Regeneration
Regeneration of new plants from the vegetative parts of the parent plant is called vegetative propagation or vegetative reproduction. Vegetative propagation is done with the help of vegetative parts such as roots, stem or leaves. These parts may also be variously modified for vegetative propagation.
Natural vegetative propagation is of different types based on the vegetative organ involved.Vegetative Propagation by Roots
Roots of some plants develop new plants either by directly producing shoots or producing buds. Shoots are produced by roots of woody plants like Dalbergia, Murraya etc. Adventitious buds are formed on the roots of plants like sweet potato, dahlia, asparagus, tapioca, etc. These buds detach from the root and develop into new plants.
Vegetative Propagation by Stem
Stem has nodes and internodes. The nodes develop leaves. In the axils of the leaves buds develop called the axillary buds. They develop into new plants on detachment from the parent plant or even when the stem portion remains attached.
There are different types of stems for vegetative propagation. They are:Subaerial Stems
The branches that arise from the stem which is very close to the surface of the ground break off from the parent plant and develop new plants.
These branches are classified as follows:Runners - For example, strawberry, grass, etc.
Suckers - For example, mint, Chrysanthemum
Offset - For example, Eichhornia (water hyacinth), Pistia, etc.
Underground Stem
The portion of the stem that is underground, in some plants, serves two functions. It tides over unfavourable conditions by storing food and becoming dormant and then germinating with the help of axillary buds when there are favourable conditions.
The underground stems may be variously modified into the following kinds:Tubers
The stem is swollen and the nodal regions are called the eyes.
For example: Potato
Rhizomes
The stem is also swollen but it is branched. The scaly leaves are bigger.
For example: Ginger, Turmeric etc.
Bulb
The stem is very small and disc-like.
For example: Onion, Garlic, Lilies, etc.
Corm
The stem is very similar to tuber but they do not have definite shape.
For example: Amorphophalus, Colocasia, Gladiolus, saffron, etc.
Vegetative Propagation by Leaves
This is not very common and is seen in plants such as Bryophyllum.
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Tissue CultureTissue culture is based on the concept of cellular totipotency. That is all the multicellular organisms basically are formed from a single cell (the zygote), by repeated multiplication and differentiation. Thus a single cell can develop into a whole organism or in other words, the cell is totipotent. This is because it contains the full set of genetic information needed to make the organism. This is called cellular totipotency. Thus, a tissue can be taken from any part of the plant and put in a suitable nutrient medium. The nutrient medium is jelly-like and is taken in a test-tube. The tissue starts dividing mitotically and produces a mass of cells. This structure is undiferentiated and is called the callus. |
