The artificial propagation of farm and garden plants has several advantages. Some of the important advantages of the artificial vegetative propagation of plants are given below:
1. The new plants produced by artificial vegetative propagation will be exactly like the parent plants. Any desirable features of the parent plant will be replicated in the new plants.
2. The fruit trees grown from seeds may take many years before they start to bear fruit. But the fruit trees grown from cuttings or by grafting start to bear fruits much earlier (only after a few growing seasons).
3. The plants grown by vegetative propagation usually need less attention in their early years than the plants grown from seeds.
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4. Many plants can be grown from just one parent plant by artificial propagation.
5. We can also get seedless plants by artificial propagation.
The cuttings, layering and grafting are the traditional methods for the artificial propagation of plants. For commercial purposes, they are being replaced by the modern methods of artificial propagation of plants involving tissue culture. In tissue culture, they just put a few plant cells (or plant tissue) in a growth medium with plant hormones in it and it grows into new plants. This is discussed below.
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The production of new plants from a small piece of plant tissue (or cells) removed from the growing tips of a plant in a suitable growth medium (called culture solution) is called tissue culture. The growth medium (or culture solution) used for growing plant tissues is very important in this process because it contains various plant nutrients in the form of ‘jelly’ (called agar) and plant hormones which are necessary for plant growth. The process of tissue culture for producing new plants is carried out as follows:
1. A small piece of plant tissue is taken from the growing point of the plant (tip of the plant) and placed on a sterile jelly which contains nutrients and plant hormones. The hormones make the cells in the plant tissue divide rapidly producing many cells which form a shapeless lump of mass called ‘callus’.
2. The callus is then transferred to another jelly containing suitable plant hormones which stimulate the callus to develop roots.
3. The callus with developed roots is then put on a yet another jelly containing different hormones which stimulate the development of shoots.
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4. The callus having roots and shoots separates into tiny plantlets. In this way, many tiny plantlets are produced from just a few original plant cells (or tissue).
5. The plantlets thus produced are transplanted into pots or soil where they can grow to form mature plants.
The tissue culture technique is being used increasingly for the production of ornamental plants like orchids, dahlia, carnation, Chrysanthemum, etc. The production of plants by the method of tissue culture is also known as micropropagation (due to the extremely small amount of plant material used).
Advantages of Tissue Culture :
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1. Tissue culture is a very fast technique. Thousands of plantlets can be produced in a few weeks’ time from a small amount of plant tissue.
2. The new plants produced by tissue culture are disease free.
3. Tissue culture can grow plants round the year, irrespective of weather or season.
4. Very little space is needed for developing new plants by tissue culture.