Lecture 4 



— 75 



Movement and Distribution 



and salt over a 24 hour interval, avoiding significant 

 loss of water from the nutrient solution other than 

 that which occurs through the plant itself. _ Under 

 these circumstances, what changes will ensue in ionic 

 concentrations and proportions in the nutrient solution 

 as a net result of the absorption of both water and ions 

 by the plant? The illustrative data available prove 



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Textfigure 18. — Changes of concentrations in a nu- 

 trient solution as barley plants absorb water and ions. 

 Relatively, a greater quantity of the ions than of water 

 is absorbed in some cases, so that the solution is diluted. 

 This is notably true of potassium ions in the above ex- 

 periment of 24 hours duration. The concentration of 

 potassium sank almost to zero. Some ions increase in 

 concentration, because water is absorbed in relatively 

 greater amount than ions. 



that ions can be absorbed from a culture solution 

 either more or less rapidly than water, depending on 

 the nature of the ions, and on all the other factors 

 governing the absorption of water and solutes. The 

 importance of factors of metabolism is indicated by 

 subjecting similar sets of plants to different root tem- 

 peratures or to different oxygen supplies to the roots. 

 The relation of salt absorbed to water absorbed varies 



