Water Management in Horticultural Crops

Role of water in plant growth

Water plays a vital role in plant life. It is essential to plants in the following ways:-

• Water is a structural constituent of plant cells and it maintains the cell form through turgor pressure. When plenty of water is available, cells are turgid and plants retain their structural form. Water accounts for the largest part of the body weight of an actively growing plant and it constitutes 85-90 per cent of body weight of young plants and 20 to 50 per cent of older or mature plants.
• Water is a source of two essential elements, oxygen and hydrogen required for synthesis of carbohydrate during photosynthesis.
• Water serves as a solvent of substances and a medium in plants allowing metabolic reactions to occur. It also acts as a solvent of plant nutrients and helps in uptake of nutrients from soils. Plants also absorb nutrients through leaves from nutrient sprays.
• Water acts as a carrier of food materials synthesized in plants.
• Transpiration is a vital process in plant and it occurs at a potential rate as long as water is available in adequate amount.
• Adequate supply of water maintains the turgor pressure of guard cells helping stomata to open fully. Water deficit, on the other hand, closes stomata partially or completely reducing water loss through transpiration.
• Water deficit slows down the growth processes.
• Leaves get heated up with solar radiation. Plants dissipate heat by increased transpiration. Water act as a buffer against high or low temperature injury as it has high heat by vaporization and high specific heat.
• Water, when available in plenty, encourages good growth, development and yield of plants. Conversely, plants die when water supply is curtailed down.