Question

The cause of guttation is mainly due to
A. Root pressure
B. Osmosis
C. Transpirational pull
D. Cohesive force

Answer 1

Hint:- Guttation is a process removal of water from the xylem sap of the plant vascular system, through pores known as hydathodes. The water is released in the form of small droplets from these pores. It mostly occurs at the edges or tips of leaves.

Complete answer:
Plants need water to perform photosynthesis and to grow. But the amount of water inside the plant body should be maintained. If the amount of water in the plant is higher than needed, the plant will release it through the process of guttation.
Guttation usually occurs at the night time, and it should not be confused with dew in which water condenses at the surface of the leaves.
The rate of transpiration is generally low during the night, as stomata are closed. As we know, water moves from an area with high water potential to an area with lower water potential. Thus, if the water content in the soil is higher than in roots, the water will enter into the roots. It will increase the root pressure. The root pressure, in turn, will force water to move out from the plant body through leaves (edges or tips) in the form of small water droplets.
Guttation is observed when the transpiration is low or stopped, and the humidity is high.
Thus the correct option is (A) Root pressure.

Additional Information: As the guttation occurs due to root pressure, it cannot be seen in large trees because the force that will be required to secrete the water out is too large.

Note:- Transpiration is also the removal of water from the plant surface but it is different from guttation. Transpiration is essential for the process of photosynthesis. The release of water during transpiration is through the stomata, while guttation occurs when the stomata are closed.