For the enterprising crop farmers who wish to engage in growing jackfruit, this how-to guide is offered as a general reference. The cultural practices will also find application in other farm crops.
1. Plant Propagation. The use of seeds is generally preferred because vegetative propagation is quite difficult. However, trees may not exhibit the characters of the parent plant, take longer time to start flowering, and are generally tall.
The seeds should be collected from healthy, mature plants which are prolific producers of fruits with desirable characteristics. Only large seeds are used. Immediately after extraction from the fruit, the seeds are washed in water to remove the slimy coating around the seeds. The horny part of the pericarp is also removed to hasten germination.
As a general rule, the seeds are sown immediately without drying because they are recalcitrant (click to read Sexual Propagation: Orthodox vs. Recalcitrant Seeds). ). If not possible, however, the seeds can be stored in air-tight plastic containers at 20 C to maintain their viability for about 3 months. In sowing, the seeds are laid flat or with their hilum facing downward. Germination should begin within 10 days. It is expected that 80-100% of the seeds will have germinated within 35 to 40 days after sowing.
Growing jackfruit can also be started through vegetative propagation using stem cuttings and by air layering or marcotting. However, special techniques are necessary, including the use of rooting hormones at the right concentrations. The Forkert method or patch budding as well as cleft grafting and wedge grafting likewise proved successful.
In Thailand, suckle grafting is extensively applied in growing jackfruit. It is a form of inarching in which young potted rootstocks are decapitated and inserted in twigs of the mother trees. SCUC (2006) also recommends veneer grafting and epicotyl grafting, also called stone grafting and soft wood grafting (click here to read the procedures in grafting).
2. Land Preparation and Holing. Just like other crops, proper land preparation is important in growing jackfruit. In sloping lands or where only a few trees are to be planted, land preparation involves the slashing of the vegetation and round weeding of the immediate peripheries of the hills. If a large number of trees is to be planted, it is best to prepare the land thoroughly by plowing. Holes are then dug 0.5-1 meter deep and wide. To ensure supply of nutrients, this will be refilled with topsoil mixed with 1/3 proportion of compost. If raw manure is used or any organic substrate, planting should be delayed for at least 15 days to allow decomposition.
3. Planting. Field planting can be done by direct seeding or by transplanting using nursery grown potted seedlings. Potted seedlings should be outplanted usually before they are one year old or before the roots leak out of the pot because the seedlings are sensitive to root disturbance. Bareroot transplanting is inapplicable to jackfruit.
Jackfruit can be planted with a spacing of 8-12 meters in square, rectangular or triangular pattern. This is equivalent to a population density of about 70 to 156 plants per hectare (28-63 plants per acre) in the square system and 80 to 180 per hectare (32-72 per acre) in the triangular or hexagonal system. SCUC (2006) recommends 8 m x 8 m for grafted trees and 10 m x 10 m to 12 m x 12 m for those raised from seeds.
The exact population, however, can only be determined by preparing a planting lay-out plan showing the positions of the hills, plant-to-plant spacing, and the distances of rows to the boundaries. This lay-out plan is similar to a construction blueprint which should be made before actually starting the farm activities in growing jackfruit.
4. Fertilizing. Fertilizer application is always a component of growing jackfruit or any crop on a continuing basis. Farm manures are applied in increasing doses from 10 to 30 kg per year as the tree matures. To ensure maximum yields of fruiting trees, complete fertilizer is applied at the rate of 1-3 kg per tree per year. Addition of muriate of potash is also generally recommended for fruiting trees. The rate is split into two equal doses, the first application preferably during the onset and the second just before the end of the rainy season. If irrigation is available, fertilizer application can be programmed every 6 months.
5. Watering. Regular watering should be done, unless rainfall is sufficient, from planting until the seedlings are fully established. Sufficient water is likewise needed during dry months when the trees are in the flower bloom and fruit development stages.
6. Weeding and Mulching. Ring weeding is practiced to keep the immediate periphery of the tree free of weeds. This operation is a regularl necessity in growing jackfruit at least during the first 3 to 4 years after planting. The weeds can be piled around the tree to serve as mulch which will conserve moisture and prevent the germination of weed seeds.
7. Pruning. The height of jackfruit, especially those raised from seed, can be regulated by cutting the main trunk about 2-3 meters from the ground. Early cutback of the main trunk can also be done to induce production of branches, allowing 4 or 5 branches to develop which are evenly distributed when viewed from the top. Properly trained, jackfruit grows with an open center which allows better light penetration.
Weak, dead, diseased and overlapping branches should be removed. This is to promote light penetration and air movement, and to prevent build up of insect pests and disease pathogen population. Branches are also removed if they hinder access to the fruits during wrapping and harvesting.
8. Intercropping. It is desirable that the spaces between the rows of the jackfruit trees are cultivated and used for the production of either annual or perennial intercrops or both. Examples of such intercrops are citrus, banana, pineapple, corn, peanut (groundnut) and other pulses, spices and vegetables. This will maximize farm productivity in addition to the benefits of proper weed control management. If not, leguminous cover crops can be seeded.
9. Insect Pest and Disease Control. It is important that one who engages in growing jackfruit should also be familiar with pests and diseases that affect the crop. The two major pests of jackfruit are the shoot and fruit borer (Diaphania caesalis) and the brown bud weevil (Ochyromera artocarpi). Caterpillars of the shoot borer tunnel into buds, young shoots and fruit. The grubs of the bud weevil bore into young buds and fruits while the adults feed on the leaves. To prevent damage, the fruits are wrapped with plastic bags when still young. Fallen, overripe and damaged fruits should be collected and buried under ground.
Blossom rot, also called fruit rot and stem rot, is a serious disease caused by the fungus Rhizopus artocarpi. It may lead to 15-32% crop losses. The disease affects the inflorescences or the tips of the flowering shoots. The inflorescences turn black, rot and drop. Another disease is the pink disease, also called pink limb blight, caused by the fungus Corticium salmonicolor. This disease infects many farm crops, including rubber, citrus, mango, durian, coffee and cacao. Control measures include thorough collection and disposal of the affected parts and fallen fruits.
10. Harvesting. Young fruits can be harvested for vegetable 2-3 months after fruit set or when the seeds are hardened. For mature fruits, selection is based on the following indices: (1) hollow sound when the fruit is tapped; (2) change in the color of the skin from pale green to greenish-yellow or brownish-yellow; (3) emission of a strong aroma; and (4) flattening of the spines with wider spaces. The stalk (peduncle) of the fruit should be cut with a sharp knife and the fruit is gently lowered to the ground.
Agriculture and Fisheries Information Service (AFIS). n.d. Jackfruit. Department of Agriculture. Retrieved October 12, 2010 from http://www.da.gov.ph/tips/jackfruit.pdf.
Morton, J. 1987. Jackfruit. In: Fruits of warm climates. pp. 58-64. Retrieved October 12, 2010 from http://www.hort.purdue.edu/newcrop/morton/jackfruit_ars.html (updated 10/12/110).
Quisumbing, Q. 1978. Medicinal Plants of the Philippines. Katha Publishing Co., Inc. pp. 228-230.
Southampton Center for Underutilized Crops (SCUC). 2006. Jackfruit Artocarpus heterophyllus, Field Manual for Extension Workers and Farmers, SCUC, Southampton, UK. Retrieved October 10, 2010 from http://www.scribd.com/doc/20042510/Jackfruit-Manual-pdf.
Verheij, E.W.M. and R.E. Coronel (eds.). 1992. Edible fruits and nuts. Plant Resources of South-East Asia N0. 2. Bogor, Indonesia: Prosea Foundation. pp. 86-91.