Question

What are the limitations of the root pressure theory?

Hint:

While root pressure does contribute to water movement in some scenarios, the cohesion-tension theory provides a more comprehensive explanation for the long-distance transport of water in plants.

Answer 1

Challenges of Root Pressure Theory: Root pressure theory, which explains the upward movement of water in plants, faces several critical challenges. 
1. Inadequate for Tall Trees: Root pressure is insufficient to move water to the heights of tall trees, where transpiration pull is the key mechanism. 
2. Ineffective Under Dry Conditions: Root pressure typically manifests during periods of low transpiration, such as at night or early mornings, and is less effective during dry periods. 
3. Not the Primary Driver: Although root pressure contributes to water movement, it is not the main driver. Transpiration pull and capillary action play more significant roles. 
4. Functioning in Non-Living Xylem: Water ascends through dead xylem vessels, which are metabolically inactive, suggesting that root pressure alone is not sufficient for water transport.