The Chinese Date or Chinese Jujube by Associate Professor Yan Guijun and A.R. Ferguson. Professor Guijun was previously with Mt Albert Research Centre in Auckland, NZ but is now Plant Production Systems Program Deputy Leader at University of Western Australia, Institute of Agriculture
Candied Chinese dates or ‘honey jujubes’ are commonly available in New Zealand supermarkets. They are the processed fruit of the Chinese date or jujube, Ziziphus zizyphus (L.) Karsten, which comes from China and has been cultivated there for more than 3,000 years. The Chinese date is one of the most important fruit crops in China, with an estimated 250,000 hectares of trees producing about 500,000 tonnes of fresh fruit annually. It is also cultivated in a number of other countries, particularly in areas with low rainfall. The fruit is eaten fresh or it is dried or processed.
The Genus Ziziphus
The Chinese date belongs to Ziziphus, a large genus in the family Rhamnaceae. The classification and nomenclature of the genus, like that of many other cultivated plants, is particularly confused. Linnaeus had placed the Chinese date in the genus Rhamnus, giving it the name R. zizyphus. Miller, in 1754, shifted the species to a new genus which he called Ziziphus, following the spelling first used by the pre-Linnaean botanist Tournefort, and this genus is still accepted today. Lamarck later adopted the spelling Zizyphus from the specific name as used by Linnaeus. This incorrect spelling has, until recently, been the more common; it seems clear, however, that the generic name should be spelled Ziziphus, since this was the first to be validly published. The generic name is probably based on the Greek name ‘zizyphon’ (which then became ‘zizyphus’ in classical Latin), although some authors derive it from ‘zizouf’, the Arabic for Z. lotus.
There are possibly 100 species in the genus Ziziphus, which is widespread through America, Africa, the Middle East, Europe, Asia, and Australia. A few species yield useful timber, but the main value of most is for their fruit. Two species are commercially important:
- Ziziphus mauritiana Lam. (Z. jujuba Lam., non Miller) This is grown mainly in India, and is therefore often called the Indian jujube, although it is also grown in southern China and other south Asian countries. The most common Indian name is ‘ber’.
- Ziziphus zizyphus (L.) Karsten (Rhamnus zizyphus L.; Z. jujuba Mill.;
- Z. sativa Gaertn.; Z. vulgaris Lam.) This is most widely grown in China and is often given the name Chinese date or Chinese jujube. Its Chinese name is ‘zao’ (pronounced ‘tsao’) and this is usually included as part of Chinese cuItivar names. In older European texts it may be called the ‘common jujube’.
In most horticultural literature the Chinese date is referred to as Zizyphus jujuba Mill., but correction of the spelling of the generic name to that used by Miller means that the combination Ziziphus zizyphus (adopting the specific epithet zizyphus first used for the species by Linnaeus) is legitimate since it is not tautonymous, i.e., the two names are technically different, as they are speIled differently. To add to the confusion, the epithet ‘jujuba’ has also been used for the Indian jujube, and that plant often appears under the binomial Zizyphus jujuba Lam. (Lamarck being the first author to use this combination for that plant).
Deciding on the appropriate name to use is a question for expert nomenclaturists (see A. Rehder in Journal of the Arnold Arboretum 3, 1922, p. 220), but it seems that Ziziphus zizyphus is the name that should be used for the Chinese date. This name is becoming more accepted – e.g., see the Supplement (1988) to the 8th edition of W.J. Bean, Trees and Shrubs Hardy in the British Isles – but much of the older literature appears muddled as, unless botanical authorities are cited, it is often very hard to determine whether it is the Chinese date or the Indian jujube that is being described.
The Indian jujube or ber (Z. mauritiana) is a spreading tree with dark green pubescent leaves and yellow or green fruit which can have a red blush. The flowers are borne in autumn, and the fruits mature in winter or early spring. The tree is normally evergreen, but the leaves are sometimes lost during the summer dry period, not in winter. The Indian jujube is sensitive to frost, and it is therefore restricted to more tropical areas.
The Chinese date or Chinese jujube (Z. zizyphus) tends to be a more upright tree with bright green, glabrous leaves. The tree is deciduous, losing its leaves in winter; it flowers in the spring, and the fruits mature in autumn. It is resistant to winter cold, and can grow in cool temperate areas such as Korea and the north of China.
Fruits of several other Ziziphus species are collected for eating. Fruits of Z. lotus (L.) Lam., which occurs naturally in the Mediterranean area, are edible if not particularly palatable; these have been identified as the fruits eaten by Homer’s Lotophagi (lotus-eaters) of The Odyssey, engendering a dreamy forgetfulness. Z. spina-christi (L.) Desf., a small prickly tree likewise found around the Mediterranean and through the Middle East, is also valued for its fruit. It has been identified as one of the plants most likely to have provided Christ’s crown of thorns. Z. spinosa (Bunge) Hu, closely related to Z. zizyphus, is a bad weed in parts of China. Its fruits are harvested from the wild because they are very rich in vitamin C (usually more than 1000 mg per 100 g fresh weight) and the seed kernels have medicinal properties.
The origin of the common name, ‘Chinese date’, is obvious. The fruit comes from China, and when dried or candied is often very reminiscent in size, shape, colour, and flavour of the fruit of the date palm (Phoenix dactylifera).
The older common name, jujube, is ultimately derived through French and Latin from the Greek ‘zizyphon’, likewise the origin of the generic name Ziziphus. From the Middle Ages onwards the name jujube was used for fruit of Ziziphus species growing in the countries bordering the Mediterranean. The fruit was used medicinally to soothe sore throats and as a remedy for coughs and, at one time, large quantities were imported into Britain from Provence and the Isles d’Hyres for this purpose. The name ‘jujube’ came to be used for lozenges made of gum arabic or gelatin and flavoured with, or in imitation of, this fruit. Eventually, by the middle of the nineteenth century, the connexion with the fruit was lost and ‘Jujube’ was used simply for any lozenge or soft sweet. This usage was still common twenty or thirty years ago.
Vegetative branching structure in Chinese date: permanent branch, secondary branch, fruiting mother branches, and fruiting branchlets (for clarity, the leaves and most fruiting branchlets are not shown; about one-quarter life-size); right, fruiting mother branch and fruiting branchlet with leaves and two fruits (most fruiting branchlets are not shown; about one-third life-size).
Types of branches produced from vegetative buds of Chinese date Location of bud Type of bud Vigour Type of branch formed permanent branch terminal strong permanent extension growth weak fruiting mother branch axillary main strong new permanent branch weak fruiting mother branch axillary lateral secondary branch secondary branch axillary main fruiting mother branch axillary lateral fruiting branchlet fruiting mother branch terminal very strong new permanent branch (only occasionally) normal extension growth of fruiting mother branch
axillary lateral fruiting branchlet
Origin and Domestication
Ziziphus zizyphus is thought to have originated in the middle Yellow River Valley (in the area included in the provinces of Shaanxi, Shanxi, Henan, Hebei, and Shangdong). This region contains most of the present plantings of Chinese date, and is also the centre of distribution of Z. spinosa, the species most closely related to Z. zizyphus and thought to be the wild progenitor of the cultivated clones of Z. zizyphus. Z. spinosa is distinguished from Z. zizyphus by being a smaller, more shrubby plant with more spines, and by its fruit being smaller and rounder, less sweet, and having a different texture. These differences are not always clear-cut, however, and there is considerable morphological variation within the two species. It is debatable whether Z. spinosa should be maintained as a distinct species, especially as it is not now possible to identify any plants of Z. zizyphus that are unequivocally of wild origin.
The process of domestication must have been long and gradual. Good-fruited plants would have been collected or propagated from the wild, and their spread would have been assisted by the tendency of most plants to sucker vigorously. Propagation techniques such as grafting were well-known to the early Chinese. Seed would have been planted, the good-fruited progeny kept and those with useless fruit discarded. Plants might have also escaped back into the wild. By the 6th Century, A.D. Jia Sixie in the agricultural encyclopedia Qi min yao shu (Essential Arts for the People), recorded 45 selections of jujube, and there are similar reports in subsequent texts. The American plant explorer Frank Meyer estimated that in the early years of this century there were probably 300 or 400 named clones of Chinese date, and today there are some 400-500 local cultivars. These cultivars can vary greatly in growth requirements and behaviour, and our account below is therefore a generalised description of the Chinese date; individual cultivars may differ in some respects.
The Chinese jujube grows into a shrub or a tall, handsome, upright tree 7-15 m in height. Young plants are often headed back to encourage the formation of a flatter, wider crown. Mature trees can resemble rather stiff silver birches; they can have an attractive weeping habit accentuated by the weight of the fruit pulling the branches towards the ground.
The trunk is dark grey with narrow furrows, but on younger branches the bark is smooth and reddish brown with a distinct bloom.
The patterns of branch growth in the Chinese date are extraordinarily complex, unlike those in any other fruiting plant, and as far as we know have not previously been described in English. Probably the most confusing feature is that in each leaf axil there are two types of bud: the main bud is a ‘normal’ bud, complete with bud scales, and can survive throughout winter; the lateral bud is smaller, lacks scales, and must continue growth the season that it is formed.
Different types of branches are produced by main buds and lateral buds, and the particular type of branch formed depends on the vigour of the bud, which in turn usually depends on its position on the plant. Fig. 1 and Table 1 summarise what is known.
(a) Permanent branches. These are strong shoots which come from strong main buds. Such shoots continue growing for many years, and develop into the permanent structure of the plant. Most axillary main buds along a strongly growing shoot remain dormant, but eventually the main shoot axis becomes less vigorous, the terminal bud becomes weaker, and extension growth is stopped by the formation of a terminal fruiting mother branch (see below). Axillary main buds further down the stem then break dormancy to produce strong shoots, which ultimately develop into new permanent branches. Occasionally, weak main buds along the shoot break dormancy and produce fruiting, mother branches.
(b) Secondary branches. These are produced from strong lateral buds along the current extension growth of permanent branches. Secondary branches typically zigzag, because the direction of branch growth changes at each node. A secondary branch reaches its maximum length in its first year of life. The terminal growing point withers and dies by the end of this first year and, in successive years, distal parts of the branch tend to wither back to a node and die. Secondary branches growing from the lower part of the current growth of a permanent branch usually abscise completely at the end of the first season, but unless removed by pruning, most other secondary branches survive for many years.
During the first year of life of a secondary branch, the lateral buds at each axil grow into fruiting branchlets but the main buds in the leaf axils remain dormant until the following year, when they can produce fruiting mother branches.
(c) Fruiting mother branches. These occasionally come from weak main buds on strong shoots (permanent branches), but most are produced by main buds of secondary branches. Fruiting mother branches look rather like conifer cones; they are very compressed shoots carrying not leaves but only a spiral of scales, in the axils of which are again main buds and lateral buds. Most of these main buds remain dormant, but the lateral buds give rise in the same season to fruiting branchlets. The following year the terminal bud of the fruiting mother branch again makes very limited growth, allowing for a new whorl of up to ten fruiting branchlets. This process can continue until the fruiting mother branches are about ten years old, when they finally become non-productive. Fruiting mother branches sometimes branch or, if nutritional conditions are right (e.g. the tree is pruned back heavily), the terminal bud can shoot out to form a permanent branch.
(d) Fruiting branchlets. These are all derived from weak lateral buds, on either a secondary branch or a fruiting mother branch. It is these fruiting branchlets that actually carry the flowers and fruits. The branchlets are typically about 10 to 20 cm long and carry between 6 and 13 leaves and generally 1 to 3 fruits. The fruiting branchlets are deciduous, and may therefore be mistaken by casual observers for compound leaves; their true nature, however, is revealed by the axillary flowers and fruits. Although fruiting branchlets die in their first winter, they sometimes do not actually drop until the following spring.
Pruning methods are determined by patterns of fruiting. The best fruits are produced on fruiting branchlets coming from fruiting mother branches carried on secondary branches from permanent branches less than ten years old. One-tenth of the oldest permanent branches should be removed each year during winter pruning. When a permanent branch is pruned, the secondary branch below the cut is also pruned back to encourage the dormant axillary main bud on the permanent branch to break dormancy and form a new main shoot, which will become a replacement permanent branch. The tree can be trained to a certain shape, with or without a central leader, by training the permanent branches.
Young plants are generally spiny. The spines are modified stipules, and therefore occur at the base of the leaf stalks. They are usually in pairs of unequal length; the longer spine is straight and up to 3.5 cm long, the shorter is viciously recurved. A few cultivars have two recurved spines of the same size. As trees age they tend to produce fewer spines, and any spines that are produced are shorter and thinner and are apt to shrivel and fall. A few cultivars appear to be spineless, but this is because their spines are shorter, thinner, and softer, and drop early.
The leaves are alternate, usually 3 to 8 cm long, narrow, ovate to oblong lanceolate, with three prominent veins running from the base. The leaves tend to be leathery, smooth and glossy-green above, somewhat paler below. Leaves turn bright yellow in autumn and fall early, usually before the fruiting branches themselves fall.
The abundant flowers are very small and insignificant, only about 0.5 cm in diameter. They occur on the fruiting branchlets in small axillary clusters of up to about half a dozen. The flowers have five sepals, five petals, five stamens opposite the petals, a bilocular ovary, and a bifurcating style. They are a not particularly appealing yellowish-green colour, but are very attractive to pollinating insects as they produce copious quantities of concentrated nectar from the nectariferous disk; they also have a sweet, fragrant scent.
Flower buds differentiate in spring. Chinese dates are therefore unlike most other temperate fruit trees such as apples, pears, or peaches in which flower buds have differentiated by the previous autumn.
Cultivars vary in the duration and intensity of flowering. Most plants have a very extended flowering season, but the period of fruit set is usually much more restricted. Several weeks may separate the first and last flowers within each axillary cluster. Furthermore, flowers in clusters near the base of a fruiting branchlet develop before those more distal on the branchlet. Early flowers often fail to set fruit because temperatures are too low; later flowers may not achieve the same size as those set earlier. Some clones will flower again if the fruits first set are lost through disease or damage. There are also clones which may flower several times during one growing season, and flowers, green (unripe) fruit, and red (ripe) fruit may be borne simultaneously on the same tree.
Although trees produce tremendous numbers of flowers, generally only 1 to 2 percent of the flowers actually set fruit. The reproductive biology of the Chinese date requires further study, but there seem to be several mechanisms to ensure cross-pollination.
• Most cultivars appear to be self-incompatible, although some can produce fruit from self-pollinated flowers or parthenocarpically. For home gardens, it is obviously an advantage to have trees that are self-compatible or that set fruit parthenocarpically. Most of the cultivars widely grown in the United States appear to be self-compatible, in that many isolated trees set heavy crops.
• The flowers are protandrous, that is, the anthers dehisce and the pollen is released as soon as the flowers open, but it is only after some hours that the stigmata become exposed through the recurving of the upper parts of the styles, and that nectar is released. This helps ensure cross pollination.
• Opening of the flowers on an individual plant appears to be synchronised, but clones can generally be divided into two classes, those with flowers opening early in the day and those that flower 6 to 12 hours later. The actual timing seems to depend on clone and on climatic conditions. Limited studies indicate that effective cross-pollination and fruit setting requires trees of opposite flowering types. Even this, however, is not always sufficient to guarantee good yields.
Introducing beehives into the orchard during flowering is a common practice to enhance fruit set. Girdling of the trees during or just prior to full bloom is a traditional way of increasing fruit set. In orchards in northern China, where it is often very dry during spring, farmers spray the flowers with fresh water to prevent premature desiccation and withering of the styles and stigmatic surfaces. An improved technique routinely used today is to spray with 10 to 20 ppm gibberellin solutions.
Fruit Growth and Harvest
Botanically, the fruit of the Chinese date is like a drupe with a succulent flesh (pericarp) surrounding the stony endocarp. A small collar of tissue at the stalk end is derived from the nectariferous disc. The sweet whitish flesh encloses a hard two-seeded stone. The skin is thin and smooth, becoming reddish brown and wrinkled on ripening.
In China the fruits mature during September and October (i.e., late summer to early autumn). The immature fruits have a green skin, and will not ripen if picked. Fruit picked later will continue to ripen after harvest. There are three main stages in fruit maturation and the use that is to be made of the fruit determines the stage at which it is harvested. (a) Skin whitish: at this stage fruits achieve their maximum size and the skin changes from green to greenish-white (milky green), whereas the flesh remains a pale green. Fruits at this stage of maturity can be candied.
(b) Crisp maturity: patches of the skin turn brown, so that the fruits appear spotted, and eventually the skin becomes reddish-brown; the flesh changes from green to white, but is still hard and crisp. Fruits for consumption fresh are best harvested when about half the skin has turned brown. Fruits tend to ripen unevenly
on the tree or after picking and, if they are to be eaten fresh, several harvests may be necessary. Experiments have shown that an alternative would be to harvest fruits when the skin becomes whitish and then ripen them by treatment with ethylene, if permitted.
(c) Full maturity: the skin changes to a dark red, the fruit becomes wrinkled, and the flesh is yellowish, soft, and spongy. The sugar content reaches a maximum. Fruit at this stage can be harvested for drying.
Fruit harvested at the earlier stages of maturity is usually picked by hand. Fruit that is to be dried can be left on the tree until it drops. Traditionally, Chinese dates were harvested by knocking the tree with a stick, followed by collection of fruit from the ground. Some growers in China have now adopted techniques in which trees are sprayed with ethylene-producing chemicals about two weeks before harvest. A large sheet is placed on the ground under the tree to catch fruits dislodged by vigorously shaking the trunk.
The skin of the Chinese date is relatively tough, and the fruit is easily handled or stored. Research in California has shown that it can be stored for several months at 10°C without significant loss of quality, but it is susceptible to chilling injury if held at temperatures below 2.2°C. It can also develop surface moulds if cool-stored. Dried fruit can be stored for up to a year.
Fruit Composition and Processing
The fresh fruit has a high sugar content, higher than in most other fruit, but only low titratable acidity. As a result the fruit, although pleasantly sweet, may seem insipid to some tastes, and the high dry matter content (25 to 35 percent fresh weight), mainly sugars, means that the fruit tends to be rather mealy. The dried fruit can have a remarkably high sugar content, as much as 70 to 80 percent fresh weight. Nutritionally, the single most valuable attribute of the fruit is its high concentration of vitamin C, between 400 and 1000 mg per 100 g fresh weight. This is much higher than in most other fruit: 80 to 100 times the concentrations in apples, 10 to 20 times that in citrus fruits, and 5 to 10 times that in ‘Hayward’ kiwifruit. The fruit also contains high concentrations of phenolics (responsible for the brown colour) and rutin, sometimes ascribed ‘vitamin P’ activity. In China, possibly half the fruit produced is dried, and roughly equal quantities of the remainder is eaten fresh or is processed. The red dates sometimes available in New Zealand shops are Chinese dates that have been allowed to dry after harvest, usually under cover. In China, red dates are eaten directly as such or they are incorporated into cakes or breads or other dishes. Honey dates are usually much larger fruits which have been cooked in a sugar solution and sometimes flavoured with honey. Traditionally, the surface of the entire fruit was scored with thin knives to allow the sugar syrup to penetrate the fruit, plumping it up and rendering it more succulent. The honey dates most readily available in New Zealand supermarkets have been pitted, and are a deep brown colour. Black dates are less common; they have been smoked. Small quantities of fruit are candied in syrup or preserved in spirits. Both the fruit and the seed have been used medicinally in China – the fruits are considered to be beneficial to body metabolism and the vascular system, and the seeds have sedative, properties. A variety of pharmacologically active compounds have been isolated from Ziziphus species.
The Chinese date is one of the toughest and most tolerant of all fruit trees, being able to withstand very poor growing conditions. It can take a remarkable amount of neglect without apparent harm, and can survive drought, extended periods of waterlogging, and temperature extremes as low as -30°C or as high as 50°C. It flowers at least a month after most other fruit trees, and production is therefore not usually affected by spring frosts. The toughness of the Chinese date should not, however, be exaggerated; it grows best in hot climates where, after adequate rain early in the growing season, the summer is long, hot, and dry, there is plenty of sunshine, and nights are warm. Drought may result in fruit drop, and the plant responds to appropriate irrigation with an increase in both growth and crop yield. It prefers sandy loams or lighter soils, but will grow on heavier clays and can tolerate saline, alkaline, or slightly acid soils. Vegetative growth and cropping are usually poor in areas with cool damp summers, and rain during the period of fruit maturation can cause the fruit of some cultivars to split. The adaptability of the Chinese date is shown by the range of conditions under which it grows in China. In the north, trees are found mainly in the mountains or hills, especially in stony areas or wasteland, but they are also planted on the coastal saline soils as shelter belts around narrow wheat or cotton fields. This type of dual cropping is effective because the Chinese date is slow to break dormancy in spring, and its late-developing canopy does not inhibit early growth of the crop. The trees also bear more fruit under these conditions than when growing in an orchard, probably because they get more sunshine and fresh air. Further south in China, trees can also be found growing on the banks between rice paddies. Comparatively few trees are planted out in regular orchards. Planting distances in such orchards depend on the cultivars grown, but would average within row spacings of about 4.5 to 6 m, with the rows 6 to 7.5 m apart. The Chinese date starts producing good crops at an early age. Most grafted trees bear some fruit in the season they were grafted, and in orchards of the cultivar ‘Li Zao’, yields can reach 23 tonnes per hectare only three seasons after grafting. Yields tend to be consistent, with little evidence of alternate (biennial) bearing. Such yields are exceptional, and neglected trees, as often found in many parts of China, would carry far less fruit. The Chinese date is one of the most important fruit crops in China. Apples, citrus, and pears are by far the most important, and then, in order of total production, come bananas, grapes, persimmons, pineapples, and the Chinese date. Most Chinese dates are produced in the north, in the provinces of Hebei, Shandong, Shanxi, Henan, and Shaanxi, with considerably smaller amounts from Gansu. Appreciable quantities are also produced further south in Hunan, Anhui, Hubei, and Guangxi.
Until recently the Chinese date was propagated primarily by root suckers, since most trees sucker very readily, especially if the ground is tilled. Now, however, more and more farmers graft or bud onto seedling rootstocks. Seed of Chinese date can be used, but fruit of the closely related Z. spinosa more often contains viable seed, and these are frequently used instead. The stones are collected in the autumn, stratified over winter, and sown in a seedbed in spring. Although the stone contains two embryos, usually only one seedling develops. The seedlings can be budded in early autumn or grafted the following spring. More than 95 percent of grafts take successfully if scionwood is coated with a thin layer of wax. Chinese dates have been successfully propagated by tissue culture, but attempts to root hardwood cuttings have generally failed.
There are 400 to 500 cultivars of Chinese date in China, but all are of local distribution and none is grown throughout the whole country. Cultivars selected for the north may grow well in provinces to the south but not crop satisfactorily; the converse is also true. The cultivar grown depends on the use made of the fruit. Smaller fruits are often dried, and these need to have a high sugar content when ripe. Fruits which are to be candied need not be sweet, but they should be large, and the flesh should be spongy so that it can absorb the sugar solution used in processing. Other cultivars have fruits which are best eaten fresh. There is enormous variation amongst the cultivars available. Fruits usually weigh 10 to 20 g (about the size of a cherry), but in some cultivars may weigh up to 50 g (the size of a smallish plum or apricot). Fruit shape is also variable, from mainly ovoid in many clones to ellipsoid, up to about 5 cm long. The fruits are sometimes flat or constricted, and one cultivar even has fruits shaped like a teapot. There are several stoneless cultivars with a kernel so soft that it is almost imperceptible when eaten. A particularly promising cultivar is ‘Zanhuang Dao Zao’, a triploid from Hebei – the only known triploid Chinese date – which has good-quality, large fruits weighing more than 25 g, and which is very tolerant of drought or barren soil. Several cultivars also have ornamental potential. One, ‘Tai Li Hong’ (‘Embryonic Red’), has fruits which are purple-red throughout most of the growing season; others, e.g., ‘Long Zhao Zao’ (‘Dragon’s Claw’) have peculiarly gnarled and twisted or falling branches. A national germplasm repository for Chinese date has recently been established in Shanxi Province.
The Chinese Date outside China
The Chinese date has been cultivated longest in China, its probable place of origin, but over the last several thousand years it has spread into neighbouring countries such as Korea, Vietnam, and Burma and areas formerly in Soviet Asia. By the beginning of the Christian era, it had been taken to Syria, probably along the Silk Road, the main pathway of communication and trade between China and the countries of the Mediterranean. According to Pliny, the Chinese date was then introduced from Syria to Italy and Sicily during the reign of the Emperor Augustus. Plantings subsequently spread throughout southern Europe and northern Africa. The olive-sized fruits from seedling trees are still sold in southern Europe today. In Provence, three main cultivars are grown, one with large yellow fruits which has been there for centuries and two Chinese cultivars. Similarly in North Africa the main cultivars now grown are of Chinese origin, including ‘Lang’ (‘Lang Zao’) and ‘Li’ (‘Li Zao’). The Chinese date was first introduced to the United States of America from
Europe in 1837, and separate introductions were made from Europe to California and neighbouring states by 1876. These were mainly seedlings producing only small, poor-quality fruit. During the period 1908 to 1914 the plant explorer, Frank Meyer, sent more than 80 of the best cultivars of Chinese date from China to the United States. Notable amongst the cultivars introduced were ‘Li’ and ‘Lang’. These introductions were the source of much of the material planted in different countries throughout the world. The Chinese date adapted well to conditions in the United States, particularly drier areas, and has naturalised along the Gulf Coast from Alabama to Louisiana. A few small orchards have been established, but the Chinese date is still largely limited to home backyards in the southeast and southwest, largely because of unfamiliarity with the fruit and insufficient information on how to grow the plant. Orchardists in California get good prices for their fresh fruit, up to US.$3.00 per kg retail; their best customers are Vietnamese immigrants. In Australia, the potential of the Chinese date as a fruit tree for semi-arid regions is being assessed. Cultivars have been imported from both the United States and Italy. Plants are occasionally seen in gardens in New Zealand. Since the Chinese date prefers cold winters and hot, dry summers and dislikes high humidity, suitable growing areas are probably restricted to the east coast of the North and South Islands. The potential for commercial orchards is probably limited, the fruit being supplied mainly as confectionary or to health food shops. The increasing numbers of recent immigrants from Taiwan and Hong Kong could also provide a worthwhile market for the fresh fruit. For home gardens, however, ornamental cultivars or cultivars that are parthenocarpic could be attractive but undemanding trees for drier districts. S.N. Dawes, then of Fruit Research Division, DSIR, imported seed and also scionwood of the cultivar ‘Li’ about 30 years ago. The late Dr Don McKenzie also imported some material. A few trees were planted at the Hort Research orchards at Havelock North and Clyde, and have made reasonable growth. However, the trees at Clyde flower very late in the season (January) and do not seem to have borne fruit. Trees have also been planted in Marlborough. It would be worth testing other cultivars of Chinese date in New Zealand, preferably using material from countries other than China; in its homeland, the Chinese date is attacked by a number of pests and diseases.
Acknowledgements We thank Roger Meyer, 16531 Mt Shelly Circle, Fountain Valley, California 92708-2440 for his detailed comments on the manuscript and for allowing us to publish some of his photographs. Roger’s nursery sells many different Chinese date cultivars, including some originally introduced into the United States by Frank Meyer. We also thank W.R. Sykes (Landcare Research) for helping confirm the botanical nomenclature.
Sheryl: Roger also marcotts his Jujube. His 267 page Jujube book for US$30 plus US$15.00 postage. He co-wrote it with Robert Chambers. Email Roger at: email@example.com
Phil Ciminata in WA imported material from California and China. Ben Waddelow from South Australia also imported several varieties from Roger Meyer in California. Di Tod has a plantation in Koorooman Vict. Jim Dawson in Gidgegannup WA sells plants. There is an unknown person also selling plants on the internet in Melbourne. Dennis Ting relates his experiences from Melbourne over the last ten years growing this fruit and the trees are between two and three metres tall now: “My two trees were the varieties “Li” and “Ta Jan” which were planted one year apart. They came as one node grafts only with no leader or shoot. For the first two or three years they only put out a cluster of fruiting canes from the node. After this a strong upright shoot grew from this bud and the structure of the tree finally began! The Jujube is unusual in that the fruiting canes are deciduous and die back and drop off in winter so you are only left with the permanent structure of the tree. Each year the number of canes arising from the nodes increases and hence your cropping potential. The flowers form at each leaf node from November to February. The fruit ripen here from late February to mid April and go from green to lime, brown spotted to finally totally brown the fruit tasted like a small crisp apple in texture and can be dried when the flesh goes yellow and spongy and the skin wrinkles like a normal dried date. I also know two other people growing Jujubes here in Melbourne and we all agree that “Li” is the better variety with more consistent bearing and heavier yields while “Ta Jan” bears a bit more irregularly and has lighter yields. The other good thing is the trees bear from an early age too.