Sweet potato cultivation in Polynesia

The sweet potato plant (Ipomoea batatas) is originally from the Americas, and became widely cultivated in Central and South America by 2500 BC. Sweet potato is thought to have been first grown as a food crop in central Polynesia around 1000–1100 AD, with the earliest archaeological evidence being fragments recovered from a single location on Mangaia in the southern Cook Islands, carbon dated between 988 and 1155 AD. Over the next few centuries, sweet potato was spread to the extremes of the Polynesian Triangle: Easter Island, Hawaii and New Zealand. The prevailing theory for the lineages of sweet potato seen in Polynesia is the tripartite hypothesis developed in the 1950s and 1960s: that an original lineage was brought from the west coast of South America circa 1000 AD, and later superseded by two lineages introduced by Spanish galleons and Portuguese traders circa 1500 AD, the Central American lineage and the Caribbean lineage. Sweet potato became a major staple more so at the extremities of Polynesian culturesuch as in pre-European contact Hawaii, Easter Island and New Zealandthan in central Polynesia. During reintroduction, the sweet potato had become entirely absent from many central Polynesian islands (such as the Cook Islands, except Mangaia). However, it is unknown whether sweet potato was introduced through Polynesian canoes reaching South America, or by South American rafts visiting eastern Polynesian islands such as Rapa Nui. It is also possible that the plant was transferred without human contact, such as floating west across the ocean after being discarded from the cargo of a boat. Genetic, cultural or linguistic links between Polynesian and Indigenous American peoples such as the Chumash people of California, and the Zenú, a pre-Columbian culture of Colombia, have been hypothesised. Dutch linguists and specialists in Indigenous American languages Willem Adelaar and Pieter Muysken have suggested that the word for sweet potato is shared by Polynesian languages and languages of South America: Proto-Polynesian * (compare Rapa Nui , Hawaiian , Māori ) may be connected with Quechua and Aymara ~ . Adelaar and Muysken assert that the similarity in the word for sweet potato is proof of either incidental contact or sporadic contact between the Central Andes and Polynesia. Natural dispersal theory Some researchers suggest that sweet potatoes might have been present in Polynesia thousands of years before humans arrived there, arriving through avian dispersal or natural rafts. A 2018 genetic analysis of sweet potato collected from the Society Islands by Joseph Banks during the first voyage of James Cook in 1769 found this lineage diverged from South American varieties at least 111,500 years ago. The paper's authors also argued a natural dispersal was likely due to the presence of Ipomoea littoralis and Ipomoea tuboides in the Pacific and Asia — species which are related to American Ipomoea species that have similar seed morphology to sweet potatoes. is circa 1300 AD, where traces were found on traditional farmlands of Kohala, Hawaii. Sweet potato was considered to be less superior or valuable compared to another crop on the islands, taro, but it was commonly grown as it could flourish in less favourable growing conditions, and only took between three and six months to mature. Introduction to Easter Island statues (pictured). Sweet potato () was introduced to Easter Island (Rapa Nui) around 1200–1300 AD. The crop, due to its drought-resistant nature, replaced yam and taro, becoming the staple food on the island and grown on 1/10th of the total land on the island. Introduction to New Zealand Sweet potato (standard Māori: , Southern Māori dialects: Whakaotirangi experimented with ways to adapt growing kūmara in the colder climate, where they would develop an unpleasant sour taste when exposed to frost. Another history involves Marama, the junior wife of Hoturoa aboard the Tainui . She brought kūmara plants with her on her journey, but, when she arrived in Aotearoa, she was unfaithful to Hoturoa with a slave. As punishment, her kūmara plants turned into (Calystegia sepium)a traditional weed of kūmara farms. These traditional varieties came in a variety of colours (red, purple and white), shapes (some cylindrical) and differing rough/smooth textures. Kūmara does not seed in New Zealand due to the climate, meaning mutations in buds and careful cultivation of these plants likely led to the new varieties. A 1997 DNA analysis of these varieties confirmed that , and are all pre-European ( was not tested in the study). Other traditional cultivars outside of this list still exist, such as (a variety used for medicinal reasons to feed the elderly, babies and the unwell), (used to make ), , and . == Cultivation and use ==

Hawaii in the Hawaiian Islands Sweet potato on the Hawaiian islands was typically grown in (stony alluvial soils), and in arid/coastal areas. Since the early 1900s, pests were introduced to the islands which impacted farmers' abilities to grow sweet potato in Hawaii, such as Cylas formicarius (the sweet potato weevil) and Omphisa anastomosalis (the sweet potato vine borer). This is to the degree that farmers often refrain from planting sweet potato in the same location for two successive seasons. There are over 300 different names for traditional sweet potato varieties, with many names likely being synonyms for the same varieties. Lithic mulching (mixing rocks into fertile soil) was used by traditional Rapa Nui gardeners in order to retain moisture in sweet potato plantations. but planting time varied annually, depending on whether a cold winter was predicted during Matariki. The positions of the stars and when the kūmara leaves beginning to wither in autumn was a sign of , or the time to harvest the crop. were located on slopes or other places with good drainage. Kūmara were placed on shelves cut into the walls of the pit, and regularly checked for rot and rotated to ensure they stayed dry. were only packed on dry, sunny days. However, in the Bay of Plenty, kūmara pits were often used for single seasons and backfilled afterwards, due to the soft tephra soil. Social and religious significance The origins of the kūmara are also explained through Māori cosmological traditions. Rongo-māui (a star in the constellation of Lyra), the husband of Pani-Tinaku and the younger brother of Whānui (the star Vega). Pani-tinaku's nephews taunt Rongo-māui for not fishing and providing food for his family. Rongo-māui decides to ascend to the heavens, and asked Whānui for some kūmara from the heavens. He refused, but Rongo-māui hid and stole kūmara. Rongo-māui impregnates his wife, and Pani-tinaku gives birth to the earthly form of kūmara: , , , , , , , , and (all traditional varieties of kūmara). She is asked by Rongo-māui to cook the kūmara, in order to remove the heavenly from the food. Pani-tinaku's nephew Māui discovers the source for these kūmara, leading Pani-tinaku to flee to the underworld. Her youngest daughter, Hine-mata-iti, became the (the Polynesian rat who steals kūmara). Whānui discovers men gardening kūmara, and realises Rongo-māui stole the kūmara, and as retribution Whānui creates , and , who every year rain down as the hawk-moth caterpillars who attack the kūmara. Kūmara became associated with Rongo-mā-Tāne, During the Classic period of Māori history when agriculture became more common, the areas where kūmara could grow the most successfully were often associated with more pā and greater population density. Around 1819, an American whaler introduced a North American variety that was larger than traditional ones to Bay of Plenty Māori; this variety became known as the (American). The (vine) variety was introduced in the 1850s by a whaler who had come from Rarotonga. Chinese New Zealand gardeners Fay Gock and Joe Gock developed a disease-resistant variety of kūmara from a mutant form of at their market garden near the Pukaki Inlet in Māngere in the 1950s. The new variety, called Owairaka Red, was released commercially in 1954. The Gocks donated stock of the new variety, called Owairaka Red, to farms in New Zealand's main kūmara-growing area around Dargaville and Ruawai in the 1960s, saving the crop from loss to black rot. In the 21st century, most commercial kūmara is grown in Northland. The three main varieties are Owairaka Red, Toka Toka Gold and Beauregard (orange), with Owairaka Red being the most common. Toka Toka Gold was introduced by the Ministry of Agriculture and Fisheries in the 1960s from an unknown source, It is named after the Tokatoka peak near Dargaville. Two new varieties were released commercially by Plant & Food Research in 2014: Purple Dawn (purple skin and purple flesh), and Orange Sunset (purple skin with orange and purple flesh). ==See also==