Growing Langka (Jackfruit)

A small to medium-sized, evergreen tree that reaches 8 to 14 m high. It has a straight cylindrical, low branched trunk that measures 30 to 100 cm in diameter and a dense, irregular or spreading crown. Bark is thick, grayish and exudes a milky sap when injured. Leaves alternate, spirally arranged, stiff and leathery, dark green and shiny above and pale green beneath. Young leaves are pale yellowish green. Fruit is large, covered with short pyramidal spines. Pericarp and pulp around the seeds are the edible portions. Pulp is thick, rich yellow, sweet and aromatic when ripe. Seeds are numerous and vary in size.

Distribution

A native to the rain forests of the Western Ghats of India, and widely cultivated throughout the tropical lowlands of both hemispheres. It is an important fruit crop in India, Burma, Sri Lanka, Malaysia, Indonesia, Thailand, the Philippines and many other tropical countries. Introduced in the Philippines during pre-historic period. Widely distributed throughout the country both cultivated and wild.

Economic uses

  • Tree : shade, agrofrestry, intercropping, reforestation crop
  • Fruit : immature fruit maybe used as vegetable, ripe fruit is made into sweets, preserves, flavoring for ice cream and ingredient for ginataan, salad and halo-halo. It may also be fermented and distilled for an alcoholic beverage.
  • Seeds : very rich in starch, delicious either boiled or roasted.
  • Rags : very rich in pectin and ideal for jelly making.
  • Wood : tool handles, timber, furniture, building materials, musical instruments.
  • Leaves : in India, leaves are stitched and used as plates and other containers. It is also used as fodder.
  • Bark : yields a white latex used for caulking boats, cementing broken chinawares and trapping birds.
  • As dye : a yellow dye, obtained by boiling mature wood or sawdust, is used for dyeing garments.

Site requirements

It thrives best in moist tropical climates below an elevation of 1,000 m in areas with well distributed rainfall. In the Philippines, it grows well on all climatic types although a warm wet surrounding is best. The tree grows well on almost any type of soil, but for best performance, it prefers a deep, well drained, sandy or clay loam soils. While the soil moisture must be kept always at high level, the tree cannot tolerate water stagnation and poor drainage.

Propagation

Jackfruit is commonly propagated sexually and asexually by marcotting, inarching, budding and grafting. Seeds should be obtained from an outstanding mother tree. A fruit may contain 100 to 500 seeds. Large and heavy seeds are preferred to insure higher germination percentage and healthy seedlings. Seeds are sown immediately upon extraction because it looses viability upon exposure. Fresh seeds germinate in 22 days while month old seeds germinate in 45 days. Soaking seeds in 25 ppm NAA for 24 hours prior to sowing is recommended.

Management

The seedlings have a long tap root system very sensitive to injury. For this reason, it is advisable to sow seeds in individual containers or planted directly in the field. In India where it is used as shade tree in coffee plantations, seeds are sown directly in the field. Three seeds are planted at the center of the hole horizontally or with their embryos pointing downward to allow early germination. On the average, seeds germinate in about 18 days. Later, the 2 weaker seedlings are removed leaving healthy and straight one to develop.

For containerized seedlings, clay loam soil mixed with compost or other source of organic matter is used as planting medium. For more rapid growth, they may be fertilized with a small amount of nitrogen containing fertilizer. Although they can tolerate full exposure to sunlight, these should be placed in partially shaded area.

For medium to large scale planting, the soil should be plowed and harrowed several times until the desired soil kilth is attained. To minimize injury to the seedlings, these should be planted in the field one year or younger. Care should be observed in order not to injure the roots and disturb the soil in which the roots are growing. Plants are carefully set in prepared holes which are later filled up with top soil mixed with compost. Leaves should be pruned in halves and likewise, the extra shoots to reduce transpiration. This may be done while the seedlings are in the nursery or before the plants are set in the holes. In the orchard, spacing is 8 to 10 m or more following the square or triangular system of planting. Planting is done best at the onset of the rainy season to avoid watering problem. Irrigation should be practiced during the first to second year particularly during the dry months. Mulching the trees may be sufficient to conserve moisture in the soil to last until the next rainy season.

About 100 to 150 g ammonium sulfate is applied per plant 1 month after planting, and an equal amount 6 months later or towards the end of the rainy season. When the trees start fruiting, 0.5 to 1.0 kg complete fertilizer may be applied per tree at the start of the rainy season and an equal amount towards the end of the rainy season. A full grown tree (15 to 20 years or older) requires 2 to 3 kg of complete fertilizer per application. In the Philippines, inflorescence rot (Rhizopus migricans), pink disease (Corticium salmonicolor) and rhizoctonia thread blight (Rhizoctonia koleroga) are common diseases and controlled by removing and burning the diseases parts and spraying with Eupravit or Bordeaux mixture at recommended dosages. Seedlings start to bear fruits 6 to 8 years after planting. Grafts bear fruits in 4 to 5 years.

Phenology

In general, flowering occurs throughout the year. In India, as well as in the Philippines, the tree is injured at intervals on the bark of the trunk and branches with a bolo to induce profuse fruiting.

source: www.denr.gov.ph

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