Editing Kiwifruit (section)

==Cultivation==
Kiwifruit can be grown in most temperate climates with adequate summer heat. Where fuzzy kiwifruit (''Actinidia chinensis var. deliciosa'') is not hardy, other species can be grown as substitutes.

===Breeding===
[[File:Kiwifruit-Actinidia deliciosa-plantation.jpg|thumb|Kiwifruit growing on supported vine]]
Often in commercial farming, different breeds are used for [[rootstock]], fruit-bearing plants, and [[pollinators]].<ref name=Morton /> Therefore, the seeds produced are [[crossbreed]]s 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, [[seedling]]s take seven years before they flower, so determining whether the kiwifruit is fruit bearing or a pollinator is time-consuming.<ref name="ucd">{{cite web |url=http://fruitandnuteducation.ucdavis.edu/education/fruitnutproduction/Kiwi/Kiwi_Propagation/ |title=Kiwifruit Propagation |publisher=University of California-Davis, Division of Agriculture and Natural Resources|date=2015|access-date=14 July 2015}}</ref> Therefore, most kiwifruits, except rootstock and new [[cultivar]]s, are propagated [[asexual reproduction|asexually]].<ref name="ucd" /> 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.<ref name="ucd" />

===Pollination===
[[File:Kiwifruit Female Flowers.JPG|thumb|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.<ref name=Morton /> Some varieties can self-pollinate, but even they produce a greater and more reliable yield when pollinated by male kiwifruit.<ref name=Morton /> 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.<ref name="Kiwifruit pollination problems">{{cite web|url=https://www.sciencelearn.org.nz/resources/72-kiwifruit-pollination-problems|title=Kiwifruit pollination problems|website=Science Learning Hub}}</ref>

Kiwifruit growers rely on [[honey bee]]s, 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.<ref>{{cite web | title=How bees transfer pollen between flowers | website=honeybeesuite.com | date=2018-07-17 | url=https://honeybeesuite.com/how-bees-transfer-pollen-between-flowers/ | archive-url=https://web.archive.org/web/20190120093519/https://honeybeesuite.com/how-bees-transfer-pollen-between-flowers/ | archive-date=2019-01-20 | url-status=dead}}</ref>

To deal with these pollination challenges, some producers blow collected pollen over the female flowers.<ref name="Kiwifruit pollination problems"/> 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.<ref name=Morton />

===Maturation and harvest===
[[File:Kiwifruit skin..jpg|thumb|Close-up of kiwifruit skin]]
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.<ref name=Morton />

===Storage===
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.<ref name=Morton />

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.<ref name=ukfoodguide>{{cite web|title=Kiwi fruit|url=http://www.ukfoodguide.net/kiwifruit.htm|archive-url=https://web.archive.org/web/20030917043709/http://www.ukfoodguide.net/kiwifruit.htm|url-status=usurped|archive-date=17 September 2003|publisher=The UK Food Guide|access-date=4 January 2013}}</ref> Once a kiwifruit is ripe, however, it is preserved optimally when stored far from other fruits, as it is sensitive to the [[Ethylene as a plant hormone|ethylene]] gas they may emit, thereby tending to over-ripen even in the refrigerator.<ref name=ukfoodguide /> If stored appropriately, ripe kiwifruit is normally kept for about one to two weeks.<ref name=ukfoodguide />

===Pests and diseases===
[[Pseudomonas syringae#P. s. pv. actinidiae|''Pseudomonas syringae'' pv. ''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).<ref>{{cite web |url=http://www.biosecurity.govt.nz/pests/kiwifruit-vine-disease |title=''Kiwifruit vine disease'' by MAF Biosecurity NZ |access-date=18 February 2014 |archive-url=https://web.archive.org/web/20170312133422/http://www.biosecurity.govt.nz/pests/kiwifruit-vine-disease |archive-date=12 March 2017 |url-status=dead }}</ref><ref>{{cite news |url=http://www.stuff.co.nz/nelson-mail/features/primary-focus/4577177/More-virulent-PSA-strain-a-new-worry-for-kiwifruit-growers |title= More virulent PSA strain a new worry for kiwifruit growers |newspaper=The Dominion Post |first = Peter |last= Watson|date= 2011-01-25 |access-date=2011-09-04 }}</ref><ref>{{cite news |url=http://www.nzherald.co.nz/business/news/article.cfm?c_id=3&objectid=10747234 |title= Relief for kiwifruit industry |newspaper=[[The New Zealand Herald]] |first = Owen |last= Hembry |date= 2011-08-25 |access-date=2011-09-04 }}</ref> In 2010 it was found in New Zealand's [[Bay of Plenty Region]] kiwifruit orchards in the North Island.<ref>{{cite web|url=http://www.biosecurity.govt.nz/media/8-11-10/suspected-bacterial-vine-infection|title=Suspected Bacterial Vine Infection|date=8 November 2010|publisher=MAF Biosecurity New Zealand|access-date=9 November 2010|archive-date=13 November 2010|archive-url=https://web.archive.org/web/20101113200914/http://www.biosecurity.govt.nz/media/8-11-10/suspected-bacterial-vine-infection|url-status=dead}}</ref> 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.<ref name="Kiwi & PSA">{{cite web |title=Kiwifruit and Psa – a timeline |url=https://www.sciencelearn.org.nz/interactive_timeline/10-kiwifruit-and-psa-a-timeline |website=Science Learning Hub – Pokapu Akoranga Putaiao |publisher=Curious Minds – New Zealand Government |access-date=25 June 2021}}</ref>

Scientists reported they had worked out the strain of PSA affecting kiwifruit from New Zealand, Italy, and Chile originated in China.<ref>{{cite journal|last=Butler|first=Margi I.|author2=Stockwell, Peter A. |author3=Black, Michael A. |author4=Day, Robert C. |author5=Lamont, Iain L. |author6= Poulter, Russel T. M. |title=''Pseudomonas syringae'' pv. ''actinidiae'' from Recent Outbreaks of Kiwifruit Bacterial Canker Belong to Different Clones That Originated in China|journal=PLOS ONE|date=February 2013|volume=8|issue=2|pages=e57464|doi=10.1371/journal.pone.0057464|pmid=23555547|bibcode=2013PLoSO...857464B |pmc=3583860|doi-access=free}}</ref>
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===Early sex identification===
In 2020, the Wuhan Botanical Research Institute of the Chinese Academy of Sciences patented a method for early identification of the sex of kiwifruit plants.<ref>{{Cite patent|number=CN111394495A|title=Universal molecular marker primers and applications for sex identification of commercial kiwifruit varieties|gdate=2020-07-10|invent1=张琼|invent2=钟彩虹|invent3=汪祖鹏|invent4=郑浩|url=https://patents.google.com/patent/CN111394495A/en}}</ref><ref>{{Cite journal |last1=Brantley |first1=Ashley K. |last2=Spiers |first2=James D. |last3=Thompson |first3=Andrew B. |last4=Pitts |first4=James A. |last5=Kessler |first5=J. Raymond |last6=Wright |first6=Amy N. |last7=Coneva |first7=Elina D. |date=2019-04-01 |title=Effective Pollination Period of Actinidia chinensis 'AU Golden Sunshine' and A. deliciosa 'AU Fitzgerald' Kiwifruit |url=https://journals.ashs.org/hortsci/view/journals/hortsci/54/4/article-p656.xml |journal=HortScience |language=en-US |volume=54 |issue=4 |pages=656–660 |doi=10.21273/HORTSCI13617-18 |issn=0018-5345|doi-access=free }}</ref><ref name=":1">{{Cite journal |last1=De Mori |first1=G. |last2=Testolin |first2=R. |last3=Cipriani |first3=G. |date=2022-06-17 |title=A molecular protocol for Early Sex Discrimination (ESD) in Actinidia spp |url=https://journals.sagepub.com/doi/10.3233/JBR-211530 |journal=Journal of Berry Research |language=EN |volume=12 |issue=2 |pages=249–266 |doi=10.3233/JBR-211530 |bibcode=2022JBerR..12..249D |issn=1878-5093|hdl=11390/1228645 |hdl-access=free }}</ref>

Kiwifruit plants are dioecious, meaning they have separate male and female plants. Crosses between male and female genotypes typically produce male and female offspring in a 1:1 ratio, regardless of ploidy level. Since only female plants bear fruit, male plants are unproductive in commercial breeding programs. Maintaining male seedlings consumes land, labor, and resources without contributing to fruit yield. The breeding process is further hindered by the species' long generation cycle, spanning at least three growing seasons and a period of winter dormancy. Managing large breeding populations over extended periods is resource-intensive, especially for fruit crops like kiwifruit, which require expensive support infrastructure.<ref name=":1" />

To address these challenges, there is a pressing need for sex-linked molecular markers. Early identification of plant sex at the seedling stage enables the efficient removal of male plants, reducing resource waste and improving breeding efficiency.<ref name=":1" />