GRAFTING and Its ADVANTAGES

GRAFTING and Its ADVANTAGES

Grafting or graftage is a horticultural technique where tissues of plants are joined so as to continue their growth together. The upper part of the combined plant is called the scion while the lower part is called the root stock or stock.

It has many advantages in improving the yield and quality of crops. Following are some important benefits from grafting as a method of propagation;

Precocity:

The ability to induce fruitfulness without the need for completing the juvenile phase is known as precocity. Juvenality is the natural state through which a seedling plant must pass before it can become reproductive. In most fruiting trees, juvenality may last between 5 and 9 years, but in some tropical fruits e.g. Mangosteen, juvenality may be prolonged for up to 15 years. Grafting of mature scions on to rootstocks can result in fruiting in as little as two years.

Dwarfing:

Grafting can be used to induce dwarfing or cold tolerance or other characteristics to the scion. Most apple trees in modern orchards are grafted on to dwarf or semi-dwarf trees and planted at high density. They provide more fruit per unit of land, higher quality fruit, and reduce the danger of accidents by harvest crews working on ladders. Care must be taken when planting dwarf or semi-dwarf trees. If such a tree is planted with the graft below the soil, then the scion portion can also grow roots and the tree will still grow to its standard size.

Ease of Propagation:

As the scion in some crops is difficult to propagate vegetatively by other means, such as cutting grafting can be used as a good alternative. In this case, cuttings of an easily rooted plant are used to provide a rootstock. In some cases, the scion may be easily propagated, but grafting may still be used because it is commercially the most cost-effective way of raising a particular type of plant.

Hybrid Breeding:

To speed maturity of hybrids in fruit tree breeding programs grafting is essential. Hybrid seedlings may take ten or more years to flower and fruit on their own roots. Grafting can reduce the time to flowering and shorten the breeding program.

Hardiness:

Because the scion has weak roots or the roots of the stock plants have roots tolerant of difficult conditions. Grafting can combat the problem related to it, for example Dogridge can be used as a root stock in gape in salinity areas.

Sturdiness:

It can be used to provide a strong, tall trunk  for certain ornamental shrubs and trees. In these cases, a graft is made at a desired height on a stock plant with a strong stem. This is used to raise 'standard' roses, which are rose bushes on a high stem, and it is also used for some ornamental trees, such as certain weeping cherries.

Disease and Pest Resistance:

In areas where soil-borne pests or pathogens would prevent the successful planting of the desired cultivar, the use of pest or disease tolerant rootstocks allow the production from the cultivar that would be otherwise unsuccessful. A major example is the use of rootstocks in combating Phylloxera.

Pollen Source:

To provide pollinizers, for example, in tightly planted or badly planned apple orchards of a single variety, limbs of crab apple may be grafted at regularly spaced intervals onto trees down rows, say every fourth tree. This takes care of pollen needs at blossom time, yet does not confuse pickers who might otherwise mix varieties while harvesting, as the mature crab apples are so distinct from other apple varieties.

Repair:

To repair damage to the trunk of a tree that would prohibit nutrient flow, such as stripping of the bark by rodents that completely girdles the trunk. In this case a bridge grafting may be used to connect tissues receiving flow from the roots to tissues above the damage that have been severed from the flow. Where a water shoot, basal shoot or sapling of the same species is growing nearby, any of these can be grafted to the area above the damage by a method called inarch grafting. These alternatives to scions must be of the correct length to span the gap of the wound.

Changing cultivars:

To change the old or less profitable cultivars in a fruit orchard to a more profitable cultivar, called top working. It may be faster to graft a new cultivar on to existing limbs of established trees than to replant an entire orchard.

Maintain consistency:

Apples are notorious for their genetic variability, even differing in multiple characteristics such as, size, color and flavor of fruits located on the same tree. In the commercial farming industry, consistency is maintained by grafting a scion with desired fruit traits onto a hardy stock.

Curiosities:

@@ A practice sometimes carried out by  is to graft related potato and tomato so that both are produced on the same plant, one above ground and one underground.

@@Cacti of widely different forms are sometimes grafted on to each other.

@@ Multiple cultivars of fruits such as apples are sometimes grafted on a single tree. This so-called family tree provides more fruit variety from small spaces such as a backyard, and also takes care of the need for pollenizers. The drawback is that the gardener must be sufficiently trained to prun them correctly, or one strong variety will usually "take over."

@@ Ornamental and functional tree shaping uses grafting techniques to join separate trees or parts of the same tree to itself.