Doing Propagation By Budding And Grafting

Published: 09th April 2009
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bud grafting), the scion consists of one single bud.

The interstock or intermediate rootstock is sometimes used in the grafting of certain fruit trees where it is known that some degree of incompatibility exists between the rootstock and scion. The plant selected as the interstock must be fully compatible with both rootstock and scion in order to overcome problems of incompatibility. The practice of grafting using an intermediate rootstock is known as double working. Cambium tissue is the main layer of meristematic tissue in the stem of the plant. It is located as a thin layer of tissue between the phloem and xylem tissues, immediately under the bark. To ensure a successful graft union it is essential that the cambium of the rootstock be placed in close contact with the cambium tissue of the scion. The grafter must fit the tissues together correctly and bind the grafted plant with tape to ensure that the tissues remain in close contact.

The rootstock and scion must be botanically closely related if a graft is to be successful.

Grafting of clones within the same species is usually successful. Grafting of species within the same genus is frequently successful. However, there are many instances where closely related species cannot be grafted. For example, all species within the genus citrus can be readily grafted onto each other; within the genus prunus there are some species such as peach (prunus persica) and apricot (prunus armeniaca), which can be grafted, together, but apricot and almond (prunus amygdalus) cannot be successfully grafted.

Grafting of different genera within the same family is sometimes successful, but there are many more failures than successes. In the grafting of citrus, the trifoliate orange (poncirus trifoliata) can be used as a rootstock for the orange (citrus sinensis). The quince (cydonia oblonga) is widely used commercially as a rootstock for pear cultivars (pyrus communis). There are also many examples of inter-generic grafting within the family solanaceae; tomato (lycopersicon esculentum) can be grafted on potato (solanum tuberosum); it can also be grafted onto tobacco (nicotiana tabacum).

Grafting is used as a propagation technique where plants cannot be economically propagated by other simpler propagation techniques. In the commercial production of clones or cultivars of fruiting and ornamental trees, propagation from seed is not possible due to colonel variation and with many types propagation from other vegetative means such as stem cuttings is not possible at present.

A wide range of fruit trees and ornamentals such as Japanese maples, conifers and flowering peach are grafted simply because it is the only sure way that they can be commercially produced in large numbers. Grafting is not nearly as important with true species since these can usually be raised economically from seed.

Using rootstocks of known and predictable performance will control the growth and performance of many fruit trees. The 'Malling' rootstock series for apples were the first 'colonel' rootstocks. In 1912, the East Malling Research Station in England began a program to select and classify a series of vegetative propagated apple rootstocks. The vigour rating of these selections ranged from very dwarfing to very vigorous in their effect on the scion.

Many fruit trees that are raised from seedlings may take six or more years before fruit is produced, as the juvenile phase of tree development is not capable of triggering fruit production. Various grafting techniques which use physiologically mature scion tissues for grafting shorten the period of juvenility and result in the tree coming into bearing much earlier in the life of the tree. Many grafted fruit trees will commence fruiting in the second year after grafting.

Dwarfing rootstocks appear to hasten fruit development and vigorous rootstocks may create slowness to start fruit production. In citrus production, fruit size is strongly influenced by the rootstock. The largest navel oranges are produced on sour lemon rootstocks, and the largest Valencia oranges are produced on trifoliata orange rootstocks.

Grafting can create interesting and unusual plant effects. Budding desired varieties onto a tall, well-developed rootstock stem could produce standard trees. Grafting can create weeping standard trees pendulous or prostrate growing forms onto tall, strong-stemmed rootstocks; e.g. weeping roses, weeping grevillea, weeping beech.

Two or more closely related fruits can be grafted onto a single rootstock to produce a multiple fruit effect with branches belonging to two or more different named varieties known as a family tree"; e.g. orange, lemon and grapefruit together on the one tree; two or more apple cultivars on the one tree.

Not everyone has the space to plant more than a single fruit tree. The tree then provides itself with perfect inter-pollination and the luxury of choice as in the case of apples, from dessert or cooking fruit.

Find tips about growing ferns and asparagus fern at the Plants And Flowers website.

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