Vízpotenciális

Vízpotenciális, often translated as water potential, is a thermodynamic concept used to describe the relative tendency of water to move from one area to another. It is a measure of the free energy of water per unit volume and is influenced by several factors. Pure water at standard temperature and pressure has a water potential of zero.

The water potential of a solution is typically negative because solutes reduce the free energy of water. This is known as solute potential or osmotic potential. Pressure potential, on the other hand, is positive and arises from the application of external pressure. For instance, turgor pressure in plant cells contributes positively to their water potential.

Water moves from areas of higher water potential to areas of lower water potential. This principle is fundamental to understanding water movement in various systems, including soil, plants, and biological cells. In plant physiology, water potential gradients drive water absorption by roots, transport through the xylem, and transpiration from leaves.

The unit of water potential is pressure, typically expressed in megapascals (MPa). Factors like soil moisture content, solute concentration in soil water, and atmospheric conditions all affect water potential and, consequently, water movement. Understanding water potential is crucial for fields such as agriculture, hydrology, and ecology.