Transportation of Water and Mineral Salts

Transport of Water and Mineral Salts

4.2

Transport of Water and Mineral Salts

Water and mineral salts can be transported from soil to leaves or shoots by root pressure,capillary action and transpirational pull.

Root pressure

Force created in root due to the presence of endodermis
Endodermal cells transport mineral salts actively from cortex to vascular tissues of root
This produces a concentration gradient between cortex and vascular tissue
Water diffuses from cortex to vascular tissue across the endodermis
Root pressure is created by pushing water up to stem

Capillary action

Created by adhesion force and cohesion force of water in fine xylem vessels

Transpitational pull

In leaf,water always evaporates from spongy mesophyll cells to leaves and finally to atmosphere via stomata
This process is known as transpiration
This creates a force which transport water and mineral salts from root xylem up to leaf continuously due to cohesive and adhesive forces of water
Transpirational pull is the main force in transportation of water and mineral salts

Guttation

Guttation is the process of removing water slowly in the form of droplets through hydatod at the margin of the leaf
Guttation occurs at night where the rate of transpiration is low and the relative air humidity is high
Root hair is the main force in guttation
This phenomenon can be observed at the leaf margin of herbaecious plant
If the plants do not undergo transpiration and guttation:

Water and mineral salts cannot be trasnported from root to shoot
The rate of photosynthesis is low due to deficiency of water
Growth of plant is retarded because lack of mineral salts
Cooling effect of plant is low

Guttation		Transpiration
Occurs at night	Transport of water and mineral salts	Occurs all day
Through hydotod	Involves xylem	Through stomata
In the form of water droplets	Root pressure	In the form of water vapour