The energy produced in plants by respiration is utilized in growth and life functions. The respiration in plants involves the exchange of Oxygen and carbon dioxide.
In plants exchange of gases occurs through stomata and large intercellular spaces present throughout the plant body. This ensures that all cells are in contact with air. Plants have a branching shape, so they have quite a large surface area in comparison to their volume.
Roots stems and leaves are involved in the gaseous exchange of plants.
The leaves of a plant have tiny pores called stomata. Exchange of respiratory gases in the leaves takes place by the process of diffusion through stomata.
Oxygen from air diffuses into a leaf through stomata and reaches all the cells where it is used in respiration. The carbon dioxide produced during respiration diffuses out from the leap into the air through the same stomata. The direction of diffusion mainly depends upon the environmental condition and requirement of plants.
During day time when Photosynthesis occurs carbon dioxide is rapidly used up while oxygen releases in the major event. During the daytime, carbon dioxide produced by respiration is all used up in photosynthesis by leaves. Even more carbon dioxide is taken in from air. Thus, the net gas exchange in leaves during day time is: O2 diffuses out; CO2 diffuses in.
On the other hand during night elimination of carbon dioxide takes place. Thus, the net gas exchange in leaves at night is O2 diffuses in; CO2 diffuses out.
Air is present in between the particles of soil. The roots of a plant take the oxygen required for respiration from the air present in between the soil particles by the process of diffusion.
Oxygen diffuses into the root hair and passes into the root cells, from where carbon dioxide moves out into the soil.
Exchange of Gases in Stems
In Woody plants, gaseous exchange occurs through the small pores found on the stems called lenticels. The oxygen from air diffusers into the stem of a Woody plant through lenticels and reaches all the inner cells of the stem for respiration. The carbon dioxide gas produced in the cells of the stem during respiration diffuses out into the air through the same lenticels.
On the other hand herbaceous plants have stomata on the stem which helps in exchange of respiratory gases.