Water Relations of Plant Cells and Tissues

Influence of 2,4-Dichlorophenoxyacetic Acid on Solute Uptake by Chlorella.

“…Glucose, water, glycerine and urea have been shown (7,8) to be influenced in their uptake by auxin treatment in a fashion similar to that found here for sucrose, mannitol and phosphate. The highly charged Na+ and S04--ions were neither accelerated nor impeded in their passage into the cell by the presence of 2,4-D which may also indicate a different mechanism of entry for these particles.…”

“…Such Auxins, particularly indoleacetic acid, are well known for their ability to influence the distribution of water and solutes within individual cells and in tissues or intact plants. Some of these effects have been attributed to changes in cell permeability resulting from auxin application (1,2,5,6,7,8,10), and direct measurements of changes in uptake of water and solutes under the influence of externally applied auxins have been made (1,7,11,13). Most studies of this subject, however, have consisted of measurements of plasmolysis-deplasmolysis time in hyper-and hypo-tonic solutions of various compounds, some of which were assumed to penetrate the cells readily, while others were assumed to be incapable of penetrating the cell 'Received for publication June 12,1958.…”

“…DISCUSSION AND CONCLUSIONS Changes in permeability or solute uptake have been shown to result from auxin application to plants (1,2,5,6,7,8,10,13,14) and are thought to be of importance in some responses to auxins (7). It seems possible that a number of auxin effects may be due, partly at least, to changes in cell permeabilitv to solutes or water or both.…”

“…It seems possible that a number of auxin effects may be due, partly at least, to changes in cell permeabilitv to solutes or water or both. In addition to responses such as growth, cell elongation and changes in transpiration of leaves or fruits (7,14), which may obviously involve permeability changes, other auxin effects on plants may also be caused by permeability changes. The inhibition of photosynthesis by 2,4-D (4,16) Larger increases in permeability measured by plasmolysis-deplasmolysis time have been reported with indoleacetic acid treatments (5,6,8), although Ordin and Bonner (12) found that "optimal" (5 mg/liter) IAA had no effect on the diffusion of DHO into Avena coleoptile sections.…”

Effect of Potassium Supply on the Acropetal Transport of Water, Inorganic Ions and Amino Acids in Young Decapitated Sunflower Plants (Helianthus annuus)

“…Investigations of Locher and Brouwer (1964) have shown that in young corn plants acropetal water transport due to root pressure contributes to about 60-70 "/o of the total transport. Root pressure is considerably influenced by metabolic (Kramer 1955) and nutri-tional factors (Minshall 1964, Hofner and Herwig 1966, Hofner 1969. The exudation rate of decapitated plants may be regarded as a qualitative measure of root pressure.…”