Question

The process of guttation takes place
a. When the root pressure is high and 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 rate of transpiration are high

Answer 1

As we are very well aware with the term Guttation which is basically the loss of water in the form of water droplets from the margin of leaves of some vascular plants like grasses and various fungi under humid conditions. It is different from the transpiration process as in transpiration loss of water is in the vapours form.

Complete answer:
• Guttation is the process of the loss of water in the form of water droplets from the margin of leaves of some vascular plants like grasses and various fungi under humid conditions.
• This is also seen in oat, tomato, cucumber and saxifraga plants.
• In moist conditions, the rate of absorption of water greatly exceeds the transpiration rate.
• At night, because of closed stomata of plants, transpiration process does not occur and when there is high soil moisture, water will accumulate in the plants which builds up the root pressure which pushes the water up in the xylem vessel and from there it comes out of the leaf margins through the special structures called Hydathodes.
• Hydathodes are special openings which are always open and present near the tip of leaves which are responsible for water loss in the form of droplets.
• Therefore, from the above explanation we can say that guttation takes place when the root pressure is high and transpiration rate is low.

Hence, the correct answer is option (A).

Note: Guttated water contains organic as well as inorganic salts and it is not a pure water. Unlike transpiration, guttation can take place during night and early hours of morning through hydathodes. Transpiration occurs during day time through the lenticels and epidermal cells and the water which is transpired is the pure water.