Let us make in-depth study of the importance and practical utility of plasmolysis.
The shrinkage of the protoplast from its cell wall due to exosmosis under the influence of hypertonic solution is called plasmolysis.
The point at which protoplast just begins to shrink away from the cell wall is known as incipient plasmolysis .The stage when the cell wall has reached its limits of contraction and the protoplast has detached from cell wall attaining spherical shape is called evident plasmolysis (Fig. 1.5).
When a plsmolysed cell is placed in hypotonic solution, endosmosis takes place and the cell returns to its original state is known as de-plasmolysis. Temporary plasmolysis is not destructive to the cell. The cell can be restored quickly to its normal turgid condition simply by returning it to a dilute medium or water. However, plasmolysis prevents normal water balance and other functions of the plant as a whole, and thus plants cannot tolerate prolonged exposure to medium more concentrated than their own cells.
Importance of Plasmolysis:
1. It is a vital phenomenon as it explains the process of osmosis.
2. Plasmolysis demonstrates the permeability of the cell wall and the semipermeable nature of the protoplasm.
3. It helps to detect whether a particular cell is living or dead as the plasmolysis does not take place in a dead cell.
4. Osmotic pressure of a cell can be determined by plasmolytic method.
Practical Utility of Plasmolysis:
Plasmolysis has many useful applications in our daily life. To quote a few:
1. It plays most vital role in the preservation of meat, jellies and other food stuffs, and thereby prevents them from being destroyed by bacteria and fungi. Salting of food stuffs (to be preserved) raises the osmotic pressure of the preservation medium. Bacteria and fungi get plasmolysed and killed due to exosmosis.
2. Plasmolysis is also involved in killing of weeds in lawns, orchards and agricultural fields by chemical weedicides.
3. It helps in preventing the growth of plants in the cracks of the walls. Salting of such plants induces plasmolysis, and the unwanted plants are killed.