Grafting Method of Plant Propagation

The method of joining parts of two plants in a manner that they form a unit and function as one plant is known as ‘grafting’.

Table of Contents

Advantages of grafting

Plants propagated by grafting are true-to-type, and bear flowers and fruits early.
The plants can be multiplied and preserved by grafting.
Local variety of older plants can be improved to superior variety by top working.
Wounded or damaged tree trunks can be repaired by special grafting methods.
Rootstock has an influence on resistance, vigour and quality of grafted plants

Disadvantages of grafting

It requires specialised skill.
It is an expensive method of propagation.
New varieties cannot be developed by grafting.
Plants produced through grafting are short lived as compared to plants propagated by seeds.
When contaminated tools or propagation material are used in grafting, newly propagated plants may also get infected.

Rootstock

The part of the graft that provides root system to the grafted plant is known as ‘rootstock’. It is, normally, raised by seeds in the seedbed, and then, transplanted in the nursery bed for budding and grafting. Rootstocks are also raised in pots and polythene bags.

Scion

The upper portion of graft combination taken from the desired plant to be multiplied is known as ‘scion’. Scion wood must be of the previous season but not from more than one-year old plant. Flowering shoots or shoots from where the harvesting is recently done must be avoided. Healthy and well-developed vegetative buds must be selected.

Types of Grafting in Plant

1-Tongue grafting

Useful for grafting relatively small material of about 6-13 mm in diameter. It is highly successful if done properly because there is considerable vascular cambium connection. It heals quickly and makes a strong union. Scion and rootstock of equal diameter is preferable for this technique for better graft union formation. The scion should contain 2 or more buds. It is done mainly during the dormant season of the plant.

For this, after heading back the stock, 1st a smooth cut is made at 2.5-6 cm long. Then a reverse cut is made downward from the point about one third of the distance from the tip and should be one half of the length of the 1st cut. Similar technique should be followed for the preparation of scion at its base. After that the rootstock and scion are inserted into each other, with the tongue interlocking.

The lower tip of the scion should not overhang the stock as there is a likelihood of the formation of large callus knots. The use of scions larger than the rootstock should be avoided for the same. It is commercially used in temperate fruits like apple, pear etc.

2-Whip grafting (Splice grafting)

It is the same as the tongue grafting, except that the second or tongue cut is not made in either the stock or scion. A simple slanting cut of the same length and angle is made in both the stock and scion. These are placed together and wrapped or tied in such a way so that there should be no space in between stock and scion.

If the scion is smaller than the stock, it should be set at one side of the stock so that the vascular cambium layers will be certain to match along that side.
Mostly used in greenhouse production of vegetable crops for grafting on disease resistant rootstocks.

3-Cleft grafting

Although cleft grafting can be done during the dormant season, the chances for successful healing of the graft union are best if the work is done in the early spring just when the buds of the stock are beginning to swell but well before the active growth has started.
The scion should be made from dormant one-year old wood.
In making cleft grafting, a heavy knife is used to make a vertical split on the stock for a length of 5-8 cm down the centre of the previously beheaded stock. After a good and straight split is made, a screwdriver, chisel or the wedge part of the cleft-grafting tool is driven into the top of the split to hold it open. Two scions are inserted, one at each side of the stock where the vascular cambium layer is located.
The scion should be 8-10 cm long, about 10-13 mm in thickness and should have 2-3 buds. The basal end of the scion should be cut into a gently sloping wedge about 5 cm long and then inserted into the split portion of the stock. A common mistake in cutting scions for this type of grafting is to make the cut on the scion too short and the slope too abrupt, so that the point of contact is only at the top.
Slightly shaving of the sides of the split in the stock will permit a smoother contact. After preparation of the scion, they are inserted into the stock properly and wrapped the stock tightly with poly grafting tape or adhesive tape at the point of graft union to hold the scions in place more securely. Thereafter, thorough waxing of the completed graft is essential.
Mostly used for rejuvenating the old orchards of the temperate fruits by top working. Apart from this, Walnut, hazelnut, pecan nut, grape are also propagated by this method.

4-Wedge grafting

A heavy, short bladed knife is used for making a V-wedge in the side of the stub, about 5 cm long. For this two cuts are made, coming together at the bottom and as far apart at the top according to the diameter of the scion. These cuts extend about 2 cm deep into the side of the stub towards the centre.
The diameter of the stock to be grafted is the same as cleft grafting- 5-10 cm and the scions are also the same size- 10-13 cm long and 10-13 mm thick. After preparation of the stock, the scions are prepared by trimming the base to a wedge shape, exactly the same size and shape of the V-wedge on the stock. In a stock of 5 cm diameter, 2 scions should be inserted while in stock of 10 cm diameter, 3 scions should be inserted.
After all the scions are firmly inserted into the place, all cut surfaces including the tip of the scion should be waxed thoroughly. Like cleft grafting, it can be made in late winter or in early spring before the bark begins to slip.
Mainly use to topwork the old orchards.

Side-Stub grafting

It is useful for the trees that are too large for the whip or tongue grafting but not large enough for cleft or wedge grafting. The best rootstock for this type of grafting is about 2.5 cm in diameter. For this type of grafting, an oblique type of cut is made into the rootstock at an angle of about 20-30°.
The cut should be 2.5 cm deep, so that when the branches are pulled back the cut will open slightly but will close when the pull is released. The scion should be about 7.5 cm long and relatively thin and should contain 2-3 buds. At the base of the scion, a wedge of about 2.5 cm long is made.