LENTICULAR TRANSPIRATION

Lenticular transpiration is the evaporation of water from a plant’s lenticels. When compared to stomatal transpiration, the amount of water lost in this manner is negligible, although it can increase in a dry environment, exactly like cuticular transpiration.

Transpiration is the process of water passing through a plant and evaporating from aerial parts including stems, leaves, and flowers. Plants need water to survive, yet only a small fraction of the water taken up by their roots is used for growth and metabolism. Remaining 97–99.5% is lost by the guttation and transpiration.

Lenticels

The Small gaps in bark of the branches and the twigs are known as lenticels. Lenticels are not found in all plants. Lenticels, which are made up of parenchymatous cells and are present on the epidermis of many plant parts (stem, petiole, fruits), are pores that are always open, unlike stomata, which regulate their extent of opening. Lenticels can be seen on the surfaces of fruits including mango, apple, and avocado. Lenticels allow gases to flow freely between the environment and the organs’ interior tissue compartments (stems and some fruits). They allow oxygen to enter while simultaneously releasing carbon dioxide and water vapour.

FACTORS AFFECTING LENTICULAR TRANSPIRATION

There are various factors that affect the lenticular transpiration-

1. External factors 
2. Internal factors

External Factors- External factors affecting the process include light, atmospheric temperature, humidity, wind velocity, and soil environment.

1. Atmospheric temperature:

Rate of the transpiration is proportional to temperature of the atmosphere.

When the temperature rises, the leaf surface generates a lot of moisture, which causes rapid transpiration.

1. Atmospheric moisture:

When the weather is dry and the humidity is low, the rate of perspiration increases.

The rate of transpiration slows down in a humid environment.

Internal Factors- It includes the root system, the leaf structure and the stem.

1. The stem:

Diameter of xylem vessels in the stem determines the rate of the transpiration.

Increased transpiration is associated with wider xylem vessels, and vice versa.

MECHANISM OF STOMATAL OPENING

Structure of stomata- Stomata (singular: stoma) are minute openings found on the epidermis of leaves, green fruits, and herbaceous stems. It’s elliptical in shape and biconvex. Two kidney-shaped epidermal cells called guard cells surround each stoma. A thin layer of cytoplasm and a large central vacuole characterise cells. 

Because of the production of a secondary layer of cellulose, the cell wall of guard cells surrounding the stomatal apertures is thicker and inelastic, whereas the remainder of the cell wall is thin and elastic. Accessory or subsidiary cells are epidermal cells that surround the guard cells of the stoma. Guard cells have a thicker cell wall that surrounds the stomatal holes.

Stomata are scattered on dicotyledonous leaves, whereas they are grouped in parallel rows on monocotyledonous leaves. Stomata can be found on both the upper and lower surfaces of the leaf, although the lower surface always has more.

Mechanism- 

When water rushes into the guard cells, they swell, causing the stomata to open due to the curved surface. When the guard cells lose water, they contract, becoming flaccid and straight, and the stomata close.

In the opening and closing of stomata, ion channels located in the guard cell membrane play a regulatory role. The presence of sugar and starch in the guard cells affects the process for closing and opening the stomata. 

The guard cells of the stomata contain sugar, which is generated by their chloroplasts in the presence of light. Because the sugar is soluble, the number of guard cells. To enable adequate gas exchange and prevent excessive water loss, the guard cell turgor is continually adjusted to ambient circumstances and hormonal signals.

Conclusion

It is the evaporation of the water from a plant’s lenticels that is known as lenticular transpiration. Although the amount of water lost in this method is small compared to stomatal transpiration, it can rise in a dry environment, just as cuticular transpiration.

Water evaporates from plants’ stems, leaves, and flowers through the process called transpiration. However, only a small percentage of the water taken up by plant roots is utilized for growth and metabolism. Guttation and transpiration squander the remaining 97–99.5% of the supplement’s weight.