Suction Tension Research Articles

OSMOTIC QUANTITIES OF PLANT CELLS IN GIVEN PHASES

Some authors use seven or eight terms, others content themselves with two or even a single one. The points of view are much divided. In order to reach an objective judgment, let us consider a cell from the pith of Impatiens noli-tangere, a cell which has been accurately measured by Ursprung and Blum (48), Molz (28), Ursprung and Beck (44), and Ursprung (46). Cf. also Beck (1). Let V represent the volume of the given cell, and the indices n, g, and s, represent the normal phase, incipient plasmolytic phase (grenzplasmolytischen), and saturation phase respectively. We distinguish (fig. 1, schematic sketch of cell) the normal volume (Vn = 14,122 units) of the unchanged cell, the volume at incipient plasmolysis (Vg= 13,209 units), and the volume at complete saturation (Vs = 14,779 units). Vn had at the time of observation the value just given, which, however, changed as the water balance within the cell changed. If we desire to measure the osmotic potential of the cell sap of the individual cell, we must begin with the phase of incipient plasmolysis. By means of the plasmolytic method we find first that the incipient plasmolysis value (i.e., the osmotic value at incipient plasmolysis) is Og = 0.38 mol cane sugar. This concentration of the cane sugar solution will cause the protoplasm of our cell to recede from the cell wall ever so little. In the absence of complicating factors, so that the volume changes of the cell have no other effects than corresponding changes in the concentration of the cell sap, one can calculate the osmotic value of the normal sap, On, from y Og = 0.38 by the equation: On = Og^= 0.355 mol cane sugar. If we place the cell sap or an isosmotic cane sugar solution in an osmometer with a semipermeable membrane, the cell sap at incipient plasmolysis would develop an osmotic pressure (physicist's terminology) or a suction force (suction tension, suction2) (our terminology3) of 10.5 atm. In the condition of equilibrium the protoplasm must have the same suction force. Hence we may write : The suction force (suction tension, suction) of the contents of the cell in the phase of incipient plasmolysis is Sig = 10.5 atm. Similarly the suction force (suction tension, suction) of the contents of

Seasonal and Diurnal Variations in the Osmotic Values and Suction Tension Values in the Aerial Portions of Ambrosia trifida

American Journal of BotanyVolume 20, Issue 1 p. 18-34 Article SEASONAL AND DIURNAL VARIATIONS IN THE OSMOTIC VALUES AND SUCTION TENSION VALUES IN THE AERIAL PORTIONS OF AMBROSIA TRIFIDA† Ervin M. Herrick, Ervin M. HerrickSearch for more papers by this author Ervin M. Herrick, Ervin M. HerrickSearch for more papers by this author First published: 01 January 1933 https://doi.org/10.1002/j.1537-2197.1933.tb08870.xCitations: 10 †Papers from the Department of Botany, the Ohio State University, No. 299. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume20, Issue1January 1933Pages 18-34 RelatedInformation

SEASONAL AND DIURNAL VARIATIONS IN THE OSMOTIC VALUES AND SUCTION TENSION VALUES IN THE AERIAL PORTIONS OF AMBROSIA TRIFIDA

The objects of this investigation were to determine the direction and magnitude of the gradients in ossmotic values and suction tension values in the aerial portions of Ambrosia trifida L. and to determine the magnitude of the daily and seasonal variations in these values. Ambrosia trifida, commonly known as the giant ragweed or horseweed, was selected for this investigation because the necessary quantity of plant material of uniform quality was available at a relatively short distance from the laboratory. The theory of the Pull of Transpiration (6, Ii, I2) has been quite generally accepted as the best explanation of the mechanism by which water ascends to the aerial parts of plants. It is not the aim of this paper to discuss or question this theory. To accept this theory it is not necessary to assume, or even expect, that the highest portions of the plant will have the greatest lifting power. However, each portion of the plant must be able to raise sufficient water to its own height and must be able to compete for water with other portions of the same plant, particularly when the water supply is deficient. It might be assumed that the tissues capable of exerting the greatest tensions on the water columns will tend to be the most successful in the competition for water. As yet few data are available concerning the relative osmotic and suction tension values in the various portions of the same planlt. Data are lacking particularly from the standpoint of the effect of a deficiency of water on these relative values. Dixon and Atkins (9) studied the seasonal variations in osmotic value of the expressed sap of the leaves of several species of evergreen shrubs. In general, they found these to have a higher osmotic value in winter than in summer. Similar results on other evergreenls were obtained by Lewis and Tuttle (22), Korstian (20), Gail (I5), and others. Meyer (25) has pointed out that the rise in osmotic values in the leaves of evergreens in the winter is largely due to an increase in soluble sugars. Several attempts have been made to determine whether or not osmotic value gradients exist from the root to the apical portions of the plant. Dixon and Atkins (io) showed that the concentration of sugars in the sap of the