I9I4] 



/. /. Skinner 



399 



gm., and the total green weight for the cultures of similar composi- 

 tion with lo p.p.m. salicylic aldehyde was 12.37 gm. 



TABLE 7 



Effect of salicylic aldehyde on wheat in nutrient culture Solutions, composed 



of Phosphate, nitrate and potash 



From the foregoing results it is seen that salicylic aldehyde, in 

 amounts as small as 10 p.p.m., is harmful to the growth of wheat in 

 culture Solutions. In regard to the composition of the nutrient So- 

 lutions affecting the harmfulness of the aldehyde, it might be said 

 that an analysis of the total green weights obtained in the case of 

 the mainly phosphatic, the mainly nitrogenous and the mainly potas- 

 sic fertilizers, given in Tables 4, 5 and 6, respectively, shows that the 

 least harmful effects occurred in the phosphatic group of cultures. 

 This group as a whole shows a depression due to salicylic aldehyde 

 of approximately 20 percent in growth, while the other two groups 

 showed approximately 2y and 29 percent below the respective group 

 of cultures without the aldehyde. 



Effect on Absorption of nutrient salts. As salicylic alde- 

 hyde has been shown to be harmful to growth in culture Solutions 

 containing nutrient salts, it will be interesting to study its effect 

 on the removal of nutrients from the Solution during the growth 

 of the plant. 



As stated above the concentration differences produced by the 

 growth of the plants in the various cultures were determined by 

 making an analysis for nitrates at the termination of every three- 

 day change, and of phosphate and potassium on a composite of the 

 Solutions from the four changes.'^ It becomes possible, therefore, 



' These determinations were made colorimetrically as described in Bul. 31 

 and Bul. 70, Bureau of Soils, U. S. Dep't Agri. 



