Vegetative Propagation: Types, Advantages and Disadvantages
Vegetative propagation is a method of asexual reproduction in plants wherein new plants are obtained from the parts of old plants like stem, roots and leaves, without the help of any reproductive organ.
There are two types of vegetative propagation:
Natural vegetative propagation
Artificial vegetative propagation
Natural Vegetative Propagation
Various structures that take part in this type of reproduction are roots, stems and leaves.
Natural Vegetative Propagation by Roots: In some plants, the adventitious roots become thick, swollen and tuberous due to storage of food. Adventitious buds are also present on them. When such roots bearing these buds are planted in the soil, new plants are produced as a result of vegetative propagation.
This type of propagation is common in Dahlia, sweet potato and mint.
Natural Vegetation Propagation by Stem: Some plants reproduce by means of stems. Those which grow above the ground are runners and suckers and those which grow underground are rhizome, tuber and bulb.
This type of propagation is common in ginger(rhizome), potato(tuber), onion(bulb).
Natural Vegetative Propagation by Leaves: The fleshy leaves of plant bear adventitious buds in the notches along the leaf margin. When the leaves fall on the ground, the buds develop into small plants under favorable conditions. These plantlets on being detached, develop into an independent plant.
This type of propagation is common in Bryophyllum.
Artificial Vegetative Propagation
Some plant growers have developed artificial methods of vegetative propagation like layering, cutting and grafting which are used in agriculture and horticulture. These methods of artificial vegetative propagation are traditional methods.
Cutting: In this type of propagation, any part of the plant- root, stem or leaf is cut and buried partly in the moist soil. After some time, the cutting develops roots and grows into a new plant which is similar to the parent plant.
Many plants like rose, chrysanthemum, grapes, sugarcane are propagated by means of cutting.
Layering: The adventitious roots are produced in the branch of the stem before the plant is detached from the parent plant. The branch of stem is called layer and the process utilised in the propagation of new plant is called layering.
In some plants, one or more branches are bent close to the ground and covered with moist soil. After sometime, the underground portion of these branches produce new adventitious roots and develops into a separate plant.
Layering is used in the propagation of plants like lemon, guava, hibiscus, bougainvillea, jasmine, raspberry, strawberry.
Layering can be done either through simple, tip or compound layering. In simple layering, the stem is bend to the ground and partially covered with soil. The tip is bend into a vertical position and staked in place. In tip layering, a hole of about 4 inches deep is dug and the shoot tip is inserted and covered with soil. First, it starts growing downwards but later on bends and starts growing upwards. Later on, it becomes a new plant. In compound layering, the stem is bend to the soil just like simple layering but stem sections are alternatively covered and exposed.
Grafting: In this method of reproduction, two plants of closely related varieties are joined together so that they live as one plant. The portion of a plant that is grafted on the other plant is called scion and the plant in which grafting is performed is called the stock.
In a graft, the cambium of both stock and scion are fused to form a connection between the two. They are bound tightly with a piece of cloth and covered by polythene sheet. By grafting, a young scion can be made to flower when it is grafted on a mature tree.
This method is applied to improve the variety of fruits like mango, apple, peas, citrus fruits and guava.
Advantages of Vegetative Propagation
- It is a cheaper, easier and more rapid method of propagation in plants than growing plants from their seeds.
- The traits or characters of the parent plant are preserved and better quality of plants can be maintained by this method.
- It results in propagation of those plants which do not produce viable seeds or produce seeds with prolonged period of dormancy.
- The plants generated from vegetative means require less time to grow and have the advantage of being more uniform and genetically similar to the parent stock.
- By this mode of reproduction, the plants skip the risky seedling stages in which a number of seeds die under adverse conditions. Many seedless varieties of grapes, banana and oranges are produced by this method.
Disadvantages of Vegetative propagation
- It induces over-crowding.
- There is no genetic variation, so there is less adaptability to the environment.
- The disease of the parent plant gets transferred to the offspring.
- The plant lose vigour.