Control of Water Transport in Local Root Regions of Attached and Isolated Roots by Means of the Osmotic Pressure of the External Solution

INVESTIGATIONS INTO THE OCCURRENCE OF ACTIVE AND PASSIVE COMPONENTS IN THE ION UPTAKE BYVICIA FABA

“…As an explanation of this.pheriomenon it was thought at the time that a change in the conductivity for salts, under influence of the osmotic action of the sucrose increases the salt uptake. This was in entire agreement with the observation that sucrose increases the conductivity for water (ROSENE 1941, BREWIG 1939, BROUWER 1954a and as a result of an unaltered mechanic suction in the xylem vessels the water uptake as well. In the undermentioned experiments it has been tried to extend the earlier data in that sense that of the same root data were obtained about water uptake and chloride uptake with and without osmotic counter suction in the root medium, both combined with low and high suction tension in the xylem vessels.…”

“…From these experiments it would appear that about 70-85 % of the ions in the transpiration stream is landed into it via a mechanism dependent on metabolism and that the correlation between water uptake and salt uptake, which is found here too is based on an increased salt uptake as a result of an increased conductivity for ions. In literature different cases are known from which the turgescence is deemed to affect the water conductivity (BREWIG 1937, 1939, ROSENE 1941, PERIS 1936, BROUWER 1953, 1954 but that this would also be the case for ion transport appears besides this investigation and the one published in 1954, from the bleeding experiments of VAN NIE, HELDER and ARISZ (1950), ARISZ, HELDER and VAN NIE (1951) and from researches by ARISZ and SCHREUDER (1956).…”

The Influence of Salts on the Exudation of Tomato Plants

“…The increase of k in the former case must result from the simul taneous decrease in the osmotic value of the medium. We did not succeed in demonstrating any specific effect of ions on k. Other authors (ROSENE 1941;HAYWARD and SPURR 1943;LONG 1943) have not found any influence on the uptake of water by roots either.…”

The Regulating Influence of Transpiration and Suction Tension on the Water and Salt Uptake by the Roots of Intact Vicia Faba Plants

“…On the basis of the result of ROSENE (1941) we may expect that the same correlation exists between suction tension in the outer solution and water conductivity of the root tissue. To check this assumption we carried out the following experiment; the results are plotted in figurel3.…”

“…This would result in the decreasing withdrawal of water by the sugar solution. ROSENE (1941) working with both excised and intact onion roots, found that the water uptake was considerably increased following a treatment with sucrose in the medium. It seems that the treatment with sugar solution makes the tissue more permeable to water.…”