372 



J. J. SKINNER 



is altered by nitrate fertilizers and that of salicylic aldehyde by 

 phosphates, and the action of both compounds is affected by 

 lime.i 



With wheat growing in nutrient solutions the absorption of 

 salts is affected differently by different organic substances.^ 

 In the experiment with which this paper deals the effect of 

 vanillin on cowpeas and its effect on the absorption of nutrients 

 from the solution is determined. The action of manganese in 

 altering the effects of both vanillin and salicylic aldehyde was 

 studied and the results are reported here. 



THE EFFECT OF VANILLIN ON COWPEAS IN NUTRIENT SOLUTIONS 

 OF DIFFERENT COMPOSITIONS 



An experiment growing cowpeas in nutrient solutions was 

 made in which the effect of vanillin was studied. The solutions 

 were composed of calcium acid phosphate, sodium nitrate and 

 potassimii sulphate, used singly and in combinations. It was 

 found that in some of these nutrient solutions the vanillin was 

 more harmful than in others. Culture jars holding 250 cc. of 

 solution were used, and two cowpea plants were grown in each 

 jar. The plants were germinated in sand and when about 1 

 inch high were put in the nutrient solution. The culture solu- 

 tions, as stated above, were composed of calcium acid phos- 

 phate, sodium nitrate and potassium sulphate, in amount of 

 80 parts per million total of P2O5, NII3 and K2O. These solu- 

 tions were changed every fifth day ; the old solutions were replaced 

 by new four times during the experiment. They were analyzed 

 to determine the amount of phosphate, nitrate and potash re- 

 moved by the plants. In this way the effect of vanillin on the 

 metabolism of plants was studied. The peas grew for 21 days, 

 from June 17 to July 8. The results are given in table 1. The 

 composition of the culture solutions is given in the second, third, 

 and fourth columns. The green weights of the plants grown 



1 Skinner, J. J., and Noll C. F., Field test on the action of fertilizers on soil 

 aldehydes Jour. Amer. Soc. Agron. 8: 273. (1916). 



- Schreiner, O., and Skinner, J. J., The toxic action of organic compounds as 

 modified by fertilizer salts. Bot. Gaz. 54: 31. 1912. 



