state the different mode of vegetative propagation
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Answer:
- Cuttings are severed uninodal leafy shoot or root fragments that can develop
- adventitious roots and shoots respectively. Uninodal leafy shoot cuttings are usually place
- into a suitable rooting substrate and kept under high humidity in propagators until roots
- and shoots are formed. Propagation by cuttings is a relatively easy method and can
- provide a large number of propagules in a very short time. Cuttings have been widely
- used in clonal propagation of forest trees where large numbers of planting stocks are
- required and recently in the production of quality germplasm of local fruit trees (Irvingia
- gabonesis, Ricinodendron hedelotii, Dacryodes edulis, Allanblackia spp), medicinal plants (Prunus
- africana, Pausinystallia johimbe).
- Grafting is a technique used to untie ‘parts’ of different plants by bring the cambium of
- each into contact and then creating a situation under which the cut surfaces can unite and
- grow away together. There are many grafting methods, some very specific for a particular
- species. They depend on seize and shape of the scions and the place on the rootstock
- onto which they are grafted; they can be carried out at various times throughout the year.
- The technique involves two important stages: the preparation of the grafting surfaces and
- the procedures for aftercare. In addition, the technique also requires grafting skill first,
- then extended experience to become familiar with the aftercare procedure without which
- newly grafted plants might be lost due to poor aftercare.
- Definitions of terms used in grafting.
- Scion -The part of the graft that will provide the new system. The scion maybe
- united either at the apex or side of the rootstock.
- Rootstock – the lower part of the graft. It normally posses a root system that
- will support the subsequent shoot development from the scion.
- Layering (marcotting) technique is similar to cuttings with the advantage that the
- propagule is detached from the parent plant only after development of roots. Its
- multiplication rate is lower than that of cuttings though the plants are larger. Methods of
- layering are the oldest used for vegetative propagation. Three ‘classes’ of layering
- methods, depending on the soil and stem relationship can be distinguished:
- •soil is mounded to the stem (mound layering, trench layering)
- • stems are lowered into the soil (simple layering, tip layering)
- •stems are not covered by soil (air layering)
- Air-layering is the technique that has been widely used in the domestication of
- indigenous fruit trees in west and central Africa in capturing the attributes of elite trees
- within genetically diverse wild populations, so avoiding the long, slow process of tree
- breeding.
- Micropropagation is a specialized method of propagation in which small pieces of plant tissues are regenerated on an artificial medium under sterile conditions. It embraces the regeneration from shoot and root tips, callus tissue, leaves, seed embryo, anthers and even single cells. Micropagation has following the applications in woody plant multiplication.
Answer:
Vegetative propagation is an asexual method of plant reproduction that occurs in its leaves, roots and stem. This can occur through fragmentation and regeneration of specific vegetative parts of plants.
Let us explore the different types of vegetative propagation and its examples in detail.
Types of Vegetative Propagation
Different types of vegetative propagation include:
Natural Vegetative Propagation
This occurs when plants grow and develop naturally without any human interference. Natural vegetative propagation can be enabled by the development of adventitious roots. Thus, new plants may emerge from the roots, stem and leaves of the parent plant.
The vegetative plant structures arising from the stem are known as rhizomes, bulbs, runners, tubers, etc. The plants propagated vegetatively are given below:
Stem
Runners grow horizontally above the ground. The buds are formed at the nodes of the runners.
Roots
New plants emerge out of swollen, modified roots known as tubers. Buds are formed at the base of the stem.
Leaves
Leaves of a few plants get detached from the parent plant and develop into a new plant.
Bulbs
Bulbs have an underground stem to which the leaves are attached. These leaves are capable of storing food. The centre of the bulb contains an apical bud that produces leaves and flowers. Shoots are developed from the lateral buds.
Also Read: Asexual Reproduction in Plants
Artificial Vegetative Propagation
This is a type of vegetative reproduction carried out by humans on the fields and laboratories. The most common types of vegetative reproduction occurring artificially include:
Cutting
In this, a part of a plant, specifically a stem or leaf is cut and planted in the soil. These cuttings are sometimes treated with hormones to induce root development. The new plant is formed from the adventitious roots developing from the cutting.
Grafting
In this, the cutting from some other plant is attached to the stem of plant rooted in the ground. The tissues of the graft become integrated with the tissues of the rooted plant and develop as a single plant over time.
Layering
In this, the stem of the plant is bent to the ground and covered with soil. Adventitious roots emerge from the plant parts covered with the soil. This attached stem with developing roots is known as a layer.
Tissue Culture
In this, the plant cells from different parts of a plant are cultured in the laboratory to develop a new plant. This technique is helpful in increasing the number of rare and endangered plant species that are unable to grow under natural conditions.
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