THE EFFECT OF POTASSIUM SALTS ON THE 

 ANATOMY OF DACTYLIS GLOMERATAK 



By 0. N. PURVIS, B.Sc. 



{Post-graduate and Gilchrist Scholar, Boyal HoUoway College, 

 Vniversity of London, and Rothamsted Experimental Station.) 



PART I. 



Potassium compounds are known to play an important role in the 

 metabolism and growth of plants. They are shown to be essential plant 

 nutrients by water culture experiments; without these compounds 

 plants are reduced in size, have an unhealthy colour, and eventually die. 

 Potassium is found abundantly in embryonic tissues, and may possibly 

 be concerned with the construction of protein material. 



It is well known that potassium salts, unlike those of sodium, pro- 

 foundly aiiect the processes of assimilation and translocation. Carbohy- 

 drate formation practically ceases in the absence of potassium salts, and 

 where translocation or storage is taking place, an increased percentage 

 of potassium is found. The amount of root formation in starchy or 

 sugar-storing root crops is reduced by decreasing the amount of potas- 

 sium, even while the leaf area, and therefore the area available for photo- 

 synthesis, remains normal. Thus, in the Rothamsted mangold plots, 

 the yields per acre are : 



Where potassium salts are omitted, there is a small decrease in the 

 weight of leaf produced, but the amount of root in the same crop is 

 reduced to less than half. 



Potassium plays an important part in the synthesis of protein, and 

 is found in large quantities in rapidly growing parts of plants (i, 2). 

 Loew(2) has put forward the suggestion that this property of potassium 

 salts is due to their condensing action on organic substances. 



1 Thesis approved for the degree of Master of Science in the University of London. 



