THE EFFECT OF TRANSPIRATION ON THE ABSORP- 
TION OF SALTS BY PLANTS 
Walter C. Muenscher 
(Received for publication November 22, 192 1) 
Various opinions have been offered regarding the relation between 
transpiration and the absorption of solutes. Those investigators who sup- 
port the older theory maintain that the quantity of salts taken into a plant 
is directly proportional to the amount of water transpired, and that the 
quantity of water transpired is in inverse ratio to the concentration of the 
solution. Some workers maintain that there is no direct relation between 
transpiration and the absorption of salts. In other words, the rate at 
which salts enter the cell is independent of the rate at which water enters 
the cell. Others accept the theory that the water and solutes of a solution 
enter a plant at independent rates, but maintain that after the solutes 
enter the plant they move along with the water in the ''transpiration 
stream." 
A large amount of literature has appeared dealing with transpiration 
and water requirements, but, with few exceptions, no papers have appeared 
which offer any considerable data on a possible relation between transpira- 
tion and the intake of solutes. In spite of this fact, many authors have 
not hesitated to employ various theories regarding the relation between 
transpiration and the absorption of salts in explaining results which they 
have obtained in investigations upon transpiration and water requirements. 
The fact still stands, however, that a careful search through the literature 
reveals no conclusive data which would substantiate the correctness of any 
of these theories. From a theoretical standpoint it would be reasonable 
to assume that the entrance of water and solutes into the plant takes place 
independently, since they enter not through openings which would allow 
for mass flow but through membranes which necessitate diffusion. Actual 
data presented are conflicting. The writer has been carrying on a number 
of experiments with reference to a possible relation between transpiration 
and the absorption and distribution of salts in plants. The results obtained 
in those experiments bearing on absorption only are reported in this paper. 
Historical 
Some of the earlier workers varied transpiration by increasing the supply 
of water or mineral nutrients and determined the effect of this change upon 
the dry weight and ash content of the plants. Lawes (1850) reported re- 
sults obtained with several legumes and cereals grown in jars of soil treated 
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