Measurement of water potential: Comparative analysis of three distinct methods in biological systems

In thermodynamics, each component within a system contains a certain amount of free energy that can perform work under constant temperature conditions (Taiz et al., 2015; Tripathi et al., 2013). The process of osmosis involves water movement driven by differences in free energy across a semi-permeable membrane (Salisbury and Ross, 1992). For non-electrolytes, this free energy per mole is called chemical potential (ᴪ). Specifically, for water, it is known as water potential (ᴪw). Osmotic pressure (OP) in a solution arises from the presence of solutes, which lowers the water potential. Thus, osmotic pressure quantifies the reduction in water potential, termed osmotic potential (ᴪs) (Westgate and Boyer 1985; Tripathi et al., 2028; Yadav et al., 2023). Though OP and ᴪs are numerically equal, ᴪs is negative (-). The pressure generated by a fluid is called pressure potential (ᴪp).