2013 Volume 51 Issue 4 Pages 165-172
This work was undertaken to estimate the hydraulic properties of roots of tissue-cultured soybean (Glycine max [L.] Merr.) subject to stress gradients from varying concentrations of nutrient salts, sugar, and heavy metals (Zn, Cu, Mn, Hg) in the culture solution. Using the paper wick method, we varied the water potential of the culture media from −0.04 to −1.45 MPa. Growth was inhibited as increasing concentration of salt or sucrose, and zinc, copper, manganese and mercury in the culture solution, and the root growth was associated with the magnitude of the growth-induced water potential and hydraulic conductance, although the degree of inhibition at a given concentration differed among individual heavy metal ions. In the zone of elongation, turgor was kept larger than 0.3 MPa under all stress conditions, and thus, the cell volume was kept almost unchanged, indicating that osmotic adjustment was occurring according to rates of water inflow associated with cell expansion.