Which factor does NOT affect transpiration?

Transpiration is the process through which water is absorbed by plant roots from the soil, moves through the plant, and is released as water vapor through small openings called stomata. Factors such as light, wind movement, and humidity directly influence the rate of transpiration.

Light affects transpiration as it stimulates the stomata to open for photosynthesis, allowing water vapor to escape. More light typically leads to increased transpiration rates. Wind movement increases the rate of transpiration by moving water vapor away from the plant surface, creating a gradient that promotes more water loss. Humidity plays a role because lower humidity increases the rate of transpiration; drier air allows more water vapor to be released from the stomata.

Soil composition, on the other hand, does not directly affect the process of transpiration itself. While good soil composition can impact the amount of water available to the plant and subsequently influence growth and health, it does not influence how quickly water is released through transpiration. Therefore, soil composition is the factor that does not directly affect the rates of transpiration.