psi crit (d) and the soil hydraulic conductivity at psi crit, k soil (psi crit), (e) as a function of soil texture. Neglecting soil water limitations (equivalent to K soil >> K plant), either by assuming an infinite root length (L root inf., black dashed line) or an early limitation by plant hydraulic conductance (K plant lim., black dasheddotted line), we would expect a uniform psi crit, independent of soil texture, close to the permanent wilting point (solid black line), and field capacity (light grey polygon), respectively. Considering soil and plant water limitations (default simulation), we would expect psi crit to become less negative with an increasing sand fraction (psi crit all soils, red curve representing a local polynomial regression fitting) as a result of the contrasting soil hydraulic conductivity curves.
