Specific conductivity of conducting and non-conducting tissues ofZea mays root

Abstract

The structure of the maize root enables one to determine the experimental specific conductivity of conducting and non-conducting tissues for the longitudinal water transfer. Using the method of Farmer and Berger in Huber and Schmidt's modification, successive differences in orders of magnitude were revealed among the experimental specific conductivities of the tissues of pith, cortex, and those of the area with concentrated xylem. The highest values of specific conductivity (cm3 cm−2 h−1 at 400 mbar per 5 mm distance, at 20° C) were determined in the area with concentrated xylem (mean value 10 018 cm3 cm−2 h−1); in the cortex area values by one order of magnitude lower were obtained (mean value 1 206 cm3 cm−2 h−1); in the pith area by two orders of magnitude lower (mean value 167 cm3 cm−2 h−1). The tissues of the area with concentrated xylem participated in the experimental root conductivity by 72 per cent, cortex tissues by 27 and pith tissues by one per cent. In this paper the individual tissues of maize root are characterized in detail from the anatomical viewpoint and the possible causes of the differences are discussed.