10 



BULLETIN" 108, 17. S. DEPARTMENT OF AGRICULTURE. 



Table VII. — -Effect of salicylic aldehyde cm wlieat in nutrient culture .solutions composed 

 of ■phosphate, nitrate, and potash. 



Composition of culture 

 solution. 



Without 

 salicylic 

 aldehyde. 



With 

 salicylic 

 aldehyde. 



Composition of culture 

 solution. 



Without 

 salicylic 

 aldehyde. 



With 

 salicylic 

 aldehyde. 



P2O5 



NH 3 



K 2 



Green 

 weight. 



Green 

 weight. 



p 2 o 5 



NH 3 K 2 



Green 

 weight. 



Green 

 weight. 



Parts -per 



million. 



32 



32 



32 



Parts per 



million. 



16 



24 



32 



Parts per 



millvm. 



32 



24 



16 



Grams. 

 2.94 

 3.12 

 2.84 



Grams. 

 1.86 

 2.30 

 1.97 



Parts per 



million. 



24 



24 



16 



Parts per 1 Parts per 



million. \ million. 



24 32 



32 24 



32 1 32 



Grams. 

 3.68 

 3.00 

 3.34 



Grams. 

 2.04 

 2.00 

 2.20 



From the foregoing results it is seen that salicylic aldehyde in 

 amounts as small as 10 parts per million is harmful to the growth of 

 wheat in nutrient solutions. In regard to the composition of the 

 nutrient solutions 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 potassic fertilizers given in Tables IV, V, and VI, respectively, 

 shows that the least harmful effects are noted in the phosphatic 

 group of cultures. This group as a whole shows a depression due 

 to salicylic aldehyde of approximately 20 per cent in growth, while 

 the other two groups showed approximately 27 and 29 per cent 

 below the respective group of cultures without the aldehyde. 



ABSORPTION OF NUTRIENT SALTS. 



As salicylic aldehyde 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 solutions during 

 the growth of the plant. 



As stated above the concentration differences produced by the 

 growth of the plants in the various cultures was 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. 1 It is possible, therefore, to com- 

 pare the results obtained in the normal cultures without salicylic 

 aldehyde and in the cultures where 10 parts per million of salicylic 

 aldehyde were present in the solution. 



The sum total of P 2 5 , NH 3 , and K 2 removed from solution by the 

 growing plants in all of the cultures under study was 1,646.6 milli- 

 grams in the normal cultures and 1,332.3 milligrams in the nutrient 

 cultures containing salicylic aldehyde. The figures show the total 

 of plant nutrients removed to be less in the cultures containing 

 salicylic aldehyde than in the normal cultures, which indicates that 

 the salicylic aldehyde cultures used less nutrients than the normal. 

 The results of the examination of the three constituents separately 

 are as follows : 



1 These determinations were made colorimetrically as described in Bui. 31 and Bui. 70, Bureau of Soils, 

 (J. S. Dept. of Agriculture. 



