1554

2: Edible fruits and nuts

Ziziphus mauritiana Lamk

Encycl. Method. Bot. 3: 319 (1789).

RHAMNACEAE

2n = 48 (tetraploid), 60 (pentaploid), 96 (octaploid)

Rhamnus jujuba L. (1753), Ziziphus jujuba (L.) Gaertn. (1788) non Miller (1768), often cited as Lamk (1789).

Indian jujube (En). Jujubier (Fr). Indonesia: widara, dara, bidara. Malaysia: bidara, jujub, epal siam. Philippines: manzanitas (Tagalog). Burma: zee-pen. Cambodia: putrea. Laos: than. Thailand: phutsaa (central), ma tan (northern). Vietnam: tao, tao nhuc.

The Indian jujube probably originates in the Middle East or the Indian subcontinent. It is cultivated on a small scale throughout the tropics and subtropics, also in South-East Asia, but is commercially important in India and China only. It often escapes from cultivation and becomes naturalized.

The fruit of good cultivars is either eaten fresh, crushed to make a refreshing drink, or it is preserved by drying or candying. In South-East Asia unripe fruit is eaten with salt. Reportedly the fruit is also boiled to produce syrup. Young leaves are cooked as a vegetable in Indonesia; the leaves also serve as fodder.
In India the tree is one of several species used to rear lac insects; twigs encrusted with the secretions are harvested to prepare shellac. Bark and fruit yield a dye. The wood is reddish, fine-textured, hard and durable and used for turnery, household utensils and implements.
The fruits, seeds, leaves, bark and roots all have medicinal applications, in particular to aid digestion and to poultice wounds. In Java, for instance, the bark is taken as a cure for indigestion while in Malaysia the poultice of the bark may be applied against stomachache.

Statistical data are available only from India where the jujube is one of the more common fruit trees cultivated practically all over the country on an estimated 22 000 ha. In South-East Asia the fruit is probably most common in Thailand where, in season, several cultivars are found in the markets. Elsewhere it is mainly grown in areas with a clear dry season: in Malaysia near the Thai border, in eastern Java and in Luzon Island (the Philippines).

Analyses made in India (first figure) and in Thailand (inside brackets) give the composition per 100 g edible portion: water 86 (71.5) g, protein 0.8 (0.7) g, fat 0.1 (1.7) g, carbohydrates 12.8 (23.7) g, Ca 30 (30) mg, P 30 (30) mg, vitamin A 70 (50) IU, vitamin C 50—150 (23) mg. The energy value amounts to 230 (470) kJ per 100 g.

Tree or bushy shrub, up to ca. 15 m tall, erect or spreading with drooping branches; twigs zigzag, tomentose; stipules spinous, solitary and straight (5—7 mm) or in dimorphic pairs, the second shorter and recurved, spines sometimes absent; trees evergreen or semi-deciduous. Leaves alternate, simple, elliptic-ovate to oblong-elliptic, 2—9 cm x 1.5—5 cm, slightly crenate or entire, glossy and glabrous above, densely white-tomentose beneath, with 3 conspicuous longitudinal veins; petiole 8—15 mm long. Inflorescences axillary cymes, 1—2 cm long, with 7—20 flowers, peduncles 2—3 mm long; flowers 2—3 mm across, yellowish, faintly fragrant; pedicels 3—8 mm long; calyx with 5 deltoid lobes, hairy outside, glabrous within; petals 5, subspathulate, concave, reflexed; stamens 5; ovary 2-celled, styles bifid, disk 10-lobed or grooved. Fruit a drupe, globose to ovoid, up to 6 cm x 4 cm in cultivation, usually much smaller when wild, skin smooth or rough, glossy, thin but tough, yellowish to reddish or blackish; flesh white, crisp, juicy, subacid to sweet, becoming mealy in fully ripe fruits. Seed in a tubercled and irregularly furrowed stone, containing 1—2 elliptic brown kernels.

Seeds remain viable for a few years although germination declines with age. Germination takes about 4 weeks, but if the kernels are extracted from the stone, they may germinate in one week. The seedling forms a strong taproot and grows rapidly, forming long straggly twigs. The tree is precocious, flowering in the leaf axils of the current season's shoots and — to a lesser extent — mature twigs.
Whereas some cultivars attain anthesis early in the morning, others do so later in the day. Moreover, the flowers are protandrous. Hence, fruit set depends on cross-pollination by insects (including bees) attracted by the fragrance and nectar. Cross-incompatibility occurs and cultivars have to be matched for good fruit set; some cultivars produce good crops parthenocarpically. Fruit development takes 4 months in early cultivars to 6 months in late cultivars.
In India the trees shed their leaves in the course of the season following fruit ripening, and then go dormant. Growth is resumed just before the onset of the rainy season and is largely limited to one extended flush. In South-East Asia flowering takes place concurrently with shoot growth in the wet season, and the fruit matures during the dry season. Flowering continues for several months, but fruits usually set during part of that period only, perhaps because compatible pollen is not always available.

Ziziphus Miller is often also written as Zizyphus. The fruit of almost all Ziziphus species is edible. Indian jujube is often confused with the Chinese jujube, Ziziphus jujuba Miller (synonym Ziziphus vulgaris Lamk), a species of ancient culture in northern China and widely grown in mild-temperate, rather dry areas of both hemispheres.
In Pakistan two botanical varieties of Indian jujube are distinguished: var. mauritiana (cultivated, medium-sized tree, leaves 6—9 cm long, fruit ovoid, 2.5—3.5 cm long) and var. spontanea (Edgew.) R.R. Stewart ex Qaiser & Nazim (wild large shrub, leaves 2—3 cm long, fruit globose, 1—1.5 cm diameter).
In India about 125 cultivars are grown, the choice depending partly on regional differences in climate and whether the orchard is rainfed or irrigated. In South-East Asia some cultivars may be of Indian origin, as suggested for instance by the names 'Bombay' and 'Calcutta' for Thai cultivars; other Thai cultivars are 'Rian Thong Phiset', 'Phiset Wan' and 'Thuai Thong'. Indian cultivars from the more arid northern states may be less adaptable in South-East Asia than those from the monsoon climate of the Deccan Plateau, e.g. 'Dodhia' (not attacked by fruit flies or fruit borers) and 'Banarsi'.

Indian jujube is a hardy tree which copes with extreme temperatures and thrives under rather dry conditions. Fruit quality is best under hot, sunny and dry conditions, but there should be a rainy season to support extension growth and flowering, ideally leaving enough residual soil moisture to carry the fruit to maturity. If harsh weather persists, the tree goes dormant. In its natural habitat the annual rainfall ranges from 125 mm to over 2000 mm, and studies in India show that some cultivars do fairly well with as little as 300—450 mm per year. The maximum temperature is given as 37—48°C and the minimum temperature as 7—13°C, but the trees may withstand light frosts. The altitudinal range goes from sea level to about 1000 m elevation.
Fairly light, deep soils are preferred, but the trees can grow on marginal land, alkaline, saline or slightly acid, light or heavy, drought-susceptible or occasionally waterlogged.

Although most existing trees have been raised from seed, vegetative propagation is increasingly practised as it is the only way to obtain trees which are true to type. Trees can be propagated on their own roots through cuttings or air layers, but budding or grafting is more common. Root suckers or seeds — often from wild Ziziphus species where these are readily available — are used to raise the rootstocks. The growing season is the time to bud: T-budding or ring budding are the recommended methods. Whip grafting is the recommended grafting method, but suckle grafting — a form of inarching — is preferred in Thailand.
In South-East Asia a spacing of 5—6 m apart is considered necessary, but in India 8—9 m square is common. Since disturbance of the taproot may be fatal, it is sometimes recommended to sow the seed and then bud or graft the seedling in situ. An alternative may be to plant the seed in shallow wiremesh baskets, raised off the ground, to force early development of lateral roots under the favourable conditions prevailing in the nursery. Because of compatibility problems it is recommended to plant a mixture of 3 cultivars.

Young trees are tied to a stake and pruned to obtain 4 or 5 well-spaced scaffold branches, which quickly fill the allotted space; intercrops can be grown only for 2 or 3 years. Clonal trees bear in the second year and may produce a sizeable crop in the fourth year. The trees flower mainly on the new shoots and are pruned to ensure that these shoots have adequate vigour for good fruit size and quality. In India the trees bear heavily and regularly; therefore the fruiting wood ages quickly and needs to be replaced gradually; this also prevents overcrowding and promotes shoot vigour. The best time to prune is after harvest, particularly if, as in India, the trees shed their leaves.
In India growers apply manure when growth is resumed, and nitrogen fertilizer as a topdressing during fruit set. The growing fruit should not suffer water shortage, and although the trees root to a great depth, the orchard is clean-cultivated and supplementary irrigation is applied when the monsoon rains are inadequate.

Fruit flies are a major cause of crop losses, the insects unfortunately having a preference for the same cultivars as humans. Damage by fruit-borers, leaf-eating caterpillars, weevils, leafhoppers and mealy bugs has also been reported. Powdery mildew can be so serious that leaves and fruitlets drop, but it can be adequately controlled. Lesser diseases are brown rot and leaf-spot.

The fruits do not all ripen at once, so 4 or more pickings are needed to clear the crop. Fruit picked unripe becomes acrid instead of ripe, and overripe fruit loses its attractive colour and crisp texture. In Thailand fruit is in the market from August to February; in the Philippines the season is from November to February.

No yield records are available in South-East Asia. For the widely-spaced trees in India, yields of 100 kg per tree for early and 200 kg for late cultivars are considered good.

The fruit is not vulnerable; it handles well and shelf life is about one week. Cold storage can extend the supply season by one month or more.

There is a wide range of variation among seedling trees. Cultivars have resulted from selection and clonal propagation; breeding is complicated by incompatibility, which is presumably aggravated by the differing ploidy levels. Extensive cultivar collections are evaluated in northern India, at research stations of the Haryana Agricultural University, Hissar and the Punjab Agricultural University, Ludhiana, but so far germplasm is not being tested in South-East Asia.

Indian jujube is common in the drier parts of South-East Asia; the fruits are well-liked because of their exceptionally firm and crisp flesh. The crop responds to selection and care by the grower. Hitherto studies of the crop have been largely limited to India, where ecological conditions are rather different. A much better understanding of growth, flowering and fruiting in South-East Asia is necessary to assess the potential for this crop in the region.

Burkill, I.H., 1966. A dictionary of the economic products of the Malay Peninsula. 2nd edition. Vol. 2. Ministry of Agriculture and Co-operatives, Kuala Lumpur. pp. 2348—2349.
Corner, E.J.H., 1988. Wayside trees of Malaya. 3rd edition. Vol. 2. The Malayan Nature Society, Kuala Lumpur. p. 610.
Latiff, A., 1989. Rhamnaceae. In: Tree Flora of Malaya. Vol. 4. p. 300.
Morton, J.F., 1987. Fruits of warm climates. Creative Resource Systems, Inc., Winterville, N.C. pp. 272—275.
Triratwattana, M., Nilsamranchit, S. & Wanichkul, K., 1982. Phuttra [Indian jujube]. Warasarn phuetsuan 17(1): 43—56.
Yamdagni, R., 1985. Ber [Indian jujube]. In: Bose, T.K. (Editor): Fruits of India: tropical and subtropical. Naya Prokash, Calcutta. pp. 520—536.

A.M. Latiff

Latiff, A.M., 1991. Ziziphus mauritiana Lamk. In: Verheij, E.W.M. and Coronel, R.E. (Editors): Plant Resources of South-East Asia No 2: Edible fruits and nuts. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea