Question

The process of Guttation takes place
(a) When the root pressure is high and the rate of transpiration is low
(b) When the root pressure is low and the rate of transpiration is high.
(c) When the root pressure equals the rate of transpiration.
(d) When the root pressure, as well as the rate of transpiration, are high.

Answer 1

Hint: Guttation is not the same as the dew, as dew condenses from the atmosphere onto the plant surface. Guttation generally happens during the night time, in which water is lost from the tips of leaves.

Complete Step by step Answer:
Guttation is the loss of water in the liquid form from certain parts of plants, usually from tips and/ or margins of leaves. In this process, the water exudes from a group of leaf cells called the hydathodes. Hydathodes are openings or pores on the leaf epidermis, which are grouped together as several thin- walled parenchyma cells.
Guttation occurs during the night or early morning when there are high atmospheric humidity and less or no transpiration occurs as most plants have their stomata closed. The process of guttation depends upon root pressure. The development of root pressure occurs as the water potential of roots is lower than the soil which leads to positive hydrostatic pressure in xylem sap present throughout the plant. Since the water- conducting xylem elements in a vascular bundle terminate at the hydathode, xylem sap is forced to flow through these hydathodes forming water droplets on the surface.
So, the correct answer is, ‘(a) When the root pressure is high and the rate of transpiration is low'.

Note:
- Guttation should not be confused with dew formation. - Guttation is a physiological process that occurs in certain plants and occurs through hydathodes present on leaf tips and leaf margins. - 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 leaf body and not on the margins, however, they may trickle down to the leaf tips and create confusion.