Why do plants need water?

All living things on the planet need water to survive. In fact, many of the animals and plants are mostly water (molecules of hydrogen and oxygen). Without it the crucial processes that keep things alive would simply grind to a halt.

One of the key tasks for water is to carry necessary nutrients from the soil into and through the plant. Water also helps dissolve the minerals and other chemicals in the soil so that they can be transported. This also keeps these important at the proper levels for use by the plant.

One of the key tasks for water lies in the photosynthesis process. During photosynthesis plants change the energy in sunlight to chemical energy, which is then stored as a particular type of sugar. This process takes place in the leaves of the plant and water is the source of electrons that make photosynthesis possible.

As mentioned earlier, most living things are primarily made of water. This is especially true of many plants. Plant cells (in which photosynthesis takes place) are mostly liquid consisting of water and the necessary elements such as minerals, sugars etc. Water evaporates from plants through cell openings (stomata). This process helps regulate the temperature of the plant. Water is stored in the roots and extreme lower section of plants and moves up to the leaves when necessary.

Another key factor in understanding why plants need water is known by the somewhat scientific name “turgidity.” Basically this means that the cells remain full and maintain their shape. If a plant doesn’t have sufficient water available in the soil and roots it will begin to lose shape. This is commonly referred to as withering. A plant without sufficient water, for all the above reasons, will eventually die.

Because many plants are mostly liquid, they will only survive in the presence of large quantities of water. Natural evaporation caused by sunlight and wind takes large amounts of water from a plant. Studies indicate that nearly all of the water used by a plant (95 percent) is consumed in the transpiration process (water loss). The other 5 percent is believed to be used in photosynthesis.

Plants will survive and may even grow at a slower rate when supplied with small amounts of water. But the best conditions for plant health and growth include plenty of water that doesn’t have chemicals that will slow or stop growth. Scientific analysis shows that many plants are at least 80 percent water. Many plants only maintain their structure and health by being 95 percent water. Plants such as trees and other “woody” types may have much less water in their systems on a regular basis, but even these are still about 50 percent water.
Research in the past century has shown that plants in tropical regions such as rain forests are able to thrive even when water levels are extreme. These plants have adapted to the point that they take in only as much water as they need. Plants that are used to drier conditions will often be overwhelmed by the wet conditions in a rain forest.