Irrigation is the artificial supply of water to the plant/crops, according to the free dictionary(http://www.thefreedictionary.com/) irrigation is define as To supply (dry land) with water by means of ditches, pipes, or streams; water artificially. Following are the some important function or role of irrigation in plant physical and physiological process;
• The plant system itself contains about 90% of water.
• Amount of water varies in different parts of plant as follows.
* Apical portion of root and shoot > 90%.
* Stem, leaves and fruits 70–90%
* Woods 50–60%
* Matured parts 15–20%
* Freshly harvested grains 15–20%
• It acts as base material for all metabolic activities. All metabolic or biochemical reactions in plant system need water.
• It plays an important role in respiration and transpiration.
• It plays an important role in photosynthesis.
• It activates germination and plays an important role in plant metabolism for vegetative and reproductive growth.
• It serves as a solvent in soil for plant nutrients.
• It also acts as a carrier of plant nutrients from soil to plant system.
• It maintains plants temperature through transpiration.
• It helps to keep the plant erect by maintaining plant’s turgidity.
• It helps to transport metabolites from source to sink.