Jackfruit Grafting Methods; Pruning Methods; Training

Jackfruit Grafting, Pruning, and Training

Today, let us get into the details of Jackfruit Grafting Methods; Pruning Methods; Training Process.

Jackfruit trees can be more profitable if cultivated under the following conditions:

  • Jackfruit is an exotic fruit developed in tropical regions of the world. It has a subtle sweet and fruity flavor. Jackfruit is a species of tree in the mulberry & breadfruit family. It is a rich source of vitamin ‘A’, vitamin ‘C’ and minerals.
  • The Jackfruit plant originated in southwest India, where it develops abundantly. And then, it spread to other parts of India, Southeast Asia, the East Indies, Thailand, Malaysia, and Indonesia.
  • The huge trees generate massive, green, oblong fruits with a bumpy, fleshy exterior. On the inside, Jackfruit contains many pale-yellow, plump bulbs, which are edible & joined at the core. The seeds can be cooked, eaten on their own, or ground into flour.
  • The Jackfruit is also called jak-fruit, jak or jaca. There are two major varieties. In one, the fruits have small, fibrous, soft, but extremely sweet carpels with a texture somewhat akin to a raw oyster. The other variety is crisp & almost crunchy though not quite as sweet. This form is more important commercially and is extra palatable to western tastes.
  • The jackfruit tree will not tolerate drought. Water frequently during warm months & warm periods in cooler months. Less water is essential during colder weather. The Jackfruit tree must have a well-drained, a frost-free location that is sunny and warm.
  • The Jackfruit is 15 m to 20 m tall at maturity, has large, stiff, glossy green leaves 15 cm to 20 cm long, and fruit up to 60 cm long & weighing up to 18 kg (about 40 pounds).
  • The Jackfruit is adapted to humid tropical and near-tropical climates. It is sensitive to frost in its early life & cannot tolerate drought. If rainfall is deficient, the tree should be irrigated. In India, it thrives in the Himalayan foothills & from sea-level to an altitude of 5,000 ft (1,500 m) in the south. It is stated that jackfruits grown above 4,000 ft are of poor quality & used only for cooking. The jackfruit tree ascends to about 800 ft (244 m) in Kwangtung, China.
  • Jackfruit can produce on a wide variety of soil but grows best on deep alluvial soil. Soil drainage is a very important factor. It cannot tolerate a waterlogged environment. The tree may die in 2 to 3 days in flooded soil conditions. The soil pH level is 5.0-7.5.
  • The jackfruit tree flourishes in rich, deep soil of medium or open texture, sometimes on deep gravelly soil. It will grow, but more slowly & not as tall in shallow limestone. In India, they say that the tree grows tall and thin on sand, short & thick on stony land. The Jackfruit tree cannot tolerate “wet feet”. If the roots touch the water, the jackfruit tree will not bear fruit or may die.
  • Early research suggests that taking jackfruit extract before a meal may lessen post-meal, raise in blood sugar levels in people with diabetes.

Propagation of Jackfruit:

Propagation is generally by seeds which can be kept no longer than a month before planting. Germination needs 3 to 8 weeks but is expedited by soaking seeds in water for 24 hours. Soaking in a 10 percent solution of gibberellic acid results in 100% germination. The seeds may be sown in situ or may be nursery-germinated and moved when no more than four leaves have appeared. A more advanced seedling, with its long & delicate taproot, is very difficult to transplant successfully. Jackfruit seedlings may serve as rootstocks and the grafting may be done at any time of year. Inarching has been practiced & advocated but presents the same problem of transplanting after separation from the scion parent. To avoid this & yet achieve consistently early bearing of fruits of known quality, air-layers produced with the aid of development promoting hormones are being distributed in India. In Florida cuttings of the young wood contain rooted under mist. Cuttings have been successfully rooted only with forced & etiolated shoots treated with indole butyric acid (preferably at 5,000 mg/l) and kept under mist.

Growing jackfruit can be started through vegetative propagation using stem cuttings and by air layering or marcotting. However, special techniques are essential, including the use of rooting hormones at the right concentrations. Jackfruit is normally propagated by seeds. Seed must be sown immediately after extraction since they lose their viability during storage. Air layering is one of the best methods to get true to type plant.

Read: Maturity of Fruits and Vegetables.

Grafting:

Grafting, in horticulture, the joining together of plant parts by means of tissue regeneration. Grafting is the act of placing a portion of one plant into or on a stem, root, or branch of another in such a way that a union will be formed & the partners will continue to grow. The part of the arrangement that provides the root is called the stock; the added piece is called the scion. When more than two parts are involved, the middle piece is known as interstock. When the scion consists of a single bud, the procedure is called budding. Grafting and budding are the most generally used vegetative propagation methods.

The principles involved in grafting are based on the matching of scion & stock cambiums. Cambial tissue in most woody trees & shrubs is an inconspicuous single cell layer covering the central core of wood & lying directly beneath the bark. Grafting method can be carried out throughout the year. However, veneer grafting is more successful during spring & the summer (March to May), and epicotyl grafting in October and November month. The availability of mature, dormant scions is a prerequisite for the successful grafting method.

Grafting involves the union of a shoot, called a scion, from a selected superior phenotype & a compatible rootstock from a desirable plant. Grafting allows the choice of a root system adapted to the specific climate and soil and resistant to pests and diseases, and its marriage with a highly creative shoot. Grafting method is the most reliable means of propagating the desired cultivar. Grafting joins mutually a piece of a mature, bearing tree (scion) with a separate seedling tree (rootstock) to form a permanent union. The scion forms the canopy of the tree & the rootstock the lower trunk and roots. Grafted Jackfruit trees will bear fruit in two to three years after planting and have a more spreading and open canopy than seedling trees. Jackfruit grafting is now becoming a viable process of propagation.

At what time to graft: Grafting method is more successful when morning temperatures are 70 to 85°F and nighttime temperatures are 55 to 65°F, keeping in mind that the key to the successful grafting process of the jackfruit is the maintenance of vigorous growth.

The approach grafting procedure is as follows:

  • Plant an adapted, growing plant as close to the base of the non-adapted variety as possible without extensively damaging the root arrangement of the established plant.
  • From both plants closely position shoots which are at least three-eighths inch diameter & preferably close to the same size. At the point where the union is to happen, a slice of bark one to two inches long is peeled from both stems. The peeled area must be the same size on each.
  • The two peeled surfaces are then bound strongly together with budding or electrical tape. Wrap completely with two entire covers around the area where the two peeled areas are in contact.
  • Remove some of the top portions of the foliage from the adapted variety 6 to 8 inches above the graft union. This will encourage the rapid healing of the grafted union.
  • The union must be completed in four weeks. This type of grafting is most successful if performed through growth season.
  • After the parts are well united (four weeks or more), the remainder of the top of the adapted, native variety can be cut off instantly above the graft union. The bottom or root system of the non-adapted, yellowing plant can be cut off instantly below the graft union.
  • The graft union is now completed and the problems of iron chlorosis & indigenous soil pathogens have been solved if the proper rootstock has been used. Immediately after the portion of each plant is removed it may be essential to reduce the leaf area of the top if wilting occurs because of lack of sufficient root system support. This condition will soon stabilize. However, if the purpose of the graft is to control soil-borne diseases, the susceptible variety must be detached from its root system & become totally dependent on the root system of the adapted variety.

Different Grafting methods used in Jackfruit:

Epicotyls Grafting:

Jackfruit seeds should be sown in poly bags (l0cm x 20cm) in the first week of July. The seedlings, when reached 12 to 14 cm height, should be used as a rootstock for grafting. Scions from the terminal shoot of a preferred good variety of one season old; having well-developed buds must be used. At the base of the individual scion, a wedge of 4.0 cm must be prepared and inserted into the split epicotyls region of the stock and tied firmly by polythene strips.

Veneer Grafting:

The modified veneer graft, with or without the retention of leaves is among the most successful methods for grafting the jackfruit. This process requires active scions of 10 to 15 cm (4 to 6 in) with a swollen terminal bud. The last fully expanded jackfruit leaf is retained. Long, shallow veneer cuts are made on both the rootstock & Scion, exposing the cambium of both. The veneer graft cut stops short of the terminal bud of the scion. A short flap of bark is left at the base of the veneer cut on the rootstock to secure the scion through the wrapping. The cut surfaces of both the scion & the rootstock are then attached and wrapped with plastic grafting tape or a rubber band, exit the terminal bud uncovered.

The grafted jackfruit tree and container are covered with a clear plastic bag and placed in a bright but shaded location and thoroughly watered. The terminal bud on the scion will unfold its leaf & continue to grow. Rootstock sprouts from below the graft must be removed. The bag can be removed after the scion begins to grow in two to four weeks. The height of the graft on the rootstock is not important. The same process can be used with leaf removal on the scion, and these scions can be stored in a plastic bag at 12°C (54°F) for up to a week. Other successful methods include chip budding, cleft, and forkert grafts. The key to all of these methods is the vigor of the rootstock & Scion, and the preparation of the bud wood.

Inarch Grafting:

Inarching as an approach grafting, both rootstock & scion plants are self-sustaining, both are cut on one side, and the cut surfaces are pressed together. But in inarching, the top of the rootstock does not extend above the position of the graft union. The scion plant, for example, a tree on which extra trunk is to be joined, is prepared by two adjacent, long vertical cuts on the bark. It is followed by two horizontal cuts that connect the vertical cuts, one at the bottom & another just below the top. The rectangular portion of bark is then removed with a short flap of bark still remaining at the top.

The rootstock, or seedling that is to become the additional trunk, is prepared by removing the top portion of the shoot, then making a deep cut during the wood at the side adjacent to the scion. The length of this cut from the decapitated section of the stem matches the cut on the scion tree. Opposite to this cut & at the tip, a shortcut is made to form it into the shape of a wedge. The cut surface of the seedling stem is pressed tightly to the cut surface of the tree with the wedged tip enclosed by the flap of bark. The seedling is then nailed to the tree or secured strongly by a tying material.

Cleft or Wedge Grafting:

A grafting method in which a rootstock is first decapitated at the portion of the stem where there is active growth, followed by a downward cut through the center of the stem starting from the stub. The scion is prepared with a slanting cut on one side at the base & a similar cut on the opposite side so that the base is a wedge or V-shaped (about 4 to 6 cm long in pencil-size scions). The base of the scion is included into the cleft at the top of the decapitated rootstock. Two small scions may be inserted, one at each side of the rootstock to make sure cambial contact.

Planting a grafted Jackfruit tree:

The timing of planting:
  • The best time for planting a jack fruit tree, either through direct seeding or transplanting, is at the beginning of the rainy season.
  • If water is available, direct seeding may be complete in early summer so that the seedlings are established before the beginning of the rainy season. The rainy season ensures plenty of water & a favorable environment for the establishment of the trees in the field.
  • The best time of day for transplanting is late afternoon to early evening, due to decrease temperatures, so that drying of young trees is minimized.
Planting:

Seedlings are planted in a square structure with a spacing of 10m x10m. June to August month is an ideal time for planting. The place chosen for the planting must be first cleared of old tree stumps and old roots to avoid termites and root disease. When necessary, the soil must be ploughed first, and then the rows are made to mark the planting intervals. Generally, jackfruits are planted at a distance of 30 ft. x 30 ft. In an acre, nearly 48 trees can be planted. In a new area, the planting interval can be reduced to 25 ft. x 25 ft. and 69 jackfruit trees can be planted in an acre.

Usually, the planting holes are left open for fourteen days before they are filled up again, and then is the bud grafted jackfruit tree planted. It is very important to remember that during planting, the bud patch is not to be covered with soil. It would otherwise cause the bud patch to rot & die. The quantity of sunlight can be reduced by using shade from coconut fronds. Generally, bud-grafted trees are planted during the rainy season so that they do not have to be watered. Since watering is quite a problem in large scale cultivation, planting must be completed when there is rain in order to make sure that the plants can grow well. This is very important to prevent the plants from being stunted. Shading from the coconut fronds can be removed after 2 weeks if the weather is fine. Otherwise, it must be left for another week or more.

For sandy soil and clay soil or the Holyrood series, legumes are essential as cover crops. Calopogonium, Centrosema & Pueraria in a ratio of 5:4:1 is usually used. Cover crops are required to prevent weeds from growing, to alter the condition and fertility of the soil & to prevent the soil from becoming too hot especially in bris areas.

Read: Weed Management in Agriculture.

Pruning of Jackfruit trees:

A well pruned Jackfruit tree.
A well pruned Jackfruit tree.

Pruning method is not commonly practiced in Jackfruit. Non-pruned seedling trees normally develop a strong central leader, which is desirable for its timber value. However, grafted jackfruit trees have a dwarfing tendency and branch very early in their growth. These branches require to be continually pruned to achieve a reasonable trunk. Thereafter, branches may be allowed to develop at desired intervals.

  • Remove the inner branches of the canopy to allow more light & air within the canopy.
  • Regularly prune weak, dead and diseased branches, and remove all parasitic plants at the end of the rainy season to prevent insect infestation & disease infection.
  • Tree height and size may be controlled, if desired, by pruning.

The height of jackfruit, particularly those raised from seed, can be regulated by cutting the main trunk about 2 to 3 meters from the ground. The early cutback of the main trunk can 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 improved light penetration.

Weak, dead, diseased and overlapping branches must be removed. This is to promote light penetration and air movement and to prevent the build-up of insect pests & disease pathogen population. Branches are removed if they hinder access to the fruits during wrapping and harvesting.

Training of Jackfruit plants:

Training is done mainly to train or shaping the tree so that it has well distributed strong scaffold branches capable of bearing heavy crops over the years without breakage of limbs. Training starts with planting a jackfruit tree. Jackfruit trees are trained so that the least amount of shading occurs inside the tree canopy. A jackfruit tree that is pyramidal in shape exposes a greater percentage of total leaf surfaces to adequate sunlight.

  • Training is a practice in which tree growth is directed into a desired shape & form.
  • Training young fruit trees are necessary for proper tree development. It is improved to direct tree growth with training than to correct it with pruning.
  • Training includes summer training & summer pruning as well as dormant pruning.
  • The goal of tree training is to direct tree growth & minimize cutting.
The principle of Training:
  • The principle of an object of training a young tree is to increase the strong framework of scaffold branches.

All methods of training must stand or fall by their ability to get a tree capable of bearing high yielding fruits without undue breakage.

Objectives of Training:
  • To admit more sunlight and air to the center of the tree & to expose maximum leaf surface to the sunlight.
  • To direct the growth of the tree so that various cultural operations, such as spraying & harvesting are performed at the lowest cost.
  • To protect the tree from sunburn & wind damage.
  • To secure a balanced distribution of fruit-bearing parts on the major limbs of the plant.

Read: Raspberry Farming.

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