Which environmental factor most directly impacts the rate of transpiration?

The rate of transpiration in plants is significantly influenced by temperature. When temperatures rise, the process of evaporation from the leaf surfaces accelerates. Higher temperatures increase the kinetic energy of water molecules, causing them to move faster and escape more readily into the atmosphere. This leads to an increase in water vapor concentration in the air surrounding the leaves, thereby enhancing the rate at which water moves from the plant to the surrounding environment.

Alongside temperature, factors such as light intensity and wind speed also play important roles in transpiration, but they do so in ways that are secondary to how directly temperature influences the evaporation process. Soil pH, while relevant to plant health, does not have a direct effect on the process of transpiration itself. Therefore, temperature stands out as the most direct environmental factor affecting the rate of transpiration.