372 



Mineral Nutrition of Plants 

 TABLE VI 



Effects of Mineral Deficiency on Reducing Sugars and Total Carbohydrates 

 (sugars plus starch) of Plants: Iron, Copper, Boron 



Plant 



Refer- 

 ence 



Mean 



0.89 



0.85 



0.96 



Mean 



0.87 



0.81 



(/2) 



Mean 



14 



i-73 



0.61 



0.61 



1 .06 



1 .06 



{20) 

 {20) 



*Values for total sugar indicated as "s." 



The effects of phosphorus deficiency on carbohydrate metabolism of 

 the tomato plant obtained by MacGillivray (25) are illustrated in 

 Table VII. Phosphorus deficiency caused a relative increase in reduc- 

 ing sugars in both leaves and stems. Whereas total carbohydrates — 

 sugars plus starch — increased to a somewhat lesser extent also in the 

 stems, a definite decrease took place in the leaves. There was on the 

 whole a tendency for all carbohydrate to concentrate in the lower 

 portions of the plant. Some degree of correlation exists therefore be- 

 tween the loci of symptoms and of greatest variations in reducing 

 sugars and total carbohydrates. 



The data of Nightingale, Schermerhorn, and Robbins (32) on the 

 effects of potassium deficiency on the tomato plant are shown in Table 

 VIII and include values for amino and protein nitrogen. Reducing 



