Nurse grafting

Last updated

Nurse grafting is a method of plant propagation that is used for hard-to-root plant material. If a desirable selection cannot be grown from seed (because a seed-grown plant will be genetically different from the parent), it must be propagated asexually (cloned) in order to be genetically identical to the parent. Nurse grafting allows a scion to develop its own roots instead of being grafted to a rootstock.

Contents

Nurse seed grafting

A large-seeded woody species, e.g. the chestnut, retains the cotyledons inside the seed coat below ground while the radicle grows downward and the shoot appears aboveground. To make a nurse seed graft, a germinating seed is needed. A knife is used to cut an opening between the petioles of the cotyledons. The scion, taken from dormant wood of the previous season's growth, is cut to a wedge shape at the end and inserted into the cut between the cotyledons, so that the cambium surfaces of each can join. The grafted plant is then set in a rooting medium with the union about 1.5 inch below the surface. [1]

This graft allows the scion to live on the seed's roots long enough to form adventitious roots of its own. This technique is used for camellias, avocados, and chestnuts. [1]

Nurse root grafting

In this technique, a scion is grafted to a piece of root to keep it alive long enough for it to form its own roots. The graft union is planted below the surface of the growing medium, as with the nurse seed method. Once the scion has formed roots of its own, the rootstock can be removed, or it will die off, as will happen in situations when the scion and rootstock are not closely related. [2]

This method works well with apple cultivars, cherries, plums, nectarines, and pears. It is also useful for propagating rare isolated plants that may be unique and should not be moved from the wild. Such a plant can be propagated by taking a small amount of material that will not harm the parent plant by its removal. [3]

Nurse root grafting is the best method for propagating tree peonies. [4] Unlike herbaceous peonies with fleshy roots, which are propagated by division, tree peonies have woody stems and extensive root systems that are impractical for division. Their woody stems have few stored reserves and stem cuttings fail before roots are produced. The problem of keeping the scion alive long enough to produce roots (generally a year) is solved by grafting a tree peony shoot on an herbaceous peony root section; the section of root sustains the scion with its ample stored energy. (In contrast, Itoh peony hybrids, which are crosses between herbaceous and tree peonies, are best propagated by stem cuttings, which root easily.)

The basic process for nurse-root grafting of peonies is as follows:

  1. Grafting should be done in late summer or early fall, when the foliage of herbaceous peonies begins to change color and tree peony stems have matured. Most cultivars of P. lactiflora can be used to supply roots.
  2. Take root sections 0.75in (2 cm) in diameter and 6in to 8in (15–20 cm) long. It is important to maintain the orientation of each root (the top is closest to the crown of the plant). Rinse clean and soak in dilute bleach solution (1:10) to sterilize.
  3. Take stem cuttings from a tree peony, up to 6in long, with 2-3 dormant buds, and soak in dilute bleach solution to sterilize.
  4. Prepare a side wedge graft: With a utility (single edge razor) blade, cut a wedge in one side of the top of the root section. (The root is much thicker than the scion.) At the end of the scion, make two oblique cuts to form a prow shape corresponding to the wedge shape in the root section. When the root and scion are joined and aligned, the green cambium layer of the scion must be in contact with the cut surface of the root, with no gaps.
  5. Hold the two sections together with a rubber band, then seal the whole area with grafting tape.
  6. Allow the union to begin to callous before planting. Label the graft and place in a sealed plastic bag with a damp tissue around the root. Keep it in a warm place for 3 to 4 weeks. Keep the root oriented downward; hanging the bag will help with this. The temperature should be around 68 degrees F (20 degrees C).
  7. Plant out the graft where it can be left undisturbed for 2 years, with the graft union 4in – 6in below the surface of the soil.
  8. When root development on the scion has taken place, which may be the following autumn, remove the rubber band.
  9. After a second season of growth, the plant should be lifted and the roots inspected. If the scion has formed its own roots, the nurse root must be removed. The plant can now be placed in its permanent location.

Related Research Articles

<span class="mw-page-title-main">Fruit tree propagation</span> Usually carried out vegetatively by grafting or budding a desired variety onto a suitable rootstock

Fruit tree propagation is usually carried out vegetatively (non-sexually) by grafting or budding a desired variety onto a suitable rootstock.

<span class="mw-page-title-main">Vascular cambium</span> Main growth tissue in the stems, roots of plants

The vascular cambium is the main growth tissue in the stems and roots of many plants, specifically in dicots such as buttercups and oak trees, gymnosperms such as pine trees, as well as in certain other vascular plants. It produces secondary xylem inwards, towards the pith, and secondary phloem outwards, towards the bark.

<span class="mw-page-title-main">Herbaceous plant</span> Plant that has no persistent woody stem above ground

Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials.

<span class="mw-page-title-main">Vegetative reproduction</span> Asexual method of reproduction in plants

Vegetative reproduction is any form of asexual reproduction occurring in plants in which a new plant grows from a fragment or cutting of the parent plant or specialized reproductive structures, which are sometimes called vegetative propagules.

<span class="mw-page-title-main">Peony</span> Genus of flowering plants in the family Paeoniaceae

The peony or paeony is a flowering plant in the genus Paeonia, the only genus in the family Paeoniaceae. Peonies are native to Asia, Europe, and Western North America. Scientists differ on the number of species that can be distinguished, ranging from 25 to 40, although the current consensus describes 33 known species. The relationships between the species need to be further clarified.

<span class="mw-page-title-main">Perennial</span> Plant that lives for more than two years

A perennial plant or simply perennial is a plant that lives more than two years. The term is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also widely used to distinguish plants with little or no woody growth from trees and shrubs, which are also technically perennials.Notably, it is estimated that 94% of plant species fall under the category of perennials, underscoring the prevalence of plants with lifespans exceeding two years in the botanical world

<span class="mw-page-title-main">Layering</span> Plant propagation technique

Layering is a type of artificial vegetative propagation in which, the root which develops from the parent plant is allowed to grow and become a seperate plant after which it is disconnected into a new plant.

<span class="mw-page-title-main">Cutting (plant)</span> Method of propagating plants

A plant cutting is a piece of a plant that is used in horticulture for vegetative (asexual) propagation. A piece of the stem or root of the source plant is placed in a suitable medium such as moist soil. If the conditions are suitable, the plant piece will begin to grow as a new plant independent of the parent, a process known as striking. A stem cutting produces new roots, and a root cutting produces new stems. Some plants can be grown from leaf pieces, called leaf cuttings, which produce both stems and roots. The scions used in grafting are also called cuttings.

A rootstock is part of a plant, often an underground part, from which new above-ground growth can be produced. It could also be described as a stem with a well developed root system, to which a bud from another plant is grafted. It can refer to a rhizome or underground stem. In grafting, it refers to a plant, sometimes just a stump, which already has an established, healthy root system, onto which a cutting or a bud from another plant is grafted. In some cases, such as vines of grapes and other berries, cuttings may be used for rootstocks, the roots being established in nursery conditions before planting them out. The plant part grafted onto the rootstock is usually called the scion. The scion is the plant that has the properties that propagator desires above ground, including the photosynthetic activity and the fruit or decorative properties. The rootstock is selected for its interaction with the soil, providing the roots and the stem to support the new plant, obtaining the necessary soil water and minerals, and resisting the relevant pests and diseases. After a few weeks, the tissues of the two parts will have grown together, eventually forming a single plant. After some years, it may be difficult to detect the site of the graft although the product always contains the components of two genetically different plants.

A bridge graft is a grafting technique used to re-establish the supply of nutrients to the rootstock of a woody perennial when the full thickness of the bark has been removed from part of the trunk.

<span class="mw-page-title-main">Secondary growth</span> Type of growth in plants

In botany, secondary growth is the growth that results from cell division in the cambia or lateral meristems and that causes the stems and roots to thicken, while primary growth is growth that occurs as a result of cell division at the tips of stems and roots, causing them to elongate, and gives rise to primary tissue. Secondary growth occurs in most seed plants, but monocots usually lack secondary growth. If they do have secondary growth, it differs from the typical pattern of other seed plants.

<span class="mw-page-title-main">Basal shoot</span> Shoot growing from an adventitious bud

Basal shoots, root sprouts, adventitious shoots, and suckers are words for various kinds of shoots that grow from adventitious buds on the base of a tree or shrub, or from adventitious buds on its roots. Shoots that grow from buds on the base of a tree or shrub are called basal shoots; these are distinguished from shoots that grow from adventitious buds on the roots of a tree or shrub, which may be called root sprouts or suckers. A plant that produces root sprouts or runners is described as surculose. Water sprouts produced by adventitious buds may occur on the above-ground stem, branches or both of trees and shrubs. Suckers are shoots arising underground from the roots some distance from the base of a tree or shrub.

This page provides a glossary of plant morphology. Botanists and other biologists who study plant morphology use a number of different terms to classify and identify plant organs and parts that can be observed using no more than a handheld magnifying lens. This page provides help in understanding the numerous other pages describing plants by their various taxa. The accompanying page—Plant morphology—provides an overview of the science of the external form of plants. There is also an alphabetical list: Glossary of botanical terms. In contrast, this page deals with botanical terms in a systematic manner, with some illustrations, and organized by plant anatomy and function in plant physiology.

<span class="mw-page-title-main">Grafting</span> Horticultural technique of joining plant tissues to grow together

Grafting or graftage is a horticultural technique whereby 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 rootstock. The success of this joining requires that the vascular tissues grow together. The natural equivalent of this process is inosculation. The technique is most commonly used in asexual propagation of commercially grown plants for the horticultural and agricultural trades. The scion is typically joined to the rootstock at the soil line; however, top work grafting may occur far above this line, leaving an understock consisting of the lower part of the trunk and the root system.

Shield budding, also known as T-budding, is a technique of grafting to change varieties of fruit trees. Typically used in fruit tree propagation, it can also be used for many other kinds of nursery stock. An extremely sharp knife is necessary; specialty budding knives are on the market. A budding knife is a small knife with a type of spatula at the other end of the handle. The rootstock or stock plant may be cut off above the bud at budding, or one may wait until it is certain that the bud is growing.

<span class="mw-page-title-main">Woody plant</span> Plant that produces wood and has a hard stem

A woody plant is a plant that produces wood as its structural tissue and thus has a hard stem. In cold climates, woody plants further survive winter or dry season above ground, as opposed to herbaceous plants that die back to the ground until spring.

<span class="mw-page-title-main">Plant stem</span> Structural axis of a vascular plant

A stem is one of two main structural axes of a vascular plant, the other being the root. It supports leaves, flowers and fruits, transports water and dissolved substances between the roots and the shoots in the xylem and phloem, photosynthesis takes place here, stores nutrients, and produces new living tissue. The stem can also be called halm or haulm or culms.

This glossary of viticultural terms list some of terms and definitions involved in growing grapes for use in winemaking.

<span class="mw-page-title-main">Tomato grafting</span>

Tomato grafting is a horticulture technique that has been utilized in Asia and Europe for greenhouse and high tunnel production and is gaining popularity in the United States. Typically, stock or rootstock are selected for their ability to resist infection by certain soilborne pathogens or their ability to increase vigor and fruit yield. The scion of the grafted tomato represents the upper portion of the plant and is selected for its fruit quality characteristics. There are several methods for grafting tomatoes and they have certain advantages and disadvantages. Once the grafts are made, the plants are moved into a chamber or environment with high relative humidity (>90%) and low light levels to reduce water stress in the scion while the graft union forms.

<span class="mw-page-title-main">Propagation of grapevines</span>

The propagation of grapevines is an important consideration in commercial viticulture and winemaking. Grapevines, most of which belong to the Vitis vinifera family, produce one crop of fruit each growing season with a limited life span for individual vines. While some centenarian old vine examples of grape varieties exist, most grapevines are between the ages of 10 and 30 years. As vineyard owners seek to replant their vines, a number of techniques are available which may include planting a new cutting that has been selected by either clonal or mass (massal) selection. Vines can also be propagated by grafting a new plant vine upon existing rootstock or by layering one of the canes of an existing vine into the ground next to the vine and severing the connection when the new vine develops its own root system.

References

  1. 1 2 Mishra, S. R. (2009). Understanding Plant Reproduction. Discovery Publishing House. pp. 55–56. ISBN   978-81-8356-481-6.
  2. Cornell University. "Reasons for Grafting and Budding". Grafting and Budding. Retrieved 17 June 2016.
  3. "Root grafting: a neglected technique with potential". Archives of the Rare Fruit Council of Australia. Retrieved 17 June 2016.
  4. Bennison, Jo. "Grafting Tree Peonies." The Plantsman, Royal Horticultural Society. March 2010, pp. 28-31. https://www.rhs.org.uk/about-the-rhs/publications/magazines/the-plantsman/2010-issues/march/grafting-tree-peonies