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  • Papaya 

    The papaya (/pəˈpaɪə/US/pəˈpɑːjə/), papaw, (/pəˈpɔː/[3]) or pawpaw (/ˈpɔːpɔː/[3])[4] is the plant species Carica papaya, one of the 21 accepted species in the genus Carica of the family Caricaceae,[5] and also the name of its fruit. It was first domesticated in Mesoamerica, within modern-day southern Mexico and Central America.[6][7] It is grown in several countries in regions with a tropical climate. In 2022, India produced 38% of the world’s supply of papayas.

    Etymology

    [edit]

    The word papaya derives from Arawak via Spanish,[8] and is also the name for the plant. The name papaw or pawpaw is used alternatively for the fruit only in some regions.[6][9]

    Description

    [edit]

    The papaya is a small, sparsely branched tree, usually with a single stem growing from 5 to 10 m (16 to 33 ft) tall, with spirally arranged leaves confined to the top of the trunk. The lower trunk is conspicuously scarred where leaves and fruit were borne. The leaves are large, 50–70 cm (20–28 in) in diameter, deeply palmately lobed, with seven lobes. All plant parts contain latex in articulated laticifers.[10]

    • Seedlings
    • Coiled phyllotaxy of papaya leaves
    • Leaf

    Flowers

    [edit]

    Papayas are dioecious. The flowers are five-parted and highly dimorphic; the male flowers have the stamens fused to the petals. There are two different types of papaya flowers. The female flowers have a superior ovary and five contorted petals loosely connected at the base.[11]: 235 

    Male and female flowers are borne in the leaf axils; the male flowers are in multiflowered dichasia, and the female ones are in few-flowered dichasia.[citation needed] The pollen grains are elongated and approximately 35 microns in length.[citation needed] The flowers are sweet-scented, open at night, and are wind- or insect-pollinated.[10][12][13]

    • Papaya flower
    • Buds
    • Female flowers
    • Male flowers
    • Close-up of male flowers
    • Pollen grains

    Fruit

    [edit]

    The fruit is a large berry about 15–45 cm (6–17+34 in) long and 10–30 cm (4–11+34 in) in diameter.[10]: 88  It is ripe when it feels soft (as soft as a ripe avocado or softer) and its skin has attained an amber to orange hue. Along the walls of the large central cavity are attached numerous black seeds.[14]

    • Unripe fruit
    • Mature tree with unripe fruit in Kinshasa
    • Ripe fruit
    • Papayas with yellow flesh
    • Longitudinal section of fruit showing orange flesh and numerous black seeds
    • Papaya seeds
    NCBI genome ID513
    Ploidydiploid
    Genome size372 million bp
    Number of chromosomes36
    Year of completion2014

    Chemistry

    [edit]

    Papaya skin, pulp, and seeds contain a variety of phytochemicals, including carotenoids and polyphenols,[15] as well as benzyl isothiocyanates and benzyl glucosinates, with skin and pulp levels that increase during ripening.[16] The carotenoids, lutein and beta-carotene, are prominent in the yellow skin, while lycopene is dominant in the red flesh (table).[17] Papaya seeds also contain the cyanogenic substance prunasin.[18] The green fruit contains papain,[6] a cysteine protease enzyme used to tenderize meat (see below).

    Distribution and habitat

    [edit]

    Native to tropical America, papaya originates from southern Mexico and Central America.[6][7][10] Papaya is also considered native to southern Florida, introduced by predecessors of the Calusa no later than AD 300.[19] Spaniards introduced papaya to the Old World in the 16th century.[6] Papaya cultivation is now nearly pantropical, spanning Hawaii, Central Africa, India, and Australia.[6]

    Wild populations of papaya are generally confined to naturally disturbed tropical forests.[7] Papaya is found in abundance on Everglades hammocks following major hurricanes, but is otherwise infrequent.[19] In the rain forests of southern Mexico, papaya thrives and reproduces quickly in canopy gaps while dying off in the mature closed-canopy forests.[7]

    Ecology

    [edit]

    See also: List of papaya diseases

    Different birds eating papaya

    Viruses

    [edit]

    Papaya ringspot virus is a well-known virus within plants in Florida.[6] The first signs of the virus are yellowing and vein-clearing of younger leaves and mottling yellow leaves. Infected leaves may obtain blisters, roughen, or narrow, with blades sticking upwards from the middle of the leaves. The petioles and stems may develop dark green greasy streaks and, in time, become shorter. The ringspots are circular, C-shaped markings that are a darker green than the fruit. In the later stages of the virus, the markings may become gray and crusty. Viral infections impact growth and reduce the fruit’s quality. One of the biggest effects that viral infections have on papaya is taste. As of 2010, the only way to protect papaya from this virus is genetic modification.[20]

    The papaya mosaic virus destroys the plant until only a small tuft of leaves is left. The virus affects both the leaves of the plant and the fruit. Leaves show thin, irregular, dark-green lines around the borders and clear areas around the veins. The more severely affected leaves are irregular and linear in shape. The virus can infect the fruit at any stage of its maturity. Fruits as young as two weeks old have been spotted with dark-green ringspots about 1 inch (25 mm) in diameter. Rings on the fruit are most likely seen on either the stem end or the blossom end. In the early stages of the ringspots, the rings tend to be many closed circles, but as the disease develops, the rings increase in diameter consisting of one large ring. The difference between the ringspot and the mosaic viruses is the ripe fruit in the ringspot has a mottling of colors, and the mosaic does not.[21]

    Fungi and oomycetes

    [edit]

    The fungus anthracnose attacks papaya, especially mature fruits. The disease starts small with very few signs, such as water-soaked spots on ripening fruits. The spots become sunken, turn brown or black, and may get bigger. In some of the older spots, the fungus may produce pink spores. The fruit ends up being soft and having an off flavor because the fungus grows into the fruit.[22]

    The fungus powdery mildew occurs as a superficial white presence on the leaf’s surface, which is easily recognized. Tiny, light yellow spots begin on the lower surfaces of the leaf as the disease starts to make its way. The spots enlarge, and white powdery growth appears on the leaves. The infection usually appears at the upper leaf surface as white fungal growth. Powdery mildew is not as severe as other diseases.[23]

    The fungus-like oomycete Phytophthora causes damping-off, root rot, stem rot, stem girdling, and fruit rot. Damping-off happens in young plants by wilting and death. The spots on established plants start as white, water-soaked lesions at the fruit and branch scars. These spots enlarge and eventually cause death. The disease’s most dangerous feature is the fruit’s infection, which may be toxic to consumers.[22] The roots can also be severely and rapidly infected, causing the plant to brown and wilt away, collapsing within days.

    Pests

    [edit]

    The papaya fruit fly lays its eggs inside of the fruit, possibly up to 100 or more eggs.[6] The eggs usually hatch within 12 days when they begin to feed on seeds and interior parts of the fruit. When the larvae mature, usually 16 days after being hatched, they eat their way out of the fruit, drop to the ground, and pupate in the soil to emerge within one to two weeks later as mature flies. The infected papaya turns yellow and drops to the ground after the papaya fruit fly infestation.[22]

    The two-spotted spider mite is a 0.5-mm-long brown or orange-red or a green, greenish-yellow translucent oval pest. They all have needle-like piercing-sucking mouthparts and feed by piercing the plant tissue with their mouthparts, usually on the underside of the plant. The spider mites spin fine threads of webbing on the host plant, and when they remove the sap, the mesophyll tissue collapses, and a small chlorotic spot forms at the feeding sites. The leaves of the papaya fruit turn yellow, gray, or bronze. If the spider mites are not controlled, they can cause the death of the fruit.[22]

    The papaya whitefly lays yellow, oval eggs that appear dusted on the undersides of the leaves. They eat papaya leaves, therefore damaging the fruit. There, the eggs developed into flies in three stages called instars. The first instar has well-developed legs and is the only mobile immature life stage. The crawlers insert their mouthparts in the lower surfaces of the leaf when they find it suitable and usually do not move again in this stage. The next instars are flattened, oval, and scale-like. In the final stage, the pupal whiteflies are more convex, with large, conspicuously red eyes.[22]

    Papayas are one of the most common hosts for fruit flies like A. suspensa, which lay their eggs in overripe or spoiled papayas. The larvae of these flies then consume the fruit to gain nutrients until they can proceed into the pupal stage. This parasitism has led to extensive economic costs for nations in Central America.[24]

    Cultivation

    [edit]

    Historical accounts from 18th-century travelers and botanists suggested that papaya seeds were transported from the Caribbean to Malacca and then to India. From Malacca or the Philippines, papaya spread throughout Asia and into the South Pacific region. Credit for introducing papaya to Hawaii is often given to Francisco de Paula Marín, a Spanish explorer and horticulturist, who brought it from the Marquesas Islands in the early 1800s. Since then, papaya cultivation has expanded to all tropical countries and many subtropical regions worldwide. Today, papaya is grown extensively across the globe, owing to its adaptability to various climates and its popularity as a tropical fruit.[25]

    Papaya plants grow in three sexes: male, female, and hermaphrodite. The male produces only pollen, never fruit. The female produces small, inedible fruits unless pollinated. The hermaphrodite can self-pollinate since its flowers contain both male stamens and female ovaries. Almost all commercial papaya orchards contain only hermaphrodites.[13]

    Originally from southern Mexico (particularly Chiapas and Veracruz), Central America, northern South America, and southern Florida[6][19] the papaya is now cultivated in most tropical countries. In cultivation, it grows rapidly, fruiting within three years. It is, however, highly frost-sensitive, limiting its production to tropical climates. Temperatures below −2 °C (29 °F) are greatly harmful, if not fatal. In Florida, California, and Texas, growth is generally limited to the southern parts of those states. It prefers sandy, well-drained soil, as standing water can kill the plant within 24 hours.[26]

    Cultivars

    [edit]

    Two kinds of papayas are commonly grown. One has sweet, red, or orange flesh, and the other has yellow flesh; in Australia, these are called “red papaya” and “yellow papaw,” respectively.[27] Either kind, picked green, is called a “green papaya.”[citation needed]

    The large-fruited, red-fleshed ‘Maradol,’ ‘Sunrise,’ and ‘Caribbean Red’ papayas often sold in U.S. markets are commonly grown in Mexico and Belize.[6][28]

    In 2011, Philippine researchers reported that by hybridizing papaya with Vasconcellea quercifolia, they had developed papaya resistant to papaya ringspot virus (PRV),[29] part of a long line of attempts to transfer resistance from Vasconcellea species into papaya.[30]

    Genetically engineered cultivars

    [edit]

    Carica papaya was the first transgenic fruit tree to have its genome sequenced.[31] In response to the papaya ringspot virus outbreak in Hawaii in 1998, genetically altered papaya were approved and brought to market (including ‘SunUp’ and ‘Rainbow’ varieties.) Varieties resistant to PRV have some DNA of this virus incorporated into the plant’s DNA.[32][33] As of 2010, 80% of Hawaiian papaya plants were genetically modified. The modifications were made by University of Hawaii scientists, who made the modified seeds available to farmers without charge.[34][35]

    In transgenic papaya, resistance is produced by inserting the viral coat protein gene into the plant’s genome. Doing so seems to cause a similar protective reaction in the plant to cross-protection, which involves using an attenuated virus to protect against a more dangerous strain. Conventional varieties of transgenic papaya has reduced resistance against heterologous (not closely related to the coat gene source) strains, forcing different localities to develop their own transgenic varieties. As of 2016, one transgenic line appears able to deal with three different heterologous strains in addition to its source.[36][30]

    Papaya production – 2022
    Country(millions of tonnes)
     India5.3
     Dominican Republic1.3
     Brazil1.1
     Mexico1.1
     Indonesia1.1
    World13.8
    Source: FAOSTAT of the United Nations[37]

    Production

    [edit]

    In 2022, global production of papayas was 13.8 million tonnes, led by India with 38% of the world total (table). Global papaya production grew significantly over the early 21st century, mainly as a result of increased production in India and demand by the United States.[38] The United States is the largest importer of papayas worldwide.[12]

    In South Africa, papaya orchards yield up to 100 tonnes of fruit per hectare.[39]

    Toxicity

    [edit]

    Papaya releases a latex fluid when not ripe, possibly causing irritation and an allergic reaction in some people. Because the enzyme papain acts as an allergen in sensitive individuals,[40] meat that has been tenderized with it may induce an allergic reaction.[6]

    Culinary use

    [edit]

    The ripe fruit of the papaya is usually eaten raw, without skin or seeds.[6] The black seeds are edible and have a sharp, spicy taste.[6] The unripe green fruit is usually cooked due to its latex content.

    Both green papaya fruit and its latex are rich in papain,[6] a cysteine protease used for tenderizing meat and other proteins, as practiced currently by indigenous Americans, people of the Caribbean region, Pacific Islands, and the Philippines.[6] It is included as a component in some powdered meat tenderizers.[6] Papaya is not suitable for foods which set due to gelatin (such as jelly or aspic) because the enzymatic properties of papain prevent gelatin from setting.[41]

    • Papaya juice
    • Papaya jam from Senegal

    Nutrition

    [edit]

    Nutritional value per 100 g (3.5 oz)
    Energy179 kJ (43 kcal)
    Carbohydrates10.82 g
    Sugars7.82 g
    Dietary fiber1.7 g
    Fat0.26 g
    Protein0.47 g
    showVitamins and minerals
    Other constituentsQuantity
    Water88 g
    Lycopene1828 µg
    Full Link to USDA Database entry
    Percentages estimated using US recommendations for adults,[42] except for potassium, which is estimated based on expert recommendation from the National Academies.[43]

    Raw papaya pulp is 88% water, 11% carbohydrates, and contains negligible fat and protein (table). In a reference amount of 100 g (3.5 oz), papaya fruit provides 43 kilocalories and is a significant source of vitamin C (69% of the Daily Value, DV) and a moderate source of folate (10% DV), but otherwise has a low content of micronutrients (table).

    Southeast Asia

    [edit]

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    Green papaya is used in Southeast Asian cooking, both raw and cooked. In some parts of Asia, the young leaves of the papaya are steamed and eaten like spinach.

    In Myanmar, the unripe papaya are cut into slices and dipped into sour, fermented, or spicy seasonings and dips. In Myanmar and Thai recipes, the unripe papaya are cut into thinner slices to make papaya salad.[44] The reason the unripe papaya is used is because of the firmer and crunchier texture.

    Papayas became a part of Filipino cuisine after being introduced to the islands via the Manila galleons.[45][46] Unripe or nearly ripe papayas (with orange flesh but still hard and green) are julienned and are commonly pickled into atchara, which is ubiquitous as a side dish to salty dishes.[47] Nearly ripe papayas can also be eaten fresh as ensaladang papaya (papaya salad) or cubed and eaten dipped in vinegar or salt. Green papaya is also a common ingredient or filling in various savory dishes such as okoytinolaginataanlumpia, and empanada, especially in the cuisines of northern Luzon.[48][49][50]

    In Indonesian cuisine, the unripe green fruits and young leaves are boiled for use as part of lalab salad, while the flower buds are sautéed and stir-fried with chilies and green tomatoes as Minahasan papaya flower vegetable dish.

    In Lao and Thai cuisine, unripe green papayas are used to make a type of spicy salad known in Laos as tam maak hoong and in Thailand as som tam. It is also used in Thai curries, such as kaeng som.

    South America

    [edit]

    In Brazil and Paraguay, the unripe fruits are used to make sweets or preserves.[citation needed]

    Traditional medicine

    [edit]

    In traditional medicine, papaya leaves have been believed useful as a treatment for malaria,[51] an abortifacient, a purgative, or smoked to relieve asthma.[6]

  • Kiwifruit 

    Kiwifruit (often shortened to kiwi outside Australia and New Zealand), or Chinese gooseberry, is the edible berry of several species of woody vines in the genus Actinidia.[1][2] The most common cultivar group of kiwifruit (Actinidia deliciosa ‘Hayward’)[3] is oval, about the size of a large hen’s egg: 5–8 centimetres (2–3 inches) in length and 4.5–5.5 cm (1+34–2+14 in) in diameter. Kiwifruit has a thin, fuzzy, fibrous, tart but edible, light brown skin and light green or golden flesh with rows of tiny, black, edible seeds. The fruit has a soft texture with a sweet and unique flavour.

    Kiwifruit is native to central and eastern China, with the first recorded description dating back to the 12th century during the Song dynasty.[1][4] In the early 20th century, cultivation of kiwifruit spread from China to New Zealand, where the first commercial plantings took place.[1] It gained popularity among British and American servicemen stationed in New Zealand during World War II, and was later became commonly exported, first to Great Britain and then to California in the 1960s.[1][5]

    From the late 20th century, countries beyond New Zealand initiated independent kiwifruit breeding programs. China developed distinct cultivars such as “Hongyang’ (red-fleshed)[6], “Jinyan” (golden-fleshed), “Donghong” (red-fleshed), and “Huayou” (green-fleshed), many of which have been patented.[7][8][9][10][11] Similarly, Italy developed yellow-fleshed cultivars, including “Soreli” and “Dorì”.[12] As of 2023, China accounted for 55% of the world’s total kiwifruit production, making it the largest global producer.[13]

    Etymology

    [edit]

    Early varieties were discovered and cultivated in China. They were described in a 1904 nursery catalogue as having “…edible fruits the size of walnuts, and the flavour of ripe gooseberries“,[14] leading to the name, Chinese gooseberry.[1]

    In the late 1950s, a major New Zealand exporter began calling it “kiwifruit” (Māorihuakiwi)[15] after being advised by a United States client that quarantine officials might mistakenly associate the unpopular name gooseberries[16] – which grow close to the ground – with suspicion of anthrax.[17] The name kiwifruit was adopted for the furry, brown fruit in relation to New Zealand’s furry, brown, national bird – the kiwi.[16] The name was first registered by Turners & Growers on 15 June 1959,[16] and commercially adopted in 1974.[1]

    In New Zealand and Australia, the word kiwi alone either refers to the bird or is used as a nickname for New Zealanders;[16] it is rarely used to refer to the fruit.[5][18] Kiwifruit has since become a common name for all commercially grown green kiwifruit from the genus Actinidia.[1] In the United States and Canada, the shortened name kiwi is commonly used when referring to the fruit.[19][20]

    History

    [edit]

    Further information: Kiwifruit industry in New Zealand

    Kiwifruit
    “Kiwifruit” in Traditional (top) and Simplified (bottom) Chinese characters
    Traditional Chinese獼猴桃
    Simplified Chinese猕猴桃
    Literal meaning“macaque peach”
    showTranscriptions

    Kiwifruit is native to central and eastern China.[1] The first recorded description of the kiwifruit dates to 12th century China during the Song dynasty.[4] As it was usually collected from the wild and consumed for medicinal purposes, the plant was rarely cultivated or bred.[21] Cultivation of kiwifruit spread from China in the early 20th century to New Zealand, where the first commercial plantings occurred.[1] After the Hayward variety was developed, the fruit became popular with British and American servicemen stationed in New Zealand during World War II. Kiwifruits were exported to Great Britain and then to California in the 1960s.[1][5]

    Close-up of Slice of Kiwifruit skin.

    In New Zealand during the 1940s and 1950s, the fruit became an agricultural commodity through the development of commercially viable cultivars, agricultural practices, shipping, storage, and marketing.[22] In the 1970s, New Zealand’s kiwifruit industry experienced significant growth. To support this expansion, the Kiwifruit Export Promotion Committee was established in 1970 to coordinate marketing efforts and later, in 1977, the Kiwifruit Marketing Licensing Authority was formed to set market standards and advise the government, giving growers some control over licensing exporters.[23] The New Zealand Kiwifruit Marketing Board, was later renamed Zespri International Limited in 1997. This rebranding marked a strategic move to enhance global recognition and market presence.[24]

    In 1978, China established the National Co-operative Group for Kiwifruit Research, initiating programs to survey wild germplasm of all Actinidia species, leading to the selection of over 1,400 candidate cultivars.[25][26] By the early 1980s, China began cultivating kiwifruit orchards, initially planting less than one hectare with the ‘Hayward’ cultivar from New Zealand. Over the next four decades, China’s kiwifruit industry expanded significantly, with the planting area of ‘Hayward’ declining to only 6.3% of the total by 2020.[27] This shift reflects the development and adoption of diverse, domestically bred cultivars. Among these are ‘Hongyang’, a red-fleshed kiwifruit selected in Sichuan from seedlings raised from wild-collected seeds,[28] ‘Jinyan’, a yellow-fleshed variety, and ‘Donghong’, another red-fleshed cultivar.[29][30]

    The Wuhan Botanical Garden of the Chinese Academy of Sciences (CAS) has played a key role in China’s kiwifruit conservation and breeding, housing the world’s largest gene bank of kiwifruit varieties. It has officially validated or protected 73 varieties and archived 426 high-quality strains, including Donghong, Jinyan, and Jintao varieties.[30]

    Species and cultivars

    [edit]

    Kiwifruit ‘Red Passion’ with a red-ring

    The genus Actinidia comprises around 60 species. Their fruits are quite variable, although most are easily recognised as kiwifruit because of their appearance and shape. The skin of the fruit varies in size, hairiness, and colour. The flesh varies in colour, juiciness, texture, and taste. Some fruits are unpalatable, while others taste considerably better than most commercial cultivars.[1][31]

    The most commonly sold kiwifruit is derived from A. deliciosa (fuzzy kiwifruit). Other species that are commonly eaten include A. chinensis (golden kiwifruit), A. coriacea (Chinese egg gooseberry), A. arguta (hardy kiwifruit), A. kolomikta (Arctic kiwifruit), A. melanandra (purple kiwifruit), A. polygama (silver vine) and A. purpurea (hearty red kiwifruit).[31]

    Fuzzy kiwifruit

    [edit]

    The larger A. deliciosa (fuzzy kiwifruit) at the rear compared to the smaller kiwi berry

    Most kiwifruit sold belongs to a few cultivars of A. deliciosa (fuzzy kiwifruit): ‘Hayward’, ‘Blake’ and ‘Saanichton 12’.[2] They have a fuzzy, dull brown skin and bright green flesh. The familiar cultivar ‘Hayward’ was developed by Hayward Wright in Avondale, New Zealand, around 1924.[31] It was initially grown in domestic gardens, but commercial planting began in the 1940s.

    ‘Hayward’ is the most commonly available cultivar in stores. It is a large, egg-shaped fruit with a sweet flavour. ‘Saanichton 12’, from British Columbia, is somewhat more rectangular than ‘Hayward’ and comparably sweet, but the inner core of the fruit can be tough. ‘Blake’ can self-pollinate, but has a smaller, more oval fruit, and the flavour is considered inferior.[2][31]

    Kiwi berries

    [edit]

    Kiwi berries are edible fruits the size of a large grape, similar to fuzzy kiwifruit in taste and internal appearance but with a thin, smooth green skin. They are primarily produced by three species: Actinidia arguta (hardy kiwi), A. kolomikta (Arctic kiwifruit) and A. polygama (silver vine). They are fast-growing, climbing vines, durable over their growing season. They are referred to as “kiwi berry, baby kiwi, dessert kiwi, grape kiwi, or cocktail kiwi”.[32]

    The cultivar ‘Issai’ is a hybrid of hardy kiwifruit and silver vine which can self-pollinate. Grown commercially because of its relatively large fruit, ‘Issai’ is less hardy than most hardy kiwifruit.[33][34]

    Actinidia chinensis

    [edit]

    Main article: Gold kiwifruit

    Golden kiwifruit Soreli

    Actinidia chinensis (yellow kiwi or golden kiwifruit) has smooth, bronze skin, with a beak shape at the stem attachment. Flesh colour varies from bright green to a clear, intense yellow. This species is ‘sweeter and more aromatic’ in flavour compared to A. deliciosa.[35] One of the most attractive varieties has a red ‘iris’ around the centre of the fruit and yellow flesh outside. The yellow fruit obtains a higher market price and, being less hairy than the fuzzy kiwifruit tastes better without peeling.[31]

    A commercially viable[36] variety of this red-ringed kiwifruit, patented as EnzaRed, is a cultivar of the Chinese hong yang variety.[37][38]

    Hort16A is a golden kiwifruit cultivar developed by HortResearch, now Plant & Food Research Institute, during the decades of 1980s and 90s.[22] It is marketed worldwide as Zespri Gold. This cultivar suffered significant losses in New Zealand in 2010–2013 due to the PSA bacterium.[39] A new cultivar of golden kiwifruit, Gold3, was found to be more disease-resistant and most growers have now changed to this cultivar.[40] ‘Gold3’, marketed by Zespri as SunGold is not quite as sweet as ‘Hort16A’,[41] and lacks its usually slightly pointed tip.

    Clones of the new variety SunGold have been used to develop orchards in China, resulting in partially successful legal efforts in China by Zespri to protect their intellectual property.[42] In 2021, Zespri estimated that around 5,000 hectares of Sungold orchards were being cultivated in China, mainly in the Sichuan province.[43]

    Cultivation

    [edit]

    Kiwifruit can be grown in most temperate climates with adequate summer heat. Where fuzzy kiwifruit (A. deliciosa) is not hardy, other species can be grown as substitutes.

    Breeding

    [edit]

    Kiwifruit growing on supported vine

    Often in commercial farming, different breeds are used for rootstock, fruit-bearing plants, and pollinators.[1] Therefore, the seeds produced are crossbreeds of their parents. Even if the same breeds are used for pollinators and fruit-bearing plants, there is no guarantee that the fruit will have the same quality as the parent. Additionally, seedlings take seven years before they flower, so determining whether the kiwifruit is fruit bearing or a pollinator is time-consuming.[44] Therefore, most kiwifruits, except rootstock and new cultivars, are propagated asexually.[44] This is done by grafting the fruit-producing plant onto rootstock grown from seedlings or, if the plant is desired to be a true cultivar, rootstock grown from cuttings of a mature plant.[44]

    Pollination

    [edit]

    Kiwifruit flowering

    Kiwifruit plants generally are dioecious, meaning a plant is either male or female. The male plants have flowers that produce pollen, the females receive the pollen to fertilise their ovules and grow fruit; most kiwifruit requires a male plant to pollinate the female plant. For a good yield of fruit, one male vine for every three to eight female vines is considered adequate.[1] Some varieties can self-pollinate, but even they produce a greater and more reliable yield when pollinated by male kiwifruit.[1] Cross-species pollination is often (but not always) successful as long as bloom times are synchronised.

    In nature, the species are pollinated by birds and native bumblebees, which visit the flowers for pollen, not nectar. The female flowers produce fake anthers with what appears to be pollen on the tips to attract the pollinators, although these fake anthers lack the DNA and food value of the male anthers.[45]

    Kiwifruit growers rely on honey bees, the principal ‘for-hire’ pollinator, but commercially grown kiwifruit is notoriously difficult to pollinate. The flowers are not very attractive to honey bees, partly because the flowers do not produce nectar and bees quickly learn to prefer flowers with nectar.

    Honey bees are inefficient cross-pollinators for kiwifruit because they practice “floral fidelity”. Each honey bee visits only a single type of flower in any foray and maybe only a few branches of a single plant. The pollen needed from a different plant (such as a male for a female kiwifruit) might never reach it were it not for the cross-pollination that principally occurs in the crowded colony; it is in the colonies that bees laden with different pollen cross paths.[46]

    To deal with these pollination challenges, some producers blow collected pollen over the female flowers.[45] Most common, though, is saturation pollination, in which the honey bee populations are made so large (by placing hives in the orchards at a concentration of about 8 hives per hectare) that bees are forced to use this flower because of intense competition for all flowers within flight distance.[1]

    Maturation and harvest

    [edit]

    Kiwifruit is picked by hand and commercially grown on sturdy support structures, as it can produce several tonnes per hectare, more than the rather weak vines can support. These are generally equipped with a watering system for irrigation and frost protection in the spring.

    Kiwifruit vines require vigorous pruning, similar to that of grapevines. Fruit is borne on ‘one-year-old and older’ canes, but production declines as each cane ages. Canes should be pruned off and replaced after their third year. In the northern hemisphere, the fruit ripens in November, while in the southern it ripens in May. Four-year-old plants can produce 15 tonnes of fruit per hectare (14,000 lb per acre) while eight-year-old plants can produce 20 tonnes (18,000 lb per acre). The plants produce their maximum at eight to ten years old. The seasonal yields are variable; a heavy crop on a vine one season generally comes with a light crop the following season.[1]

    Storage

    [edit]

    Fruit harvested when firm will ripen when stored properly for long periods. This allows fruit to be stored for up to 8 weeks after harvest.[1]

    Firm kiwifruits ripen after a few days to a week when stored at room temperature, but should not be kept in direct sunlight. Faster ripening occurs when placed in a paper bag with an apple, pear, or banana.[47] Once a kiwifruit is ripe, however, it is preserved optimally when stored far from other fruits, as it is sensitive to the ethylene gas they may emit, thereby tending to over-ripen even in the refrigerator.[47] If stored appropriately, ripe kiwifruit is normally kept for about one to two weeks.[47]

    Pests and diseases

    [edit]

    Pseudomonas syringae actinidiae (PSA) was first identified in Japan in the 1980s. This bacterial strain has been controlled and managed successfully in orchards in Asia. In 1992, it was found in northern Italy. In 2007/2008, economic losses were observed, as a more virulent strain became more dominant (PSA V).[48][49][50] In 2010 it was found in New Zealand’s Bay of Plenty Region kiwifruit orchards in the North Island.[51] The yellow-fleshed cultivars were particularly susceptible. New, resistant varieties were selected in research funded by the government and fruit growers so that the industry could continue.[52]

    Scientists reported they had worked out the strain of PSA affecting kiwifruit from New Zealand, Italy, and Chile originated in China.[53]

    Production

    [edit]

     China2,362,658
     New Zealand662,744
     Italy391,100
     Greece317,080
     Iran295,142
     Chile116,029
    World4,433,060
    Source: FAOSTAT of the United Nations[13]

    In 2023, world kiwifruit production was 4.4 million tonnes, led by China with 55% of the total (table). In China, kiwifruit is grown mainly in the mountainous area upstream of the Yangtze River, as well as Sichuan.[54] Other major producers were New Zealand and Italy (table).

    Production history

    [edit]

    New Zealand

    [edit]

    Kiwifruit exports rapidly increased from the late 1960s to the early 1970s in New Zealand. By 1976, exports exceeded the amount consumed domestically.[55] Outside of Australasia, New Zealand kiwifruit are marketed under the brand-name label Zespri.[56] The general name, “Zespri”, has been used for the marketing of all cultivars of kiwifruit from New Zealand since 2012.[22][35] In 1990, the New Zealand Kiwifruit Marketing Board opened an office for Europe in AntwerpBelgium.[22]

    Italy

    [edit]

    In the 1980s, Italy began cultivating and exporting kiwifruit, leveraging its existing grape-growing infrastructure and techniques. Its proximity to the European market further boosted production, and by 1989, Italy had become the world’s leading kiwifruit producer. Additionally, Italy’s growing season does not significantly overlap with those of New Zealand or Chile, reducing direct competition with these major exporters.[57][58]

    China

    [edit]

    In 1978, China began developing its own kiwifruit cultivars. The Wuhan Botanical Garden, part of the Chinese Academy of Sciences (CAS), played a large role in breeding and improving domestic varieties suited to local conditions. Commercial cultivation initially began in the early 1980s on less than one hectare using the Hayward variety from New Zealand. But by 2020, kiwifruit orchards had expanded to 290,000 hectares and ‘Hayward’ accounted for only 6.3% of the total planting area, as domestically bred varieties gained prominence. To support commercialization and branding, CASGOLD, the first CAS-backed agricultural brand, was created. By 2023, China had become the world’s largest kiwifruit producer, surpassing Italy and New Zealand. However, most of its kiwifruit is consumed domestically, with little exported.[27][30][13][26]

    Human consumption

    [edit]

    pavlova with strawberries, passionfruit, kiwifruit and cream
    Nutritional value per 100 g (3.5 oz)
    Energy262 kJ (63 kcal)
    Carbohydrates15.8 g
    Sugars12.3 g
    Dietary fiber1.4 g
    Fat0.28 g
    Protein1.02 g
    showVitamins and minerals
    Other constituentsQuantity
    Water82 g
    Link to USDA FoodData Central entry
    Percentages estimated using US recommendations for adults,[59] except for potassium, which is estimated based on expert recommendation from the National Academies.[60]
    Nutritional value per 100 g (3.5 oz)
    Energy255 kJ (61 kcal)
    Carbohydrates14.66 g
    Sugars8.99 g
    Dietary fiber3 g
    Fat0.52 g
    Protein1.14 g
    showVitamins and minerals
    Other constituentsQuantity
    Water83 g
    Link to USDA FoodData Central entry
    Percentages estimated using US recommendations for adults,[59] except for potassium, which is estimated based on expert recommendation from the National Academies.[60]

    Kiwifruit may be eaten raw, made into juices, used in baked goods, prepared with meat, or used as a garnish.[1] The whole fruit, including the skin, is suitable for human consumption; however, the skin of the fuzzy varieties is often discarded due to its texture.[61] Sliced kiwifruit has long been used as a garnish atop whipped cream on pavlova, a meringue-based dessert. Traditionally in China, kiwifruit was not eaten for pleasure but was given as medicine to children to help them grow and to women who have given birth to help them recover.[1]

    Raw kiwifruit contains actinidain (also spelled actinidin) which is commercially useful as a meat tenderizer[62] and possibly as a digestive aid.[63] Actinidain also makes raw kiwifruit unsuitable for use in desserts containing milk or any other dairy products because the enzyme digests milk proteins. This applies to gelatin-based desserts since the actinidain will dissolve the proteins in gelatin, causing the dessert to either liquefy or prevent it from solidifying.

    Nutrition

    [edit]

    In a 100-gram (3.5 oz) amount, green kiwifruit provides 255 kilojoules (61 kilocalories) of food energy, is 83% water and 15% carbohydrates, with negligible protein and fat (table). It is particularly rich in vitamin C (103% DV) and vitamin K (34% DV), potassium, and has a moderate content of vitamin E (10% DV) and copper, with no other micronutrients in significant content. Gold kiwifruit has similar nutritional value to green kiwifruit, but contains higher vitamin C content (179% DV) and insignificant vitamin K content (table). Both types of kiwifruit are rich in dietary fiber.

    Kiwifruit seed oil contains on average 62% alpha-linolenic acid, an omega-3 fatty acid.[64] Kiwifruit pulp contains carotenoids, such as provitamin A beta-carotene,[65] lutein and zeaxanthin.[66]

    Allergies

    [edit]

    Allergy to kiwifruit was first described in 1981, and there have since been reports of the allergy presenting with numerous symptoms from localized oral allergy syndrome to life-threatening anaphylaxis.[67]

    The actinidain found in kiwifruit can be an allergen for some individuals, including children.[68][69][70] The most common symptoms are unpleasant itching and soreness of the mouth, with wheezing as the most common severe symptom; anaphylaxis may occur.[68][69]