Transpiration is of immense importance in plant life as it is of great benefit to the plant.
Beneficial roles of transpiration
(i) Gasneous exchange:
Transpiration is essential in the life of land plants. It helps in the absorption of carbondioxide (CO J from the atmosphere during photosynthesis as the openings of stomata in day time facilitate gaseous exchange.
The leaves absorb the radiant energy. Some of the light energy is utilised in photosynthesis, rest is converted into heat energy resulting in an increase in leaf temperature. However, rapid loss of water in the form of water vapour from the aerial parts of the plant through transpiration brings down their temperature. Transpiration thus provides a significant cooling effect which keeps the plant from being over heated.
Effect on mineral transport:
Mineral salts remain dissolved in the soil water and are absorbed by the roots. Minerals that arc absorbed and accumulated in the xylem duct of the root move up and are distributed in the plant by the transpiration stream.
Effect on water movement:
The absorbed water is transported from roots to leaves through the xylem vessels which is greatly influenced by transpiration pull. Water loss due to transpiration results in the development of low water potential in the leaf tissues. Thus water moves from the xylem vessels to the leaf cells and helps in the ascent of sap.
Development of mechanical tissues:
Greater amount of transpiration helps in the development of mechanical tissues in plants. The plants become healthier and more compact the cell walls become thick and cutinized and the plants are able to resist the attack of fun and bacteria.
Maintenance of turgidity:
Transpiration maintains an optimum degree of turgor in cells. Under favourable conditions plants absorb excess amount of water, which is given off by transpiration to maintain the optimum turgor for better growth.
Increase of taste of fruits:
The solutes inside the cell become more concentrated when transpiration is rapid the concentration of sugar solution in the cells of fruits increases and fruits taste sweeter.
Transpiration as a necessary evil
Curtis has said transpiration is a necessary evil because of the following facts:
(i) A large amount of absorbed water is lost during transpiration which is harmful to plants.
(ii) Unnecessary wastage of energy takes place during the process of water absorption which is lost due to transpiration.
(iii) When the rate of transpiration is high in plants growing in soil deficient in water, an internal water deficit develops in plants which may affect metabolic process.
(iv) Many xerophytes plants undergo structural modifications and adaptations to check transpiration.
Considering both the beneficial and harmful effects of transpiration, it may be concluded that it is definitely advantageous in spite of its harmful features.