The plant reproduces both by sexual and asexual means. The asexual mode of reproduction plays a significant role in plant generation continuation because of its short duration productivity. Vegetative propagation is one of the major types of asexual reproduction in plants.
Vegetative propagation is defined as a type of asexual reproduction in which new plants are formed from vegetative parts of the parent plant (e.g., stems, leaves, or other structures). Non-reproductive parts or structures vary with plants; it is gemmae and spores in nonvascular plants, whereas roots, stems, leaves, and nodes in a vascular plant. Thus, produced offsprings via vegetative propagation are genetically and morphologically identical to their parent plant. Vegetative propagation in plants occurs through fragmentation and regeneration of vegetative structures of the plant.
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Types of Vegetative propagation
Vegetative propagation, a type of asexual reproduction, is categorized mainly into two parts. These include; natural vegetative propagation and artificial vegetative propagation.
Natural Vegetative propagation
It is a type of vegetative propagation occurring naturally without human obtrusion. It occurs when the axillary bud grows into the lateral shoot and develops its adventitious roots. Plant structure that permits natural vegetative propagation via stem includes; bulbs, tubers, rhizomes, stolons, and corms, while tubers also stretch from roots, and plantlets emerge from a leaf. The plant structures that undergo natural vegetative propagation are described below with their examples:
Bulbs in vegetative propagation
Image source: Science Learning Hub – Pokapū Akoranga Pūtaiao, University of Waikato
These are round, distended part of the stem which is found underground. It consists of a central shoot that leads to the development of new plants. A bulb also consists of a bud surrounded by a sheet of leaves. These leaves are the source of food storage and nourishment. Example of plant that generates from bulb includes; onion, garlic, tulips, etc.
Tubers
These are swollen vegetative parts that store food needed during a dormant stage in winter which is developed from the roots or stems of the parent plant. Stem tuber arises from rhizomes or runners. The upper surface of the stem tuber gives rise to a new plant shoot system (leaves and stem), while the lower surface gives rise to the root system. Examples of stem tubers include; potatoes and yams. Likewise, the root tuber arises from the root that, on enlargement, gives rise to the new plant. Examples of root tubers include; sweet potato and dahlias.
Rhizomes
Rhizomes are root-like modified stem that grows horizontally under or along the surface of the ground. They are the storehouse of nutrients such as proteins and starches. As the rhizome extends, root and shoot develop from the node, with the shoot growing upward, forming new plantlets. Some plants that propagate by rhizomes include; ginger, turmeric, etc.
Stolons
Stems that grow horizontally are known as stolons. They are also known as runners. They are similar to rhizomes, but they originate from existing stems. During this process, runner or stolons growth, buds developed from the node lead to the formation of roots and shoots. This type of propagation is seen in strawberries, mints, etc.
Corms
These are bulb-like underground stems. Although they are similar in physical appearance to bulbs, they vary structurally. Corms consist of solid internal tissue, but bulbs only contain layers of leaves. Plants that develop from corm include; gladiolus, taro, etc.
Plantlets
These vegetative structures develop from the leaf of the plant giving rise to a new plant. As the plantlet matures, it grows roots, drops from the leaf, and develops into new plants. Examples of plants that propagate via the development of plantlets include; kalanchoe. Plantlets can also develop from runners; examples include spider plants.
Artificial vegetative propagation
It is the type of vegetative reproduction in which new plants are produced from the parent plants by humans in laboratories or fields. There are various types of artificial vegetative propagation. These include; cutting, grafting, layering, suckering, and tissue culture.
Cutting
It is one of the most general methods horticulturists use to produce a new plant. In this method, a segment of a plant, whichever stem or leaves, is cut and transplanted into soil, which has roots and grows into a new plant. The cutting parts are sometimes treated with hormones to generate roots before planting. Softwood fruiting and ornamental plants are propagated by cutting techniques.
Grafting
The joining of bud, stem, or branch from one plant to another plant’s stem or roots produces a new plant that has desired combined characteristics of both the parent plant, known as grafting. In this method, the stem piece is called the scion, and a plant with roots is called a rootstock. In grafting, once the tissue system of the scion becomes grafted or integrated into the rootstock, they fuse under favorable conditions. Thus, the scion will grow and develop to look like the same parent plant. Plants that undergo grafting include roses, apples, avocado, etc.
Layering
Layering involves bending plant branches or stems in order to touch the ground. Thus, the connected part of the plant is buried or layered with soil. Under favorable conditions, the covered portion begins to grow and forms attached shoots with new roots, known as layers. During growth, the offspring plant draws nutrients and water from the parent plant. When offspring develops sufficient roots, it can be separated from the parent plant. This phenomenon also occurs naturally. Air layering is also the type of layering in which braches are scarped and covered with plastic to reduce moisture loss. In developing new roots, branches are removed from trees and planted separately. Forsythia, rhododendron, and many climbing vines are some examples of plants that propagate through layering methods.
Suckering
A sucker is a shoot or stems with leaves that arise from the existing root structure of the parent plant. During the growth of suckers, they get nutrients from the parent plant. It can be propagated once its root system is formed, known as suckering phenomenon.
Tissue culture
It is also known as micropropagation, a defined specialized method in which plant cells are regenerated on an artificial medium under aseptic conditions. In tissue culture, plant tissue or cells are placed in a sterilized container and nurtured in a special medium until the mass of cells is formed, known as a callus. Thus produced callus is then cultured in a hormone-enriched medium that leads them to develop into plantlets.
Advantages of Vegetative propagation
The advantages of vegetative propagation include:
- Vegetative propagation helps to produce many plants with desirable traits of economic value.
- It also helps to maintain consistency in the taste and quality of plants or crops for sale.
- As the plant matures within a short duration of time, this method helps to save time and money.
Disadvantages of vegetative propagation
Although vegetative propagation is very useful, it has many disadvantages as well, which include:
- Vegetative propagation does not allow any degree of biodiversity.
- Plants produced from vegetative propagation are more short-lived than plants produced via seed propagation.
- As propagation is a skilled technique, more expertise is required to perform it, which leads to an increase in expenses.
- If a particular plant is susceptible to disease, then there is a chance of losing entire crops.
Reference
- Basic techniques for propagating plants. The Connecticut Agricultural Experiment Station. Retrieved on 10th August 2022, from https://portal.ct.gov/CAES/Fact-Sheets/Plant-Pathology/Basic-Techniques-for-Propagating-Plants
- Vegetative plant propagation. Science Learning Hub. Retrieved on 9th August 2022, from https://www.sciencelearn.org.nz/resources/1662-vegetative-plant-propagation
