Stomatal regulation prevents plants from critical water potentials during drought: Result of a model linking soil–plant hydraulics to abscisic acid dynamics

Understanding stomatal regulation during drought is essential to correctly predict vegetation-atmosphere fluxes. Stomatal optimization models posit that stomata maximize the carbon gain relative a penalty caused by water loss, such as xylem cavitation. However, mechanism allows behave optimally unknown. Here, we introduce model of results in similar behaviour without presupposing an optimality principle. By contrast, proposed explains closure based on well-known component regulation: abscisic acid (ABA). The ABA level depends its production rate, which assumed increase with declining leaf potential, and degradation assimilation rate. Our predicts open until ratio potential proportional level, at minimum. As prerequisite, simulates soil–plant hydraulics photosynthesis under varying environmental conditions. wet soils low vapour pressure deficit (VPD), when there no limitation, controlled relationship between conductance. In dry or high VPD, soil hydraulic conductivity limits supply, triggered sharp decline transpiration rate increases. Being adaptive changing atmospheric conditions, can explain how plants are enabled avoid critical potentials for properties