Grafting and budding
By Admin On 26-01-2018
Grafting and budding are horticultural techniques used to join parts from two or more plants so that they appear to grow as a single plant. In grafting, the upper part (scion) of one plant grows on the root system (rootstock) of another plant. In the budding process, a bud is taken from one plant and grown on another.
Although budding is considered a modern art and science, grafting is not new. The practice of grafting can be traced back 4,000 years to ancient China and Mesopotamia. As early as 2,000 years ago, people recognized the incompatibility problems that may occur when grafting olives and other fruiting trees.
Since grafting and budding are asexual or vegetative methods of propagation, the new plant that grows from the scion or bud will be exactly like the plant it came from. These methods of plant reproduction are usually chosen because cuttings from the desired plant root poorly (or not at all). Also, these methods give the plant a certain characteristic of the rootstock - for example, hardiness, drought tolerance, or disease resistance. Since both methods require extensive knowledge of nursery crop species and their compatibility, grafting and budding are two techniques that are usually practiced only by more experienced nursery operators.
Most woody nursery plants can be grafted or budded, but both processes are labor intensive and require a great deal of skill. For these reasons they can be expensive and come with no guarantee of success. The nurseryman must therefore see in them a marked advantage over more convenient propagation techniques to justify the time and cost.
Clones or varieties within a species can usually be grafted or budded interchangeably. For example, Pink Sachet dogwood can be budded or grafted onto White Flowering dogwood rootstock and vice versa. Bradford pear can be grafted or budded onto Callery pear rootstock and vice versa. However, Pink Sachet dogwood cannot be grafted or budded onto Callery pear.
Grafting and budding can be performed only at very specific times when weather conditions and the physiological stage of plant growth are both optimum. The timing depends on the species and the technique used. For example, conditions are usually satisfactory in June for budding peaches, but August and early September are the best months to bud dogwoods. Conversely, flowering pears can be grafted while they are dormant (in December and January) or budded during July and August.
When to Graft?
Unlike budding, which can be performed before or during the growing season, most grafting is done during winter and early spring while both scion and rootstock are still dormant. Containerized plants may be moved indoors during the actual grafting process; after grafting, these plants are placed in protected areas or in unheated overwintering houses. Field-grown stock, of course, must be grafted in place. Some deciduous trees are commonly grafted as bare rootstock during the winter and stored until spring planting. Indoor winter grafting is often referred to as bench grafting because it is accomplished at a bench.
Selecting and Handling Scion Wood
The best quality scion wood usually comes from shoots grown the previous season. Scions should be severed with sharp, clean shears or knives and placed immediately in moistened burlap or plastic bags. It is good practice during the harvesting of scions and the making of grafts to clean the cutting tools regularly. This may be done by flaming or immersing them in a sterilizing solution. Isopropyl (rubbing) alcohol also works well as a sterilant, although it evaporates quite readily. An alternative sterilizing solution may be prepared by mixing one part household bleach with nine parts water (by volume). However, this bleach solution can be highly corrosive to certain metals.
For best results, harvest only as much scion wood as can be used for grafting during the same day. Select only healthy scion wood that is free from insect, disease, or winter damage. Be sure the stock plants are of good quality, healthy, and true to type. Scion wood that is frozen at harvest often knits more slowly and in lower percentage. If large quantities of scion wood must be harvested at one time, follow these steps:
· Cut all scions to a uniform length, keep their basal ends together, and tie them in bundles of known quantity (for example, 50 scions per bundle).
· Label them, recording the cultivar, date of harvest, and location of the stock plant.
· Wrap the base of the bundles in moistened burlap or sphagnum, place them in polyethylene or waterproof paper bags, and seal the bags.
· Store the bundles for short periods, if necessary, either iced down in insulated coolers or in a commercial storage unit at 32° to 34°F.
· Never store scions in refrigerated units where fruits or vegetables are currently kept or have been stored recently. Stored fruits and vegetables release ethylene gas, which can cause woody plant buds to abort, making the scions useless.
· Keep the scions from freezing during storage.
Budding
Budding is a grafting technique in which a single bud from the desired scion is used rather than an entire scion containing many buds. Most budding is done just before or during the growing season. However, some species may be budded during the winter while they are dormant.
Budding requires the same precautions as grafting. Be sure that the scion and rootstock are compatible, that the scion has mature buds, and that the cambia of the scion and rootstock match. Be especially careful to prevent drying or contamination of grafting materials. With practice, the speed with which the process can be performed and the percentage of successful grafts those that "take" - should equal or surpass those of other grafting techniques used on the same species. Generally, deciduous fruit and shade trees are well suited to budding.
therefore, grafting and budding techniques combine the science and the art of horticulture. The scientific aspects include comparability, timing, disease and insect resistance, drought, tolerance, and hardiness. Information on these topics may be found in have a broad working knowledge of a variety of texts and pamphlets. Acquiring practical skills in the art of grafting and budding, on the other hand, requires hours and even years of practice to perfect. Usually the careful supervision of a trained propagator is required for the serious student of budding and grafting to learn this art.
From this publication it should be clear that many types of budding and grafting techniques are available. Individual propagators usually have a broad working knowledge of all of these techniques but a high degree of skill in only two or three.
These budding and grafting techniques can be used successfully, especially on a commercial basis, to propagate clonal plant materials. In fact, perpetuating many of our horticultural clones depends on the successful application of these techniques.