Figure 8.

Relation between critical soil matric potential (ψ ^c _soil) and soil and root hydraulic parameters. Relation between ψ ^c _soil and (a) τ, which determines the slope of soil hydraulic conductivity, (b) root hydraulic conductance in wet conditions (K _{root_max}), (c) root length (RL _total) and (d) ratio of RL _total to K _{root_max}. Fittings were justified using analysis of covariance (ANCOVA) for sand and other soils, and only one regression line was justified in (c). r ² of the regression is 0.35 in (a), 0.31 (without sand) and 0.999 (sand only) in (b), 0.25 in (c) and 0.50 (without sand) and 0.98 (sand only) in (d) [Color figure can be viewed at wileyonlinelibrary.com]