When the diffusion pressure of water in a solution is reduced, it is known as diffusion pressure deficit or DPD. Due to the DPD, a solution will always tend to compensate the deficit by absorbing more water. DPD is also known as suction pressure.

A process generally happens in the morning when there is no/less transpiration where water with impurities are oozed out. Guttation occurs due to root pressure and is often observed in uninjured vascular plants. It refers to the process of removal of excess water from plants. The water is secreted in the form of droplets via pores called Hydathodes that are present on the tips and edges of leaves.

Atmometer is a scientific instrument which is used for measuring the rate of evaporation of a liquid to the atmosphere from a moist surface in a given time. It is also called evaporimeter. This instrument is normally in the form of a glass tube with open ends from which water can evaporate. These are commonly used for evaporation through transpiration measurements of crops by farmers.