Relations of Manganese and Other Cations 



179 



TABLE 1. Experiment Continued for Five Days. Data for Ten Plants 



Composition of solution 



Average 



Average 



length 



length 



of tops 



of roots 



(centimeters) 



(centimeters) 











Slight 







1.5 



2.5 



2.0 



3.5 



2.0 



3.0 



N/2,000 MnCU. 

 N/3,000 MnCl2. 

 N/4,000 MnCl2. 

 N/10,000 MnCl 

 Distilled water . 



From the above table it is seen that a solution of N/3000 MnCl2 pre- 

 vents root growth, and that N/4000 represents the greatest dilution 

 causing injury during the five-days exposure. 



Manganese salts in full nutrient solution. — The poisonous action of 

 manganese toward pea seedlings is greatly reduced when the solvent is 

 a nutrient solution. A number of cultures were set up, in which 

 nutrient solutions were made as follows:* 



Ca(N03)2 4.0 



KH2PO4 1.0 



KNO3 1.0 



MgS04 1.0 



KCl 0.5 



FeCl3 0.1 



Distilled water 3.0 



In the above nutrient solution the lethal concentration of manganese 

 chlorid is four hundred times as strong as in distilled water. 



grams 



gram 



gram 



gram 



gram 



gram 



liters 



TABLE 2. 



Experiment in Full Nutrient Solution, Continued for Thirty Days. 

 Data for Ten Plants 



Composition of solution 



Green weight 

 of tops 

 (grams) 



Average length i Average length 



of tops 

 (centimeters) 



of roots 

 (centimeters) 



N/4 MnCU 



N/5 MnCh 



N/10 MnCh 



N/20 MnCh 



N/50 MnCl-2 



N/100 MnCl2. . . . 

 N/200 MnCl2. . . . 

 N/500 MnCl2. . . . 

 Nutrient solution. 





 



0.64 

 0.85 

 1.50 

 2.20 

 3.20 

 7.20 

 10.40 











5.0 



8.0 

 15.0 

 13.0 

 13.0 

 12.0 

 10.0 



* All full nutrient solutions employed in the experiments that follow, unless otherwise indicated, were 

 composed as given here. 



