Coconut Ecomuseum: The absent and desired coconut palms of New Zealand

Dr R. Bourdeix has traveled to New Zealand, worked in collaboration with New Zealand researchers, but he has not conducted research on the coconut palm in New Zealand.

There is a good reason for this: currently coconut palms mostly do not grow in New Zealand, as the climate is too cold for the varieties that have been tested so far. This is, moreover, one of the greatest regrets of the Maori populations. Some came long ago from warmer islands. They desperately tried, time and time again, to grow coconut trees in their new country.

This coconut (Cocos nucifera) on Raoul Island in the Kermadecs (part of New Zealand,

halfway between New Zealand mainland and Tonga). Photographed in 2004, it was brought by people.

Coconuts regularly wash up on Kermadec shores, but none have germinated.

Polynesians living in the Austral Islands (southern French Polynesia) also suffer greatly from scant coconut production. Because it gives any landscape a more ‘tropical’ look, many people attempt growing coconuts in non-tropical climates. Studies conducted in Florida shows that palms subjected to long periods of low temperature have soft, sunken, reddish areas on the trunk. These cold-damaged trunk areas are often invaded by secondary fungi and/or bacteria that cause trunk-rot and, several months later, the collapse of the entire crown. Fertilization may improve cold tolerance (Broschat 2010).

There is a significant potential market for cold-tolerant coconut varieties able to survive in countries with a temperate climate. Measurement of coldness on leaves by electrical conductivity have been develloped in China. (Caom et al. 2009). The first cold-hardiness studies in Hainan Island (China) indicated the existence of genetic variability. The semi-lethal temperatures ranged from 7.3 to 12.4 ℃ according to the cultivar. Local Hainan Tall coconut varieties had the strongest growth vigour but lower yield when compared with some introduced cultivars (He-shuai et al. 2009).

During much of the past 65 million years—the Tertiary period—New Zealand’s climate was significantly wanner than it is today. Reef corals flourished in northern waters and coconut palms grew over much of the country as mean annual temperatures hovered between 20 and 25°C. (Auckland’s mean annual temperature today is 15°.)

Evidence that a more subtropical New Zealand once supported coconuts takes the form of fossil coconuts which are periodically washed up on Coopers Beach, near Mangonui, after being eroded from lignite and sandstone reefs that lie just offshore. The nuts were first reported in the scientific literature in 1926, and have since been found not just in Northland but in inland sites in South Canterbury, Hawkes Bay and Gisborne. They are about the size of walnuts, but have been flattened by long burial in the marine sediments where they lodged so many million years ago. Carbonisation has rendered them black and as hard as bullets.

Coconut fossil (about 5 cm long)
found in New Zealand.

A species of Ecuadorian palm closed to coconut has been successfully propagated here by Auckland nurseryman and South American plant enthusiast Dick Endt. Its seeds bear a striking resemblance to the fossilised New Zealand coconuts dating from 10-45 million years ago. Dick Endt brought seeds of the Andean coconut, Parajubaea cocoides, back to New Zealand after a South American collecting foray in the mid 1970s (see “Lost Crops of the Incas,” New Zealand Geographic, Issue 10) and has been growing the palms at his Oratia nursery ever since.

References

Broschat, T.K. 2010. Fertilization improves cold tolerance in coconut palm. HortTechnology 20(5):852-855.

Caom H.X., Song, W.Y., Sun, C.X., Chen, S.T., Tang, L.X., Zhao, S.L. 2009. Measurement of coldness by electrical conductivity method in associated with the Logistic Equation in coconut seedlings. Journal

Fan, H.K., Bourdeix, R. & Ranasinghe, T.K.G. (2018). 2.5.7 Breeding for drought and other abiotic stresses - Chapter 2. Where we are today. In R. Bourdeix & A. Prades (Eds.), A Global Strategy for the Conservation and Use of Coconut Genetic Resources 2018-2028. (pp. 87-88). Montpellier, France. Bioversity International.

Guangxi Zhiwu/Guihaia 29(4):510-513.

He-shuai, L.I., Cheng-xu, S.U.N., Hong-xing, C.A.O., Huan-qi, Z.H.O.U., Hai-kuo, F.A.N. 2009. Preliminary studies on morphological characteristics and adaptability of different coconut varieties. Acta Agriculturae Jiangxi 11(15)