Figure 2.

K_p in relation to phloem loading type. Leaf transpiration (E) and water potential (ψ_leaf) were measured at midafternoon. Predawn leaf water potential was used as an estimate of soil water potential (ψ_soil) after adjusting for gravitational potential. K_p was calculated as K_p = E/(ψ_soil – ψ_leaf). Apo, Apoplastic loading; PT, polymer trapping; Pas, passive loading; s, Suc; sa, sugar alcohols. Values are means ± se (n = 4–9 species). Different letters above the bars indicate significant differences using Duncan’s multiple range test at P < 0.05 after ANOVA.