiian chiefs in 1792. The sweet orange came to be grown across the Hawaiian Islands, but its cultivation stopped after the arrival of the Mediterranean fruit fly in the early 1900s.[11][24] Florida farmers obtained seeds from New Orleans around 1872, after which orange groves were established by grafting the sweet orange on to sour orange rootstocks.[11]

    Etymology

    Main article: Orange (word)

    The word “orange” derives from Sanskrit नारङ्ग (nāraṅga), meaning ‘orange tree’. The Sanskrit word reached European languages through Persian نارنگ (nārang) and its Arabic derivative نارنج (nāranj).[25] The word entered Late Middle English in the 14th century via Old French pomme d’orenge.[26] Other forms include Old Provençal auranja,[27] Italian arancia, formerly narancia.[25] In several languages, the initial n present in earlier forms of the word dropped off because it may have been mistaken as part of an indefinite article ending in an n sound. In French, for example, une norenge may have been heard as une orenge. This linguistic change is called juncture lossThe color was named after the fruit,[28] with the first recorded use of orange as a color name in English in 1512.[29][30]

    Etymology of ‘orange’

    Composition

    Nutrition

    Nutritional value per 100 g (3.5 oz)
    Energy197 kJ (47 kcal)
    Carbohydrates11.75 g
    Sugars9.35 g
    Dietary fiber2.4 g
    Fat0.12 g
    Protein0.94 g
    showVitamins and minerals
    Other constituentsQuantity
    Water86.75 g
    Link to USDA Database entry
    Percentages estimated using US recommendations for adults,[31] except for potassium, which is estimated based on expert recommendation from the National Academies.[32]

    Orange flesh is 87% water, 12% carbohydrates, 1% protein, and contains negligible fat (see table). As a 100-gram reference amount, orange flesh provides 47 calories, and is a rich source of vitamin C, providing 64% of the Daily Value. No other micronutrients are present in significant amounts (see table).

    Phytochemicals

    Oranges contain diverse phytochemicals, including carotenoids (beta-carotenelutein and beta-cryptoxanthin), flavonoids (e.g. naringenin)[33] and numerous volatile organic compounds producing orange aroma, including aldehydesestersterpenesalcohols, and ketones.[34] Orange juice contains only about one-fifth the citric acid of lime or lemon juice (which contain about 47 g/L).[35]

    Taste

    Octyl acetate, a volatile compound contributing to the fragrance of oranges

    The taste of oranges is determined mainly by the ratio of sugars to acids, whereas orange aroma derives from volatile organic compounds, including alcoholsaldehydesketonesterpenes, and esters.[36][37] Bitter limonoid compounds, such as limonin, decrease gradually during development, whereas volatile aroma compounds tend to peak in mid- to late-season development.[38] Taste quality tends to improve later in harvests when there is a higher sugar/acid ratio with less bitterness.[38] As a citrus fruit, the orange is acidic, with pH levels ranging from 2.9[39] to 4.0.[39][40] Taste and aroma vary according to genetic background, environmental conditions during development, ripeness at harvest, postharvest conditions, and storage duration.[36][37]

    Cultivars

    Common

    Common oranges (also called “white”, “round”, or “blond” oranges) constitute about two-thirds of all orange production. The majority of this crop is used for juice.[4][6]

    Valencia

    Main article: Valencia orange

    The Valencia orange is a late-season fruit; it is popular when navel oranges are out of season. Thomas Rivers, an English nurseryman, imported this variety from the Azores and catalogued it in 1865 under the name Excelsior. Around 1870, he provided trees to S. B. Parsons, a Long Island nurseryman, who in turn sold them to E. H. Hart of Federal Point, Florida.[41]

    Main article: Navel orange

    Navel oranges have a characteristic second fruit at the apex, which protrudes slightly like a human navel. They are mainly an eating fruit, as their thicker skin makes them easy to peel, they are less juicy and their bitterness makes them less suitable for juice.[4] The parent variety was probably the Portuguese navel orange or Umbigo.[42] The cultivar rapidly spread to other countries, but being seedless it had to be propagated by cutting and grafting.[43]

    The Cara Cara is a type of navel orange grown mainly in VenezuelaSouth Africa and California’s San Joaquin Valley. It is sweet and low in acid,[44] with distinctively pinkish red flesh. It was discovered at the Hacienda Cara Cara in Valencia, Venezuela, in 1976.[45]

    Blood

    Main article: Blood orange

    Blood oranges, with an intense red coloration inside, are widely grown around the Mediterranean; there are several cultivars.[11] The development of the red color requires cool nights.[46] The redness is mainly due to the anthocyanin pigment chrysanthemin (cyanidin 3-O-glucoside).[47]

    Acidless

    Acidless oranges are an early-season fruit with very low levels of acid. They also are called “sweet” oranges in the United States, with similar names in other countries: douce in France, sucrena in Spain, dolce or maltese in Italy, meski in North Africa and the Near East (where they are especially popular), succari in Egypt, and lima in Brazil.[4] The lack of acid, which protects orange juice against spoilage in other groups, renders them generally unfit for processing as juice, so they are primarily eaten. They remain profitable in areas of local consumption, but rapid spoilage renders them unsuitable for export to major population centres of Europe, Asia, or the United States.[4]

    Cultivation

    Climate

    Like most citrus plants, oranges do well under moderate temperatures—between 15.5 and 29 °C (59.9 and 84.2 °F)—and require considerable amounts of sunshine and water. They are principally grown in tropical and subtropical regions.[6]

    As oranges are sensitive to frost, farmers have developed methods to protect the trees from frost damage. A common process is to spray the trees with water so as to cover them with a thin layer of ice, insulating them even if air temperatures drop far lower. This practice, however, offers protection only for a very short time.[48] Another procedure involves burning fuel oil in smudge pots put between the trees. These burn with a great deal of particulate emission, so condensation of water vapor on the particulate soot prevents condensation on plants and raises the air temperature very slightly. Smudge pots were developed after a disastrous freeze in southern California in January 1913 destroyed a whole crop.[49]

    Propagation

    Further information: Fruit tree propagation and Citrus rootstock

    Commercially grown orange trees are propagated asexually by grafting a mature cultivar onto a suitable seedling rootstock to ensure the same yield, identical fruit characteristics, and resistance to diseases throughout the years. Propagation involves two stages: first, a rootstock is grown from seed. Then, when it is approximately one year old, the leafy top is cut off and a bud taken from a specific scion variety, is grafted into its bark. The scion is what determines the variety of orange, while the rootstock makes the tree resistant to pests and diseases and adaptable to specific soil and climatic conditions. Thus, rootstocks influence the rate of growth and have an effect on fruit yield and quality.[50] Rootstocks must be compatible with the variety inserted into them because otherwise, the tree may decline, be less productive, or die.[50] Among the advantages to grafting are that trees mature uniformly and begin to bear fruit earlier than those reproduced by seeds (3 to 4 years in contrast with 6 to 7 years),[51] and that farmers can combine the best attributes of a scion with those of a rootstock.[52]

    Harvest

    Canopy-shaking mechanical harvesters are being used increasingly in Florida to harvest oranges. Current canopy shaker machines use a series of six-to-seven-foot-long tines to shake the tree canopy at a relatively constant stroke and frequency.[53] Oranges are picked once they are pale orange.[54]

    Degreening

    Oranges must be mature when harvested. In the United States, laws forbid harvesting immature fruit for human consumption in Texas, Arizona, California and Florida.[55] Ripe oranges, however, often have some green or yellow-green color in the skin. Ethylene gas is used to turn green skin to orange. This process is known as “degreening”, “gassing”, “sweating”, or “curing”.[55] Oranges are non-climacteric fruits and cannot ripen internally in response to ethylene gas after harvesting, though they will de-green externally.[56]

    Storage

    Commercially, oranges can be stored by refrigeration in controlled-atmosphere chambers for up to twelve weeks after harvest. Storage life ultimately depends on cultivar, maturity, pre-harvest conditions, and handling.[57] At home, oranges have a shelf life of about one month, and are best stored loose.[58]

    • Spraying oranges in an orchard in Australia
    • Orange grove in California
    • Picking oranges, Israel
    • Harvest, Israel
    • Market stall, Morocco

    Pests and diseases

    Pests

    Cottony cushion scale insects devastated orange groves across California in the 19th century, and were the first pest to be subject to successful biological control.[41]

    The first major pest that attacked orange trees in the United States was the cottony cushion scale (Icerya purchasi), imported from Australia to California in 1868. Within 20 years, it wiped out the citrus orchards around Los Angeles, and limited orange growth throughout California. In 1888, the USDA sent Alfred Koebele to Australia to study this scale insect in its native habitat. He brought back with him specimens of an Australian ladybirdNovius cardinalis (the Vedalia beetle), and within a decade the pest was controlled. This was one of the first successful applications of biological pest control on any crop.[41] The orange dog caterpillar of the giant swallowtail butterfly, Papilio cresphontes, is a pest of citrus plantations in North America, where it eats new foliage and can defoliate young trees.[59]

    Diseases

    Further information: List of citrus diseases

    The Asian citrus psyllid, Diaphorina citri, is a major vector of citrus greening disease.[60]

    Citrus greening disease, caused by the bacterium Liberobacter asiaticum, has been the most serious threat to orange production since 2010. It is characterized by streaks of different shades on the leaves, and deformed, poorly colored, unsavory fruit. In areas where the disease is endemic, citrus trees live for only five to eight years and never bear fruit suitable for consumption.[61] In the western hemisphere, the disease was discovered in Florida in 1998, where it has attacked nearly all the trees ever since. It was reported in Brazil by Fundecitrus Brasil in 2004.[61] As from 2009, 0.87% of the trees in Brazil’s main orange growing areas (São Paulo and Minas Gerais) showed symptoms of greening, an increase of 49% over 2008.[62] The disease is spread primarily by psyllid plant lice such as the Asian citrus psyllid (Diaphorina citri Kuwayama), an efficient vector of the bacterium.[60] Foliar insecticides reduce psyllid populations for a short time, but also suppress beneficial predatory ladybird beetles. Soil application of aldicarb provided limited control of Asian citrus psyllid, while drenches of imidacloprid to young trees were effective for two months or more.[63] Management of citrus greening disease requires an integrated approach that includes use of clean stock, elimination of inoculum via voluntary and regulatory means, use of pesticides to control psyllid vectors in the citrus crop, and biological control of the vectors in non-crop reservoirs.[61]

    Greasy spot, a fungal disease caused by the ascomycete Mycosphaerella citri, produces leaf spots and premature defoliation, thus reducing the tree’s vigour and yield. Ascospores of M. citri are generated in pseudothecia in decomposing fallen leaves.[64]

    Production

    Production of oranges – 2022
    CountryProduction (millions of tonnes)
     Brazil16.9
     India10.2
     China7.6
     Mexico4.8
     Egypt3.4
     United States3.1
    World76.4
    Source: FAOSTAT of the United Nations[65]

    Main article: Citrus production

    In 2022, world production of oranges was 76 million tonnes, led by Brazil with 22% of the total, followed by India, China, and Mexico.[65] The United States Department of Agriculture has established grades for Florida oranges, primarily for oranges sold as fresh fruit.[66] In the United States, groves are located mainly in FloridaCalifornia, and Texas.[67] The majority of California’s crop is sold as fresh fruit, whereas Florida’s oranges are destined to juice products. The Indian River area of Florida produces high quality juice, which is often sold fresh and blended with juice from other regions, because Indian River trees yield sweet oranges but in relatively small quantities.[68]

    Culinary use

    Dessert fruit and juice

    Further information: Orange juice

    Oranges, whose flavor may vary from sweet to sour, are commonly peeled and eaten fresh raw as a dessert. Orange juice is obtained by squeezing the fruit on a special tool (a juicer or squeezer) and collecting the juice in a tray or tank underneath. This can be made at home or, on a much larger scale, industrially.[69] Orange juice is a traded commodity on the Intercontinental Exchange.[70] Frozen orange juice concentrate is made from freshly squeezed and filtered juice.[71]

    Marmalade

    Main article: Marmalade

    Oranges are made into jam in many countries; in Britain, bitter Seville oranges are used to make marmalade. Almost the whole Spanish production is exported to Britain for this purpose. The entire fruit is cut up and boiled with sugar; the pith contributes pectin, which helps the marmalade to set. The first recipe was by an Englishwoman, Mary Kettilby, in 1714. Pieces of peel were first added by Janet Keiller of Dundee in the 1790s, contributing a distinctively bitter taste.[72] Orange peel contains the bitter substances limonene and naringin.[73][74]

    Extracts

    Further information: Limonene

    Zest is scraped from the coloured outer part of the peel, and used as a flavoring and garnish in desserts and cocktails.[75]

    Sweet orange oil is a by-product of the juice industry produced by pressing the peel. It is used for flavoring food and drinks; it is employed in the perfume industry and in aromatherapy for its fragrance. The oil consists of approximately 90% D-limonene, a solvent used in household chemicals such as wood conditioners for furniture and—along with other citrus oils—detergents and hand cleansers. It is an efficient cleaning agent with a pleasant smell, promoted for being environmentally friendly and therefore preferable to petrochemicals. It is, however, irritating to the skin and toxic to aquatic life.[76][77]

    In human culture

    Oranges have featured in human culture since ancient times. The earliest mention of the sweet orange in Chinese literature dates from 314 BC.[13] Larissa Pham, in The Paris Review, notes that sweet oranges were available in China much earlier than in the West. She writes that Zhao Lingrang’s fan painting Yellow Oranges and Green Tangerines pays attention not to the fruit’s colour but the shape of the fruit-laden trees, and that Su Shi’s poem on the same subject runs “You must remember, / the best scenery of the year, / Is exactly now, / when oranges turn yellow and tangerines green.”[78]

    The scholar Cristina Mazzoni has examined the multiple uses of the fruit in Italian art and literature, from Catherine of Siena‘s sending of candied oranges to Pope Urban, to Sandro Botticelli‘s setting of his painting Primavera in an orange grove. She notes that oranges symbolised desire and wealth on the one hand, and deformity on the other, while in the fairy-stories of Sicily, they have magical properties.[79] Pham comments that the Arnolfini Portrait by Jan van Eyck contains in a small detail one of the first representations of oranges in Western art, the costly fruit perhaps traded by the merchant Arnolfini himself.[78] By the 17th century, orangeries were added to great houses in Europe, both to enable the fruit to be grown locally and for prestige, as seen in the Versailles Orangerie completed in 1686.[80]

    The Dutch Post-Impressionist artist Vincent van Gogh portrayed oranges in paintings such as his 1889 Still Life of Oranges and Lemons with Blue Gloves and his 1890 A Child with Orange, both works late in his life. The American artist of the Ashcan SchoolJohn Sloan, made a 1935 painting Blond Nude with Orange, Blue Couch, while Henri Matisse‘s last painting was his 1951 Nude with Oranges; after that he only made cut-outs.[81]