PSI in brief

PsiHub objectives

Water plays a central role in plant biology. The study of plant water use is now a well-structured and formalised field of study that could bring together many disciplines involved in understanding and predicting how ecosystems function under global change.

The challenge for the Psi-Hub network is to use plant water functioning as a conceptual foundation for connecting with other disciplines in order to answer questions that go far beyond physiology and focus on species ecology, biogeography and the functioning of terrestrial ecosystems.

To this end, the network aims to bring together different disciplines around the water functioning of plants.

In other words, the aim is to make the disciplinary field of plant hydraulics predictive, operational and ‘useful’ for society. By drawing an analogy with a ‘hub’, Psi-Hub implicitly suggests that the discipline that studies the water status of plants can connect plant physiology to many disciplines of ecology.

Figure 1: Illustration of how atmospheric drought (VPD) and soil drought (soil water potential, Ψsoil) interact to drive plant water status (a) and water stress (b). Water status triggers water stress by altering various plant functions sequentially. Note that for the sake of clarity, the contribution of capacitance was neglected in the equation of plant water status (leaf water potential, yleaf), but it can be integrated (Cochard et al. 2021; Ruffault et al. 2022b). Other variables include Ksoil-leaf (soil-to-leaf hydraulic conductance), Gleaf (leaf conductance to water vapour), Eleaf (leaf transpiration), Patm (atmospheric pressure).