What are the factors affecting Transpiration Pull? 

Due to the evaporation of water from the cells present on the surface of the leaves (transpiration) a vacuum space is created. To fill that vacuum water droplets from the other cells rush inside. This rush of water towards the vacuum creates a mechanical force that enables to pull up water absorbed by the roots through the stems. This anti-gravitational force results in an upward movement of water through the xylem is known as transpiration pull. In tall trees, transpiration pull can draw water up to 50 meters in height.

Transpiration pull is affected by the rate of transpiration and the rate of transpiration depends upon:

• Light- More amount of light causes more transpiration.
• Temperature- Higher temperature enhances the rate of transpiration.
• Humidity- When air is dry, diffusion of water out of the leaf is rapid.
• Wind- Transpiration is less when there is no breeze.