Water is essential for biological life.
Water in cells provides the medium for the numerous chemical reactions, which when coordinated by a series of enzymes is the basis of biology. Introduction Despite the apparent abundance of water on earth, fresh water is relatively scarce. To cope with these challenges, plants have evolved efficient root systems, and mechanisms for the strict regulation of water loss from the leaves. These features are essential in order to prevent desiccation and death of the leaves. Thus, the supply of plant-available water in the soil often limits plant productivity although species differ in their ability to cope with limited water supply.