Plant obtain variety
of substances like water, minerals, nutrients, food and gases like O2 and CO2 from surrounding. Plant productivity is mainly affected
by the non-availability of water.
Water is the most important factor for all the vital activities of plants. Water is considered as 'elixier of life'. Plant cells and tissues contain
about 90 to 95 % water. All the plants absorb water and mineral salts from the soil by their root system.
Water maintain the turgidity and shape of cells.
1.
It is in the liquid form at room temperature.
2.
It is the best solvent for most of the solutes also called
as universal solvent.
3.
It is inert inorganic compound
having neutral pH when in pure form.
4.
Water is the best transporting medium for dissolved minerals
and food molecules.
5.
Water is the best aqueous medium for all biochemical reactions occurring in the cell.
6.
Water is essential raw material
for photosynthesis.
7.
Water has high specific
heat, high heat of vaporization and high heat of fusion, thus acts as thermal buffer.
8.
Water molecule have good adhesive
and cohesive forces of attraction because of which it can easily rise in capillaries.
These various properties
of water are due to hydrogen
bonds between the water molecules.
Thus, water is a significant molecule which connect
physical world with biological processes.
-: Water absorbing
organs: -
Root: - Root is the main organ of water and mineral
absorption. In terrestrial plants water is absorbed
in the form of liquid from soil. While in epiphytes like orchids
water is absorbed in the form of vapours
from air by specialised epiphytic roots having velamen.
Regions of root: - The typical root has four regions
as: –
1.
region of cell division,
2. region
of elongation,
3.
region of absorption
(root hairs)
4. region of maturation.
