ACTION OF ALPHA-CROTONIC ACID ON PLANTS 
171 
In the first experiment using the two triangle sets of solutions, crotonic 
acid was added to one set in amounts of 50 parts per million, the other being 
used as a control or check set. The experiment ran from December 6 to 
Fig. 3. Green weight in grams of wheat plants in nutrient solutions containing varying 
ratios of phosphate, nitrate, and potash, the source of P2O5 being calcium acid phosphate, 
(i) Without crotonic acid, and (2) with 50 p. p.m. crotonic acid. 
December 18, 19 16. The green weight for each culture is given in the two 
charts in figure 3. The crotonic acid reduced growth very much as shown 
by comparing the green weight figures. The roots of the plants grown in 
crotonic acid solutions were also severely retarded in their development. 
The green weight of the 66 cultures in the normal set was 143.6 grams, and 
that of the crotonic acid set 69.16 grams. The efifect of the crotonic acid 
was to depress the green weight 52 percent. 
The crotonic acid had a more severe effect in some of the solutions than 
Table 2 
Showing the influence of phosphate in overcoming the harmful effect of a-crotonic acid. 
Green weight of wheat plants in nutrient solutions composed of CaH4(P04)2, NaNOs, 
and K2SO4. Cultures arranged according to content of P2O5. 
Culture No. (See 
Fig 2) 
Parts per Million of 
P2O0 in Nutrient 
Solution 
Average Green Weight of Culture 
Without Crotonic With 50 P.p m,. 
Acid Crotonic Acid 
Percentage Decrease 
Due to Crotonic 
Acid 
grams 
grams 
I 
80 
1. 00 
.70 
30 
2-3 
72 
1-35 
.78 
42 
4-6 
64 
1.60 
•77 
51 
7-10 
56 
1.74 
.80 
53 
11-15 
48 
1.88 
•99 
47 
16-21 
40 
2,02 
I. II 
45 
22-28 
32 
2.73 
1.06 
55 
29-36 
24 
2.46 
1.05 
57 
37-45 
16 
2.41 
1.07 
56 
46-55 
8 
2.50 
1^15 
54 
56-66 
0 
2.20 
1.03 
55 
