374 Mineral Nutrition of Plants 



sugars in the deficient plants decreased in the leaves and increased in 

 the stems. Total carbohydrate gave consistent decreases in all parts of 

 the plant. The net result was a relative increase in reducing sugars as 

 compared with total carbohydrate because of potassium deficiency. 

 Carbohydrates tended to increase in the lower parts of the plant, where 

 symptoms of potassium deficiency are most extreme. 



Protein content also seems to become higher in the lower leaves and 

 stems of plants lacking in potassium. Amino nitrogen shows a definite 

 increase as compared with normal plants, due either to proteolysis or 

 more probably to a block in protein formation. The quantities of all 

 constituents parallel each other in kind as between upper and lower 

 leaves. The effects of deficiency in causing a relative increase in break- 

 down products — amino acids and reducing sugars — are plainly visible 

 in the roots. 



The sampling procedure followed by Richards and Templeman (^6) 

 and Gregory and Baptiste (/j) depended on the analysis of successive 

 leaves of barley plants as each reached maturity. The effects of defi- 

 ciencies would be expected to increase in severity with successive leaves 

 unless the element lacking was rapidly and completely mobile. 



Examination of the data of Richards and Templeman (j6) in 

 Table IX discloses that the relative quantities of amino and protein 

 nitrogen remained unaltered by nitrogen deficiency; whereas the 

 former showed marked increases with phosphorus and potassium de- 

 ficiencies. These displacements in relative quantities were caused in part 

 by a relative fall in protein with insufficient phosphorus. Protein ap- 

 parently did not decrease with potassium deficiency. These authors 

 concluded that phosphorus was necessary for the formation of protein, 

 and that potassium did not participate in this process. The increased 

 amino acid content of leaves lacking potassium in barley was attributed 

 to proteolysis. 



The results for carbohydrates with barley plants subject to nitrogen, 

 phosphorus, and potassium deficiency have been reported by Gregory 

 and Baptiste (/j). Some of their data have been tabulated in Table X. 

 Total carbohydrates were not determined, unfortunately. Total sugars 

 seemed to show an increase with deficiencies in nitrogen and phos- 

 phorus, but to diminish sharply with lack of potassium. 



