Question

Which one of the following is responsible for guttation?
(A) Root pressure
(B) Transpiration
(C) Photosynthesis
(D) Osmosis

Answer 1

Hint: Guttation is usually known as a process seen in certain plants like tomato, strawberry, etc, and is sometimes confused with dewdrops. It was found that it takes place at night and it occurs to maintain water balance in the plant body.

Complete solution:
Guttation in easy terms is defined as the excretion of drops of xylem sap on the tips or edges of leaves of some vascular plants, like grasses. In the absence of sunshine, plants lose excess water within the sort of liquid through hydathodes because most plants have their stomata closed in the dark. When there's a high soil moisture level, water will enter plant roots, because the water potential of the roots is less than within the soil solution. The water will accumulate within the plant, creating small root pressure. The root pressure helps to force some water to exude through special leaf tip or edge structures, hydathodes, or water glands, forming drops.

Additional Information:
Guttation occurs during the night or early morning when there is high atmospheric humidity and less or no transpiration occurs as most plants have their stomata closed. The method of guttation depends upon root pressure. The event of root pressure occurs because the water potential of roots is less than the soil which results in positive hydrostatic pressure in xylem sap present throughout the plant. Since the water-conducting xylem elements during a vascular strand terminate at the hydathode, xylem sap is forced to flow through these hydathodes forming water droplets on the surface.

So, the correct answer is ‘Root pressure’.

Note:
- Dewdrops are formed as a result of condensation of the atmospheric moisture on the cold surface of the leaves at night or in the early morning.
- Unlike guttation, dewdrops are generally formed on the body of the leaf of the plant and not on the margins, however, they may trickle down to the leaf tips and create confusion.