Ziziphus mauritiana is a spiny, evergreen bushy shrub 1.5 to 2 m tall, to a tree 10 to 12 m tall with a trunk diameter of about 30 cm. It may be erect or wide-spreading, with gracefully drooping thorny branches, zigzag branchlets, thornless or set with short, sharp straight or hooked spines. The Bark is dark grey or dull black, irregularly fissured. The leaves are variable, alternate, in 2 rows, oblong-elliptic, 2.5-6 x 1.5-5 cm, with tip rounded or slightly notched base; finely wavy-toothed on edges, shiny green and hairless above; dense, whitish, soft hairs underneath. The leaves are readily eaten by camels, cattle and goats and are considered nutritious.
Ziziphus mauritiana inflorescence axillary cymes, 1-2 cm long, with 7-20 flowers; peduncles 2-3 mm long; flowers 2-3 mm across, greenish-yellow, faintly fragrant; pedicels 3-8 mm long; calyx with 5 deltoid lobes, hairy outside, glabrous within; petals 5, subspathulate, concave, reflexed. The flowers are protandrous. Some cultivars attain anthesis early in the morning, and others do so later in the day. Hence, fruit set depends on cross-pollination by insects attracted by the fragrance and nectar. The pollen is thick and heavy. It is not airborne but is transferred from flower to flower by honeybees. The flowers are pollinated also by ants and other insects, and in the wild state the trees do not set fruits by self-pollination. Some cultivars produce good crops parthenocarpically.
Ziziphus mauritiana is a quick growing tree that starts producing fruits within three years. The fruit is of variable shape and size. It can be oval, obovate, oblong or round, and that can be 2.5-6.25 cm long, depending on the variety. The flesh is white and crisp. When slightly underipe, this fruit is a bit juicy and has a pleasant aroma. The fruit's skin is smooth, glossy, thin but tight. Fruits are first green, turning yellow as they ripen. The fully mature fruit is entirely red, soft, juicy with wrinkled skin and has pleasant aroma. The ripe fruit is sweet and sour in taste. Both flesh texture and taste are reminiscent of apples. When under ripe the flesh is white and crispy, acid to subacid to sweet in taste. Fully ripe fruits are less crisp and somewhat mealy; overripe fruits are wrinkled, the flesh buff-colored, soft, spongy and musky. At first the aroma is apple like and pleasant but it becomes peculiarly musky when overripe. There is a single, hard, oval or oblate, rough central stone which contains 2 elliptic, brown seeds, 6mm long.
Ziziphus mauritiana tree has a high tolerance to both water-logging and drought and can grow where annual rainfall ranges from 125 to 2,225 mm, but is more widespread in areas with an annual rainfall of 300 to 500 mm. In China and India, wild trees are found up to an elevation of 1,650 m. The minimum temperature for survival is 7º-13º and the maximum temperature is 50°C. This species flourishes in alkaline soils with a pH as high as 9.2. However, deep sandy loam to loamy soils with neutral or slightly alkaline pH are considered optimum for growth. In India, the tree grows best on sandy loam, neutral or slightly alkaline.
Ziziphus mauritiana propagates by seeds, seedlings, direct sowing, root suckers as well as by cuttings. The seeds are spread by birds, native animals and humans who eat the fruits and disperse the seeds. Seed pretreatment is beneficial. Storage of the seed for 4 months to let it after-ripen improves germination. The hard stone restricts germination and cracking the shell or extraction of seeds hastens germination. Without pretreatment the seeds normally germinate within six weeks whereas extracted seeds only need one week to germinate. Studies indicate that germination can be improved by soaking seeds in sulfuric acid. Germination time can also be shortened to 7 days by carefully cracking the endocarp. Its seedlings do not tolerate transplanting, therefore the best alternatives are to sow the seeds directly in the field or to use polythene tubes placed in the nursery bed. Seedlings are ready for budding in 3 to 4 months.
In India, there are 90 or more cultivars depending on the habit of the tree, leaf shape, fruit form, size, color, flavor, keeping quality, and fruiting season. Seedling trees bear 5,000 to 10,000 small fruits per year. Superior grafted trees may yield as many as 30,000 fruits. The best cultivar fruits normally averaging 66 to the kg, yields 77 kg annually. The crop is grown in India, Pakistan, Bangladesh and parts of Africa.
It has been traditional to apply manure and ash as fertilizer up to the 5th year. More advanced farmers utilize only commercial fertilizer (NPK). Zinc and boron sprays are sometimes applied to enhance glossiness of the fruits. Irrigation is highly beneficial. Water-stress will cause immature fruit drop. In India, water has been applied as many as 35 times during the winter months. Wild varieties of Ziziphus are usually used as the root-stock. The most common being Ziziphus rotundifolia in India and Ziziphus spina-christi in Africa.
This fruit tree was introduced to Israel by Y. Mizrahi, A. Nerd and J.A. Aronson from Ben-Gurion University. The following varieties were tested in various sites in the Negev – 'Umran' which bears large, sweet, golden-yellow fruits turning chocolate-brown when fully ripe of good keeping and shipping quality, 'Gola' which bears medium to large, golden-yellow, juicy fruits of good flavor, 'Kaithli' which bears medium size soft and sweet fruits, and 'Seo ber' ('Seb') which bears medium to large, moderately juicy fruits, that are astringent unless peeled or not eaten until light-brown, when it is very sweet and excellent. Two more lines Q-29 and B5/4 were selected locally from seedlings. A semi-commercial plantation was planted by a farmer in 1993, in Neot Hakiar at the southern tip of the Dead Sea, and the first yield was sold in 1995 in the local market, mainly to immigrants from India who were familiar with the fruit.
The fruit is eaten raw, stewed, or pickled or used in beverages. It is a good source of carotene, vitamins A and C, and fatty oils. Slightly underripe fruits are candied by a process of pricking, immersing in a salt solution. Ripe fruits are preserved by sun-drying and a powder is prepared for out-of-season purposes. It contains 20 to 30% sugar, up to 2.5% protein.
This species is indigenous from Afghanistan through north India to southern China, Malaysia, and Queensland in Australia. The use of Ziziphus mauritiana in India can be traced back as early as 1000 BC. It is now widely distributed and has become naturalized in tropical Africa, Burma, Barbados, Jamaica, Guadeloupe, Iran, Martinique, Sri Lanka, Syria and parts of the Mediterranean. It is commercially important in India and China only. It can form dense stands and become invasive in some areas, including Fiji and Australia and has become a serious environmental weed in Northern Australia
Ziziphus mauritiana yields a medium-weight to heavy hardwood with a density of 535-1080 kg/m³. Heartwood is buff-coloured, pale red or brown to dark brown, sometimes banded or with dark streaks, not sharply demarcated from pale brown sapwood; grain straight, occasionally wavy; texture fine to coarse; wood fairly lustrous. It seasons well but may split slightly during seasoning; easy to work and takes a high finish. It is hard and strong. The wood is used for general construction, furniture and cabinet work, tool handles, agricultural implements, tent pegs, golf clubs, gun stocks, sandals, yokes, harrows, toys, turnery, household utensils, bowling pins, baseball bats, and packaging. It is also suitable for the production of veneer and plywood.
The branches are used as framework in house construction. This species is used as firewood in many areas and the wood makes good charcoal with a heat content of almost 4,900 kcal per kg. In tropical Africa, the flexible branches are wrapped as retaining bands around conical thatched roofs of huts, and are twined together to form thorny corral walls to retain livestock. The bark, including the root bark, has served in tanning; when pounded and mashed in water, it yields brown and grey or reddish dyes.
The fatty-acid methyl ester of Ziziphus mauritiana seed oil meets all of the major biodiesel requirements in the USA (ASTM D 6751-02, ASTM PS 121-99), Germany (DIN V 51606) and European Union (EN 14214). The average oil yield is 4.95 kg oil/tree or 1371 kg oil/hectare. Ziziphus mauritiana trees are a host for the lac insect, Kerria lacca, which sucks the juice from the leaves and encrusts them with an orange-red resinous substance. Long ago, the lac was used for dyeing, but now the purified resin is the shellac that is used in fine lacquer work and to produce sealing wax and varnish.
This species was first described by the French biologist J.B. Lamarck, from a specimen in a botanical garden in Paris, but he did not state why he decided to name it after Mauritius Island.
Written by Amram Eshel (with some information provided by N. Tel-Zur & O. Reisman-Berman)