Actinidia chinensis var. deliciosa

Description and ecology

Actinidia chinensis var. deliciosa is a vigorous, woody, twining vine or climbing shrub reaching 9 metres (30 ft).

The black-lyre leafroller moth ("Cnephasia" jactatana) is one of the few commercially significant pests of this plant.

Fungal pathogen Fusarium acuminatum has been found to be a ripe rot pathogen of Actinidia chinensis var. deliciosa in New Zealand.

Leaves

Its leaves are alternate, long-petioled, deciduous, oval to nearly circular, cordate at the base, and 7.5–12.5 cm (3–5 in) long. Young leaves are coated with red hairs; mature leaves are dark-green and hairless on the upper surface, and downy-white with prominent, light-colored veins beneath.

Flowers

The flowers are fragrant, dioecious or unisexual, borne singly or in threes in the leaf axils, are five- to six-petalled, white at first, changing to buff-yellow, 2.5–5 cm (1–2 in) broad, and both sexes have central tufts of many stamens, though those of the female flowers with no viable pollen. The flowers also lack nectar. Male and female flowers appear on different plants (dioecious), and both sexes have to be planted nearby for fruit set. Commercial orchards often use bees, although the more labor-intensive hand pollination is sometimes employed. Male flowers are gathered and processed to extract their pollen. This is then sprayed back onto the female flowers.

Fruits

The oblong fruits are up to 6.25 cm (2.5 in) long. The russet-brown skin of the fruits is densely covered with short, stiff, brown hairs. The flesh is firm until fully ripened; it is glistening, juicy and luscious. The color of the flesh is bright green, or sometimes yellow, brownish, or off-white, except for the white, succulent center from which radiates many fine, pale lines. The flavor is subacid to quite acid; the flavor is suggested to be similar to that of the gooseberry or strawberry.

Uses

Nutrition

Habitat

The taxon is native to central-southern China, found growing in mountain forests between 800–1,400 m (2,600–4,600 ft) above sea-level. The native range includes Chongqing, Gansu, Guangxi, Guizhou, Henan, Hubei, Hunan, Jiangxi, Shaanxi, Sichuan and Yunnan. Commercial cultivars first developed in New Zealand in the early 20th century from seeds sourced from China, and the plant is widely cultivated globally.

Wild Actinidia chinensis var. deliciosa tends to grow in inland and colder regions of southwestern China, while Actinidia chinensis var. chinensis tends to grow in south-eastern China in warmer, coastal provinces. The two varieties have overlapping ranges in southeastern Shaanxi, southwestern Henan, western Hubai and Hunan, where intermediate forms between the two varieties can be found.

History

Traditional Chinese names for the fruit include míhóutáo (Chinese: 獼猴桃; trans. "macaque peach"), húlítáo (Chinese: 狐狸桃; trans. "fox peach"), ténglí (Chinese: 藤梨; trans. "vine pear") and yángtáo (Chinese: 羊桃; trans. "sheep peach"), however no traditional distinction existed between Actinidia chinensis var. chinensis and Actinidia chinensis var. deliciosa, with míhóutáo and yángtáo being names used to refer to both varieties. The first known references to Actinidia plants in China date to the Tang dynasty in the 800s, when sporadic attempts were made to cultivate the fruit. This includes a Tang Dynasty poem written by Cen Shen, set in Shaanxi, which describes a plant growing above a well; suggesting that the plant may have been cultivated in gardens during this period. In the Běncǎo Yǎnyì (Chinese: 本草衍義), a 12th century medicinal compendium by Kou Zongshi, describes the plant as growing along pathways deep in the mountains of China, and notes that monkeys eat the fruit. Míhóutáo, including Actinidia chinensis var. deliciosa, were traditionally seen as a wild plant, and were often collected and sold at markets in central Chinese provinces.

In 1847, specimens of the plant were collected by the agent for the Royal Horticultural Society, London. Cultivation spread from China in the early 20th century when seeds were introduced to New Zealand by Mary Isabel Fraser, the principal of Whanganui Girls' College, who had been visiting mission schools in China. The seeds were planted in 1906 by a Wanganui nurseryman, Alexander Allison, with the vines first fruiting in 1910. People who tasted the fruit thought it had a gooseberry flavor, so began to call it the Chinese gooseberry, but being from the genus Actinidia, it is not related to the gooseberry family, Grossulariaceae.

Over time, numerous cultivars were developed by different growers, all originating from the same plant material that was brought to New Zealand by Fraser. In the early 1950s, Harold Mouat of the Fruit Research Division of the Department of Scientific and Industrial Research, classified and standardised many of the known important varieties, which included Abbott, Allison, Bruno, Gracie, Hayward, Montgomery and Elmwood. The familiar cultivar Actinidia chinensis var. deliciosa 'Hayward' was developed by Hayward Wright in Avondale, New Zealand, around 1924.

The first commercial orchards in New Zealand were established by Fred J. Walker near Whanganui in the early 1930s. From 1953, the fruit began to be exported to Britain and Australia, primarily Abbott cultivar and a minority of Bruno. In 1959, Turners and Growers renamed the fruit kiwifruit for the export market, and the global market for kiwifruit greatly grew in the 1960s and 1970s. Hayward was first exported in 1959 to the United States, and by the late 1960s, Hayward had become the dominant cultivar of kiwifruit exported from New Zealand, and by 1975 the sole export, until the late 1990s.

In 1957, the China National Botanical Garden sourced wild Actinidia chinensis var. deliciosa seeds from the Qinling mountains of Shaanxi, growing the first specimens in a botanical institute in China. By 1974, Chinese horticulturists began surveying wild germplasm of Actinidia species growing in mountainous central China, looking to develop cultivars which could compete with the popularity of New Zealand kiwifruit cultivars. While trial cultivars which were investigated and developed from the wild plants primarily focused on Actinidia chinensis var. deliciosa, these surveys of wild plants revealed the potential for sweet, yellow-fleshed Actinidia chinensis var. chinensis fruit to be developed as kiwifruit cultivars. These wild plant surveys led to the developments of many Chinese cultivars of Actinidia chinensis var. deliciosa, including Qinmei, Guichang and Miliang No. 1. The cultivars are a rare example of crop development, where plants only a few generations removed from wild plants became commercial crops.

By the 1970s, interest in kiwifruit production led to Hayward cultivar Actinidia chinensis var. deliciosa orchards to be planted across the world. In Italy between 600–800 ha (1,500–2,000 acres) of kiwifruit orchards were in operation, which by 1988 had grown to just under 10,000 ha (25,000 acres). In 2006 Italy was the leading producer of kiwifruit in the world, followed by New Zealand, Chile, France, Greece, Japan, and the United States. In 2016, global production of kiwifruit was 4.3 million metric tons (4.7 million short tons), led by China with 56% of the world total—followed by Italy and New Zealand being the other major producers. In China, it is grown mainly in the mountainous area upstream of the Yangtze River. It is also grown in other Chinese regions, including Sichuan.

By the late 1990s, New Zealand kiwifruit growers and kiwifruit exporters Zespri began to market a gold kiwifruit cultivar grown from Actinidia chinensis var. chinensis, as opposed to Actinidia chinensis var. deliciosa. By 2010, Actinidia chinensis sales make up a third of total kiwifruit sales in the New Zealand industry, reducing the dominance of Actinidia chinensis var. deliciosa. Similarly, gold and red varieties of Actinidia chinensis in China began to become more commercially available in the 1990s, and by 2002 50% of the total kiwifruit vines were of Actinidia chinensis varieties.

In 2010 and 2011, kiwifruit vines worldwide, in Italy, France, and New Zealand, suffered devastating attacks by a bacterial disease caused by Pseudomonas syringae pv. actinidiae, with some of the New Zealand attacks by the virulent strain PSA-V. The disease was noticed in Japan in the 1980s, and subsequently in northern Italy (1992) and South Korea.

Cultivars