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.
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.
