All publications of Naeem ul Hassan . Jhang Sadr , پاکستان
This is a agricultural manner in which the plant tissues are connected so as to continue their rise collectively. The upward part of the joined plant is known as scion and on the other hand downward part is known as root stock. The progression of this combination demands that the vascular tissues should grow collectively and this type of joining is known as inosculation. This method is extensively used in asexual propagation of plants grown on large scale for horticultural and agricultural dealings. In almost all cases a plant is selected for roots called stock or root stock. And then for stems, leaves, flowers, or fruits another plant is selected known as scion. The scion plant possesses desired genes to be cloned in future yielding by means of stock-scion plant. The vascular cambium of stock and scion should be set in association with each other for fruitful grafting. Studies have shown that attachment of phloem sets up after 3 days and in case of xylem it established after 7 days of pioneer grafting. Grafting joints are not much stronger than the natural ones because only the new formed tissues will fuse with each other not the older ones.
FACTORS FOR SUCCESSFUL GRAFTING
- Compatibility for stock and scion:
As grafting happen when the vascular tissues of stock and scion connects. The plants like monocots can’t be grafted because they are deficient in vascular bundles. It is a common perceptive that more the two plants resemble with each other genetically the more the grafting will be successful. The chance of success for grafting of plants from same species is greater than the plants from different species. Sometimes the plants of same genus also show successful grafting.
- Cambium alignment and pressure:
For successful grafting you should apply firm pressure on the joint where vascular cambium of stock and scion connects so that the tissue connects with each other quickly and the orientation of the joint should be in the line of normal growth. This will enhance the swift movement of water and nutrients from root stock to scion.
- Completed during appropriate stage of plant:
The time when stock and scion of plant are able to yield callus the grafting will be completed. Temperature also effects grafting and high temperature can cease callus formation.
- Proper care of graft site:
When the grafting is done it is necessary to take good care of plant till the plant restores its health. You can use different grafting tapes and waxes to save plant from excessive water loss at the joint of stock and scion. If the plant structure is weak you should provide support to the plant by twine or string.
- Cutting tools:
You have to make sure that the cutting tools are pointed and sharp so that they will give less damage to the tissues of plant; to prevent the transmission of disease it is necessary to keep the tools clean. Cutting knife for usual grafting should have blade of 3 inches and handle of 4 inches. The knives used especially for grafting are bud-grafting knives, surgical knives, and pruning knives. If the size of stock is too large cleavers, chisels, and saws can be used to cut.
- Disinfecting tools:
Using tools treated with disinfectants will make sure that the grafting place is free from pathogens. Absolute alcohol is a standard sterilizing agent.
- Graft seals:
These seals make the grafting spot hydrated. These should be tight enough to stop excessive water loss and loose enough to assist plant growth. Specialized types of clay, wax, petroleum jelly and adhesive tapes are used as graft seals.
- Tying and support materials:
If the structure of plant is weak then it is necessary to provide support to the plant to keep scion and stock in the place. Strips, twine, nails and splints are the support materials for grafting.
- Grafting machines:
Grafting machines are available to reduce the time consumed because doing it by hand consumes a lot of time and skill. There are machines which have ability to graft 800 seedlings per hour.
This method is utilized to connect plants together that are tough to graft. In this method plants are grown near to each other and both have root stocks and then joined and grow collectively from that point of joining. Each scion and stock has its own parents. This grafting will complete at any time of year.
Bud grafting is also known as chip budding in which a bud is used in place of twig. The most usual example of budding is rose grafting. First cut off the shoot of the stock plant then a bud is taken from the host plant; the ground surface of bud is placed under the bark of the stem of stock plant. On stock plant any bud except grafted bud which starts emerging is cut off.
In this method first of all give a small cut in the stock with the help of a sharp knife and then put sharp end of scion into the stock. The best season for this type of grafting is early spring. This method is best for scion of 1cm on a stock of large diameter. First give a clean from to the downward on the stock or branch to make a cleft of 3cm. The scion should have long deep edge. Now put the scion into the cleft and push it down to the end. Now tape the scion from the upper end of the stock to keep the scion in spot and now overspread grafting wax. It helps to prevent excessive water loss.
In whip grafting a slanting cut is given to the stock and scion and then connected. Then the grafted end is sealed with a soft sealant to reduce water loss and attack of germs. The most usual variation is a whip and a tongue and graft it is a tough variation but the chances of success is very high as the cambium connection between scion and stock is very good. This grafting method is used in fruit trees grown on large scale. This method is commonly utilized with stock of diameter 1cm and the diameter of scion should be nearly equal to stock.
In this method less stock is required as compared to cleft grafting and it will possess shape of a tree. Commonly 6-8 buds of scion are used in this technique. A cut is given on the branch of length 1cm and then the scion is inserted into the branch. Scion must have an angle of 35 degree to the stock. And then it should be covered with grafting materials.
It is also known as banana graft and is usually utilized for pecans. It is declared for most cambium covering but this technique is tough. In this the diameters of the stock and scion should be of same size. Skin of the stock is striped into four flaps and the hardwood is eliminated this will look like a striped banana. This technique is very tough to learn.
Awl grafting consumes minimum time and resources as compared to other grafting techniques. This method is discovered accidently by an experienced grafter. In this method grafting is done by utilizing a screwdriver to give a cut in the bark not to cut the cambium layer. Then the scion is inserted into the stock.
Veneer grafting is also known as inlay grafting, this technique is utilized for stock having diameter greater than 3cm and the thickness of scion should be as pencil. A cleavage is made on the stock to same size of scion then it is inserted into the cleft and covered with tape.
In this method a small sized scion is grafted on a thick stock. On the thick stock 4cm parallel deep cut is given to the stock and then the bark is removed from the wood. The scion is of wedge shape, cambium showing off on both side is inserted into the backside of stock, with flat face towards the wood.
CULTIVATED PLANTS PROPAGTED BY GRAFTING:
• Apple – grafting
• Avocado – grafting
• Citrus (lemon, orange, grapefruit, Tangerine, dayap) – grafting
• Grapes – stem cuttings, grafting, aerial layering
• Mango – ¬grafting
• Nut crops (walnut, pecan) – grafting
• Peach – grafting
• Pear – grafting
• Rubber Plant - bud grafting
Naeem ul Hassan & Dr. Muhammad yaseen
Department of Agriculture Extension,
College of Agriculture, UOS, Sargodha