154 



M. M. McCooL 



concentrations of strontium the toxicity is entirely overcome. It is to be 

 noted further that the addition of N/100, N/250, N/500, or N/1000 

 Sr(N03)2 to N/20 Ca(N03)2 results in a greater production of both tops 

 and roots than occurs in N/20 Ca(N03)2 alone. The increase in growth 

 cannot be attributed to the addition of the nitrate radical to the calcium 

 solution, inasmuch as similar relations exist between the chlorids of these 

 metals. 



The more concentrated solutions of strontium cause an increase in 

 diameter of the roots of pea seedlings. Slight elongation takes place and 

 no lateral roots are formed. As indicated in Table '21, less concentrated 

 solutions are required to injure the roots than to produce injury to the tops. 



TABLE 21. 



Experiment with Canada Field Pea. Duration, Twenty-four Days. 

 Data for Ten Plants 



Composition of solution 



Green 

 weight 

 of tops 

 (grams) 



N/20 Ca(NO3)2+N/100 Sr(N03)2. . 

 N/20 Ca(NO3)2+N/250 St(N0s)2. . 

 N/20 Ca(NO3)2+N/500 Sr(N03)2. . 

 N/20 Ca(NO3)2+N/l,000 Sr(N03)2. 

 N/100 Ca(NO3)2+N/250 Sr(N03)2. 

 N/100 Ca(NO3)2+N/500 Sr(N03)2. 



N/20Ca(NO3)2 



N/100 Ca(N03)2 



N/50 Sr(N03)2 



N/100 Sr(N03)2 



N/500 Sr(N03)2 



N/1,000 Sr(N03)2 



Distilled water 



Green 

 weight 



Total 

 green 



Average 

 length 

 of tops 

 (centi- 

 meters) 



of roots 

 (grams) 



weight 

 (grams) 



4.40 



12.20 



23.0 



4.20 



11.40 



22.5 



4.27 



11.52 



23.5 



4.70 



13.90 



24.0 



3.70 



11.55 



19.0 



3.45 



10.80 



18.5 



3.20 



10.50 



16.0 



3.70 



11.65 



16.0 





 1.20 





2.0 

 5.5 



2.80 



1.35 



4.55 



8.5 



1.50 



3.90 



8.0 



1.70 



3.45 



6.0 



Average 

 length 

 of roots 

 (centi- 

 meters) 



13.0 



12.5 



14.0 



11.0 



9.0 



8.0 



11.5 



7.9 



Slight 



4.0 



3.5 



6.0 



6.5 



TABLE 22. Experiment with Canada Field Pea. 



FOR Ten Plants 



Duration, Thirty Days. Data 



Composition of solution 



Green 

 weight 

 of tops 

 (grams) 



Green 

 weight 

 of roots 

 (grams) 



Total 



green 



weight 



(grams) 



Average 

 length 

 of tops 

 (centi- 

 meters) 



Average 

 length 



of roots 

 (centi- 

 meters) 



N/10 CaCU 



N/10 CaCl2-|-N/500 SrCl 



N/500 SrCl2 



Distilled water 



4.10 

 4.30 

 1.45 

 1.65 



4.60 

 6.10 

 1.24 

 1.82 



8.70 



10.40 



2.69 



3.47 



7.0 

 9.0 

 6.0 

 5.0 



12.0 



14.0 



-5.5 



6.0 



