First of all we know that what is transpiration pull. The word transpiration means that "Escape of water from plants", especially leaves, in the forms of water vapours is called transpiration. Leaves have small opening which is called stomata. These stomata are used for leaving the water vapours from the plants. One leaf have millions of stomata. Therefore, when the water is transpired from the surface cells of a leaf, a deficiency of water is created in their cell sap.
The surface cells pulls the water from the upper layers by the process of osmosis. The cells of upper layers in response pull the water from the xylem vessels of the leaf which is turn take water from branches and branches from the xylem of stem. Xylem vessel pulling the water from root and root from the soil. In this way, a process is developed from the roots to the leaves. So, we also say that the upward movement of water is called transpiration stream and also transpiration pull.
When plants have deficiency of water, then stomata remain closed and if plants have more water then, stomata opens and vapour leaves the plants into air or atmosphere. These stomata also known as "guard cells". These guards cells helps the opening and closing of the stomata. Transpiration is one of the most important process in the life of the plant. The important function of transpiration is that this cause the cooling effect which is very important for plants. Rate of transpiration depends on many factors. Some are we written as. These are light, temperature, humidity, soil moisture, wind, stomata. These factors are very important for plants.
Transpiration is a vital process in the life of plants. It prevents the leaves for over heating and keeps the plants cool. And roots continously absorbs the water frm=om the soil. Transpiration pull make water to rise in the plant and in this way ascent of sap takes place. Water and minerals are absorbed and then distributed to all parts of plants which is very necessary for the preparation of food the process in which food is prepared are called photosynthesis.