I9I4] J- J- Skinner 395 



Fig. 7 (Plate 7) shows the appearance of the pots when the 

 clover was well up and clearly indicates the inhibitory effect of the 

 salicylic aldehyde. The control was of a deep green color, while the 

 treated pot showed not only a poor growth, but also a much faded 

 color and had a decidedly unhealthy appearance. 



The green weights taken at the termination of the experiment 

 were 8.5 gm. from the control pot and only 4.2 gm. from the sali- 

 cylic-aldehyde-treated pot, a decrease of approximately 50 percent. 



In the foregoing, salicylic aldehyde has been shown to be harm- 

 ful to wheat and rice seedlings in distilled water, to wheat, corn, 

 cowpeas, cabbage and rice in nutrient Solutions, to wheat, com and 

 clover in soil in pots. 



SOLUTION CULTURES WITH VARIOUS FERTILIZER 



INGREDIENTS 



Effect on growth. The effect of salicylic aldehyde on wheat 

 plants was further studied by growing the seedlings in nutrient cul- 

 ture Solutions containing the ordinary fertilizer salts, calcium acid 

 phosphate, sodium nitrate, and potassium sulphate, in various pro- 

 portions. Some of the cultures contained calcium acid phosphate 

 only, some sodium nitrate only and some potassium sulphate only. 

 Other Solutions were composed of mixtures of two salts, calcium 

 acid phosphate and sodium nitrate, calcium acid phosphate and potas- 

 sium sulphate, and sodium nitrate and potassium sulphate. Still 

 other Solutions had all three constituents in various proportions. 

 The compositions of the various Solutions are given in the first three 

 columns of the tables which are to follow later.^ 



Two sets of cultures were prepared : to one set were added 

 merely the nutrient salts ; to a similar set 10 p.p.m. of salicylic alde- 

 hyde were added to each culture, in addition to the nutrient salts. 

 The culture Solutions were changed every three days, four changes 

 being made in the course of the experiment. The Solutions were 

 analyzed for nitrates immediately after each change. The phos- 

 phate and potassium were determined on a composite Solution of the 

 four changes. The culture grew from May I5th to May 27th, 

 1912. 



« The Solutions were prepared as described in Bul. yo, Bureau of Soils, U. S. 

 Dep't Agri. (1910). 



