Question

State three external conditions which favour high rate of transpiration.

Answer 1

Environmental factors that favour a high rate of transpiration:

The environmental factors affecting the rate of transpiration are light, humidity, temperature, and air.

Temperature:

1. A high temperature lowers the relative humidity and opens the stomata even in darkness.
2. As a result, the rate of transpiration increases.

Light:

1. The stomata open during the day and close in the dark.
2. The presence of light is directly proportional to the rate of transpiration.
3. As a result, the rate of transpiration increases.

Air:

1. If the air is still, the transpiration rate is low.
2. This is because the water vapour accumulates around the transpiring organs and reduces the diffusion pressure deficit of the air.
3. If the air is moving, the saturated air around the leaves is removed and the transpiration rate increases.