jamun

Jamun (Syzygium cumini)

I. Introduction

The jamun is an important indigenous minor fruit of commercial value. It is also known as black plum, Indian black cherry, Ram jamun etc. in different parts of India. The tree is tall and handsome, evergreen, generally grown for shade and windbreak on roads and avenues.

The original home of jamun is India or the East Indies. It is also found in Thailand, Philippines, Madagascar and some other countries. The jamun has successfully been introduced into many other subtropical regions including Florida, California, Algeria, Israel, etc.

In India, the maximum number of jamun trees are found scattered throughout the tropical and subtropical regions. It also occurs in the lower range of the Himalayas up to an elevation of 1,300 meters and in the Kumaon hills up to 1,600 meters. It is widely grown in the larger parts of India from the Indo-Gangetic plains in the North to Tamil Nadu in the South. The data about its total acreage in India are not available.

II. Soil

The jamun tree can be grown on a wide range of soils. However, for high yield potential and good plant growth, deep loam and a well drained soil are needed. Such soils also retain sufficient soil moisture which is beneficial for optimum growth and good fruiting. Jamun can grow well under salinity and waterlogged conditions too. However, it is not economical to grow jamun on very heavy or light sandy soils.

III. Climate

Jarnun prefers to grow under tropical and subtropical climate. It is also found growing in lower ranges of the Himalayas up to an altitude of 1300 meters. The jamun requires dry weather at the time off towering and fruit setting. In subtropical areas, early rain is considered to be beneficial for ripening of fruits and proper development of its size, colour and taste.

A. Species

The genus Eugenia comprises of 1,000 species of evergreen trees and shrubs, most of them being tropical in origin. Some of the old world Eugenia species are now placed in the genus Syzygium. It belongs to the family Myrtaceae. Many of these species yield edible fruits and some of these are of ornamental and medicinal value. A wild species S.frniticosum with small edible fruits is grown as windbreaks. The large evergreen tree has small dark purple fruits with prominent elongated seeds. The fruit is an astringent (causing contraction of body tissue) even when ripe. A popular fruit is the rose apple or gulab-jamun (S.jambos). It is found in South India and West Bengal. The tree is very ornamental. The fruit is yellow in colour, generally insipid in taste and has high pectin content.

S. zeylanica, small tree with edible fruits, is found on the Western Ghats and S. malaccensis (Malay rose apple) found in South India. Another related fruit found in South India is Surinam cherry (S. uniflora). It is a small tree with blight red aromatic fruits. S. javanicum (water apple) is also found in South India and West Bengal. S.densiflora is used as rootstock in jamun (S. cumini) and is resistant to the attack of termites.

B. Varieties

There are no standard varieties of this fruit under cultivation. The common variety grown under North Indian conditions is "Ram Jarnun". It produces big sized, oblong fruits, deep purple or bluish-black in colour at full ripe stage. The pulp of the ripe fruit is purple pink and the fruit is juicy and sweet. The stone is small in size. The variety ripens in the month of June- July and it is very common both in rural as well as in urban markets.

Another late maturing variety bears small sized, slightly round fruits, deep purple or blackish in colour at full ripe stage. The colour of the pulp is purple, less juicy, the weight and sweetness of pulp is also less in comparison to that of 'Ram J arnun'. The stone present in this variety is comparatively large in size. Fruits ripen in the month of August.

At present, there are a number of seedling strains of jarnun in India which provide a good scope for selection of better varieties.

V. Propagation

The jamun is propagated both by seed and vegetative methods. Due to existence of polyembryony, it comes true to parent through seed. Though vegetative methods followed in most cases have attained some success, seed propagation is still preferred. However, seed propagation is not advisable as it results in late bearing.

The seeds have no dormancy. Fresh seeds can be sown. Germination takes place in about 10 to 15 days. Seedlings are ready for transplanting for the use as rootstock in the following spring (February to March) or monsoon i.e. August to September.

Propagation of jarnun is economical and convenient. Budding is practiced on one year old seedling stocks, having 10 to 14 mm thickness. The best time for budding is July to August in low rainfall areas. In the areas where rains start easily and are heavy, budding operations are attempted early in May-June. Shield, patch and forkert methods of budding have proved very successful. The possibility of better success has been reported in forkert method compared to shield or 'T' budding.

Jamun can also be propagated by inarching but it is not adopted commercially. In this method one year old seedlings raised in pots are inarched with mother jamun trees with the help of wooden stands during June-July.

About 60% air layers are obtained with 500 ppm IBA in lanolin paste, provided air layering is done in spring and not in the rainy season.

Better rooting through cutting is obtained in Jamun under intermittent mist. Semi-hardwood cuttings of both S. jambos and S.javanica, 20-25 cm long, taken from the spring flush and planted in July treated with 2000 ppm IBA (indole butyric acid) give better results.

VI. Planting

Jamun is an evergreen tree and can be planted both in spring i.e. February -March and the monsoon season i.e. July-August. The latter season is considered better as the trees planted in February- March have to pass through a very hot and dry period in May and June soon after planting and generally suffer from mortalities from the unfavourable weather conditions.

Prior to planting, the field is properly cleared and ploughed. Pits of 1 x 1 x 1 m size are dug at the distance of 10m both ways. Usually, work of digging of pits is completed before the onset of monsoon. The pit are filled with mixture of75% top soil and 25% well rotten farmyard manure or compost.

Another common way of growing jamun trees is to plant them as shade trees near the farm dwellings and wells. Here they provide a welcome shadow besides fruit.

VII. Fertilizer Application

The jamun trees are generally not manured. This is not because they do not require manuring or fail to respond to it but because they can stand a good deal of neglect. An annual dose of about 19 kg faI1nyard manure during the pre-beating period and 75 kg per tree bearing trees is considered.

Normally, seedling jamun trees start bearing at the age of 8 to 10 years while grafted or budded trees come into bearing in 6 to 7 years. On very rich soils, the trees have a tendency to put on more vegetative growth with the result that fruiting 

is delayed. When the trees show such a tendency, they should not be supplied with any manure and fertilizer and irrigation should be given sparingly and withheld in September-October and again in February-March.

This helps in fruit bud formation, blossoming and in fruit setting. Sometimes this may not prove effective and even more drastic treatments such as ringing and root pruning may have to be resorted to.. A fruit grower has, therefore, to be cautious in manuring and fertilizing jamun trees and hence, has to adjust the doses according to the growth and fruiting of trees.

VIII. Irrigation

In early stages, the jamun tree requires frequent irrigations but af1cr the trees gets established, the interval between irrigations can be greatly decreased. Young trees require 8 to 10 irrigations in a year. The mature trees require only about half the number, which should be applied during May and June when the fruit is ripening. During autumn and winter months, just an occasional irrigation may be applied when the soil is dry. This will also save the trees from the ill effects of frost in winter.

IX. Training and Pruning

Regular pruning in jamun is not required. However, in later years the dry twigs and crossed branches are removed. While training the plants, the framework of branches is allowed to develop above 60 to 100 cm from the ground level.

X. Insect Pests

Among the pests, white fly and leaf eating caterpillar cause great damage to the tree.

XI. Diseases

Among the diseases, the fungal disease anthracnose is notable .

XII. Flowering and Fruiting 

Flowers are borne in the axils of leaves on branchlets. In North Indian conditions, flowering starts in the first week of March and continues up to the end of April. The pollen fertility is higher in the beginning of the season. The maximum receptivity of stigma is one day after anthesis.

The jamun is a cross-pollinated and the pollination is done by honey bees, houseflies and wind. The maximum fruit set can be obtained by hand pollination when it is done after one day of anthesis. Thereafter, a sharp decline is observed in fruit set.

There is heavy drop of flowers and fruits within 3 to 4 weeks after blooming. Later natural fruit drop can be reduced with two sprays of GA3 60 ppm, one at full bloom and another 15 days after initial setting of fruits.

The pattern of growth and fruit development of jamun can be divided into three phases: the first phase from 15-52 days after fruit set having slow growth of fruit, the second phase from 52 to 58 days after fruit set having fast growth and the third and last phase from 58 to 60 days after fruit set having slow growth and very little addition in fruit weight.

XIII. Harvesting and Yield

The seedling jamun plants start bearing after 8 to 10 years of planting, while grafted ones bear after 6 to 7 years. However, commercial bearing starts after 8 to 10 years of planting and continues till the tree becomes 50 to 60 years old. The fruit ripens in the month of June -July. The main characteristic of ripe fruit at full size is deep purple or black colour. The fruit should be picked immediately when it is ripe, because it can not be retained on the tree in ripe stage. The ripe fruits are hand picked singly by climbing the tree with bags slung on the shoulder. Care should be taken to avoid all possible damage to fruits.

The average yield of fruits from a full grown seedling tree is about 80 to 100 kg and from a grafted one 60 to 70 kg per year.