378 Mineral Nutrition of Plants 



The data in Table XIII are included to illustrate the relative increase 

 in reducing sugar as compared with total carbohydrate in the iron 

 deficiency of the pineapple plant. A similar response was obtained with 

 ammonium and nitrate nitrogen. 



TABLE XIII 

 Effect of Iron Deficiency on the Carbohydrate Content of the Pineapple 5 



Leaves 

 Young 

 Active 

 Mature 

 Old 



Mean 



1.03 



0.89 



■83 



0.80 



*Computed from the data of Sideris and Young (40) 

 jSugars plus starch 



CHEMICAL MECHANISM OF VISUAL SYMPTOM PRODUCTION 



The writer has reported (48) that characteristic responses in gross 

 morphology of tobacco seedlings take place in aseptic culture on a 

 complete mineral agar with traces of each of the free amino acids. 

 Isoleucine in quantities of 20-100 p.p.m. caused production of french- 

 ing-like symptoms including network chlorosis, inhibition of stem and 

 branch elongation, abnormal increase in leaf number, and inhibition of 



