JACKFRUIT (Artocarpus heterophyllus)
Jackfruit tree is a species of the mulberry family (Moraceae). It originated in Asia, but it is now widespread in other parts of the tropics. It is an evergreen tree, 10-15 m tall with dark green oval shaped leaves. All parts of the tree contain sticky white latex. It has a life span of 60-70 years. Jackfruit is the largest tree-borne fruit in the world, reaching 36 kg in weight and up to 90 cm long and 50 cm in diameter. It is widely cultivated along the Kenyan coast.
It is low in saturated fat, cholesterol and sodium and high in Vitamin C, Manganese and potassium. It also contains iron, vitamins B1 (thiamine), B2 (riboflavin) and niacin.
Jackfruit is adapted to humid tropical lowlands at altitude 0-1200m asl.
The tree requires evenly distributed rainfall of 850 -1500mm. It does not tolerate frequent drought.
The jackfruit flourishes in rich, deep well drained soil of medium or open texture. Planting on top of an old compost heap would be ideal. The tree does not tolerate water logging.
Dig planting holes of 1 x 1 x 1 m size. Separate top soil and sub-soil This should be done at least 4 weeks before planting, keep it open for 2 weeks, and then add to each hole a mixture of top, soil and 20 kg organic matter and water liberally to help settle the soil in the hole.
Jack fruit can be planted directly using seeds or indirectly by seedlings raised in the nursery. The seedlings can also be budded or grafted.
Optimal germination can be obtained by using fresh and cleaned seed. Dried seeds stored for more than one month will not germinate. Germination takes 3 to 8 weeks.
For best germination lay the seed either flat or with scar from the point of attachment facing down.
Dig a hole and sow a few fresh seed at the site. If a large orchard is to be established, it may be better to raise seedlings in the nursery.
Sow seeds in line, 30 cm apart, in a well-prepared nursery bed or in polythene bags filled with soil (70%) mixed with organic matter 30%. Plant seeds 2-3 cm deep.
Seedbed should be shaded partially to protect emerging seedlings from direct sun.
Do not keep seedlings long in the nursery since the roots develop quickly and the root pruning sets back vigour and can even be fatal.
The seedlings should be moved when no more than 4 leaves have appeared.
A rootstock is ready for grafting when it is 9–15 months old and is approximately 1cm in diameter.
The scions should be 5–15 cm long, 1 cm in diameter (pencil size), mature and dormant. It should be selected from a superior mother plants.
Remove polythene bags around the root system completely before planting.
Plant 1.5 year old grafted plants or seedlings, 1.2 m tall, positioning them upright at the centre of the holes with the root collar (the bulge in the stem where the roots and the stem meet) at ground level, i.e. plant the tree at the same level as it was in the nursery.
- 12 x 12 m in fertile soil when intercropped with other crops
- 10 x 10 m in homestead areas.
- 8 x 8 m for grafted plants
1-3 kg of compound fertilizer per tree is recommended twice per year. Applying 12kg of well rotten manure combined with 200g CAN and 400g superphosphate per tree annually may be an alternative.
Water the trees immediately after transplanting.
In the first few months, the trees should be regularly watered to maintain the soil moisture around the tree, and particularly if they show signs of wilting. The frequency of watering will depend on soil conditions and the weather.
Little or no pruning is required other than to remove any dead branches from the tree, so that there is sufficient light for the developing fruit. Flowering can be induced by making a cut in the bark of the stem; 1-2 months later a flower stalk emerges at the point where the wound was made.
| Shoot-borer caterpillar (Diaphania caesalis)
||The insects lay eggs on tender shoots and flower buds. On hatching, the reddish brown larvae bore into shoot, flower buds and fruits, resulting in the dampness of affected parts. Larvae make small holes and enter the fruit, leaving fresh excreta
||Cover fruits with polythene bags
Remove affected parts
Use recommended insecticide e.g. Bulldock Star, Decis, Dynamec 1.8 EC
||Cause damage to fruits
||Fruits can be protected from birds by bagging them with leaves or other materials.
|Bud weevil (Ochyromera artocarpi)
||The small whitish grubs of bud weevil bore into tender flower buds and fruits and induce premature drop.
The adult weevils are greenish brown in colour and eat the leaves.
|Remove the infested shoots, flower buds and fruits.
There are no diseases of economic importance that attack Jack fruit.
Jackfruit starts to fruit about 8 years after planting if the trees are raised from seed. Grafted seedlings may produce fruit earlier. Fruiting is more or less continuous but with peak season each year. When mature, there is usually a change of fruit colour from light green to yellow-brown. Spines are closely spaced, yield to moderate pressure, and there is a dull, hollow sound when the fruit is tapped. After ripening, they turn brown and deteriorate rather quickly.
The average yield is about 70-100kg per year or 250 fruits per tree every year.
Post harvest handling
The fruit can keep for 3-6 weeks in cold storage of 110-130C and relative humidity of 85-95%.
Avoid damage to the skin which causes browning, resulting in poor external appearance.
The cut stalk will exude latex, which permanently stains clothing. When latex exudation stops, wrap the fruits individually in newspapers and pack them in a suitable container.
Mechanical damage, exposure to sunlight and rough handling during transport reduce the fruit quality.
The fruits are consumed fresh or processed as juices. Jack fruit chunks are cooked in lightly salted water until tender and then served. The flesh can also be used in fruit salads, soups, or made into pickles .The seeds can be boiled or roasted and eaten as nuts. During preparation cooking oil is applied on the hands and utensils to prevent gummy latex from sticking on them. The pulp has pineapple and banana aroma. Trees are used for fuel wood, shade or to support climbing crops.