Plant Grafting

Plant Grafting Essay, Research Paper

The Wonderful World of Grafting

Grafting has been used for thousands of years. It is said that the Chinese have been grafting plants since 1000 BC. It was and still is used all over the world. Even Aristotle mentioned it as a metaphor, “If some of the branches were broken off, and you, a wild olive shoot, were grafted in their place to share the richness of the olive tree, do not boast over the branches” (Allen, 59).

If you want to learn how two, three, or more different plants can grow together as one, read on about the wonderful world of grafting and be amazed! Grafting has been used for many purposes, but it was not till the 16th century that it became popular. Not only was it a way to repair plants, it was also a form of art. Grafting flourished in the Renaissance period when many

paintings and other art work were done of grafting, such as a plaque done by the great Florentine sculptor, Luca della Robbia.

In horticulture, grafting is a sort of propagation. This is the art and science of establishing and replacing plant life that is used in daily methods. Propagation is separated into two categories. One is sexual propagation, and the other is called asexual propagation.

Asexual propagation simply means to reproduce a plant without having to start out from a seed. Another name that is often used for asexual propagation, is artificial propagation. The most effective way to artificially propagate, is through grafting.

Grafting means to join two plants with cut surfaces together until they can unite. The union is done when the tissues in the plant connect and weave together. After some time, the wound between the plants will heal, and the grafting case will be one plant. In many cases, the grafting point heals so well that it can’t

even be seen, unless under a microscope. This union is just an act of tissue regeneration.

Grafting has many purposes. It can be used to repair a injured plant, such an example would be to graft a branch of a certain tree to another, more desirable, but injured tree to maintain it’s composure. Another important purpose is to strengthen a plant’s resistance to a certain kind of disease and also to strengthen the power to adapt to certain climates. For example, one plant can’t live in dry areas, but if you graft it to a plant that is already living in this area, it may start to adapt to this climate, because the same dry weather adapting genes in the dry area plant are now growing into the first plant. Next, It can grow multi fruit, or multi flowered plants. It can also take a great demanded plant into faster production by grafting part of the more desirable plant onto a less desirable one. Grafting can also make a plant germinate more by grafting the desired plant onto a more

productive one. A final, and most attractive purpose of grafting is to produce a nonexistent form of plant.

Before anything, a few words should be said about the plants. A plant is a complicated organism, and isn’t always fully understood. “Plants breathe, but have no lungs, they digest food but have no stomachs,” stated A.S. Hitchcock (World of Plants 2). Just like humans, too much of anything for them is bad. Plants usually cannot just grow in water or just soil.

No two plants are the same. Although most plants get most of their food from soil water, not all plants take in the same amount of each nutrient. For example, on plant can be taking in twice the amount of calcium as it’s neighbor. Although plants need a lot of things to feed and grow on, they have an infinite amount of sodium, magnesium, and silicon. Nitrogen and phosphorus on the other hand, need to be replaced. This can be done with fertilizer.

Every plant has three parts to it. It has the root, the body, and the stem. The root is used to hold the plant in place so it

doesn’t fly away, and it’s also used to absorb nourishment. The body is used to transport the nourishment. Finally, the stem is used to give the plant weight for support so that it does not fall. It also the place where most of the heat and light nourishment is caught.

The root is just about the most important piece of the plant. It is where the vertical growth takes place. It happens in a short point just behind the root cap, which is a thin replaceable cap that protects the root’s growing point as it burrows into the ground. Although only the growing point grows in length, all of the root grows in thickness. Just above the point of growth, fuzzy root hairs grow out. These hairs absorb water, and other nutrients. The most important thing about the root is that it is the life of the plant, and it needs oxygen. So, if the growing area it flooded, or the air is not able to be found, the whole plant will die.

Almost all plants can be grafted {Allen states that a New York newspaper once naively and erroneously reported the introduction of a table d’hote tree on which, through grafting, such disparate crops as tomatoes, cucumbers, and potatoes grew in profusion (Allen 60)}, but not most plants can be grafted together. In order for two plants to be grafted, they should belong to the same genus, or genera. The more alike two plants are, the more likely they can be grafted. Allen states that there was once a man who claims to graft a rose to a black currant to produce a black rose, a botanical impossibility (Allen 59-60).

Most grafts fail, so selecting similar plants helps to improve the take percentage. Take is the word that describes if the two plants can live together. If the plants do not take, it means the grafted plants cannot live together, and the case will be a failure. The success or failure of any graft is totally based on the compatibility of each plant part, the closeness of the fit, and the cambial contact. These all need to be accounted for.

Before grafting is explained in detail, a few terms should be explained to avoid confusion. The two most important parts of

the graft are the scion and the stock. The scion, is the piece of twig or shoot that is the aerial piece. This is the piece that is the dependent plant. This word can also be spelled cion. The stock is the host plant. It provides the scion with nourishment, and is the piece that is rooted into the soil. This is also called the rootstock, and understock. Sometimes, a piece is added between the scion and the stock. This is called the interstock.

Grafting has grown to such popularity that many ways to graft have been invented. “It’s so easy to do,” states a retired park manager, Richard Walter, “I’m surprised more people don’t try it (Allen 59). Grafts are classified in many ways. Some are,

1. Time- summer graft, winter graft, etc.

2. Place- root graft crown graft, etc.

3. Part used- root graft, twig graft, etc.

4. Description of method- whip, cleft, bud, bridge.

This part of the paper will only explain the methods of grafting because the other categories are self explanatory. First,

there is the cleft graft. This kind of grafting is usually used for grafting tree branches or to introduce new pollen sources. This graft should be done in late winter or early spring. A cleft graft is done by making a vertical V-slit at the top of the stock. Than, the twig or branch of the scion is shaved also like a V, and the scion is pushed into the stock. The last steps are to bandage the wound with strips of bonding tape, and covering the area with grafting wax.

Next, is the whip graft. This graft is done in the winter, and is used to change in to most any varieties. During a whip graft, cut both the scion and the stock diagonally, and put a vertical cut at the middle of the diagonal cuts. Next, force the two together so that the two pieces match, and the vertical cut pieces interlock.

The bridge graft or inarching, is one that is widely used. It is used to repair injured plants that are generally gnawed on by

rodents. This should be done when the bark starts to peel easily, in the spring. Take a piece of twig from the plant, and stick it on

either side of the gnawed part. This means to cut a T shape on either side of the wound and slip the twig under. Cover with wax, and the wound will heal.

The bud graft is last. Many people do not consider as a type of grafting because it only uses a single bud instead of a whole branch, or twig. Using one bud is a very good advantage. It is easier to protect, and this type of grafting usually has a higher survival percentage than the rest of the methods. There is only one disadvantage. For this kind of grafting to work, timing is crucial. It has to be done during a brief period in the spring when the bark slips (peels off easily).

This type of grafting uses one bud that is cut off from the plant used. On the stock, a T-shaped cut is made. Next, the scion (bud) is inserted into the cut. Lastly, the surrounding area is covered with grafting wax to prevent evaporation or falling out.

For a graft to work, two things must be in order. First, the plants have to be compatible (they have to be similar or from the

same genus), and second, the cambiums have to meet. What is cambium? Cambium is a thin layer of dividing cells between the meat of the plant, and the skin, or in some cases, the bark. These cells help the plant grow in thickness. They also act as conductors for food to the leaves. To cut a full ring of cambium without giving extra nutrients will often kill a plant.

Now, what do these cells really do? And how do they work? As a part of the cambium layer, callus tissue is produced. This tissue acts like white blood cells in a human body. They close and heal wounds as the blood cells would. The survival of the graft of two compatible plants is based solely on the closeness of the cambium layer of both plants. A snug fit can improve growth and take greatly. “If the two pieces fit together closely and are set just right, they will knit in a few weeks and we’ll have a new plant,” stated Walters (Allen 59). This can be achieved with tape, rubber,

pins or even nails. Another way to insure growth, is to place the plant, in a temperature between 80-85 degrees Fahrenheit. At this temperature, callus forms faster, thus improving the take.

When the two cambiums meet, the cells grow together, and interlace till finally, the plant is one, healed and healthy. As the plant heals, the cambium also produces food and water conducting vessels so that all the nutrients taken by the root can circulate through the whole plant instead of just the stock.

In addition to the protection of the cambium, the grafted area also needs additional protection to keep the plants from drying out. The most effective tool to use for this is grafting wax. The wax, if used right, will increase the case’s percentage of living. This wax is made of resin, beeswax, powder charcoal, and raw linseeds. This wax can be softened in the hand and serves as great protection for the plant against evaporation, and pesky insects. The wax is recommended, but if it is not applied, do not place the plant in direct sunlight so that it does not evaporate.

After the grafting is finished, the only thing to do is wait. The union usually starts between two to four weeks. After the two plants have finally grown together, the union point is often stronger than the rest of the plant. In fact, if a grafted plant is to break, in most cases, the break will be above or below the grafting point.

For the experiment I had to do, the graft method used was different from any of those listed above. These cases were done before most of the research had started, to give time for the cacti to grow. Two cactuses were used for the simplest of the three grafts performed. The two were the Moon cactus, and one similar to the Peruvian apple cactus. For the experiment, each of the plants were shaved straight across, at the bottom of the scion, and top of the stock. The two were than placed on top of each other so that the flesh of the cacti were in contact. To keep them in place, two pins were stuck through both cacti. It was than

placed on a counter, and the grafting point was moistened every day to delay evaporation.

After many weeks of studying, every plant’s scion had died, but most of the stock are still living. The conclusion that has been drawn from this is that, each case was poorly contained. Even though the cacti were well watered, they were placed in direct sunlight for about six hours a day, which caused immediate evaporation. Also, in one of the cases, the cambiums were barely touching. So although the cases all failed, experience and knowledge were gained. The cases would not fail again, now that I have learned everything about grafting.

If the graft had worked, when it is finished, the scion and the stock will grow their own fruits and flowers. There usually isn’t too much mixing. The end of a graft is the greatest gift. It is a accomplishment, and this is the reward. If you want to learn about, or how to do grafting, be sure to check out the books in my bibliography. They will help you dearly.