Transpiration of Plant

Transpiration

The loss of water from the surface of plant through evaporation process. This loss of water is occurring through these things;

1. Through stomata
2. Through the cuticle present
3. Through special openings called lenticels

The stomata are present in the leaves of plants. The cuticle present in the epidermis of leaf and lenticels are present in stems of some plants.

Most of the transpiration occur through stomata and is called stomatal transpiration. The cells which provide large surface area for the evaporation of water is called mesophyll cells. From here water diffuse into the air space through stomata and then pass to the outside air and maintain the temperature. It is estimated that 90% of water that enter a plant is lost via transpiration.

Opening and closing of stomata

Some plants open their stomata during night when overall water stress is low. But most plant keep their stomata open at day time and close them at night. Through guard cells stomata regulate the transpiration. Through each other there are 2 guard cells of a stoma are attached at the end. When there are exes in water in the guard cells their shape is like the bean. And stomata become opens. When guard cells loss all the water and become flaccid, their inner sides touch each other and stomata closes. The concentration of solutes(glucose) in guard cells is responsible for opening and closing of stomata. Now last few years it is studies that light causes the movement of potassium ions from epidermal cells into guard cells, water follows these ions and enter into the guard cells. Thus their turgidity increases and stomata opens. As the day passed, guard cells make glucose i.e. become hypertonic.so water stay in them. At the end of the day, potassium ions flow back from guard cells to epidermal and the concentration of glucose also fall. Due to this water moves to epidermal cells and guard cells losses turgor. It causes the closure of stomata. On the other hand, in some plant this process is inversely proceed that’s why their stomata closed at day time and open at night.