Grafting
Grafting is a horticultural technique of joining
two different parts of a plant or more plant. And they are join together in
such a way that both the parts behaves as one part and continue their growth as
a single plant. Part above the union or joint which later on behaves as bearing
part or shoot is called scion or scion (Hottes, A.C. ,1925), while the lower
part with root known as root stock or stock. And in some cases an inter stock
is used in between scion and stock which is known as inter-stock, and this
inter-stock should be compatible to both of the scion and stock. The technique
is the most commonly used in asexual propagation of commercially grown plants
for the horticultural and agricultural trades.
The success of grafting depends on
compatibility, contact of cambium, and closeness between the scion and the
root stock. In the grafted plants the quality of fruits, quantity of fruits,
bearing habits etc. all depends upon the scion while the amount of nutrient
uptake, root vigor, rooting habit, tolerance to the various level of moisture
and soil conditions depends upon the root stock quality (Shrestha et.al., 2001)
Thus due to this above reasons grafting gives the extra advantages of combined desirable
qualities of both the scion and the root stock. Budding and grafting increase
the productivity of certain horticultural crops because they make it possible
to do; Change varieties or cultivar, advantage of particular root stocks,
benefit from inter-stocks, perpetuate clones, produce certain plant forms,
repair damaged plants Increase the growth rate of seedlings All the plants
which are grafted cannot be done by same methods so there are different methods
of grafting. They are;
·
Splice grafting
·
Approach grafting
·
Bridge grafting
·
Side grafting
·
Cleft grafting
·
Saddle grafting
A] Splice grafting:
This method is generally followed in those plants, which have quick reuniting
capacity. Here one stock and scion is chosen and upper slanting cut on stock
and lower slanting cut on scion is done, on equal size diameter stock-scion.
This method is generally followed in those plant which have pithy stem or have
wood that is not flexible enough to permit tight fit. It is generally performed
in dormant season and the tying material must be cut after parts of the graft
have been united. Any sort of shoot growth in root stock must be removed. This
method is generally applied in apple, pear, cherries and etc.
Figure 1. Splice graft (single oblique cuts made
on stock and scion, stock and scion placed to match cambium, the graft tied in
position)
B] Approach grafting or inarching:
In this method of grafting, selected shoot of desired plant is grafted/united
with branches of mother plant and is grown together. Here, similar type of
narrow cuts are given in both the stems of stock and scion. And the cuts are
placed together and is tied securely with the help of plastic tape. Jute thread
are also been found for tying. After the proper union of the graft, the portion
above the graft in stock is cut down and the portion below the scion is cut
down. Thus a new individual plant can be obtained. This method is generally practiced
in mango.
Figure 2. Approach grafting / Inarching (the
removal of slice of wood and bark from stock and scion, joining the stock and
scion, tying the graft union)
C] Bridge grafting:
Bridge grafting is used to "bridge" a diseased or damaged area of a
plant. Damaged and destruction may be done by rabbits, rodents, mechanical
injury, insects and diseases. The scion of same plant species are collected
during the dormant period and inserted in the bark making a bride over the
girdled portion of the stem. The exposed portions are then covered with the
help of grafting wax. Thus, by the help of this method damaged tree can be
repaired.
Figure 3. Bridge graft
D] Side grafting or veneer grafting:
This is by-far the best method of propagation. Since it is easier, more
economical, gives a higher degree of success and is ideal for in-situ orchards.
It is a detached method of grafting i.e. shoot of mother plant is detached from
the mother plant prior to grafting and taken for grafting in the nursery. A
slanting cut on one side of the stock stem is given and the bark along with
wood is removed giving an oblique cut. Then, a slanting cut on one side of the
scion is made which will just fit with the notch of stock. It is then wrapped
tightly with wide tape, keeping the terminal ends free in such a way that the
cambium rings of both stock and scion come in close contact with each other.
After the successful union (after about three weeks), when the scion begins to
grow at the top, the upper part of the stock is removed. The plastic wrap is
removed.
Figure 4. Side veneer graft
E] Cleft grafting:
Cleft grafting is one of the simplest and most popular forms of grafting. This
method is generally followed for the top-working of the trees. It is also used
to propagate different plants that are difficult to root. This type of grafting
is done during the winter and early spring while both scion and root-stock are
still on dormant. It may be performed on main stems or on lateral branches. In
cleft grafting, firstly the limb or the main is cut-off at right angle and the
vertical slits are made on the center of the stem deep enough which can hold
the scion. Scion is prepared by cutting at its base edge having a long narrow
tapering wedge shaped edge, which is later on be placed into the stock. Proper
placement of the scion is very much important so that there will be the proper
contact in between the cambium layer of both the root stock and the scion.
Figure 5. Cleft grafting
F] Saddle grafting:
A saddle (inverted V-shaped) cut is made on the lower edge of the scion and the
upright V-shaped cut is made on the stock. Both the components are then fitted
together allowing the contact of the cambium layers. If the cut given in the
scion is wedge and that in stock is saddle (V-shaped), then that grafting is
called wedge grafting.
Figure 6. Saddle grafting
References:
Hottes,
A.C. (1925). Practical plant propagation: an exposition of the art and science
of increasing plants as practiced by the nurseryman, florist and gardener. New
York: A.T. De La Mare.
Shrestha
G.K., S M Sakya, D R Baral and D M Gautam, 2001: Fundamentals of horticulture.
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