Leaf anatomical characteristics associated with shoot hydraulic conductance, stomatal conductance and stomatal sensitivity to changes of leaf water status in temperate deciduous trees

Some anatomical characteristics in leaves relating to hydraulic conductance and stomatal conductance were examined in six temperate deciduous tree spe cies. The fourth power of the radius of the conducting elements in xylem (r (4)) and the area of mesophyll and epidermal cells per unit length of leaf cross-section (u) were high in leaves with high hydraulic conductance (L). Stomatal conductance (g(s)) and stomatal sensitivity to an increase in leaf water potential (s(i)) correlated positively with the length of stomatal p ore (l), but negatively with the guard cell width (z) and the length of the dorsal side of the guard cells (l(d)). Stomatal sensitivity to a decrease in leaf water potential (s(d)) correlated negatively with l and positively with z and l(d). The anatomical characteristics associated with hydraulic c onductance (r(4) and u) and those associated with stomatal conductance and sensitivity to changes of leaf water potential (l, z and l(d)) were correla ted. We conclude that hydraulic conductance may depend on anatomical charac teristics of xylem, mesophyll and epidermis, and stomatal conductance and i ts sensitivity to changing water potential may depend on anatomical charact eristics of stomata. The correlation of shoot hydraulic conductance with st omatal conductance and its sensitivity may be based largely on the correlat ion between the anatomical characteristics of the water conducting system a nd stomata in these trees.