ABSTRACT
Leaf water potential is the thermodynamic expression of the water status of leaves, which is widely used in plant science research in the last 40 years. In this article, a description of the physical principles leading to the definition of the leaf water potential and its component potentials is initially given. Then, the way of development of water deficits in leaves and the compartmentation of the water and its component potentials in leaf cells and tissues subjected to different degrees of water shortage are presented. Some useful implications for the development of adaptive mechanisms to drought result from this analysis. Finally, the existing methods for the determination of leaf water potential are presented and classified in groups according to their basic principles.
