Pick the incorrect statement regarding apoplast movement

The correct option is: "continuous water stream gets tension when water is absorbed by root hairs"

To understand why this statement is incorrect regarding apoplastic movement, let us break down the concepts of apoplastic water movement in plants step-by-step:

1. What is Apoplast Movement?
The apoplast is the non-living system of cell walls and intercellular spaces in plants through which water and solutes can move freely. Unlike the symplast, apoplast movement does not involve crossing the cell membrane or entering the cytoplasm.

2. Analysis of the Statements:

• Gradient-dependent: Apoplastic movement is passive and depends entirely on a concentration or water potential gradient. Water moves from an area of higher water potential to an area of lower water potential. Hence, the statement "gradient-dependent" is correct.
• Movement of water is through mass flow: Since the apoplast is an open, continuous path of cell walls and intercellular spaces, water moves rapidly in bulk, which is called mass flow. Hence, the statement "movement of water is through mass flow" is correct.
• Mass flow of water takes place as a result of cohesive and adhesive properties of water: As water evaporates from the leaves (transpiration), it pulls the water column upward. This continuous mass flow through the cell walls is maintained due to the cohesive forces (attraction between water molecules) and adhesive forces (attraction between water molecules and the hydrophilic cell wall surfaces). Hence, this statement is correct.
• Continuous water stream gets tension when water is absorbed by root hairs: During water absorption by root hairs, water enters the roots passively or actively, but this does not create the tension (negative pressure) in the apoplast. The tension in the continuous water column is actually generated at the leaf end due to transpiration (evaporation of water from the intercellular spaces of leaves to the atmosphere). Transpiration pull exerts a tension on the continuous stream of water in the apoplast, not the initial absorption of water by root hairs. Therefore, this statement is incorrect.