Explain transpirational pull and cohesion tension theory in trees ? (not too short not too long)
Explain transpirational pull and cohesion tension theory in trees ? (not too short not too long)
The theory was proposed by Dixon and Jolly. It is also called ascent of sap. It has two main features:
a) Cohesion of water and adhesion between water and xylem
Water molecules are attracted to each other hence remains as a continuous channel. Also water molecules remain attracted by adhesive forces to the xylem elements. Both these forces play a role in maintaining the continuity of water column from the root to the leaves.
b) Transpiration pull :
It is the pulling force generated in the xylem elements due to loss of water by transpiration. the loss of water creates a negative hydrostatic pressure that exerts pulling force.
The transpiration pull exerts a pulling force on whole of the water column in the xylem of the plant and pushes the water column in the upward direction called ascent of sap.
The theory was proposed by Dixon and Jolly. It is also called ascent of sap. It has two main features:
a) Cohesion of water and adhesion between water and xylem
Water molecules are attracted to each other hence remains as a continuous channel. Also water molecules remain attracted by adhesive forces to the xylem elements. Both these forces play a role in maintaining the continuity of water column from the root to the leaves.
b) Transpiration pull :
It is the pulling force generated in the xylem elements due to loss of water by transpiration. the loss of water creates a negative hydrostatic pressure that exerts pulling force.
The transpiration pull exerts a pulling force on whole of the water column in the xylem of the plant and pushes the water column in the upward direction called ascent of sap.
