Question

Under what conditions do plants transpire (a) more quickly and (b) most slowly?

Answer 1

Plants, like all living organisms, require an excretory system to expel excess water from their bodies. The process of removing excess water from the plant body is referred to as transpiration. The evaporation of water from the surface of the leaves is the most common cause.

Complete answer:
Water molecules in plant tissues are removed from the aerial parts of the plants during the transpiration process. Only a small portion of the water absorbed by plants is used for growth and development. The remainder is expelled through transpiration.

In plants, there are three types of transpiration:
1. Stomatal Perspiration: It is the evaporation of water from the plant's stomata. The majority of the water from the plants is transpired in this manner. When the stomata open, the water near the surface of the leaves turns into vapour and evaporates.

2. Transpiration of Lenticules: Lenticels are tiny holes in the bark of branches and twigs. Lenticular transpiration is the process by which water evaporates from the lenticels of plants. Lenticels are not found in all plants. Lenticels lose only a small amount of water.

3. Cuticular Transpiration: It is the evaporation of water from the plant's cuticle. The cuticle is a waxy covering on the surface of plant leaves. Cuticular transpiration accounts for 5-10% of the water lost by the leaves. More water is transpired through the cuticles during dry conditions when the stomata are closed.

(a) Plants transpire more quickly in certain climatic conditions, such as warm temperatures, moist soil, dry air, a sunny day, and a windy day.
(b) Plants transpire more slowly when their leaves are fewer in number, have a smaller surface area, and there is an increase in humidity.

Note: The following cellular factors influence the rate of transpiration:
- The leaf's orientation,
- The plant's water status,
- The Leaf's Structural Distinctions,
- The total number of stomata in a leaf and their distribution.

The following are the environmental factors that influence transpiration rate: Light, humidity, temperature, atmospheric pressure, and wind speed or velocity are all factors to consider.